From Seed to Savior: Understanding the Biocontrol Abilities of Seed-Derived Streptomyces Strains against Seed borne Bean Bacterial Diseases

From Seed to Savior: Understanding the Biocontrol Abilities of Seed-Derived Streptomyces Strains against Seed borne Bean Bacterial Diseases | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article From Seed to Savior: Understanding the Biocontrol Abilities of Seed-Derived Streptomyces Strains against Seed borne Bean Bacterial Diseases Faezeh Salehi, Nader Hasanzadeh, Javad Razmi, cobra moslemkhani, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7967969/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract Phaseolus vulgaris L. (Common bean) is the most important legume for direct consumption worldwide and a leading food used to fight global hunger. The seed-borne bacterial pathogens, Xanthomonas phaseoli pv. phaseoli ( Xpp ) and Curtobacterium flaccumfaciens pv. flaccumfaciens ( Cff ) are considered an important constraint in crop production. Certain strains of Streptomyces exhibit the ability to inhibit pathogenic bacteria, attributed to their production of various antimicrobial compounds. The Streptomyces FS2 and FS123 strains that exhibited high similarity with Streptomyces murinus and Streptomyces collinus based on 16S rRNA gene sequences were isolated from bean seeds, and antibacterial activities against the Xpp and Cff and also their effects on seedling growth index were investigated in this study. Both FS2 and FS123 strains successfully inhibit the growth of the Xpp and Cff in the zone of inhibition test. Assessments under greenhouse conditions exhibited strain FS123 with a dual behavior increase in disease severity and the area under the disease progress curve (AUDPC) of common bacterial blight disease (CBB) and a significant decrease of bacterial wilt (BW) disease. Our experiments showed that treating bean seeds with FS2 strain protects against both seed-borne diseases. We found that the pathogens population is affected due to plant treatment with the Streptomyces strains, especially in leaf tissues and endophytic situations. Also, the FS2 strain demoted plant growth despite the disease suppression. The total length of plantlets decreased by 68.52% and 17.89%, and total weights decreased by 44.79% and 10%, respectively, in FS2 + Xpp and FS2 + Cff treatment. Our results demonstrate the interesting biocontrol potential of the Streptomyces strains in bean protection against Xpp and Cff pathogens and open up promising perspectives for controlling these seed-borne diseases. However, attention to the damaging effect of the Streptomyces strains towards plant growth is crucial before introducing biocontrol materials. Xanthomonas phaseoli pv. phaseoli Curtobacterium flaccumfaciens pv. flaccumfaciens Plant growth-promoting Streptomycetes Phaseolus vulgaris Common bacterial blight Bacterial wilt Figures Figure 1 Introduction Seeds harbor diverse populations of microorganisms, forming a seed microbiota co-evolved with their plant hosts. This microbiota plays a crucial role in early developmental stages, influencing key processes such as seed dormancy and germination (War et al., 2023 ). Moreover, it affects overall plant function, health, productivity, and ecological interactions (Nelson, 2018 ). The dynamics within this microbiota also shape the relationships between pathogens and other seed-borne microbes (Rybakova et al., 2017 ). The next-generation sequencing (NGS) technologies of microbial communities indicated that the Streptomyces genus has frequently been found in different plant microbiomes (Goodrich et al., 2014 ; Viaene et al., 2016 ; AbdElgawad et al., 2020 ). Streptomyces, as a rhizosoil Actinomycetes, is an efficient colonizer of plant roots to the aerial parts (Sousa & Olivares, 2016 ; Viaene et al., 2016 ; Vurukonda et al., 2018 ) with great antagonistic activities due to their abilities to produce antimicrobial substances (Gebily et al., 2021 ; Ling et al., 2020 ; Behera et al., 2022 ), and responsible for comprising 66.67% of all naturally occurring antibiotics (Khan et al., 2023 ). The filamentous and sporulating characteristics of Streptomyces enhance survival in adverse environments. Plant growth-promoting streptomycetes (PGPS) enhance multiple biosynthetic pathways in plants, such as inorganic phosphate solubilization, chelating compound biosynthesis, phytohormone production, phytopathogens inhibition, and abiotic stress alleviation (Vurukonda et al., 2018 ). Consequently, they exhibit superior competitive abilities against various rhizobial microorganisms based on three primary strategies: competition for ecological niches and nutritional resources, antibiosis, and parasitism (Khan et al., 2023 ). Many reports indicated that Streptomyces could control plant pathogens via important traits such as producing siderophore, antibiotics, plant growth regulators, volatile compounds, phytohormones and different enzymes like cellulases, chitinase and lipase (Goudjal et al., 2013 ; Couillerot et al., 2013 ; Jones and Elliot, 2017 ; Nazari et al., 2023 ; Olanrewaju and Babalola, 2019 ). Seed-borne bacterial pathogens of beans, in particular, Xanthomonas phaseoli pv. phaseoli ( Xpp ) and Curtobacterium flaccumfaciens pv. flaccumfaciens ( Cff ), as the agents responsible for common bacterial blight (CBB) and bacterial wilt (BW) diseases, cause phytosanitary challenges for bean ( Phaseolus vulgaris L) production. CBB is a globally significant and challenging disease to manage, prevalent across 104 countries, resulting in yield losses of up to 45% in susceptible varieties, and it adversely affects seed quality, thereby threatening both the seed industry and edible seed production (Chen et al., 2021 ). BW is one of the most destructive common bean diseases globally (Munene et al., 2023 ), impacting crop yield and marketability of harvested beans (Osdaghi et al., 2020 ). They are continuously problematic and can cause significant economic losses in fields under favorable conditions (Gitaitis and Walcott, 2007 ; Osdaghi et al., 2020 ; Sammer and Reiher, 2012 ; Boersma et al., 2015 ; Perry and Pauls, 2012 ). Most of the research on seed health focused on seed-borne pathogens regardless of the potential functions of other seed-borne microorganisms (Klaedtke et al., 2014 ), which is a big challenge and limitation. Therefore, besides limited information about the Streptomyces population on seeds, the implications of Streptomyces upon seed-borne bacterial pathogens must be clarified. Thus, this study was conducted to investigate the impact of Streptomyces strains, which are isolated from bean seed, on Cff and Xpp , as well as their biocontrol potential and their effects on plant growth. Materials and methods Seed samples and bacterial isolation Bean seeds were sampled from the Fars, Markazi, Lorestan and Zanjan provinces of Iran, according to the instructions of the International Seed Testing Association. Samples were analyzed for two seed-borne pathogens, Xanthomonas phaseoli pv. phaseoli ( Xpp ) and Curtobacterium flaccumfaciens pv. flaccumfaciens ( Cff ), and Streptomyces isolates. Reference isolates of Xpp (X0S) and Cff (LA7) were received from the Seed and Plant Certification and Registration Institute, Iran. Serial dilutions of seeds suspension in saline buffer containing 0.02% v/v tween 20 and 0.85% NaCl (with tenfold the weight of the seed) were spread on YDC and NA medium. Yellow, orange and red color colonies in YDC and tough, leathery with filamentous growth colonies on NA were selected for gram, oxidase, catalase and HR analysis (Schaad et al., 2001 ). DNA extraction DNA extraction Bacterial DNA isolation was done using a modified method by Rademaker and Bruijn ( 1997 ). 50µl of 10% KOH was added to 500µl of freshly bacterial suspension (24 hours) and heated for 15 minutes at 95°C until the solution became clear. Microtubes were centrifuged at 10000 rpm for 2 minutes. The supernatant containing template DNA was used for PCR analysis after measuring DNA quality and quantity using Nanodrop. 16S rRNA gene amplification The PCR products of the 16S rRNA region of selected Streptomyces isolates, which were amplified by 1492R (TACGGYTACCTTGTTACGACTT) and 27F (AGAGTTTGATCMTGGCTCAG) primers, were sent to the Bio Magic Gene Company to determine the nucleotide sequence. The DNA sequences were compared with those existing in the GenBank database using the BLAST search program ( http://www.ncbi.nlm.nih.gov/ ), and the obtained sequences were deposited in the GenBank database. In vitro antagonistic activity assay of Streptomyces isolates Inhibition zones The antimicrobial activities of Streptomyces isolates were examined by measuring the inhibition zones. The direct effect of Streptomyces isolates on the growth of Xpp and Cff was evaluated via spreading 100 µl of Xpp or Cff at 1 \(\:\times\:\) \(\:{10}^{7}\) CFU/ml concentration on the nutrient agar plates. After drying the surface of the culture medium, Streptomyces agar plugs were placed on the plates. The plates were incubated at 28 ºC for 72 hours, and clear zones around the discs were measured in mm. Phytate-degrading ability Streptomyces isolates were spotted on phytase screening medium containing 1.5%glucose, 0.05% KCl, 0.01% MgSO4.7H2O, 0.01% NaCl, 0.5% (NH4NO3, 0.01% CaCl2.2H2 O, 0.001% MnSO4.7H 2 O, 0.001% FeSO4.7H 2 O, Agar 15, pH 6.5 with 0.5% sodium phytate). The colonies with phytate degrading ability exhibit translucent zones. Production of indole acetic acid The ability of Streptomyces isolates to produce indole acetic acid hormone was measured by a modified Salkowski colorimetric method described by Bent et al. ( 2001 ). The isolates were cultured in Nutrient Broth (NB) medium containing 0.2 g/l L-tryptophan for 48 hours at 28°C with 100 rpm rotary shaking. Then, they were centrifuged for 15 minutes at a temperature of 4°C with a speed of 13000 rpm. The supernatant was collected (1 ml), mixed with 2 ml of Salkowski's reagent (250 ml of sterile distilled water, 150 ml of sulfuric acid, 7.5 ml of 0.5 M FeCl 3 ), and kept in the dark for 20 minutes. The change in the color of the medium to pinkish red indicates the production of auxin; finally, their concentration was evaluated at the wavelength of 535 nm (Bent et al., 2001 ). Nitrogen-fixing capacity Okon's NFb medium (Narayan and Gupta, 2018 ) was used for assess isolates' nitrogen-fixing ability. One liter medium contains 5 g malic acid, 4 g KOH, and 0.05 g FeSO 4 . 7H 2 O, 0.5 g K 2 HPO 4 ; 0.01 g MnSO 4 .H2O, 0.1 g MgSO 4 2H 2 O, 0.02 g NaCl, 0.01 g CaCl 2 ·2H 2 O, 0.002 g Na 2 MoO 4 ·2H 2 O; 2 mL bromothymol blue solution (0.5% bromothymol blue in ethanol) and 18 g Agar. The pH was adjusted to 6.5, and the medium was sterilized at 121°C for 15 min. The color change of the culture medium from green to blue indicates nitrogen fixation. ACC deaminase activity The isolates were screened for ACC deaminase activity on the sterile minimal DF (Dworkin and Foster) salts media (DF salts per liter: 4.0 g KH2PO4, 6.0 g Na2HPO4, 0.2 g MgSO4.7H2O, 2.0 g glucose, 2.0 g gluconic acid and 2.0 g citric acid with trace elements: 1 mg FeSO4.7H2O, 10 mg H3BO3, 11.19 mg MnSO4.H2O, 124.6 mg ZnSO4.7H2O, 78.22 mg CuSO4.5H2O, 10 mg MoO3, pH 7.2) amended with 3 mM ACC instead of (NH4)2SO4 as sole nitrogen source (Dworkin & Foster, 1958 ; Penrose & Glick, 2003 ). The inoculated plates were incubated at 28°C for 3 days, and the growth of colonies was assayed. Production of proteinase and cellulase The ability of Streptomyces isolates to produce cellulase enzyme was assayed using Czapek mineral salt agar medium (Borkar, 2017 ), and the proteinase production was evaluated as described by Majumdar and Chakraborty ( 2017 ). Biofilm tests The Crystal violet staining method with ELISA plates (Sorroche et al., 2012 ) was used to assess biofilm formation quantitatively. The OD 560 and OD 600 of dissolved crystal violet was recorded and data were analyzed as described by Basson et al. ( 2008 ). All of antagonistic activity experiments were done in three technical and biological replicates. Greenhouse experiments The experiment was performed in the controlled condition at temperatures of 28 ± 2°C. Experiments were evaluated in a completely randomized design with three technical and biological replicates (In each pot, ten plants were assessed). Inoculated (with Xpp and Cff ) and non-inoculated bean seeds were grown in Streptomyces treated and not treated soil (in a mixture of equal proportions of field soil and peat moss and sand). According to Akbari et al. ( 2020 ), soil treatment by Streptomyces strains was done via inoculum preparation. Spores suspension in a sterile 0.9% NaCl solution were prepared from the five-day culture of isolates. 50 µl of spore suspension (10 6 cfu/ml) was transferred to 25 mL broth nutrient broth medium after four-day incubation at 28°C; bacterial cells and spores separated by centrifuge at 1000g for 10 min and added in 50 mL a sterile NaCl solution which then mixed with 500 g autoclaved soil. Streptomyces spore suspension was added to the soil, and the final cfu/g was adjusted to 10 6 cfu/g. Bean seeds were treated with 1% CMC and 1× 10 7 CFU/ml suspension of each bacterial pathogen ( Xpp and Cff ) for half an hour. Treated seeds were sown in soil treated with Streptomyces suspension. Planting untreated seeds in treated and non-treated soil was used as a control group. Disease symptoms and severity index as a basis for AUDPC 1 calculation were assessed daily from one week to 30 days after the planting. Then, the area under the disease progress curve (AUDPC) was calculated. Statistical analysis was performed with SPSS version 16 software (SPSS Inc., Chicago, IL). Determine bacterial transmission and population The transmission and endophyte and epiphyte population size of Xpp and Cff isolates were evaluated in the stem and leaf of plants as described by Osdaghi et al. ( 2016 ). Three subsamples of each treatment in three replicates were harvested at 20 and 27 days after soil inoculation. Samples of leaf and stem (1gr) separately were macerated in 10 ml saline buffer and, by spread plate method, were plated onto YDC, and 7 days post-incubation Bacterial population (CFU/g) were determined (Toussaint et al., 2012 ). The bacteria belonging to Xpp and Cff were confirmed by specific PCR. Results and discussion Two distinct strains of Streptomyces , designated FS2 and FS123, were procured from the Yaghut and Dadfar cultivars, respectively. These strains were characterized from a total of 37 samples of bean seeds and 365 isolated bacterial specimens. The strain FS2 and strain FS123 exhibited high similarity with Streptomyces murinus (98.81%) and Streptomyces collinus (98.61%) that were deposited in NCBI GenBank with PQ164170 and PQ164167 accession numbers based on the 16S rRNA gene sequencing, respectively. The Streptomyces strains exhibited different antagonistic and growth-promoting properties (Table 1 ). The antagonistic potential of the FS2 and FS123 isolates was confirmed by inhibition zone assay against Xpp and Cff in laboratory conditions. Antibiotic production is a salient property of Streptomyces, which can appear on an agar plate as a clear zone around a target microorganism (Liu et al., 2013 ; Sharma et al., 2014 ). The members of Streptomyces species or their commercial products are particularly interesting due to their abilities to inhibit many of bacterial pathogens such as Pectobacterium carotovorum subsp. carotovorum , Pectobacterium atrosepticum , Streptomyces scabies , Ralstonia solanacearum , Xanthomonas euvesicatoria , Xanthomonas oryzae , Xanthomonas citri , Pseudomonas tabaci , and Erwinia amylovora (Shirokikh et al., 2023 ; Ebrahimi-Zarandi et al., 2022 ; Kang et al., 2009 ; Thakur and Yadav, 2023 ). Biosynthesis of cellulolytic enzyme was detected in both Streptomyces isolates (Table 1 ). The cellulase activity of FS2 was found to be twice that of FS123. One of the antagonistic modes of action of Streptomyces isolates is cellulase activity, especially against fungal pathogens (Sadeghi et al., 2017 ). Cellulase enzymes can break down the cellulose of plant cell wall components, although bacterial cellulases' role is more complicated than simply breaking down plant cell wall cellulose (Medie et al., 2012 ). The ability of the bacteria to produce cellulases indicates their potential to suppress some disease development (Wilson, 2008 ). So far, cellulolytic activity, in addition to providing conditions for the successful colonization of bacteria, can promote plant growth and enhanced seed germination and may suppress disease by triggering plant defence mechanisms (Phitsuwan et al., 2013 ; Suwitchayanon et al., 2018 ). Besides antimicrobial compounds, both Streptomyces isolates produced phytase enzymes. Phytases as phosphates solubilization extracellular enzymes can mineralize complex organic phosphates (Walpola & Yoon, 2012 ). It defined P-solubilizing Streptomyces can affect plant growth and yield performance by improving phosphorus uptake (Htwe et al., 2019 ). They may also increase plant resistance against pathogens as ISR-triggered PGPRs and improve plant immune system (Walters et al., 2013 ; Abbasi et al., 2020 ). Indole-3-acetic acid (IAA) production, which plays critical roles in crosstalk between plants, microbes and root colonization (Ahmad et al., 2022 ), was verified in both isolates. IAA can implicate the health status of the plant host and enhance plant growth (Jaemsaeng et al., 2018 ). Table 1 Some physiological and antagonistic traits of the Streptomyces strains isolated from bean seeds isolates Inhibition zone Against Xpp Inhibition zone Against Cff IAA Cellulase Protease Nitrogen Fixation Phytase Phosphatase ACC deaminase Biofilm (OD:590) FS2 +++ +++ + ++ - - ++ ++ - +++ FS123 ++ ++ ++ + - - + + - + -: Negative; +: Positive; ++: Intermediate Positive; +++: Strong Positive Analysis of variance for CBB and BW disease severity index and AUDPC after planting Xpp and Cff inoculated seeds in soil treated with Streptomyces isolates (FS2 and FS123) showed a significant difference in the studied treatment (Table 2 ). Table 2 The mean squares of the disease severity index and area under the disease progress curve after planting Xpp and Cff inoculated seeds in soil treated with Streptomyces isolates Source DF Mean squares DSI 10dpi DSI 15dpi AUDPC Treatment 8 3.371** 5.972** 112.813** Error 15 0.053 0.081 0.918 CV% 27.608 25.565 19.723 **: significant at the 5% probability level The mean comparison results indicated that soil treatment with FS2 could control both of diseases, and the lowest values in all variables (DSI and AUDPC) were assigned to soil treatment with FS2 (Table 3 ). Some Streptomyces strains with effective antagonistic properties exhibit a high potential to control disease and can be developed for the biological control of pathogens (Suwitchayanon et al., 2018 ; Khan et al., 2023 ). FS2's achievement in mitigating both diseases due to its capacity to generate more high antimicrobial components (Table 1 ) and high biofilm production by FS2 can improve bacterial root colonization (Horstmann et al., 2020 ). Our results showed that Streptomyces FS123 caused an increase in disease severity and the area under the disease progress curve (AUDPC) of Bean bacterial blight disease (CBB) and in a contradictory behavior significant decrease of Bean bacterial wilt (BW) disease (Table 3 ). The different behavior of this isolate could possibly have occurred for a variety of reasons. Proposed mechanism could be: 1) The increase in CBB severity may be due to the specific strains of Streptomyces producing antibiotics that are less effective against the pathogen causing CBB, or the CBB agent might possess resistance mechanisms to these compounds; 2) Streptomyces may elicit specific plant defense mechanisms that inadvertently enhance susceptibility to certain pathogens like the one causing CBB. This phenomenon, known as induced susceptibility, suggests that the plant’s immune system, while active against BW pathogens, may become less effective at combating CBB pathogens (Pieterse et al., 2014 ); 3) The presence of Streptomyces can change the microbial community dynamics within the rhizosphere or on leaf surfaces. This could potentially create a competitive environment that favors the BW pathogen while allowing the CBB pathogen to thrive, especially if nutrient availability is altered; 4) The interactions between the pathogens involved in CBB and BW could play a critical role; It’s possible that Streptomyces alters the interaction dynamics between these pathogens, leading to an increase in virulence for CBB pathogens while suppressing BW pathogens; 5) Within the communities of Streptomyces in soil ecosystems, comprehending the ramifications of interspecies signaling on the interactions among species, particularly concerning nutrient competition and antagonistic behaviors, could be crucial for the successful Streptomyces-mediated suppression of phytopathogens (Jauri, 2013 ); 6) Interactions with plants can inhibit natural plant defenses against pathogens (Vurukonda et al., 2018 ) or negatively modulate plant defense and facilitate root colonization by pathogens (Schrey and Tarkka., 2008); 7) The possibility should also be considered that secondary metabolites, including antibiotics and siderophores synthesized by Streptomyces FS123, may interact with plant hormones and their respective signaling pathways. Such interactions could result in the attenuation of the plant's salicylic acid (SA)-mediated defense mechanisms, thereby rendering it more vulnerable to the pathogen responsible for causing CBB. Ishiyama et al. ( 2004 ) demonstrated that the Streptomyces WA46 metabolizes salicylate through a distinctive biochemical pathway involving a CoA derivative (Ishiyama et al. 2004 ). So, understanding these complex plant-bacteria interactions is crucial for developing effective management practices, as the dual behavior of Streptomyces FS123 can inform novel approaches to enhance crop resilience against bacterial diseases. Table 3 Mean comparison of CBB and BW disease severity index and the AUDPC in inoculated bean seeds planted in Streptomyces treated and not treated soil. Treatment DSI 10dpi DSI 15dpi AUDPC % (10–15) Xpp 1.800 b 2.800 b 1150 b Fs123 + Xpp 2.833 a 3.667 a 1625 a Fs2 + Xpp 0.000 d 0.15 d 37.5d Cff 2.000 b 2.250 c 1062.5 bc Fs123 + Cff 0.300 d 0.333 d 158.2 d Fs2 + Cff 0.000 d 0.100 d 25d Similar letters in each column are not significantly different based on the Duncan Multiple Range test (p ≤ 0.05). Endophyte and epiphyte populations of Xpp and Cff on common bean were measured 10, 20 and 27 days after sowing infected bean seed in the soil treated with the Streptomyces strains. The population density of Xpp and Cff varied in stems and leaf tissue and showed different trends in endophytic and epiphytic situations (Fig. 1 ). Endophyte and epiphyte survival of Xpp and Cff on bean plants have been reported previously (Karavina et al., 2011 ; Osdaghi et al., 2018 ). Research exhibited that epiphytic populations can affect disease onset times (Weller & Saettler, 1980 ), but the endophytic population is responsible for disease induction. Multiplication of Xpp in the intercellular spaces showed a more prominent role in the occurrence of the disease and the emergence of disease symptoms (Karavina et al., 2011 ). The pathogen's population was affected due to soil treatment with each of the Streptomyces strains (Fig. 1 ). Our results showed that the changes of endophyte and epiphyte populations of Xpp and Cff in untreated plants follow a nearly similar trend; Meanwhile, it has been affected after the treatment with FS2 and FS123, especially in endophyte situation. Although the Streptomyces treatment limited the growth rate of both pathogens, 27 days post inoculation (dpi), the high final log-transformed bacterial population was observed despite the lack of development of disease symptoms. It seems that the Streptomyces treatments have increased plant tolerance against diseases. Other research exhibited that plant inoculations with Streptomyces can increase plant tolerance due to the induction of systemic defence (Conn et al., 2008 ). Recent studies demonstrated that Streptomyces sp. DLS2013 stimulates the increased expression of defense mechanisms involving salicylic acid and jasmonic acids in tomato plants, leading to enhanced production of antimicrobial compounds (Bellameche et al., 2024 , Cassanelli et al. 2025 ). Another research revealed that Streptomyces RFS-23 activates plant defence response against viral infections, promoting the expression of genes related to salicylic and abscisic acid biogenesis (Chen et al., 2022 ). Taha et al., 2021 found that Streptomyces LC597360 significantly increases the activity of defence-related enzymes against Tomato mosaic virus (Taha et al., 2021 ). These studies show that induction mechanism can be in three clusters of transcriptional changes, systemic resistance and enzymatic activity. In tolerated conditions, active pathogen cells may survive as epiphytes or endophytes (in latent forms) with unapparent or symptomless infection (Hayward, 1974 ). Streptomyces treatments delayed the appearance of the symptoms and the onset of CBB and BW disease. These results were consistent with pathogens' population dynamics during the evaluation period (Fig. 1 ). Table 4 shows that soil treatments with Fs2 and Fs123 significantly affected the germination indices of studied Cff and Xpp inoculated and non-inoculated seeds at the 1% probability level. Table 4 Analysis of variance (mean squared) of seed germination indices of Phaseolus vulgaris after Cff and Xpp inoculated and non-inoculated seed sowing in treated soil with Streptomyces isolates Fs2 and Fs123. Source DF Total length Root length Stem length Total weight Root weight Stem weight Treatment 7 982.043** 32.115** 686.202** 1.216** 0.120** 0.789** Error 99 32.552 8.246 20.680 0.073 0.010 0.059 CV% 14.853 21.509 18.173 18.045 19.465 20.348 **: significant at the 1% probability level The highest total seedling and stem lengths were assigned to treatment with Fs123, and the lowest value was assigned to Fs2 + Xpp treatment. Regarding root length, except for the Fs2 + Xpp treatment, which had the lowest value among the treatments, the other bacterial treatments were in the same group without significant differences. Seed treatment with Cff significantly increased root and stem weight more than other treatments and was nearly 1.2 times greater than untreated plants (Table 5 ). Although many of C. flaccumfaciens 's strains are phytopathogenic bacteria, some exhibit plant growth promotion potential and can increase the growth of host plants (Schillaci et al., 2022 ; Cardinale et al., 2015 ). Xpp treated seeds in the soil without Streptomyces, did not show any significant difference compared to the control (Table 5 ) . Table 5 Comparison of average treatments for investigated plant growth traits. Treatment Total length (g) Root length (mm) Stem length (mm) Total weight (g) Root weight (g) Stem weight (g) Xpp 38.563 cd 12.906 a 25.656 c 1.652 b 0.258 bc 1.193 b Fs123 + Xpp 42.625 abc 13.750 a 28.188 bc 1.403 bc 0.203 c 0.971 c Fs2 + Xpp 12.786 f 8.286 b 5.643 e 0.810 c 0.114 d 0.696 c Cff 41.467 bc 12.967 a 28.500 bc 1.925 a 0.349 a 1.475 a Fs123 + Cff 45.000 ab 14.600 a 30.500 ab 1.420 bc 0.233 bc 1.187 b Fs2 + Cff 33.344 e 14.281 a 19.063 d 1.334 c 0.280 b 1.054 bc Fs123 46.133 a 13.867 a 30.267 ab 1.636 b 0.294 b 1.311 ab Fs2 35.333 de 13.917 a 21.250 d 1.588 b 0.323 a 1.083 bc Not treatment 40.608 abc 12.285 a 28.323 bc 1.467 bc 0.261 bc 1.206 b Similar letters in each column are not significantly different based on the Duncan Multiple Range test (p ≤ 0.05). Planting inoculated and non-inoculated seeds with Cff and Xpp (separately) in the soil treated with Fs123 isolate, showed no significant difference in any evaluated plant growth traits. Fs2 isolate decreases the stem length in non-inoculated seeds. Soil treatment with Fs2 successfully controlled CBB and BW disease in all experiments. However, it caused the most significant decrease in seedling length and weight of Xpp -infected plants, up to 68.2% and 50.03%, respectively, compared to the control. Our results showed a negative correlation between the effect of FS2 on plant growth and biocontrol efficacy. Studies revealed that high concentrations of some antimicrobial metabolites can negatively affect plant growth (Sharifi et al., 2019 ). Deising et al. ( 2017 ) underscored the notion that although microbial secondary metabolites possess the capacity to augment plant resilience in the face of stressors, their excessive synthesis may result in deleterious effects, thereby jeopardizing plant health and growth (Deising et al., 2017 ). Worsley et al., 2020 elucidated that the two Streptomyces strains, N1 and N2, decreased the A. thaliana biomass due to their synthesis of polyenes that bind to sterols, including the plant cell wall phytosterols, which likely exerted an adverse effect on the plant. They show that not all Streptomyces strains that are competitive in the rhizosphere and endosphere necessarily have a beneficial effect on host fitness (Worsley et al., 2020 ). Also, some Streptomyces strains can produce factors that may indirectly harm plant tissues, despite their role in biocontrol; These factors include enzymes such as chitinases, pectinase or cellulases (Kumar et al., 2020 ), which may help in competition against pathogens but can also disrupt plant cells if overproduced or misdirected. Meanwhile, in natural conditions the introduction of Streptomyces may change the soil microbial community structure, affecting beneficial microorganisms such as mycorrhizal fungi that are crucial for nutrient uptake. This shift can potentially reduce plant health and growth. Jin et al., 2024 shown that the bacterial community residing on the surface of arbuscular mycorrhizal hyphae was in part regulated by Streptomyces (Jin et al., 2024 ). On the contrary, some research has clarified that the seedling growth index significantly correlated with the control capability of Streptomyces (Schrey and Tarkka, 2008 ). Assessment of Streptomyce's effect on plant growth indices and their biocontrol activity is crucial to prevent unintended disruptions in seed germination and plant growth. Streptomyces strains have shown significant potential in promoting plant growth and protecting against various pathogens (Hata et al., 2021 ; Kaari et al., 2022 ; Faddetta et al., 2023 ; Wang et al., 2023 ). But, controlling plant disease with Streptomyces strains is associated with some challenges (Khan et al., 2023 ). However, their effects can vary depending on the strain and plant species. Various studies showed that Streptomyces treatments have improved seed germination index in rice (Hata et al., 2021 ), tomato (Faddetta et al., 2023 ) and mustard (Wang et al., 2023 ). Nevertheless, it's important to note that some studies have observed occasional transient adverse effects on germination and plant growth, although these effects did not persist during further development (Kunova et al., 2016 ). This highlights the importance of thorough assessment to identify strains that consistently provide benefits without causing harm. Additionally, the efficacy of Streptomyces as biocontrol agents can vary depending on the target pathogen and environmental conditions (Colombo et al., 2019 ). In conclusion, a comprehensive evaluation of Streptomyces strains is essential to select those with the most promising plant-growth-promoting and biocontrol properties while minimizing potential adverse effects. This ensures the development of effective and safe biological alternatives to chemical pesticides and fertilizers, contributing to sustainable agricultural practices (Umer et al., 2021 ; Vurukonda et al., 2018 ). Conclusions Biocontrol agents isolated from the same habitat as the target pathogen might be more effective due to co-evolution. In this study, we aimed to highlight the effect of plant treatment with Streptomyces strains FS2 and FS123, which were isolated from contaminated bean seeds with common bacterial blight (CBB) and bacterial wilt (BW) disease. This study provides insight into the antimicrobial activities of the Streptomyces strains against two seed-borne pathogens, Xpp and Cff . Our investigation showed that the FS2 strain, with significant control of both pathogens, synthesized the metabolites that can negatively affect plant growth. Applying the Streptomyces strains delays disease onset and decreases the pathogen population in epiphyte and endophyte situations in treated plants. Metabolite production of FS2 and FS123 may contribute to the activation of plant defence mechanisms and lead to plant disease protection, which needs more study. Our data provide an informative basis for selecting novel biocontrol agents focusing on their effects on plant growth indices. The biocontrol potential of Streptomyces murinus and Streptomyces collinus on Xanthomonas phaseoli pv. phaseoli and Curtobacterium flaccumfaciens pv. flaccumfaciens were investigated in this study for the first time. Based on our knowledge and findings, this marks a novel finding of S. murinus in the biocontrol of bean Common bacterial blight and bacterial wilt disease. Streptomyces FS2 generated a variety of metabolites; thus, the precise roles of these metabolites in the biocontrol process warrant additional investigation. Identifying the appropriate Streptomyces strain that effectively targets a particular phytopathogen while preserving the growth indexes poses a significant challenge. Consequently, selecting and characterizing individual Streptomyces strains for potential use as microbial antagonists is crucial in sustainable food systems, circular economy and fighting global hunger. Meanwhile, investigating seed-microbial interactions in drought-resistant crops, such as legumes, can enhance the resilience of food systems in the face of climate change. Declarations Conflict of interest The authors declare that they have no conflict of interest. Ethics approval This research does not contain any studies with human participants or animals performed by any of the authors Informed consent None Acknowledgements This present research was financially supported by Seed and Plant Certification and Registration Institute (SPCRI), Iran Data availability The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request. References Abbasi, S., Safaie, N., Sadeghi, A., & Shamsbakhsh, M. (2020). Tissue-specific synergistic bio-priming of pepper by two Streptomyces species against Phytophthora capsici. PloS one , 15(3), e0230531. AbdElgawad, H., Abuelsoud, W., Madany, M. M., Selim, S., Zinta, G., Mousa, A. S., & Hozzein, W. N. (2020). Actinomycetes enrich soil rhizosphere and improve seed quality as well as productivity of legumes by boosting nitrogen availability and metabolism. Biomolecules , 10 (12), 1675. Ahmad, E., Sharma, P. K., & Khan, M. S. (2022). IAA biosynthesis in bacteria and its role in plant-microbe interaction for drought stress management. Plant Stress Mitigators: Action and Application (pp. 235–258). Springer Nature Singapore. Akbari, A., Gharanjik, S., Koobaz, P., & Sadeghi, A. (2020). Plant growth promoting Streptomyces strains are selectively interacting with the wheat cultivars especially in saline conditions. Heliyon , 6 (2). Basson, A., Flemming, L. A., & Chenia, H. Y. (2008). Evaluation of adherence, hydrophobicity, aggregation, and biofilm development of Flavobacterium johnsoniae-like isolates. Microbial ecology , 55 (1), 1–14. Behera, H. T., Mojumdar, A., Behera, S. S., Das, S., & Ray, L. (2022). Biocontrol of wilt disease of rice seedlings incited by Fusarium oxysporum through soil application of Streptomyces chilikensis RC1830. Letters in Applied Microbiology , 75 (5), 1366–1382. Bellameche, F., Cassanelli, S., Caradonia, F., Cortiello, M., Perez, S., Stefani, E., & Giovanardi, D. (2024). Foliar application of a Streptomyces sp. on tomato plants: an insight into the induction of defence-related genes through RNA-Seq analysis. In: Abstracts of presentations at the XXIX Congress of the Italian Phytopathological Society. Journal of Plant Pathology 106, 1423–1534 (2024). https://doi.org/10.1007/s42161-024-01752-7 Bent, E., Tuzun, S., Chanway, C. P., & Enebak, S. (2001). Alterations in plant growth and in root hormone levels of lodgepole pines inoculated with rhizobacteria. Canadian Journal of Microbiology , 47 (9), 793–800. Boersma, J. G., Hou, A., Gillard, C. L., McRae, K. B., & Conner, R. L. (2015). Impact of common bacterial blight on the yield, seed weight and seed discoloration of different market classes of dry beans (Phaseolus vulgaris L). Canadian Journal of Plant Science , 95 (4), 703–710. Borkar, S. G. (2017). Laboratory techniques in plant bacteriology . CRC. Cardinale, M., Ratering, S., Suarez, C., Montoya, A. M. Z., Geissler-Plaum, R., & Schnell, S. (2015). Paradox of plant growth promotion potential of rhizobacteria and their actual promotion effect on growth of barley (Hordeum vulgare L.) under salt stress. Microbiological research , 181 , 22–32. Cassanelli, S., Bellameche, F., Caradonia, F., Cortiello, M., Perez Fuentealba, S., & Giovanardi, D. (2025). Foliar application of Streptomyces sp. DLS2013 induces transcriptional changes on tomato plants and confers resistance to Pseudomonas syringae pv. tomato . Journal of Plant Diseases and Protection , 132 (1), 1–20. Chen, D., Ali, M. N. H. A., Kamran, M., Magsi, M. A., Mora-Poblete, F., Maldonado, C., et al. (2022). The Streptomyces chromofuscus Strain RFS-23 induces systemic resistance and activates plant defense responses against Tomato yellow leaf curl virus infection. Agronomy , 12 (10), 2419. Chen, N. W., Ruh, M., Darrasse, A., Foucher, J., Briand, M., Costa, J., et al. (2021). Common bacterial blight of bean: a model of seed transmission and pathological convergence. Molecular Plant Pathology , 22 (12), 1464–1480. Colombo, E. M., Kunova, A., Cortesi, P., Saracchi, M., & Pasquali, M. (2019). Critical assessment of Streptomyces spp. able to control toxigenic Fusaria in cereals: a literature and patent review. International Journal of Molecular Sciences , 20 (24), 6119. Conn, V. M., Walker, A. R., & Franco, C. M. (2008). Endophytic actinobacteria induce defense pathways in Arabidopsis thaliana. Molecular Plant-Microbe Interactions , 21 , 208–218. Couillerot, O., Vatsa, P., Loqman, S., OuhdouchY, Jane, H., Renault, J-H., Clément, C., & Barka, E. A. (2013). Biocontrol and biofertilizer activities of the Streptomyces anulatus S37: an endophytic actinomycetewith biocontrol and plant- rowth promoting activities. IOBC-WPRS Bull , 86 , 271–276. Deising, H. B., Gase, I., & Kubo, Y. (2017). The unpredictable risk imposed by microbial secondary metabolites: how safe is biological control of plant diseases? Journal of Plant Diseases and Protection , 124 , 413–419. Dworkin, M., & Foster, J. (1958). Experiments with some microorganisms which utilize ethane and hydrogen. Journal Of Bacteriology , 75 , 592–603. Ebrahimi-Zarandi, M., Riseh, S., R., & Tarkka, M. T. (2022). Actinobacteria as effective biocontrol agents against plant pathogens, an overview on their role in eliciting plant defense. Microorganisms , 10 (9), 1739. Faddetta, T., Polito, G., Abbate, L., Alibrandi, P., Zerbo, M., Caldiero, C., Reina, C., Puccio, G., Vaccaro, E., Abenavoli, M. R., & Cavalieri, V. (2023). Bioactive metabolite survey of actinobacteria showing plant growth promoting traits to develop novel biofertilizers. Metabolites, 13(3), p.374. Gebily, D. A., Ghanem, G. A., Ragab, M. M., et al. (2021). Characterization and potential antifungal activities of three Streptomyces spp. as biocontrol agents against Sclerotinia sclerotiorum (Lib.) de Bary infecting green bean. Egyptian Journal of Biological Pest Control , 31 , 1–5. Goodrich, J. K., Di Rienzi, S. C., Poole, A. C., et al. (2014). Conducting a microbiome study. Cell , 158 (2), 250–262. Goudjal, Y., Toumatia, O., Sabaou, N., Barakate, M., Mathieu, F., & Zitouni, A. (2013). Endophytic actinomycetes from spontaneous plants of Algerian Sahara: indole-3-acetic acid production and tomato plants growth promoting activity. World Journal of Microbiology and Biotechnology , 29 , 1821–1829. Hata, E. M., Yusof, M. T., & Zulperi, D. (2021). Induction of systemic resistance against bacterial leaf streak disease and growth promotion in rice plant by Streptomyces shenzhenesis TKSC3 and Streptomyces sp. SS8. The plant pathology journal , 37 (2), 173. Hayward, A. C. (1974). Latent infections by bacteria. Annual Review of Phytopathology , 12 (1), 87–97. Horstmann, J. L., Dias, M. P., Ortolan, F., Medina-Silva, R., Astarita, L. V., & Santarém, E. R. (2020). Streptomyces sp. CLV45 from Fabaceae rhizosphere benefits growth of soybean plants. Brazilian Journal of Microbiology , 51 , 1861–1871. Htwe, A. Z., Moh, S. M., Soe, K. M., Moe, K., & Yamakawa, T. (2019). Effects of biofertilizer produced from bradyrhizobium and streptomyces griseoflavus on plant growth, nodulation, nitrogen fixation, nutrient uptake, and seed yield of mung bean, cowpea, and soybean. Agronomy. 9, 77. 10.3390/ agronomy9020077 Ishiyama, D., Vujaklija, D., & Davies, J. (2004). Novel pathway of salicylate degradation by Streptomyces sp. strain WA46. Applied and environmental microbiology , 70 (3), 1297–1306. Jaemsaeng, R., Jantasuriyarat, C., & Thamchaipenet, A. (2018). Molecular interaction of 1-aminocyclopropane- -carboxylate deaminase (ACCD)-producing endophytic Streptomyces sp. GMKU 336 towards salt-stress resistance of Oryza sativa L. cv. KDML105. Scientific Reports , 8 (1), 1950. Jauri, P. V. (2013). Ecology of interspecies signaling among Streptomyces and its relationship to pathogen suppression (Doctoral dissertation, University of Minnesota). 95 p. Jin, Z., Jiang, F., Wang, L., Declerck, S., Feng, G., & Zhang, L. (2024). Arbuscular mycorrhizal fungi and Streptomyces: brothers in arms to shape the structure and function of the hyphosphere microbiome in the early stage of interaction. Microbiome , 12 (1), 83. Jones, S. E., & Elliot, M. A. (2017). Streptomyces exploration: competition, volatile communication and new bacterial behaviors. Trends in microbiology , 25 (7), 522–531. Kaari, M., Joseph, J., Manikkam, R., Sreenivasan, A., & Venugopal, G. (2022). Biological control of Streptomyces sp. UT4A49 to suppress tomato bacterial wilt disease and its metabolite profiling. Journal of King Saud University-Science , 34 (1), 101688. Kang, Y. S., Lee, Y., Cho, S. K., Lee, K. H., Kim, B. J., Kim, M., & Cho, M. (2009). Antibacterial activity of a disaccharide isolated from Streptomyces sp. strain JJ45 against Xanthomonas sp. FEMS microbiology letters , 294 (1), 119–125. Karavina, C., Mandumbu, R., Parwada, C., & Tibugari, H. (2011). A review of the occurrence, biology and management of common bacterial blight. Journal of Agricultural Technology , 7 (6), 1459–1474. Khan, S., Srivastava, S., Karnwal, A., & Malik, T. (2023). Streptomyces as a promising biological control agents for plant pathogens. Frontiers in Microbiology , 14 , 1285543. Klaedtke, S. M., Barret, M., Chable, V., & Jacques, A. (2014). Microbial communities associated to common bean seed; A mechanism of local adaptation of plants. In : Book of Abstracts for International Congress on diversity strategies for organic and low input agriculture and their food systems, p. 103. Kumar, M., Kumar, P., Das, P., Solanki, R., & Kapur, M. K. (2020). Potential applications of extracellular enzymes from Streptomyces spp. in various industries. Archives of Microbiology , 202 , 1597–1615. Kunova, A., Bonaldi, M., Saracchi, M., Pizzatti, C., Chen, X., & Cortesi, P. (2016). Selection of Streptomyces against soil borne fungal pathogens by a standardized dual culture assay and evaluation of their effects on seed germination and plant growth. BMC microbiology , 16 , 1–11. Ling, L., Han, X., Li, X., et al. (2020). A Streptomyces sp. NEAU- V9: isolation, identification, and potential as a biocontrol agent against Ralstonia solanacearum of tomato plants. Microorganisms , 8 (3), 351. Liu, G., Chater, K. F., Chandra, G., Niu, G., & Tan, H. (2013). Molecular regulation of antibiotic biosynthesis in Streptomyces. Microbiology and molecular biology reviews , 77 (1), 112–143. Majumdar, S., & Chakraborty, U. (2017). Optimization of protease production from plant growth promoting Bacillus amyloliquefaciens showing antagonistic activity against phytopathogens. Int J Pharm Bio Sci , 8 (2), 635–642. Medie, F. M., Davies, G. J., Drancourt, M., & Henrissat, B. (2012). Genome analyses highlight the different biological roles of cellulases. Nature Reviews Microbiology , 10 (3), 227–234. Munene, L., Mugweru, J., & Mwirichia, R. (2023). Management of bacterial wilt caused by Curtobacterium flaccumfaciens pv. flaccumfaciens in common bean ( Phaseolus vulgaris ) using rhizobacterial biocontrol agents. Letters in Applied Microbiology , 76 (1), ovac011. Narayan, R., & Gupta, N. C. (2018). Isolation, cultural and physiological characterisation of Azospirillum from acidic soils of Ranchi. Journal of Pharmacognosy and Phytochemistry , 7 (4), 2611–2617. Nazari, M. T., Schommer, V. A., Braun, J. C. A. (2023). Using Streptomyces spp. as plant growth promoters and biocontrol agents. Rhizosphere , 100741. Nelson, E. B. (2018). The seed microbiome: origins, interactions, and impacts. Plant and Soil , 422 , 7–34. Olanrewaju, O. S., & Babalola, O. O. (2019). Streptomyces: implications and interactions in plant growth promotion. Applied microbiology and biotechnology , 103 , 1179–1188. Osdaghi, E., Taghavi, S. M., Hamzehzarghani, H., & Lamichhane, J. R. (2016). Occurrence and Characterization of the Bacterial Spot Pathogen X anthomonas euvesicatoria on Pepper in Iran. Journal of Phytopathology , 164 (10), 722–734. Osdaghi, E., Taghavi, S. M., Hamzehzarghani, H., Fazliarab, A., Harveson, R. M., Tegli, S., & Lamichhane, J. R. (2018). Epiphytic Curtobacterium flaccumfaciens strains isolated from symptomless solanaceous vegetables are pathogenic on leguminous but not on solanaceous plants. Plant Pathology , 67 (2), 388–398. Osdaghi, E., Young, A. J., & Harveson, R. M. (2020). Bacterial wilt of dry beans caused by Curtobacterium flaccumfaciens pv. flaccumfaciens: A new threat from an old enemy. Molecular plant pathology , 21 (5), 605–621. Gitaitis, R., & Walcott, R. (2007). The epidemiology and management of seedborne bacterial diseases. Annual Review Of Phytopathology , 45 , 371–397. Penrose, D. M., & Glick, B. R. (2003). Methods for isolating and characterizing ACC deaminase-containing plant growth-promoting rhizobacteria. Physiologia Plantarum , 118 , 10–15. 10.1034/j.1399-3054.2003.00086.x Perry, G., & Pauls, K. P. (2012). Common bacterial blight in Phaseolus vulgaris. Agricultural Research Updates , 2 (1), 239–264. Phitsuwan, P., Laohakunjit, N., Kerdchoechuen, O., Kyu, K. L., & Ratanakhanokchai, K. (2013). Present and potential applications of cellulases in agriculture, biotechnology, and bioenergy. Folia microbiologica , 58 , 163–176. Pieterse, C. M., Zamioudis, C., Berendsen, R. L., et al. (2014). Induced systemic resistance by beneficial microbes. Annual review of phytopathology , 52 (1), 347–375. Rademaker, J., & Bruijn, F. (1997). Characterization and classification of microbes by repPCR genomic fingerprinting and computer assisted pattern analysis. In G. Caetano-Anolles, & P. Gresshoff (Eds.), DNA markers: Protocols, Applications and Overviews (pp. 151–171). John Wiley & Sons, Inc.. In :. Rybakova, D., Mancinelli, R., Wikström, M., et al. (2017). The structure of the Brassica napus seed microbiome is cultivar-dependent and affects the interactions of symbionts and pathogens. Microbiome , 5 , 1–16. Sadeghi, A., Koobaz, P., Azimi, H., Karimi, E., & Akbari, A. R. (2017). Plant growth promotion and suppression of Phytophthora drechsleri damping-off in cucumber by cellulase-producing Streptomyces. BioControl , 62 , 805–819. Sammer, U. F., & Reiher, K. (2012). Curtobacterium flaccumfaciens pv. flaccumfaciens on soybean in Germany– threat for farming. Journal of Phytopathology , 160 (6), 314–316. Schaad, N. W., Jones, J. B., & Chun, W. (2001). Laboratory guide for the identification of plant pathogenic bacteria (Vol. 3No. Ed.). American Phytopathological Society (APS. Schillaci, M., Raio, A., Sillo, F. (2022). Pseudomonas and Curtobacterium strains from olive rhizosphere characterized and evaluated for plant growth promoting traits. Plants , 11 (17), 2245. Schrey, S. D., & Tarkka, M. T. (2008). Friends and foes: streptomycetes as modulators of plant disease and symbiosis. Antonie Van Leeuwenhoek , 94 , 11–19. Sharifi, R., Kiani, H., Ahmadzadeh, M., & Behboudi, K. (2019). Optimization of acetoin production by biological control strain Bacillus Subtilis‎ GB03 using statistical experimental design. Biological Journal of Microorganism , 8 (32), 47–57. Sharma, A., Gautam, S., & Saxena, S. (2014). Streptomyces. In C. A. Batt, & R. K. Robinson (Eds.), Encyclopedia of food microbiology (Vol. 3, pp. 560–566). Elsevier. Shirokikh, I. G., Osterman, I. A., Lukianov, D. A., et al. (2023). Biocontrol Potential of Novel Borrelidin-Producing Streptomyces rochei 3IZ-6 Isolated from Soil. Eurasian Soil Science , 56 (5), 619–627. Sorroche, F. G., Spesia, M. B., Zorreguieta, Á., & Giordano, W. (2012). A positive correlation between bacterial autoaggregation and biofilm formation in native Sinorhizobium meliloti isolates from Argentina. Applied and environmental microbiology , 78 (12), 4092–4101. Sousa, J., & Olivares, F. (2016). Plant growth promotion by Streptomycetes: ecophysiology, mechanisms and applications. Chemical and Biological Technologies in Agriculture , 3 (24), 1–12. Suwitchayanon, P., Chaipon, S., Chaichom, S., & Kunasakdakul, K. (2018). Potentials of Streptomyces rochei ERY1 as an endophytic actinobacterium inhibiting damping-off pathogenic fungi and growth promoting of abbage seedling. Chiang Mai J Sci , 45 , 692–700. Taha, M., Ghaly, M., Atwa, H., & Askoura, M. (2021). Evaluation of the effectiveness of soil Streptomyces isolates for induction of plant resistance against Tomato mosaic virus (ToMV). Current Microbiology , 78 (8), 3032–3043. Thakur, R., & Yadav, S. (2023). Thermotolerant and halotolerant Streptomyces sp. isolated from Ajuga parviflora having biocontrol activity against Pseudomonas syringae and Xanthomonas campestris acts as a sustainable bioadditive in growth promotion of Cicer arietinum. Physiological and Molecular Plant Pathology , 127 , 102059. Toussaint, V., Benoit, D. L., & Carisse, O. (2012). Potential of weed species to serve as a reservoir for Xanthomonas campestris pv. vitians, the causal agent of bacterial leaf spot of lettuce. Crop Protection , 41 , 64–70. Umer, M., Mubeen, M., Iftikhar, Y., Shad, M. A., Usman, H. M., Sohail, M. A., Atiq, M. N., Abbas, A., & Ateeq, M. (2021). Role of Rhizobacteria on plants growth and biological control of plant diseases: A review (Vol. 5, pp. 59–73). Plant Prot. Viaene, T., Langendries, S., Beirinckx, S., Maes, M., & Goormachtig, S. (2016). Streptomyces as a plant's best friend? FEMS microbiology ecology , 92 (8), fiw119. Vurukonda, S. S. K. P., Giovanardi, D., & Stefani, E. (2018). Plant growth promoting and biocontrol activity of Streptomyces spp. as endophytes. International journal of molecular sciences , 19 (4), 952. Walpola, B. C., & Yoon, M. H. (2012). Prospectus of phosphate solubilizing microorganisms and phosphorus availability in agricultural soils: a review. Afr J Microbiol Res , 6 , 6600–6605. 10.5897/AJMR12.889 Walters, D. R., Ratsep, J., & Havis, N. D. (2013). Controlling crop diseases using induced resistance: challenges for the future. Journal of experimental botany , 64 (5), 1263–1280. War, A. F., Bashir, I., Reshi, Z. A., Kardol, P., & Rashid, I. (2023). Insights into the seed microbiome and its ecological significance in plant life. Microbiological Research , 269 , 127318. Weller, D. M., & Saettler, A. W. (1980). Colonization and Distribution of Xanthomonas phaseoli in field-grown navy beans. Phytopathology , 70 , 500–506. Wilson, D. B. (2008). Three microbial strategies for plant cell wall degradation. Annals of the New York Academy of Sciences , 1125 (1), 289–297. Wang, Z., Gao, C., Yang, J., Du, R., Zeng, F., Bing, H., Xia, B., Shen, Y., & Liu, C. (2023). Endophytic Streptomyces sp. NEAU-ZSY13 from the leaf of Perilla frutescens, as a promising broad-spectrum biocontrol agent against soil-borne diseases. Frontiers in Microbiology , 14 , 1243610. Worsley, S. F., Newitt, J., Rassbach, J., et al. (2020). Streptomyces endophytes promote host health and enhance growth across plant species. Applied and Environmental Microbiology , 86 (16), e01053–e01020. Footnotes The area under the disease progress curve Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Major revisions 16 Feb, 2026 Reviewers agreed at journal 24 Nov, 2025 Reviewers invited by journal 24 Nov, 2025 Editor invited by journal 13 Nov, 2025 Editor assigned by journal 12 Nov, 2025 First submitted to journal 07 Nov, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7967969","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":550205186,"identity":"9ceb4533-0fac-4818-bf7d-405c17a46257","order_by":0,"name":"Faezeh Salehi","email":"","orcid":"","institution":"Azad University: Islamic Azad University","correspondingAuthor":false,"prefix":"","firstName":"Faezeh","middleName":"","lastName":"Salehi","suffix":""},{"id":550205187,"identity":"06a877d5-9b69-4a84-8bd4-0205b6388f48","order_by":1,"name":"Nader Hasanzadeh","email":"","orcid":"","institution":"Azad University: Islamic Azad University","correspondingAuthor":false,"prefix":"","firstName":"Nader","middleName":"","lastName":"Hasanzadeh","suffix":""},{"id":550205188,"identity":"e7303ad6-f5e6-44af-bc06-1c520e254a6e","order_by":2,"name":"Javad Razmi","email":"","orcid":"","institution":"Azad University: Islamic Azad University","correspondingAuthor":false,"prefix":"","firstName":"Javad","middleName":"","lastName":"Razmi","suffix":""},{"id":550205189,"identity":"96080e38-7597-4eae-b255-f7af80bf2c61","order_by":3,"name":"cobra moslemkhani","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA4ElEQVRIiWNgGAWjYHACxgMMDAkJIMYDBoYDxOmBaWE2IFkLmwRRWnTb2x8c+JiTlsc/u8esmqfmjhw/A/PDRzfwaDE7c8bg4MxtOcUSd86Y3eY59sxYsoHN2DgHn5YbOQyHebdVJDbcyAFqYTucuOEAD5s0fi3pDw7/BWqZD9RSzPOPKC0JBocZt+UkbgBqYeZtI0YLyC+929ISN95IK5ac23fYWLKZkF+Otz988HNbcuK8G8kbP7z5dliOn7354WN8WpAAhwETD4hmJk45CLA/YPxBvOpRMApGwSgYQQAACIdaFp3FxAEAAAAASUVORK5CYII=","orcid":"","institution":"Seed and plant certification and registration institute","correspondingAuthor":true,"prefix":"","firstName":"cobra","middleName":"","lastName":"moslemkhani","suffix":""},{"id":550205190,"identity":"d7529223-9621-4776-8bf0-89f9f7f89ec9","order_by":4,"name":"saman Sheidaei","email":"","orcid":"","institution":"Seed and Plant Certification Research Institute","correspondingAuthor":false,"prefix":"","firstName":"saman","middleName":"","lastName":"Sheidaei","suffix":""}],"badges":[],"createdAt":"2025-10-28 16:36:37","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7967969/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7967969/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":97139778,"identity":"194b1809-669f-453b-bcc5-a56d6386c1a3","added_by":"auto","created_at":"2025-12-01 10:02:29","extension":"xml","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":8649,"visible":true,"origin":"","legend":"","description":"","filename":"ejppEJPPD2500845.xml","url":"https://assets-eu.researchsquare.com/files/rs-7967969/v1/43dc17ee129cd26bd8826c32.xml"},{"id":96995908,"identity":"4dfdc628-28fd-4762-a2d5-19a8b807e0cf","added_by":"auto","created_at":"2025-11-28 12:18:50","extension":"xml","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":937,"visible":true,"origin":"","legend":"","description":"","filename":"EJPPD250084527949.go.xml","url":"https://assets-eu.researchsquare.com/files/rs-7967969/v1/34a41766ea3b36800a082817.xml"},{"id":96995906,"identity":"496f1b08-c922-4684-93b9-1f7f0b1a2d24","added_by":"auto","created_at":"2025-11-28 12:18:50","extension":"xml","order_by":3,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":920,"visible":true,"origin":"","legend":"","description":"","filename":"EJPPD2500845Import.xml","url":"https://assets-eu.researchsquare.com/files/rs-7967969/v1/116208be6ff1cd592e9ae344.xml"},{"id":97138022,"identity":"6599a169-5e7c-4d8e-98d4-74261f29158c","added_by":"auto","created_at":"2025-12-01 09:58:25","extension":"xml","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":184450,"visible":true,"origin":"","legend":"","description":"","filename":"EJPPD25008450enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-7967969/v1/16559165d94b1c09101d7077.xml"},{"id":96995913,"identity":"cc5131c1-55a0-4322-8118-4ecaf8106294","added_by":"auto","created_at":"2025-11-28 12:18:50","extension":"png","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":89145,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7967969/v1/3cbf90461341cbda9a2c42f8.png"},{"id":96995909,"identity":"0182f537-fdfc-4c7f-947f-c615724fb6bf","added_by":"auto","created_at":"2025-11-28 12:18:50","extension":"png","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":83620,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7967969/v1/8335621f4f046a4b3ac25225.png"},{"id":97139173,"identity":"8359ea01-1814-47d8-953c-50d6702882a2","added_by":"auto","created_at":"2025-12-01 09:59:42","extension":"xml","order_by":9,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":182870,"visible":true,"origin":"","legend":"","description":"","filename":"EJPPD25008450structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7967969/v1/db31488b948a03af89ae9f81.xml"},{"id":96995912,"identity":"a95c149b-2d2d-40cb-a53a-63f5b8c9c419","added_by":"auto","created_at":"2025-11-28 12:18:50","extension":"html","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":193274,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7967969/v1/0c550a260ab1f61959b0c688.html"},{"id":96995905,"identity":"8865c382-222e-467f-8894-0599ea969147","added_by":"auto","created_at":"2025-11-28 12:18:50","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":525574,"visible":true,"origin":"","legend":"\u003cp\u003ePopulation dynamics of \u003cem\u003eXpp\u003c/em\u003eand \u003cem\u003eCff\u003c/em\u003e in stem and leaves of bean seeds planted in treated soil with Streptomyces strains (FS2 and FS123). \u003cem\u003eXpp\u003c/em\u003e:\u003cem\u003e Xanthomonas phaseoli \u003c/em\u003epv\u003cem\u003e. phaseoli\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e: \u003cem\u003eCurtobacterium flaccumfaciens\u003c/em\u003epv. \u003cem\u003eflaccumfaciens\u003c/em\u003e.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7967969/v1/54f6c62cd5b3a4ad6d493fcb.jpeg"},{"id":97144974,"identity":"a4739f66-194b-4250-b98f-22c043a8b225","added_by":"auto","created_at":"2025-12-01 10:12:37","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1624678,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7967969/v1/7640485c-39cb-4a5d-b6c6-2e57e21ac392.pdf"}],"financialInterests":"","formattedTitle":"From Seed to Savior: Understanding the Biocontrol Abilities of Seed-Derived Streptomyces Strains against Seed borne Bean Bacterial Diseases","fulltext":[{"header":"Introduction","content":"\u003cp\u003eSeeds harbor diverse populations of microorganisms, forming a seed microbiota co-evolved with their plant hosts. This microbiota plays a crucial role in early developmental stages, influencing key processes such as seed dormancy and germination (War et al., \u003cspan citationid=\"CR79\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Moreover, it affects overall plant function, health, productivity, and ecological interactions (Nelson, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). The dynamics within this microbiota also shape the relationships between pathogens and other seed-borne microbes (Rybakova et al., \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2017\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe next-generation sequencing (NGS) technologies of microbial communities indicated that the Streptomyces genus has frequently been found in different plant microbiomes (Goodrich et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Viaene et al., \u003cspan citationid=\"CR75\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; AbdElgawad et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Streptomyces, as a rhizosoil Actinomycetes, is an efficient colonizer of plant roots to the aerial parts (Sousa \u0026amp; Olivares, \u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Viaene et al., \u003cspan citationid=\"CR75\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Vurukonda et al., \u003cspan citationid=\"CR76\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) with great antagonistic activities due to their abilities to produce antimicrobial substances (Gebily et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Ling et al., \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Behera et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), and responsible for comprising 66.67% of all naturally occurring antibiotics (Khan et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The filamentous and sporulating characteristics of Streptomyces enhance survival in adverse environments. Plant growth-promoting streptomycetes (PGPS) enhance multiple biosynthetic pathways in plants, such as inorganic phosphate solubilization, chelating compound biosynthesis, phytohormone production, phytopathogens inhibition, and abiotic stress alleviation (Vurukonda et al., \u003cspan citationid=\"CR76\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Consequently, they exhibit superior competitive abilities against various rhizobial microorganisms based on three primary strategies: competition for ecological niches and nutritional resources, antibiosis, and parasitism (Khan et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Many reports indicated that Streptomyces could control plant pathogens via important traits such as producing siderophore, antibiotics, plant growth regulators, volatile compounds, phytohormones and different enzymes like cellulases, chitinase and lipase (Goudjal et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Couillerot et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Jones and Elliot, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Nazari et al., \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Olanrewaju and Babalola, \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eSeed-borne bacterial pathogens of beans, in particular, \u003cem\u003eXanthomonas phaseoli\u003c/em\u003e pv. \u003cem\u003ephaseoli\u003c/em\u003e (\u003cem\u003eXpp\u003c/em\u003e) and \u003cem\u003eCurtobacterium flaccumfaciens\u003c/em\u003e pv. \u003cem\u003eflaccumfaciens\u003c/em\u003e (\u003cem\u003eCff\u003c/em\u003e), as the agents responsible for common bacterial blight (CBB) and bacterial wilt (BW) diseases, cause phytosanitary challenges for bean (\u003cem\u003ePhaseolus vulgaris\u003c/em\u003e L) production. CBB is a globally significant and challenging disease to manage, prevalent across 104 countries, resulting in yield losses of up to 45% in susceptible varieties, and it adversely affects seed quality, thereby threatening both the seed industry and edible seed production (Chen et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). BW is one of the most destructive common bean diseases globally (Munene et al., \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), impacting crop yield and marketability of harvested beans (Osdaghi et al., \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). They are continuously problematic and can cause significant economic losses in fields under favorable conditions (Gitaitis and Walcott, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Osdaghi et al., \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Sammer and Reiher, \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Boersma et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Perry and Pauls, \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eMost of the research on seed health focused on seed-borne pathogens regardless of the potential functions of other seed-borne microorganisms (Klaedtke et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), which is a big challenge and limitation. Therefore, besides limited information about the Streptomyces population on seeds, the implications of Streptomyces upon seed-borne bacterial pathogens must be clarified. Thus, this study was conducted to investigate the impact of Streptomyces strains, which are isolated from bean seed, on \u003cem\u003eCff\u003c/em\u003e and \u003cem\u003eXpp\u003c/em\u003e, as well as their biocontrol potential and their effects on plant growth.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eSeed samples and bacterial isolation\u003c/h2\u003e\u003cp\u003e Bean seeds were sampled from the Fars, Markazi, Lorestan and Zanjan provinces of Iran, according to the instructions of the International Seed Testing Association. Samples were analyzed for two seed-borne pathogens, \u003cem\u003eXanthomonas phaseoli\u003c/em\u003e pv. \u003cem\u003ephaseoli\u003c/em\u003e (\u003cem\u003eXpp\u003c/em\u003e) and \u003cem\u003eCurtobacterium flaccumfaciens\u003c/em\u003e pv. \u003cem\u003eflaccumfaciens\u003c/em\u003e (\u003cem\u003eCff\u003c/em\u003e), and Streptomyces isolates. Reference isolates of \u003cem\u003eXpp\u003c/em\u003e (X0S) and \u003cem\u003eCff\u003c/em\u003e (LA7) were received from the Seed and Plant Certification and Registration Institute, Iran.\u003c/p\u003e\u003cp\u003eSerial dilutions of seeds suspension in saline buffer containing 0.02% v/v tween 20 and 0.85% NaCl (with tenfold the weight of the seed) were spread on YDC and NA medium. Yellow, orange and red color colonies in YDC and tough, leathery with filamentous growth colonies on NA were selected for gram, oxidase, catalase and HR analysis (Schaad et al., \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2001\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eDNA extraction\u003c/h3\u003e\n\u003cdiv class=\"Heading\"\u003eDNA extraction\u003c/div\u003e\u003cp\u003eBacterial DNA isolation was done using a modified method by Rademaker and Bruijn (\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e1997\u003c/span\u003e). 50\u0026micro;l of 10% KOH was added to 500\u0026micro;l of freshly bacterial suspension (24 hours) and heated for 15 minutes at 95\u0026deg;C until the solution became clear. Microtubes were centrifuged at 10000 rpm for 2 minutes. The supernatant containing template DNA was used for PCR analysis after measuring DNA quality and quantity using Nanodrop.\u003c/p\u003e\u003cp\u003e\u003cb\u003e16S rRNA gene amplification\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe PCR products of the 16S rRNA region of selected Streptomyces isolates, which were amplified by 1492R (TACGGYTACCTTGTTACGACTT) and 27F (AGAGTTTGATCMTGGCTCAG) primers, were sent to the Bio Magic Gene Company to determine the nucleotide sequence. The DNA sequences were compared with those existing in the GenBank database using the BLAST search program (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://www.ncbi.nlm.nih.gov/\u003c/span\u003e\u003cspan address=\"http://www.ncbi.nlm.nih.gov/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e), and the obtained sequences were deposited in the GenBank database.\u003c/p\u003e\n\u003ch3\u003eIn vitro antagonistic activity assay of Streptomyces isolates\u003c/h3\u003e\n\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003eInhibition zones\u003c/h2\u003e\u003cp\u003eThe antimicrobial activities of Streptomyces isolates were examined by measuring the inhibition zones. The direct effect of Streptomyces isolates on the growth of \u003cem\u003eXpp\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e was evaluated via spreading 100 \u0026micro;l of \u003cem\u003eXpp\u003c/em\u003e or \u003cem\u003eCff\u003c/em\u003e at 1\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\times\\:\\)\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{10}^{7}\\)\u003c/span\u003e\u003c/span\u003eCFU/ml concentration on the nutrient agar plates. After drying the surface of the culture medium, Streptomyces agar plugs were placed on the plates. The plates were incubated at 28 \u0026ordm;C for 72 hours, and clear zones around the discs were measured in mm.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003ePhytate-degrading ability\u003c/h3\u003e\n\u003cp\u003eStreptomyces isolates were spotted on phytase screening medium containing 1.5%glucose, 0.05% KCl, 0.01% MgSO4.7H2O, 0.01% NaCl, 0.5% (NH4NO3, 0.01% CaCl2.2H2 O, 0.001% MnSO4.7H\u003csub\u003e2\u003c/sub\u003eO, 0.001% FeSO4.7H\u003csub\u003e2\u003c/sub\u003eO, Agar 15, pH 6.5 with 0.5% sodium phytate). The colonies with phytate degrading ability exhibit translucent zones.\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eProduction of indole acetic acid\u003c/h2\u003e\u003cp\u003eThe ability of Streptomyces isolates to produce indole acetic acid hormone was measured by a modified Salkowski colorimetric method described by Bent et al. (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2001\u003c/span\u003e). The isolates were cultured in Nutrient Broth (NB) medium containing 0.2 g/l L-tryptophan for 48 hours at 28\u0026deg;C with 100 rpm rotary shaking. Then, they were centrifuged for 15 minutes at a temperature of 4\u0026deg;C with a speed of 13000 rpm. The supernatant was collected (1 ml), mixed with 2 ml of Salkowski's reagent (250 ml of sterile distilled water, 150 ml of sulfuric acid, 7.5 ml of 0.5 M FeCl\u003csub\u003e3\u003c/sub\u003e), and kept in the dark for 20 minutes. The change in the color of the medium to pinkish red indicates the production of auxin; finally, their concentration was evaluated at the wavelength of 535 nm (Bent et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2001\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eNitrogen-fixing capacity\u003c/h3\u003e\n\u003cp\u003eOkon's NFb medium (Narayan and Gupta, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) was used for assess isolates' nitrogen-fixing ability. One liter medium contains 5 g malic acid, 4 g KOH, and 0.05 g FeSO\u003csub\u003e4\u003c/sub\u003e. 7H\u003csub\u003e2\u003c/sub\u003eO, 0.5 g K\u003csub\u003e2\u003c/sub\u003eHPO\u003csub\u003e4\u003c/sub\u003e; 0.01 g MnSO\u003csub\u003e4\u003c/sub\u003e.H2O, 0.1 g MgSO\u003csub\u003e4\u003c/sub\u003e 2H\u003csub\u003e2\u003c/sub\u003eO, 0.02 g NaCl, 0.01 g CaCl\u003csub\u003e2\u003c/sub\u003e\u0026middot;2H\u003csub\u003e2\u003c/sub\u003eO, 0.002 g Na\u003csub\u003e2\u003c/sub\u003eMoO\u003csub\u003e4\u003c/sub\u003e\u0026middot;2H\u003csub\u003e2\u003c/sub\u003eO; 2 mL bromothymol blue solution (0.5% bromothymol blue in ethanol) and 18 g Agar. The pH was adjusted to 6.5, and the medium was sterilized at 121\u0026deg;C for 15 min. The color change of the culture medium from green to blue indicates nitrogen fixation.\u003c/p\u003e\n\u003ch3\u003eACC deaminase activity\u003c/h3\u003e\n\u003cp\u003eThe isolates were screened for ACC deaminase activity on the sterile minimal DF (Dworkin and Foster) salts media (DF salts per liter: 4.0 g KH2PO4, 6.0 g Na2HPO4, 0.2 g MgSO4.7H2O, 2.0 g glucose, 2.0 g gluconic acid and 2.0 g citric acid with trace elements: 1 mg FeSO4.7H2O, 10 mg H3BO3, 11.19 mg MnSO4.H2O, 124.6 mg ZnSO4.7H2O, 78.22 mg CuSO4.5H2O, 10 mg MoO3, pH 7.2) amended with 3 mM ACC instead of (NH4)2SO4 as sole nitrogen source (Dworkin \u0026amp; Foster, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e1958\u003c/span\u003e; Penrose \u0026amp; Glick, \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). The inoculated plates were incubated at 28\u0026deg;C for 3 days, and the growth of colonies was assayed.\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eProduction of proteinase and cellulase\u003c/h2\u003e\u003cp\u003eThe ability of Streptomyces isolates to produce cellulase enzyme was assayed using Czapek mineral salt agar medium (Borkar, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), and the proteinase production was evaluated as described by Majumdar and Chakraborty (\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2017\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eBiofilm tests\u003c/h2\u003e\u003cp\u003eThe Crystal violet staining method with ELISA plates (Sorroche et al., \u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e2012\u003c/span\u003e) was used to assess biofilm formation quantitatively. The OD\u003csub\u003e560\u003c/sub\u003e and OD\u003csub\u003e600\u003c/sub\u003e of dissolved crystal violet was recorded and data were analyzed as described by Basson et al. (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2008\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eAll of antagonistic activity experiments were done in three technical and biological replicates.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003eGreenhouse experiments\u003c/h2\u003e\u003cp\u003eThe experiment was performed in the controlled condition at temperatures of 28\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C. Experiments were evaluated in a completely randomized design with three technical and biological replicates (In each pot, ten plants were assessed). Inoculated (with \u003cem\u003eXpp\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e) and non-inoculated bean seeds were grown in Streptomyces treated and not treated soil (in a mixture of equal proportions of field soil and peat moss and sand).\u003c/p\u003e\u003cp\u003eAccording to Akbari et al. (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), soil treatment by Streptomyces strains was done via inoculum preparation. Spores suspension in a sterile 0.9% NaCl solution were prepared from the five-day culture of isolates. 50 \u0026micro;l of spore suspension (10\u003csup\u003e6\u003c/sup\u003e cfu/ml) was transferred to 25 mL broth nutrient broth medium after four-day incubation at 28\u0026deg;C; bacterial cells and spores separated by centrifuge at 1000g for 10 min and added in 50 mL a sterile NaCl solution which then mixed with 500 g autoclaved soil. Streptomyces spore suspension was added to the soil, and the final cfu/g was adjusted to 10\u003csup\u003e6\u003c/sup\u003e cfu/g.\u003c/p\u003e\u003cp\u003eBean seeds were treated with 1% CMC and 1\u0026times; 10\u003csup\u003e7\u003c/sup\u003e CFU/ml suspension of each bacterial pathogen (\u003cem\u003eXpp\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e) for half an hour. Treated seeds were sown in soil treated with Streptomyces suspension. Planting untreated seeds in treated and non-treated soil was used as a control group. Disease symptoms and severity index as a basis for AUDPC\u003csup\u003e1\u003c/sup\u003e calculation were assessed daily from one week to 30 days after the planting. Then, the area under the disease progress curve (AUDPC) was calculated. Statistical analysis was performed with SPSS version 16 software (SPSS Inc., Chicago, IL).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003e\u003cb\u003eDetermine bacterial transmission and population\u003c/b\u003e\u003c/h2\u003e\u003cp\u003eThe transmission and endophyte and epiphyte population size of \u003cem\u003eXpp\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e isolates were evaluated in the stem and leaf of plants as described by Osdaghi et al. (\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Three subsamples of each treatment in three replicates were harvested at 20 and 27 days after soil inoculation. Samples of leaf and stem (1gr) separately were macerated in 10 ml saline buffer and, by spread plate method, were plated onto YDC, and 7 days post-incubation Bacterial population (CFU/g) were determined (Toussaint et al., \u003cspan citationid=\"CR73\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). The bacteria belonging to \u003cem\u003eXpp\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e were confirmed by specific PCR.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results and discussion","content":"\u003cp\u003eTwo distinct strains of \u003cem\u003eStreptomyces\u003c/em\u003e, designated FS2 and FS123, were procured from the Yaghut and Dadfar cultivars, respectively. These strains were characterized from a total of 37 samples of bean seeds and 365 isolated bacterial specimens. The strain FS2 and strain FS123 exhibited high similarity with \u003cem\u003eStreptomyces murinus\u003c/em\u003e (98.81%) and \u003cem\u003eStreptomyces collinus\u003c/em\u003e (98.61%) that were deposited in NCBI GenBank with PQ164170 and PQ164167 accession numbers based on the 16S rRNA gene sequencing, respectively.\u003c/p\u003e\n\u003cp\u003eThe Streptomyces strains exhibited different antagonistic and growth-promoting properties (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). The antagonistic potential of the FS2 and FS123 isolates was confirmed by inhibition zone assay against \u003cem\u003eXpp\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e in laboratory conditions. Antibiotic production is a salient property of Streptomyces, which can appear on an agar plate as a clear zone around a target microorganism (Liu et al., \u003cspan class=\"CitationRef\"\u003e2013\u003c/span\u003e; Sharma et al., \u003cspan class=\"CitationRef\"\u003e2014\u003c/span\u003e). The members of Streptomyces species or their commercial products are particularly interesting due to their abilities to inhibit many of bacterial pathogens such as \u003cem\u003ePectobacterium carotovorum\u003c/em\u003e subsp. \u003cem\u003ecarotovorum\u003c/em\u003e, \u003cem\u003ePectobacterium atrosepticum\u003c/em\u003e, \u003cem\u003eStreptomyces scabies\u003c/em\u003e, \u003cem\u003eRalstonia solanacearum\u003c/em\u003e, \u003cem\u003eXanthomonas euvesicatoria\u003c/em\u003e, \u003cem\u003eXanthomonas oryzae\u003c/em\u003e, \u003cem\u003eXanthomonas citri\u003c/em\u003e, \u003cem\u003ePseudomonas tabaci\u003c/em\u003e, and \u003cem\u003eErwinia amylovora\u003c/em\u003e (Shirokikh et al., \u003cspan class=\"CitationRef\"\u003e2023\u003c/span\u003e; Ebrahimi-Zarandi et al., \u003cspan class=\"CitationRef\"\u003e2022\u003c/span\u003e; Kang et al., \u003cspan class=\"CitationRef\"\u003e2009\u003c/span\u003e; Thakur and Yadav, \u003cspan class=\"CitationRef\"\u003e2023\u003c/span\u003e). Biosynthesis of cellulolytic enzyme was detected in both Streptomyces isolates (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). The cellulase activity of FS2 was found to be twice that of FS123. One of the antagonistic modes of action of Streptomyces isolates is cellulase activity, especially against fungal pathogens (Sadeghi et al., \u003cspan class=\"CitationRef\"\u003e2017\u003c/span\u003e). Cellulase enzymes can break down the cellulose of plant cell wall components, although bacterial cellulases\u0026apos; role is more complicated than simply breaking down plant cell wall cellulose (Medie et al., \u003cspan class=\"CitationRef\"\u003e2012\u003c/span\u003e). The ability of the bacteria to produce cellulases indicates their potential to suppress some disease development (Wilson, \u003cspan class=\"CitationRef\"\u003e2008\u003c/span\u003e). So far, cellulolytic activity, in addition to providing conditions for the successful colonization of bacteria, can promote plant growth and enhanced seed germination and may suppress disease by triggering plant defence mechanisms (Phitsuwan et al., \u003cspan class=\"CitationRef\"\u003e2013\u003c/span\u003e; Suwitchayanon et al., \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e). Besides antimicrobial compounds, both Streptomyces isolates produced phytase enzymes. Phytases as phosphates solubilization extracellular enzymes can mineralize complex organic phosphates (Walpola \u0026amp; Yoon, \u003cspan class=\"CitationRef\"\u003e2012\u003c/span\u003e). It defined P-solubilizing Streptomyces can affect plant growth and yield performance by improving phosphorus uptake (Htwe et al., \u003cspan class=\"CitationRef\"\u003e2019\u003c/span\u003e). They may also increase plant resistance against pathogens as ISR-triggered PGPRs and improve plant immune system (Walters et al., \u003cspan class=\"CitationRef\"\u003e2013\u003c/span\u003e; Abbasi et al., \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e). Indole-3-acetic acid (IAA) production, which plays critical roles in crosstalk between plants, microbes and root colonization (Ahmad et al., \u003cspan class=\"CitationRef\"\u003e2022\u003c/span\u003e), was verified in both isolates. IAA can implicate the health status of the plant host and enhance plant growth (Jaemsaeng et al., \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eSome physiological and antagonistic traits of the Streptomyces strains isolated from bean seeds\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eisolates\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eInhibition zone\u003c/p\u003e\n \u003cp\u003eAgainst \u003cem\u003eXpp\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eInhibition zone\u003c/p\u003e\n \u003cp\u003eAgainst \u003cem\u003eCff\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eIAA\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCellulase\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eProtease\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eNitrogen Fixation\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePhytase\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePhosphatase\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eACC deaminase\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eBiofilm\u003c/p\u003e\n \u003cp\u003e(OD:590)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFS2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e+++\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e+++\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e++\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e++\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e++\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e+++\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFS123\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e++\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e++\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e++\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e+\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"11\"\u003e-: Negative; +: Positive; ++: Intermediate Positive; +++: Strong Positive\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003eAnalysis of variance for CBB and BW disease severity index and AUDPC after planting \u003cem\u003eXpp\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e inoculated seeds in soil treated with Streptomyces isolates (FS2 and FS123) showed a significant difference in the studied treatment (Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv align=\"char\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eThe mean squares of the disease severity index and area under the disease progress curve after planting \u003cem\u003eXpp\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e inoculated seeds in soil treated with Streptomyces isolates\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eSource\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eDF\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMean squares\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eDSI 10dpi\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eDSI 15dpi\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eAUDPC\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTreatment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.371**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.972**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e112.813**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eError\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.053\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.081\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.918\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCV%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e27.608\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e25.565\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e19.723\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\"\u003e**: significant at the 5% probability level\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eThe mean comparison results indicated that soil treatment with FS2 could control both of diseases, and the lowest values in all variables (DSI and AUDPC) were assigned to soil treatment with FS2 (Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). Some Streptomyces strains with effective antagonistic properties exhibit a high potential to control disease and can be developed for the biological control of pathogens (Suwitchayanon et al., \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e; Khan et al., \u003cspan class=\"CitationRef\"\u003e2023\u003c/span\u003e). FS2\u0026apos;s achievement in mitigating both diseases due to its capacity to generate more high antimicrobial components (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e) and high biofilm production by FS2 can improve bacterial root colonization (Horstmann et al., \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e). Our results showed that Streptomyces FS123 caused an increase in disease severity and the area under the disease progress curve (AUDPC) of Bean bacterial blight disease (CBB) and in a contradictory behavior significant decrease of Bean bacterial wilt (BW) disease (Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). The different behavior of this isolate could possibly have occurred for a variety of reasons. Proposed mechanism could be: 1) The increase in CBB severity may be due to the specific strains of Streptomyces producing antibiotics that are less effective against the pathogen causing CBB, or the CBB agent might possess resistance mechanisms to these compounds; 2) Streptomyces may elicit specific plant defense mechanisms that inadvertently enhance susceptibility to certain pathogens like the one causing CBB. This phenomenon, known as induced susceptibility, suggests that the plant\u0026rsquo;s immune system, while active against BW pathogens, may become less effective at combating CBB pathogens (Pieterse et al., \u003cspan class=\"CitationRef\"\u003e2014\u003c/span\u003e); 3) The presence of Streptomyces can change the microbial community dynamics within the rhizosphere or on leaf surfaces. This could potentially create a competitive environment that favors the BW pathogen while allowing the CBB pathogen to thrive, especially if nutrient availability is altered; 4) The interactions between the pathogens involved in CBB and BW could play a critical role; It\u0026rsquo;s possible that Streptomyces alters the interaction dynamics between these pathogens, leading to an increase in virulence for CBB pathogens while suppressing BW pathogens; 5) Within the communities of Streptomyces in soil ecosystems, comprehending the ramifications of interspecies signaling on the interactions among species, particularly concerning nutrient competition and antagonistic behaviors, could be crucial for the successful Streptomyces-mediated suppression of phytopathogens (Jauri, \u003cspan class=\"CitationRef\"\u003e2013\u003c/span\u003e); 6) Interactions with plants can inhibit natural plant defenses against pathogens (Vurukonda et al., \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e ) or negatively modulate plant defense and facilitate root colonization by pathogens (Schrey and Tarkka., 2008); 7) The possibility should also be considered that secondary metabolites, including antibiotics and siderophores synthesized by Streptomyces FS123, may interact with plant hormones and their respective signaling pathways. Such interactions could result in the attenuation of the plant\u0026apos;s salicylic acid (SA)-mediated defense mechanisms, thereby rendering it more vulnerable to the pathogen responsible for causing CBB. Ishiyama et al. (\u003cspan class=\"CitationRef\"\u003e2004\u003c/span\u003e) demonstrated that the Streptomyces WA46 metabolizes salicylate through a distinctive biochemical pathway involving a CoA derivative (Ishiyama et al. \u003cspan class=\"CitationRef\"\u003e2004\u003c/span\u003e). So, understanding these complex plant-bacteria interactions is crucial for developing effective management practices, as the dual behavior of Streptomyces FS123 can inform novel approaches to enhance crop resilience against bacterial diseases.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eMean comparison of CBB and BW disease severity index and the AUDPC in inoculated bean seeds planted in Streptomyces treated and not treated soil.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTreatment\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eDSI 10dpi\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eDSI 15dpi\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eAUDPC % (10\u0026ndash;15)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eXpp\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.800 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.800 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1150 b\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFs123\u0026thinsp;+\u0026thinsp;\u003cem\u003eXpp\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.833 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.667 a\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1625 a\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFs2\u0026thinsp;+\u0026thinsp;\u003cem\u003eXpp\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.000 d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.15 d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e37.5d\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eCff\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.000 b\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.250 c\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1062.5 bc\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFs123\u0026thinsp;+\u0026thinsp;\u003cem\u003eCff\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.300 d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.333 d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e158.2 d\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFs2\u0026thinsp;+\u0026thinsp;\u003cem\u003eCff\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.000 d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.100 d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25d\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003eSimilar letters in each column are not significantly different based on the Duncan Multiple Range test (p\u0026thinsp;\u0026le;\u0026thinsp;0.05).\u003c/p\u003e\n\u003cp\u003eEndophyte and epiphyte populations of \u003cem\u003eXpp\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e on common bean were measured 10, 20 and 27 days after sowing infected bean seed in the soil treated with the Streptomyces strains. The population density of \u003cem\u003eXpp\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e varied in stems and leaf tissue and showed different trends in endophytic and epiphytic situations (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). Endophyte and epiphyte survival of \u003cem\u003eXpp\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e on bean plants have been reported previously (Karavina et al., \u003cspan class=\"CitationRef\"\u003e2011\u003c/span\u003e; Osdaghi et al., \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e). Research exhibited that epiphytic populations can affect disease onset times (Weller \u0026amp; Saettler, \u003cspan class=\"CitationRef\"\u003e1980\u003c/span\u003e), but the endophytic population is responsible for disease induction. Multiplication of \u003cem\u003eXpp\u003c/em\u003e in the intercellular spaces showed a more prominent role in the occurrence of the disease and the emergence of disease symptoms (Karavina et al., \u003cspan class=\"CitationRef\"\u003e2011\u003c/span\u003e). The pathogen\u0026apos;s population was affected due to soil treatment with each of the Streptomyces strains (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). Our results showed that the changes of endophyte and epiphyte populations of \u003cem\u003eXpp\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e in untreated plants follow a nearly similar trend; Meanwhile, it has been affected after the treatment with FS2 and FS123, especially in endophyte situation. Although the Streptomyces treatment limited the growth rate of both pathogens, 27 days post inoculation (dpi), the high final log-transformed bacterial population was observed despite the lack of development of disease symptoms. It seems that the Streptomyces treatments have increased plant tolerance against diseases. Other research exhibited that plant inoculations with Streptomyces can increase plant tolerance due to the induction of systemic defence (Conn et al., \u003cspan class=\"CitationRef\"\u003e2008\u003c/span\u003e). Recent studies demonstrated that Streptomyces sp. DLS2013 stimulates the increased expression of defense mechanisms involving salicylic acid and jasmonic acids in tomato plants, leading to enhanced production of antimicrobial compounds (Bellameche et al., \u003cspan class=\"CitationRef\"\u003e2024\u003c/span\u003e, Cassanelli et al. \u003cspan class=\"CitationRef\"\u003e2025\u003c/span\u003e). Another research revealed that Streptomyces RFS-23 activates plant defence response against viral infections, promoting the expression of genes related to salicylic and abscisic acid biogenesis (Chen et al., \u003cspan class=\"CitationRef\"\u003e2022\u003c/span\u003e). Taha et al., \u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e found that Streptomyces LC597360 significantly increases the activity of defence-related enzymes against Tomato mosaic virus (Taha et al., \u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e). These studies show that induction mechanism can be in three clusters of transcriptional changes, systemic resistance and enzymatic activity.\u003c/p\u003e\n\u003cp\u003eIn tolerated conditions, active pathogen cells may survive as epiphytes or endophytes (in latent forms) with unapparent or symptomless infection (Hayward, \u003cspan class=\"CitationRef\"\u003e1974\u003c/span\u003e). Streptomyces treatments delayed the appearance of the symptoms and the onset of CBB and BW disease. These results were consistent with pathogens\u0026apos; population dynamics during the evaluation period (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003eTable 4 shows that soil treatments with Fs2 and Fs123 significantly affected the germination indices of studied \u003cem\u003eCff\u003c/em\u003e and\u0026nbsp;\u003cem\u003eXpp\u003c/em\u003e inoculated and non-inoculated seeds at the 1% probability level.\u003cbr\u003e\n \u003ctable id=\"Tab4\" border=\"1\"\u003e\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003c/p\u003e\n\u003ctable id=\"Tab5\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eAnalysis of variance (mean squared) of seed germination indices of \u003cem\u003ePhaseolus vulgaris\u003c/em\u003e after \u003cem\u003eCff\u003c/em\u003e and \u003cem\u003eXpp\u003c/em\u003e inoculated and non-inoculated seed sowing in treated soil with Streptomyces isolates Fs2 and Fs123.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSource\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eDF\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTotal length\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eRoot length\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eStem length\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTotal weight\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eRoot weight\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eStem weight\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTreatment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e982.043**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e32.115**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e686.202**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.216**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.120**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.789**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eError\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e32.552\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e8.246\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e20.680\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.073\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.010\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.059\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCV%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e14.853\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e21.509\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e18.173\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e18.045\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e19.465\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e20.348\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"8\"\u003e**: significant at the 1% probability level\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003eThe highest total seedling and stem lengths were assigned to treatment with Fs123, and the lowest value was assigned to Fs2\u0026thinsp;+\u0026thinsp;\u003cem\u003eXpp\u003c/em\u003e treatment. Regarding root length, except for the Fs2\u0026thinsp;+\u0026thinsp;\u003cem\u003eXpp\u003c/em\u003e treatment, which had the lowest value among the treatments, the other bacterial treatments were in the same group without significant differences. Seed treatment with \u003cem\u003eCff\u003c/em\u003e significantly increased root and stem weight more than other treatments and was nearly 1.2 times greater than untreated plants (Table \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e). Although many of \u003cem\u003eC. flaccumfaciens\u003c/em\u003e\u0026apos;s strains are phytopathogenic bacteria, some exhibit plant growth promotion potential and can increase the growth of host plants (Schillaci et al., \u003cspan class=\"CitationRef\"\u003e2022\u003c/span\u003e; Cardinale et al., \u003cspan class=\"CitationRef\"\u003e2015\u003c/span\u003e). \u003cem\u003eXpp\u003c/em\u003e treated seeds in the soil without Streptomyces, did not show any significant difference compared to the control (Table \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e) .\u003c/p\u003e\n\u003cp\u003e\u003c/p\u003e\n\u003ctable id=\"Tab6\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eComparison of average treatments for investigated plant growth traits.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTreatment\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTotal length\u003c/p\u003e\n \u003cp\u003e(g)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eRoot length (mm)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eStem length (mm)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTotal weight (g)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eRoot weight (g)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eStem weight (g)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eXpp\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e38.563\u003csup\u003ecd\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.906\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25.656 \u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.652\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.258\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.193\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFs123\u0026thinsp;+\u0026thinsp;\u003cem\u003eXpp\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e42.625\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.750\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e28.188\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.403\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.203\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.971\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFs2\u0026thinsp;+\u0026thinsp;\u003cem\u003eXpp\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.786\u003csup\u003ef\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.286\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.643\u003csup\u003ee\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.810 \u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.114 \u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.696 \u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eCff\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e41.467\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.967\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e28.500\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.925\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.349\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.475\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFs123\u0026thinsp;+\u0026thinsp;\u003cem\u003eCff\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e45.000\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.600\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30.500\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.420\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.233\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.187\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFs2\u0026thinsp;+\u0026thinsp;\u003cem\u003eCff\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e33.344\u003csup\u003ee\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.281\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e19.063\u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.334\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.280\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.054\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFs123\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e46.133\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.867\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30.267\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.636\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.294\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.311\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFs2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e35.333\u003csup\u003ede\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.917\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21.250\u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.588\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.323\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.083\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNot treatment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40.608\u003csup\u003eabc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.285\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e28.323\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.467\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.261\u003csup\u003ebc\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.206\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003eSimilar letters in each column are not significantly different based on the Duncan Multiple Range test (p\u0026thinsp;\u0026le;\u0026thinsp;0.05).\u003c/p\u003e\n\u003cp\u003ePlanting inoculated and non-inoculated seeds with \u003cem\u003eCff\u003c/em\u003e and \u003cem\u003eXpp\u003c/em\u003e (separately) in the soil treated with Fs123 isolate, showed no significant difference in any evaluated plant growth traits. Fs2 isolate decreases the stem length in non-inoculated seeds. Soil treatment with Fs2 successfully controlled CBB and BW disease in all experiments. However, it caused the most significant decrease in seedling length and weight of \u003cem\u003eXpp\u003c/em\u003e-infected plants, up to 68.2% and 50.03%, respectively, compared to the control. Our results showed a negative correlation between the effect of FS2 on plant growth and biocontrol efficacy. Studies revealed that high concentrations of some antimicrobial metabolites can negatively affect plant growth (Sharifi et al., \u003cspan class=\"CitationRef\"\u003e2019\u003c/span\u003e). Deising et al. (\u003cspan class=\"CitationRef\"\u003e2017\u003c/span\u003e) underscored the notion that although microbial secondary metabolites possess the capacity to augment plant resilience in the face of stressors, their excessive synthesis may result in deleterious effects, thereby jeopardizing plant health and growth (Deising et al., \u003cspan class=\"CitationRef\"\u003e2017\u003c/span\u003e). Worsley et al., \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e elucidated that the two Streptomyces strains, N1 and N2, decreased the \u003cem\u003eA. thaliana\u003c/em\u003e biomass due to their synthesis of polyenes that bind to sterols, including the plant cell wall phytosterols, which likely exerted an adverse effect on the plant. They show that not all Streptomyces strains that are competitive in the rhizosphere and endosphere necessarily have a beneficial effect on host fitness (Worsley et al., \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e). Also, some Streptomyces strains can produce factors that may indirectly harm plant tissues, despite their role in biocontrol; These factors include enzymes such as chitinases, pectinase or cellulases (Kumar et al., \u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e), which may help in competition against pathogens but can also disrupt plant cells if overproduced or misdirected. Meanwhile, in natural conditions the introduction of Streptomyces may change the soil microbial community structure, affecting beneficial microorganisms such as mycorrhizal fungi that are crucial for nutrient uptake. This shift can potentially reduce plant health and growth. Jin et al., \u003cspan class=\"CitationRef\"\u003e2024\u003c/span\u003e shown that the bacterial community residing on the surface of arbuscular mycorrhizal hyphae was in part regulated by Streptomyces (Jin et al., \u003cspan class=\"CitationRef\"\u003e2024\u003c/span\u003e). On the contrary, some research has clarified that the seedling growth index significantly correlated with the control capability of Streptomyces (Schrey and Tarkka, \u003cspan class=\"CitationRef\"\u003e2008\u003c/span\u003e).\u003c/p\u003e\n\u003cp\u003eAssessment of Streptomyce\u0026apos;s effect on plant growth indices and their biocontrol activity is crucial to prevent unintended disruptions in seed germination and plant growth. Streptomyces strains have shown significant potential in promoting plant growth and protecting against various pathogens (Hata et al., \u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e; Kaari et al., \u003cspan class=\"CitationRef\"\u003e2022\u003c/span\u003e; Faddetta et al., \u003cspan class=\"CitationRef\"\u003e2023\u003c/span\u003e; Wang et al., \u003cspan class=\"CitationRef\"\u003e2023\u003c/span\u003e). But, controlling plant disease with Streptomyces strains is associated with some challenges (Khan et al., \u003cspan class=\"CitationRef\"\u003e2023\u003c/span\u003e). However, their effects can vary depending on the strain and plant species. Various studies showed that Streptomyces treatments have improved seed germination index in rice (Hata et al., \u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e), tomato (Faddetta et al., \u003cspan class=\"CitationRef\"\u003e2023\u003c/span\u003e) and mustard (Wang et al., \u003cspan class=\"CitationRef\"\u003e2023\u003c/span\u003e). Nevertheless, it\u0026apos;s important to note that some studies have observed occasional transient adverse effects on germination and plant growth, although these effects did not persist during further development (Kunova et al., \u003cspan class=\"CitationRef\"\u003e2016\u003c/span\u003e). This highlights the importance of thorough assessment to identify strains that consistently provide benefits without causing harm. Additionally, the efficacy of Streptomyces as biocontrol agents can vary depending on the target pathogen and environmental conditions (Colombo et al., \u003cspan class=\"CitationRef\"\u003e2019\u003c/span\u003e). In conclusion, a comprehensive evaluation of Streptomyces strains is essential to select those with the most promising plant-growth-promoting and biocontrol properties while minimizing potential adverse effects. This ensures the development of effective and safe biological alternatives to chemical pesticides and fertilizers, contributing to sustainable agricultural practices (Umer et al., \u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e; Vurukonda et al., \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eBiocontrol agents isolated from the same habitat as the target pathogen might be more effective due to co-evolution. In this study, we aimed to highlight the effect of plant treatment with \u003cem\u003eStreptomyces\u003c/em\u003e strains FS2 and FS123, which were isolated from contaminated bean seeds with common bacterial blight (CBB) and bacterial wilt (BW) disease. This study provides insight into the antimicrobial activities of the Streptomyces strains against two seed-borne pathogens, \u003cem\u003eXpp\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e. Our investigation showed that the FS2 strain, with significant control of both pathogens, synthesized the metabolites that can negatively affect plant growth. Applying the Streptomyces strains delays disease onset and decreases the pathogen population in epiphyte and endophyte situations in treated plants. Metabolite production of FS2 and FS123 may contribute to the activation of plant defence mechanisms and lead to plant disease protection, which needs more study. Our data provide an informative basis for selecting novel biocontrol agents focusing on their effects on plant growth indices. The biocontrol potential of \u003cem\u003eStreptomyces murinus\u003c/em\u003e and \u003cem\u003eStreptomyces collinus\u003c/em\u003e on \u003cem\u003eXanthomonas phaseoli\u003c/em\u003e pv. \u003cem\u003ephaseoli\u003c/em\u003e and \u003cem\u003eCurtobacterium flaccumfaciens\u003c/em\u003e pv. \u003cem\u003eflaccumfaciens\u003c/em\u003e were investigated in this study for the first time. Based on our knowledge and findings, this marks a novel finding of \u003cem\u003eS. murinus\u003c/em\u003e in the biocontrol of bean Common bacterial blight and bacterial wilt disease. Streptomyces FS2 generated a variety of metabolites; thus, the precise roles of these metabolites in the biocontrol process warrant additional investigation. Identifying the appropriate Streptomyces strain that effectively targets a particular phytopathogen while preserving the growth indexes poses a significant challenge. Consequently, selecting and characterizing individual Streptomyces strains for potential use as microbial antagonists is crucial in sustainable food systems, circular economy and fighting global hunger. Meanwhile, investigating seed-microbial interactions in drought-resistant crops, such as legumes, can enhance the resilience of food systems in the face of climate change.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e\u003cp\u003eThe authors declare that they have no conflict of interest.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eEthics approval\u003c/strong\u003e\u003cp\u003eThis research does not contain any studies with human participants or animals performed by any of the authors\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eInformed consent\u003c/strong\u003e\u003cp\u003eNone\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e\u003cp\u003eThis present research was financially supported by Seed and Plant Certification and Registration Institute (SPCRI), Iran\u003c/p\u003e\u003ch2\u003eData availability\u003c/h2\u003e\u003cp\u003eThe datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAbbasi, S., Safaie, N., Sadeghi, A., \u0026amp; Shamsbakhsh, M. (2020). Tissue-specific synergistic bio-priming of pepper by two Streptomyces species against Phytophthora capsici. \u003cem\u003ePloS one\u003c/em\u003e, 15(3), e0230531.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAbdElgawad, H., Abuelsoud, W., Madany, M. M., Selim, S., Zinta, G., Mousa, A. S., \u0026amp; Hozzein, W. N. (2020). Actinomycetes enrich soil rhizosphere and improve seed quality as well as productivity of legumes by boosting nitrogen availability and metabolism. \u003cem\u003eBiomolecules\u003c/em\u003e, \u003cem\u003e10\u003c/em\u003e(12), 1675.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAhmad, E., Sharma, P. K., \u0026amp; Khan, M. S. (2022). IAA biosynthesis in bacteria and its role in plant-microbe interaction for drought stress management. \u003cem\u003ePlant Stress Mitigators: Action and Application\u003c/em\u003e (pp. 235\u0026ndash;258). Springer Nature Singapore.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAkbari, A., Gharanjik, S., Koobaz, P., \u0026amp; Sadeghi, A. (2020). Plant growth promoting Streptomyces strains are selectively interacting with the wheat cultivars especially in saline conditions. \u003cem\u003eHeliyon\u003c/em\u003e, \u003cem\u003e6\u003c/em\u003e(2).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBasson, A., Flemming, L. A., \u0026amp; Chenia, H. Y. (2008). Evaluation of adherence, hydrophobicity, aggregation, and biofilm development of Flavobacterium johnsoniae-like isolates. \u003cem\u003eMicrobial ecology\u003c/em\u003e, \u003cem\u003e55\u003c/em\u003e(1), 1\u0026ndash;14.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBehera, H. T., Mojumdar, A., Behera, S. S., Das, S., \u0026amp; Ray, L. (2022). Biocontrol of wilt disease of rice seedlings incited by Fusarium oxysporum through soil application of Streptomyces chilikensis RC1830. \u003cem\u003eLetters in Applied Microbiology\u003c/em\u003e, \u003cem\u003e75\u003c/em\u003e(5), 1366\u0026ndash;1382.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBellameche, F., Cassanelli, S., Caradonia, F., Cortiello, M., Perez, S., Stefani, E., \u0026amp; Giovanardi, D. (2024). Foliar application of a Streptomyces sp. on tomato plants: an insight into the induction of defence-related genes through RNA-Seq analysis. In: Abstracts of presentations at the XXIX Congress of the Italian Phytopathological Society. \u003cem\u003eJournal of Plant Pathology\u003c/em\u003e 106, 1423\u0026ndash;1534 (2024). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s42161-024-01752-7\u003c/span\u003e\u003cspan address=\"10.1007/s42161-024-01752-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBent, E., Tuzun, S., Chanway, C. P., \u0026amp; Enebak, S. (2001). Alterations in plant growth and in root hormone levels of lodgepole pines inoculated with rhizobacteria. \u003cem\u003eCanadian Journal of Microbiology\u003c/em\u003e, \u003cem\u003e47\u003c/em\u003e(9), 793\u0026ndash;800.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBoersma, J. G., Hou, A., Gillard, C. L., McRae, K. B., \u0026amp; Conner, R. L. (2015). Impact of common bacterial blight on the yield, seed weight and seed discoloration of different market classes of dry beans (Phaseolus vulgaris L). \u003cem\u003eCanadian Journal of Plant Science\u003c/em\u003e, \u003cem\u003e95\u003c/em\u003e(4), 703\u0026ndash;710.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBorkar, S. G. (2017). \u003cem\u003eLaboratory techniques in plant bacteriology\u003c/em\u003e. CRC.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCardinale, M., Ratering, S., Suarez, C., Montoya, A. M. Z., Geissler-Plaum, R., \u0026amp; Schnell, S. (2015). Paradox of plant growth promotion potential of rhizobacteria and their actual promotion effect on growth of barley (Hordeum vulgare L.) under salt stress. \u003cem\u003eMicrobiological research\u003c/em\u003e, \u003cem\u003e181\u003c/em\u003e, 22\u0026ndash;32.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCassanelli, S., Bellameche, F., Caradonia, F., Cortiello, M., Perez Fuentealba, S., \u0026amp; Giovanardi, D. (2025). Foliar application of Streptomyces sp. DLS2013 induces transcriptional changes on tomato plants and confers resistance to \u003cem\u003ePseudomonas syringae\u003c/em\u003e pv. \u003cem\u003etomato\u003c/em\u003e. \u003cem\u003eJournal of Plant Diseases and Protection\u003c/em\u003e, \u003cem\u003e132\u003c/em\u003e(1), 1\u0026ndash;20.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChen, D., Ali, M. N. H. A., Kamran, M., Magsi, M. A., Mora-Poblete, F., Maldonado, C., et al. (2022). The \u003cem\u003eStreptomyces chromofuscus\u003c/em\u003e Strain RFS-23 induces systemic resistance and activates plant defense responses against Tomato yellow leaf curl virus infection. \u003cem\u003eAgronomy\u003c/em\u003e, \u003cem\u003e12\u003c/em\u003e(10), 2419.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChen, N. W., Ruh, M., Darrasse, A., Foucher, J., Briand, M., Costa, J., et al. (2021). Common bacterial blight of bean: a model of seed transmission and pathological convergence. \u003cem\u003eMolecular Plant Pathology\u003c/em\u003e, \u003cem\u003e22\u003c/em\u003e(12), 1464\u0026ndash;1480.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eColombo, E. M., Kunova, A., Cortesi, P., Saracchi, M., \u0026amp; Pasquali, M. (2019). Critical assessment of Streptomyces spp. able to control toxigenic Fusaria in cereals: a literature and patent review. \u003cem\u003eInternational Journal of Molecular Sciences\u003c/em\u003e, \u003cem\u003e20\u003c/em\u003e(24), 6119.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eConn, V. M., Walker, A. R., \u0026amp; Franco, C. M. (2008). Endophytic actinobacteria induce defense pathways in Arabidopsis thaliana. \u003cem\u003eMolecular Plant-Microbe Interactions\u003c/em\u003e, \u003cem\u003e21\u003c/em\u003e, 208\u0026ndash;218.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCouillerot, O., Vatsa, P., Loqman, S., OuhdouchY, Jane, H., Renault, J-H., Cl\u0026eacute;ment, C., \u0026amp; Barka, E. A. (2013). Biocontrol and biofertilizer activities of the Streptomyces anulatus S37: an endophytic actinomycetewith biocontrol and plant- rowth promoting activities. \u003cem\u003eIOBC-WPRS Bull\u003c/em\u003e, \u003cem\u003e86\u003c/em\u003e, 271\u0026ndash;276.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDeising, H. B., Gase, I., \u0026amp; Kubo, Y. (2017). The unpredictable risk imposed by microbial secondary metabolites: how safe is biological control of plant diseases? \u003cem\u003eJournal of Plant Diseases and Protection\u003c/em\u003e, \u003cem\u003e124\u003c/em\u003e, 413\u0026ndash;419.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDworkin, M., \u0026amp; Foster, J. (1958). Experiments with some microorganisms which utilize ethane and hydrogen. \u003cem\u003eJournal Of Bacteriology\u003c/em\u003e, \u003cem\u003e75\u003c/em\u003e, 592\u0026ndash;603.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eEbrahimi-Zarandi, M., Riseh, S., R., \u0026amp; Tarkka, M. T. (2022). Actinobacteria as effective biocontrol agents against plant pathogens, an overview on their role in eliciting plant defense. \u003cem\u003eMicroorganisms\u003c/em\u003e, \u003cem\u003e10\u003c/em\u003e(9), 1739.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFaddetta, T., Polito, G., Abbate, L., Alibrandi, P., Zerbo, M., Caldiero, C., Reina, C., Puccio, G., Vaccaro, E., Abenavoli, M. R., \u0026amp; Cavalieri, V. (2023). Bioactive metabolite survey of actinobacteria showing plant growth promoting traits to develop novel biofertilizers. Metabolites, 13(3), p.374.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGebily, D. A., Ghanem, G. A., Ragab, M. M., et al. (2021). Characterization and potential antifungal activities of three Streptomyces spp. as biocontrol agents against Sclerotinia sclerotiorum (Lib.) de Bary infecting green bean. \u003cem\u003eEgyptian Journal of Biological Pest Control\u003c/em\u003e, \u003cem\u003e31\u003c/em\u003e, 1\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGoodrich, J. K., Di Rienzi, S. C., Poole, A. C., et al. (2014). Conducting a microbiome study. \u003cem\u003eCell\u003c/em\u003e, \u003cem\u003e158\u003c/em\u003e(2), 250\u0026ndash;262.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGoudjal, Y., Toumatia, O., Sabaou, N., Barakate, M., Mathieu, F., \u0026amp; Zitouni, A. (2013). Endophytic actinomycetes from spontaneous plants of Algerian Sahara: indole-3-acetic acid production and tomato plants growth promoting activity. \u003cem\u003eWorld Journal of Microbiology and Biotechnology\u003c/em\u003e, \u003cem\u003e29\u003c/em\u003e, 1821\u0026ndash;1829.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHata, E. M., Yusof, M. T., \u0026amp; Zulperi, D. (2021). Induction of systemic resistance against bacterial leaf streak disease and growth promotion in rice plant by Streptomyces shenzhenesis TKSC3 and Streptomyces sp. SS8. \u003cem\u003eThe plant pathology journal\u003c/em\u003e, \u003cem\u003e37\u003c/em\u003e(2), 173.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHayward, A. C. (1974). Latent infections by bacteria. \u003cem\u003eAnnual Review of Phytopathology\u003c/em\u003e, \u003cem\u003e12\u003c/em\u003e(1), 87\u0026ndash;97.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHorstmann, J. L., Dias, M. P., Ortolan, F., Medina-Silva, R., Astarita, L. V., \u0026amp; Santar\u0026eacute;m, E. R. (2020). Streptomyces sp. CLV45 from Fabaceae rhizosphere benefits growth of soybean plants. \u003cem\u003eBrazilian Journal of Microbiology\u003c/em\u003e, \u003cem\u003e51\u003c/em\u003e, 1861\u0026ndash;1871.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHtwe, A. Z., Moh, S. M., Soe, K. M., Moe, K., \u0026amp; Yamakawa, T. (2019). Effects of biofertilizer produced from \u003cem\u003ebradyrhizobium\u003c/em\u003e and \u003cem\u003estreptomyces griseoflavus\u003c/em\u003e on plant growth, nodulation, nitrogen fixation, nutrient uptake, and seed yield of mung bean, cowpea, and soybean. Agronomy. 9, 77. 10.3390/ agronomy9020077\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eIshiyama, D., Vujaklija, D., \u0026amp; Davies, J. (2004). Novel pathway of salicylate degradation by \u003cem\u003eStreptomyces\u003c/em\u003e sp. strain WA46. \u003cem\u003eApplied and environmental microbiology\u003c/em\u003e, \u003cem\u003e70\u003c/em\u003e(3), 1297\u0026ndash;1306.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJaemsaeng, R., Jantasuriyarat, C., \u0026amp; Thamchaipenet, A. (2018). Molecular interaction of 1-aminocyclopropane- -carboxylate deaminase (ACCD)-producing endophytic Streptomyces sp. GMKU 336 towards salt-stress resistance of Oryza sativa L. cv. KDML105. \u003cem\u003eScientific Reports\u003c/em\u003e, \u003cem\u003e8\u003c/em\u003e(1), 1950.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJauri, P. V. (2013). Ecology of interspecies signaling among Streptomyces and its relationship to pathogen suppression (Doctoral dissertation, University of Minnesota). 95 p.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJin, Z., Jiang, F., Wang, L., Declerck, S., Feng, G., \u0026amp; Zhang, L. (2024). Arbuscular mycorrhizal fungi and Streptomyces: brothers in arms to shape the structure and function of the hyphosphere microbiome in the early stage of interaction. \u003cem\u003eMicrobiome\u003c/em\u003e, \u003cem\u003e12\u003c/em\u003e(1), 83.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJones, S. E., \u0026amp; Elliot, M. A. (2017). Streptomyces exploration: competition, volatile communication and new bacterial behaviors. \u003cem\u003eTrends in microbiology\u003c/em\u003e, \u003cem\u003e25\u003c/em\u003e(7), 522\u0026ndash;531.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKaari, M., Joseph, J., Manikkam, R., Sreenivasan, A., \u0026amp; Venugopal, G. (2022). Biological control of Streptomyces sp. UT4A49 to suppress tomato bacterial wilt disease and its metabolite profiling. \u003cem\u003eJournal of King Saud University-Science\u003c/em\u003e, \u003cem\u003e34\u003c/em\u003e(1), 101688.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKang, Y. S., Lee, Y., Cho, S. K., Lee, K. H., Kim, B. J., Kim, M., \u0026amp; Cho, M. (2009). Antibacterial activity of a disaccharide isolated from Streptomyces sp. strain JJ45 against Xanthomonas sp. \u003cem\u003eFEMS microbiology letters\u003c/em\u003e, \u003cem\u003e294\u003c/em\u003e(1), 119\u0026ndash;125.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKaravina, C., Mandumbu, R., Parwada, C., \u0026amp; Tibugari, H. (2011). A review of the occurrence, biology and management of common bacterial blight. \u003cem\u003eJournal of Agricultural Technology\u003c/em\u003e, \u003cem\u003e7\u003c/em\u003e(6), 1459\u0026ndash;1474.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKhan, S., Srivastava, S., Karnwal, A., \u0026amp; Malik, T. (2023). Streptomyces as a promising biological control agents for plant pathogens. \u003cem\u003eFrontiers in Microbiology\u003c/em\u003e, \u003cem\u003e14\u003c/em\u003e, 1285543.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKlaedtke, S. M., Barret, M., Chable, V., \u0026amp; Jacques, A. (2014). Microbial communities associated to common bean seed; A mechanism of local adaptation of plants. \u003cem\u003eIn\u003c/em\u003e: Book of Abstracts for International Congress on diversity strategies for organic and low input agriculture and their food systems, p. 103.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKumar, M., Kumar, P., Das, P., Solanki, R., \u0026amp; Kapur, M. K. (2020). Potential applications of extracellular enzymes from Streptomyces spp. in various industries. \u003cem\u003eArchives of Microbiology\u003c/em\u003e, \u003cem\u003e202\u003c/em\u003e, 1597\u0026ndash;1615.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKunova, A., Bonaldi, M., Saracchi, M., Pizzatti, C., Chen, X., \u0026amp; Cortesi, P. (2016). Selection of Streptomyces against soil borne fungal pathogens by a standardized dual culture assay and evaluation of their effects on seed germination and plant growth. \u003cem\u003eBMC microbiology\u003c/em\u003e, \u003cem\u003e16\u003c/em\u003e, 1\u0026ndash;11.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLing, L., Han, X., Li, X., et al. (2020). A Streptomyces sp. NEAU- V9: isolation, identification, and potential as a biocontrol agent against Ralstonia solanacearum of tomato plants. \u003cem\u003eMicroorganisms\u003c/em\u003e, \u003cem\u003e8\u003c/em\u003e(3), 351.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLiu, G., Chater, K. F., Chandra, G., Niu, G., \u0026amp; Tan, H. (2013). Molecular regulation of antibiotic biosynthesis in Streptomyces. \u003cem\u003eMicrobiology and molecular biology reviews\u003c/em\u003e, \u003cem\u003e77\u003c/em\u003e(1), 112\u0026ndash;143.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMajumdar, S., \u0026amp; Chakraborty, U. (2017). Optimization of protease production from plant growth promoting \u003cem\u003eBacillus amyloliquefaciens\u003c/em\u003e showing antagonistic activity against phytopathogens. \u003cem\u003eInt J Pharm Bio Sci\u003c/em\u003e, \u003cem\u003e8\u003c/em\u003e(2), 635\u0026ndash;642.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMedie, F. M., Davies, G. J., Drancourt, M., \u0026amp; Henrissat, B. (2012). Genome analyses highlight the different biological roles of cellulases. \u003cem\u003eNature Reviews Microbiology\u003c/em\u003e, \u003cem\u003e10\u003c/em\u003e(3), 227\u0026ndash;234.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMunene, L., Mugweru, J., \u0026amp; Mwirichia, R. (2023). Management of bacterial wilt caused by \u003cem\u003eCurtobacterium flaccumfaciens\u003c/em\u003e pv. \u003cem\u003eflaccumfaciens\u003c/em\u003e in common bean (\u003cem\u003ePhaseolus vulgaris\u003c/em\u003e) using rhizobacterial biocontrol agents. \u003cem\u003eLetters in Applied Microbiology\u003c/em\u003e, \u003cem\u003e76\u003c/em\u003e(1), ovac011.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNarayan, R., \u0026amp; Gupta, N. C. (2018). Isolation, cultural and physiological characterisation of Azospirillum from acidic soils of Ranchi. \u003cem\u003eJournal of Pharmacognosy and Phytochemistry\u003c/em\u003e, \u003cem\u003e7\u003c/em\u003e(4), 2611\u0026ndash;2617.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNazari, M. T., Schommer, V. A., Braun, J. C. A. (2023). Using Streptomyces spp. as plant growth promoters and biocontrol agents. \u003cem\u003eRhizosphere\u003c/em\u003e, 100741.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNelson, E. B. (2018). The seed microbiome: origins, interactions, and impacts. \u003cem\u003ePlant and Soil\u003c/em\u003e, \u003cem\u003e422\u003c/em\u003e, 7\u0026ndash;34.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOlanrewaju, O. S., \u0026amp; Babalola, O. O. (2019). Streptomyces: implications and interactions in plant growth promotion. \u003cem\u003eApplied microbiology and biotechnology\u003c/em\u003e, \u003cem\u003e103\u003c/em\u003e, 1179\u0026ndash;1188.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOsdaghi, E., Taghavi, S. M., Hamzehzarghani, H., \u0026amp; Lamichhane, J. R. (2016). Occurrence and Characterization of the Bacterial Spot Pathogen X anthomonas euvesicatoria on Pepper in Iran. \u003cem\u003eJournal of Phytopathology\u003c/em\u003e, \u003cem\u003e164\u003c/em\u003e(10), 722\u0026ndash;734.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOsdaghi, E., Taghavi, S. M., Hamzehzarghani, H., Fazliarab, A., Harveson, R. M., Tegli, S., \u0026amp; Lamichhane, J. R. (2018). Epiphytic Curtobacterium flaccumfaciens strains isolated from symptomless solanaceous vegetables are pathogenic on leguminous but not on solanaceous plants. \u003cem\u003ePlant Pathology\u003c/em\u003e, \u003cem\u003e67\u003c/em\u003e(2), 388\u0026ndash;398.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOsdaghi, E., Young, A. J., \u0026amp; Harveson, R. M. (2020). Bacterial wilt of dry beans caused by Curtobacterium flaccumfaciens pv. flaccumfaciens: A new threat from an old enemy. \u003cem\u003eMolecular plant pathology\u003c/em\u003e, \u003cem\u003e21\u003c/em\u003e(5), 605\u0026ndash;621.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGitaitis, R., \u0026amp; Walcott, R. (2007). The epidemiology and management of seedborne bacterial diseases. \u003cem\u003eAnnual Review Of Phytopathology\u003c/em\u003e, \u003cem\u003e45\u003c/em\u003e, 371\u0026ndash;397.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePenrose, D. M., \u0026amp; Glick, B. R. (2003). Methods for isolating and characterizing ACC deaminase-containing plant growth-promoting rhizobacteria. \u003cem\u003ePhysiologia Plantarum\u003c/em\u003e, \u003cem\u003e118\u003c/em\u003e, 10\u0026ndash;15. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1034/j.1399-3054.2003.00086.x\u003c/span\u003e\u003cspan address=\"10.1034/j.1399-3054.2003.00086.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePerry, G., \u0026amp; Pauls, K. P. (2012). Common bacterial blight in Phaseolus vulgaris. \u003cem\u003eAgricultural Research Updates\u003c/em\u003e, \u003cem\u003e2\u003c/em\u003e(1), 239\u0026ndash;264.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePhitsuwan, P., Laohakunjit, N., Kerdchoechuen, O., Kyu, K. L., \u0026amp; Ratanakhanokchai, K. (2013). Present and potential applications of cellulases in agriculture, biotechnology, and bioenergy. \u003cem\u003eFolia microbiologica\u003c/em\u003e, \u003cem\u003e58\u003c/em\u003e, 163\u0026ndash;176.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePieterse, C. M., Zamioudis, C., Berendsen, R. L., et al. (2014). Induced systemic resistance by beneficial microbes. \u003cem\u003eAnnual review of phytopathology\u003c/em\u003e, \u003cem\u003e52\u003c/em\u003e(1), 347\u0026ndash;375.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRademaker, J., \u0026amp; Bruijn, F. (1997). Characterization and classification of microbes by repPCR genomic fingerprinting and computer assisted pattern analysis. In G. Caetano-Anolles, \u0026amp; P. Gresshoff (Eds.), \u003cem\u003eDNA markers: Protocols, Applications and Overviews\u003c/em\u003e (pp. 151\u0026ndash;171). John Wiley \u0026amp; Sons, Inc.. \u003cem\u003eIn\u003c/em\u003e:.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRybakova, D., Mancinelli, R., Wikstr\u0026ouml;m, M., et al. (2017). The structure of the Brassica napus seed microbiome is cultivar-dependent and affects the interactions of symbionts and pathogens. \u003cem\u003eMicrobiome\u003c/em\u003e, \u003cem\u003e5\u003c/em\u003e, 1\u0026ndash;16.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSadeghi, A., Koobaz, P., Azimi, H., Karimi, E., \u0026amp; Akbari, A. R. (2017). Plant growth promotion and suppression of Phytophthora drechsleri damping-off in cucumber by cellulase-producing Streptomyces. \u003cem\u003eBioControl\u003c/em\u003e, \u003cem\u003e62\u003c/em\u003e, 805\u0026ndash;819.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSammer, U. F., \u0026amp; Reiher, K. (2012). Curtobacterium flaccumfaciens pv. flaccumfaciens on soybean in Germany\u0026ndash; threat for farming. \u003cem\u003eJournal of Phytopathology\u003c/em\u003e, \u003cem\u003e160\u003c/em\u003e(6), 314\u0026ndash;316.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSchaad, N. W., Jones, J. B., \u0026amp; Chun, W. (2001). \u003cem\u003eLaboratory guide for the identification of plant pathogenic bacteria\u003c/em\u003e (Vol. 3No. Ed.). American Phytopathological Society (APS.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSchillaci, M., Raio, A., Sillo, F. (2022). \u003cem\u003ePseudomonas\u003c/em\u003e and \u003cem\u003eCurtobacterium\u003c/em\u003e strains from olive rhizosphere characterized and evaluated for plant growth promoting traits. \u003cem\u003ePlants\u003c/em\u003e, \u003cem\u003e11\u003c/em\u003e(17), 2245.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSchrey, S. D., \u0026amp; Tarkka, M. T. (2008). Friends and foes: streptomycetes as modulators of plant disease and symbiosis. \u003cem\u003eAntonie Van Leeuwenhoek\u003c/em\u003e, \u003cem\u003e94\u003c/em\u003e, 11\u0026ndash;19.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSharifi, R., Kiani, H., Ahmadzadeh, M., \u0026amp; Behboudi, K. (2019). Optimization of acetoin production by biological control strain Bacillus Subtilis\u0026lrm; GB03 using statistical experimental design. \u003cem\u003eBiological Journal of Microorganism\u003c/em\u003e, \u003cem\u003e8\u003c/em\u003e(32), 47\u0026ndash;57.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSharma, A., Gautam, S., \u0026amp; Saxena, S. (2014). Streptomyces. In C. A. Batt, \u0026amp; R. K. Robinson (Eds.), \u003cem\u003eEncyclopedia of food microbiology\u003c/em\u003e (Vol. 3, pp. 560\u0026ndash;566). Elsevier.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShirokikh, I. G., Osterman, I. A., Lukianov, D. A., et al. (2023). Biocontrol Potential of Novel Borrelidin-Producing Streptomyces rochei 3IZ-6 Isolated from Soil. \u003cem\u003eEurasian Soil Science\u003c/em\u003e, \u003cem\u003e56\u003c/em\u003e(5), 619\u0026ndash;627.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSorroche, F. G., Spesia, M. B., Zorreguieta, \u0026Aacute;., \u0026amp; Giordano, W. (2012). A positive correlation between bacterial autoaggregation and biofilm formation in native Sinorhizobium meliloti isolates from Argentina. \u003cem\u003eApplied and environmental microbiology\u003c/em\u003e, \u003cem\u003e78\u003c/em\u003e(12), 4092\u0026ndash;4101.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSousa, J., \u0026amp; Olivares, F. (2016). Plant growth promotion by Streptomycetes: ecophysiology, mechanisms and applications. \u003cem\u003eChemical and Biological Technologies in Agriculture\u003c/em\u003e, \u003cem\u003e3\u003c/em\u003e(24), 1\u0026ndash;12.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSuwitchayanon, P., Chaipon, S., Chaichom, S., \u0026amp; Kunasakdakul, K. (2018). Potentials of Streptomyces rochei ERY1 as an endophytic actinobacterium inhibiting damping-off pathogenic fungi and growth promoting of abbage seedling. \u003cem\u003eChiang Mai J Sci\u003c/em\u003e, \u003cem\u003e45\u003c/em\u003e, 692\u0026ndash;700.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTaha, M., Ghaly, M., Atwa, H., \u0026amp; Askoura, M. (2021). Evaluation of the effectiveness of soil Streptomyces isolates for induction of plant resistance against Tomato mosaic virus (ToMV). \u003cem\u003eCurrent Microbiology\u003c/em\u003e, \u003cem\u003e78\u003c/em\u003e(8), 3032\u0026ndash;3043.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eThakur, R., \u0026amp; Yadav, S. (2023). Thermotolerant and halotolerant Streptomyces sp. isolated from Ajuga parviflora having biocontrol activity against Pseudomonas syringae and Xanthomonas campestris acts as a sustainable bioadditive in growth promotion of Cicer arietinum. \u003cem\u003ePhysiological and Molecular Plant Pathology\u003c/em\u003e, \u003cem\u003e127\u003c/em\u003e, 102059.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eToussaint, V., Benoit, D. L., \u0026amp; Carisse, O. (2012). Potential of weed species to serve as a reservoir for Xanthomonas campestris pv. vitians, the causal agent of bacterial leaf spot of lettuce. \u003cem\u003eCrop Protection\u003c/em\u003e, \u003cem\u003e41\u003c/em\u003e, 64\u0026ndash;70.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eUmer, M., Mubeen, M., Iftikhar, Y., Shad, M. A., Usman, H. M., Sohail, M. A., Atiq, M. N., Abbas, A., \u0026amp; Ateeq, M. (2021). \u003cem\u003eRole of Rhizobacteria on plants growth and biological control of plant diseases: A review\u003c/em\u003e (Vol. 5, pp. 59\u0026ndash;73). Plant Prot.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eViaene, T., Langendries, S., Beirinckx, S., Maes, M., \u0026amp; Goormachtig, S. (2016). Streptomyces as a plant's best friend? \u003cem\u003eFEMS microbiology ecology\u003c/em\u003e, \u003cem\u003e92\u003c/em\u003e(8), fiw119.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eVurukonda, S. S. K. P., Giovanardi, D., \u0026amp; Stefani, E. (2018). Plant growth promoting and biocontrol activity of Streptomyces spp. as endophytes. \u003cem\u003eInternational journal of molecular sciences\u003c/em\u003e, \u003cem\u003e19\u003c/em\u003e(4), 952.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWalpola, B. C., \u0026amp; Yoon, M. H. (2012). Prospectus of phosphate solubilizing microorganisms and phosphorus availability in agricultural soils: a review. \u003cem\u003eAfr J Microbiol Res\u003c/em\u003e, \u003cem\u003e6\u003c/em\u003e, 6600\u0026ndash;6605. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.5897/AJMR12.889\u003c/span\u003e\u003cspan address=\"10.5897/AJMR12.889\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWalters, D. R., Ratsep, J., \u0026amp; Havis, N. D. (2013). Controlling crop diseases using induced resistance: challenges for the future. \u003cem\u003eJournal of experimental botany\u003c/em\u003e, \u003cem\u003e64\u003c/em\u003e(5), 1263\u0026ndash;1280.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWar, A. F., Bashir, I., Reshi, Z. A., Kardol, P., \u0026amp; Rashid, I. (2023). Insights into the seed microbiome and its ecological significance in plant life. \u003cem\u003eMicrobiological Research\u003c/em\u003e, \u003cem\u003e269\u003c/em\u003e, 127318.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWeller, D. M., \u0026amp; Saettler, A. W. (1980). Colonization and Distribution of \u003cem\u003eXanthomonas phaseoli\u003c/em\u003e in field-grown navy beans. \u003cem\u003ePhytopathology\u003c/em\u003e, \u003cem\u003e70\u003c/em\u003e, 500\u0026ndash;506.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWilson, D. B. (2008). Three microbial strategies for plant cell wall degradation. \u003cem\u003eAnnals of the New York Academy of Sciences\u003c/em\u003e, \u003cem\u003e1125\u003c/em\u003e(1), 289\u0026ndash;297.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWang, Z., Gao, C., Yang, J., Du, R., Zeng, F., Bing, H., Xia, B., Shen, Y., \u0026amp; Liu, C. (2023). Endophytic Streptomyces sp. NEAU-ZSY13 from the leaf of Perilla frutescens, as a promising broad-spectrum biocontrol agent against soil-borne diseases. \u003cem\u003eFrontiers in Microbiology\u003c/em\u003e, \u003cem\u003e14\u003c/em\u003e, 1243610.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWorsley, S. F., Newitt, J., Rassbach, J., et al. (2020). Streptomyces endophytes promote host health and enhance growth across plant species. \u003cem\u003eApplied and Environmental Microbiology\u003c/em\u003e, \u003cem\u003e86\u003c/em\u003e(16), e01053\u0026ndash;e01020.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Footnotes","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003e The area under the disease progress curve\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-plant-pathology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejpp","sideBox":"Learn more about [European Journal of Plant Pathology](http://link.springer.com/journal/10658)","snPcode":"10658","submissionUrl":"https://www.editorialmanager.com/ejpp/default2.aspx","title":"European Journal of Plant Pathology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Xanthomonas phaseoli pv. phaseoli, Curtobacterium flaccumfaciens pv. flaccumfaciens, Plant growth-promoting Streptomycetes, Phaseolus vulgaris, Common bacterial blight, Bacterial wilt","lastPublishedDoi":"10.21203/rs.3.rs-7967969/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7967969/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cem\u003ePhaseolus vulgaris\u003c/em\u003e L. (Common bean) is the most important legume for direct consumption worldwide and a leading food used to fight global hunger. The seed-borne bacterial pathogens, \u003cem\u003eXanthomonas phaseoli\u003c/em\u003e pv. \u003cem\u003ephaseoli\u003c/em\u003e (\u003cem\u003eXpp\u003c/em\u003e) and \u003cem\u003eCurtobacterium flaccumfaciens\u003c/em\u003e pv. \u003cem\u003eflaccumfaciens\u003c/em\u003e (\u003cem\u003eCff\u003c/em\u003e) are considered an important constraint in crop production. Certain strains of \u003cem\u003eStreptomyces\u003c/em\u003e exhibit the ability to inhibit pathogenic bacteria, attributed to their production of various antimicrobial compounds. The \u003cem\u003eStreptomyces\u003c/em\u003e FS2 and FS123 strains that exhibited high similarity with \u003cem\u003eStreptomyces murinus\u003c/em\u003e and \u003cem\u003eStreptomyces collinus\u003c/em\u003e based on 16S rRNA gene sequences were isolated from bean seeds, and antibacterial activities against the \u003cem\u003eXpp\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e and also their effects on seedling growth index were investigated in this study. Both FS2 and FS123 strains successfully inhibit the growth of the \u003cem\u003eXpp\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e in the zone of inhibition test. Assessments under greenhouse conditions exhibited strain FS123 with a dual behavior increase in disease severity and the area under the disease progress curve (AUDPC) of common bacterial blight disease (CBB) and a significant decrease of bacterial wilt (BW) disease. Our experiments showed that treating bean seeds with FS2 strain protects against both seed-borne diseases. We found that the pathogens population is affected due to plant treatment with the \u003cem\u003eStreptomyces\u003c/em\u003e strains, especially in leaf tissues and endophytic situations. Also, the FS2 strain demoted plant growth despite the disease suppression. The total length of plantlets decreased by 68.52% and 17.89%, and total weights decreased by 44.79% and 10%, respectively, in FS2\u0026thinsp;+\u0026thinsp;\u003cem\u003eXpp\u003c/em\u003e and FS2\u0026thinsp;+\u0026thinsp;\u003cem\u003eCff\u003c/em\u003e treatment. Our results demonstrate the interesting biocontrol potential of the \u003cem\u003eStreptomyces\u003c/em\u003e strains in bean protection against \u003cem\u003eXpp\u003c/em\u003e and \u003cem\u003eCff\u003c/em\u003e pathogens and open up promising perspectives for controlling these seed-borne diseases. However, attention to the damaging effect of the \u003cem\u003eStreptomyces\u003c/em\u003e strains towards plant growth is crucial before introducing biocontrol materials.\u003c/p\u003e","manuscriptTitle":"From Seed to Savior: Understanding the Biocontrol Abilities of Seed-Derived Streptomyces Strains against Seed borne Bean Bacterial Diseases","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-28 12:18:46","doi":"10.21203/rs.3.rs-7967969/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major revisions","date":"2026-02-17T00:17:18+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2025-11-25T03:32:20+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-11-24T23:00:13+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"European Journal of Plant Pathology","date":"2025-11-14T02:27:06+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-11-12T13:22:33+00:00","index":"","fulltext":""},{"type":"submitted","content":"European Journal of Plant Pathology","date":"2025-11-08T01:21:06+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-plant-pathology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejpp","sideBox":"Learn more about [European Journal of Plant Pathology](http://link.springer.com/journal/10658)","snPcode":"10658","submissionUrl":"https://www.editorialmanager.com/ejpp/default2.aspx","title":"European Journal of Plant Pathology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"977f90e9-b27a-4369-a456-001580b12a31","owner":[],"postedDate":"November 28th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-18T11:13:13+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-28 12:18:46","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7967969","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7967969","identity":"rs-7967969","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}