Epiphytic bacteria from Tacinga inamoena (K. Schum.) N.P. Taylor & Stuppy improve plant growth in cucumber seedlings

Epiphytic bacteria from Tacinga inamoena (K. Schum.) N.P. Taylor & Stuppy improve plant growth in cucumber seedlings | 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 Epiphytic bacteria from Tacinga inamoena (K. Schum.) N.P. Taylor & Stuppy improve plant growth in cucumber seedlings Ellie José Pereira, Vinícius Souza, Caliane Silva Braulio, Adailson Feitoza Jesus Santos This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7935575/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 03 Mar, 2026 Read the published version in International Microbiology → Version 1 posted 9 You are reading this latest preprint version Abstract Under stress conditions, the phyllosphere of host plants harbors microorganisms with potential for the development of agricultural bioinputs. In this study, the potential of Brevibacillus sp. UPT4 and Pantoea sp. SPM1, two epiphytic strains from Tacinga inamoena isolated from the Caatinga biome, was assessed through in vitro assays and a greenhouse experiment. The experiment was conducted in a randomized block design with four treatments (individual strains, bacterial consortium, and control) and five replicates. Biometric parameters (shoot and root length, stem diameter, root volume, and biomass allocation to shoot and root) were measured and analyzed by the Scott-Knott test at a probability level of 5%, as well as Redundancy Analysis (RDA). The strains exhibited auxin production, nitrogen fixation, and tolerance to abiotic stresses, showing significant increases (p < 0.05) in shoot and root parameters (13.58% to 194.86%) compared to the control. RDA indicated that most of the variability observed in the parameters was associated with auxin production and stress tolerance. These findings highlight the potential of epiphytic bacteria isolated from the Caatinga biome as promising tools to address challenges posed by climate change. Agriculture Bioinputs Caatinga Crops Phyllosphere Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction The rapid growth of the global population poses significant challenges to food security, with projections estimating approximately 10 billion inhabitants by 2050. It is anticipated that population expansion, combined with changes in consumption patterns and increased per capita income, will raise global food demand by around 44% (OECD-FAO 2024; Sands et al. 2023 ). Concurrently, economic and territorial conflicts, together with the escalating climate crisis, exacerbate global food insecurity (Safi et al. 2024 ; Marson and Sacconel 2023). In Brazil, vegetable production plays a strategic role in food security. Within this context, cucumber ( Cucumis sativus L.) stands out due to its high domestic demand and market acceptance, despite its pronounced susceptibility to phytopathogens and adverse environmental conditions. This susceptibility often leads to the intensive use of chemical pesticides and fertilizers to ensure crop productivity (Mallick 2022 ). However, the indiscriminate application of these inputs negatively affects soil and water quality, generates toxic residues in the environment, and disrupts the composition and dynamics of microbial communities associated with crops (Kaur and Sharma 2022). In this scenario, biofertilizers based on plant growth-promoting bacteria (PGPB) emerge as promising tools for developing ecologically sustainable agriculture in the face of climate change. These microorganisms act through multiple mechanisms, including phytohormone production, biological nitrogen fixation (BNF), nutrient solubilization, and induction of systemic resistance (ISR), thereby supporting crop development under stress conditions (Srivastava and Joshih 2021 ; Bahloul 2021 ; Shahwayr et al. 2023; Alzate Zuluaga et al. 2024 ). Plants naturally exposed and adapted to conditions of water scarcity and high solar radiation, such as Cactaceae species, may harbor in their phyllosphere microbial communities resilient to environmental adversities (Liu et al. 2023 ; Flores-Nuñez et al. 2024). Studies have demonstrated the potential of these microorganisms to promote the growth of various agricultural crops, integrating innovative approaches for the development of new agricultural technologies (Devarajan et al. 2021 ; Sharath et al. 2021 ; Agbodiato and Babalola 2024; Khosravi et al. 2024 ). Thus, to contribute to the development of efficient biostimulants and foster sustainable agricultural practices, this study aimed to evaluate the effects of phyllosphere bacteria from Tacinga inamoena (K. Schum.) N.P. Taylor & Stuppy on the vegetative growth of cucumber seedlings. Materials and methods Microorganisms Brevibacillus sp. UPT4 and Pantoea sp. SPM1 were isolated from the surface of T. inamoena cladodes and deposited in the microbial collection of the Laboratory of Microbial Ecology and Biotechnology of the Semi-Arid Region, State University of Bahia (LEBIMS – UNEB), Paulo Afonso, Bahia state, Brazil. Brevibacillus sp. UPT4 was isolated in Serra do Umbuzeiro (Latitude: − 9.58103091088262; Longitude: − 38.2047843933105), Paulo Afonso, Bahia state, Brazil. Pantoea sp. SPM1 was isolated in Environmental Protection Area Serra Branca (Latitude: − 9.945193254158575; Longitude: − 38.57322551035467), located in the municipality of Jeremoabo, Bahia state, Brazil. Evaluation of plant growth-promoting potential and tolerance to abiotic stresses Indole-3-acetic acid (IAA) production Bacterial cultures (OD 600nm = 0.3) were inoculated into tryptic soy broth (TSB) supplemented with L-tryptophan (5 mM) and incubated under constant agitation (150 rpm) at 28 ± 2°C for 72 h. Cultures were centrifuged at 10,000 rpm for 10 min, and the cell-free supernatant was transferred to tubes containing Salkowski reagent (2% FeCl₃ in 35% HClO₄) (1:1), following Gordon and Weber ( 1951 ). The mixture was incubated in the dark for 30 min, and IAA concentration was determined spectrophotometrically at 530 nm, using a standard curve of IAA. Asymbiotic nitrogen fixation Bacterial cultures (OD 600nm = 0.3) were inoculated into tubes containing semi-solid nitrogen-free Burk’s medium (Wilson and Knight 1952 ) with the following composition (g L⁻¹): glucose (10), agar (1.8), K₂HPO₄ (0.52), KH₂PO₄ (0.41), CaCl₂ (0.2), MgSO₄·7H₂O (0.1), Na₂SO₄ (0.05), FeSO₄·7H₂O (0.005), and Na₂MoO₄·2H₂O (0.0025), pH adjusted to 7.0. Tubes were incubated at 28 ± 2°C for 7 days, and the formation of a sub-surface pellicle indicated asymbiotic nitrogen fixation capacity. Phosphorus (P) and potassium (K) solubilization Bacterial colonies were streaked onto Pikovskaya’s agar (TM Media®) and Aleksandrow agar (TM Media®) plates for the determination of phosphorus and potassium solubilization capacity, respectively. Plates were incubated at 28 ± 2°C for 15 days, and solubilization activity was evidenced by halo formation around the bacterial colonies. Growth under reduced water activity (Aw) Strains were streaked onto tryptic soy agar (TSA) supplemented with different concentrations of sorbitol (285, 405, 520, and 780 g L⁻¹), corresponding to water activity (Aw) values of 0.957, 0.919, 0.897, and 0.807, respectively (Hallworth et al. 1998). Plates were incubated at 28 ± 2°C for 48 h, and tolerance to water stress was determined based on bacterial growth at each Aw level. Salt tolerance Strains were streaked onto TSA supplemented with NaCl at concentrations of 0, 2, 4, 6, 8, and 10%. Plates were incubated at 28 ± 2°C for 48 h, and salt tolerance was evaluated based on bacterial growth at each concentration. Evaluation of plant growth promotion in cucumber Experimental design The experiment was conducted in a greenhouse covered with polyethylene film and sidewalls protected with 30% shade cloth, under natural photoperiod, with average temperatures of 36 ± 2°C (day) and 24 ± 2°C (night), at the State University of Bahia (UNEB), Campus VIII, Paulo Afonso, Bahia, Brazil, in December 2024. Cucumber seeds were surface-sterilized with 70% ethanol (1 min), 1% NaOCl (3 min), and rinsed three times with sterile distilled water. Seeds were then microbiolized by immersion in bacterial inoculum adjusted to OD 600nm = 1.0 with xanthan gum (0.1%) as an adhesive agent. The control treatment consisted of seeds immersed only in 0.1% xanthan gum solution. The experimental design was a completely randomized block design with four treatments and five replicates, totaling 20 experimental units. Treatments included: (T1) uninoculated control, (T2) co-inoculation of Pantoea sp. SPM1 and Brevibacillus sp. UPT4, (T3) inoculation with Pantoea sp. SPM1, and (T4) inoculation with Brevibacillus sp. UPT4. Seeds were sown in pots containing 2 kg of soil with the following chemical characteristics: pH 7.91; 89.5 mg/dm³ P (Mehlich-1); 0.64 cmolc/dm³ K+; 9.99 cmolc/dm³ calcium (Ca 2+ ); and electrical conductivity of 1.00 dS/m. Plants were irrigated daily to maintain adequate soil water content, which was monitored by daily weighing of the pots in the late afternoon, considering both plant fresh mass and soil mass. Evaluations were performed 25 days after emergence (DAE). Shoots were cut at the cotyledonary node, separating roots and shoots. Stem diameter was measured in millimeters using a digital caliper. Shoot length (SL) and root length (RL) were measured with a graduated ruler. Root volume (RV) was determined by water displacement in a graduated cylinder. Shoots and roots were placed in paper bags and oven-dried at 60 ± 2°C until constant weight, which was used to determine shoot biomass allocation (SBA) and root biomass allocation (RBA). Statistical analysis Data were subjected to analysis of variance (ANOVA) using the F-test (p < 0.05). When significant differences were detected, means were compared using the Scott-Knott test at the 5% probability level. Relationships between in vitro assay parameters and cucumber growth experiment variables were assessed by Redundancy Analysis (RDA) based on Pearson’s correlation matrix. Statistical analyses were performed in RStudio software (v. 4.3.3) (R Core Team 2024 ). Results Functional profile of Brevibacillus sp. UPT4 and Pantoea sp. SPM1 indicates potential for plant growth promotion and tolerance to abiotic stresses Both strains exhibited multiple traits associated with plant growth promotion and tolerance to abiotic stresses (Table 1 ). Brevibacillus sp. UPT4 and Pantoea sp. SPM1 demonstrated the ability to produce indole-3-acetic acid (IAA), with concentrations of 58.93 and 53.19 µg/mL, respectively. Similarly, both strains displayed the capacity for asymbiotic nitrogen fixation. Regarding the solubilization of mineral nutrients, only Pantoea sp. SPM1 exhibited potassium-solubilizing ability, whereas neither strain demonstrated phosphorus-solubilizing capacity. With respect to growth under abiotic stress conditions, both strains were able to grow under low water availability as well as under saline stress. Pantoea sp. SPM1 sustained growth at NaCl concentrations of up to 8%, while Brevibacillus sp. UPT4 tolerated up to 4% NaCl. Table 1 Functional traits associated with plant growth promotion and tolerance to abiotic stresses exhibited by Brevibacillus sp. UPT4 and Pantoea sp. SPM1. STRAIN IAA ANF K P Aw NaCl Pantoea sp. SPM1 53.19 + + - 0.957 8% Brevibacillus sp. UPT4 58.93 + - - 0.957 4% Notes: IAA = Indole-3-acetic acid production (µg/mL); ANF = Asymbiotic nitrogen fixation; K = Potassium solubilization; P = Phosphorus solubilization; Aw = Growth under reduced water activity; NaCl = Salinity tolerance. Epiphytic strains from T. inamoena modulate growth, root architecture, and biomass allocation in cucumber seedlings The experiment demonstrated a significant effect ( p < 0.05) of strain inoculation on cucumber growth. For shoot length (SL), distinct responses were observed among the treatments (Fig. 1 a), with the bacterial consortium (Fig. 1 b) and Brevibacillus sp. UPT4 (Fig. 1 c) standing out, promoting increases of 38.52% and 56.59%, respectively, compared to the control treatment (Fig. 2 a). Similarly, for stem diameter (SD), co-inoculation and inoculation with Brevibacillus sp. UPT4 resulted in values 13.58% and 20.20% higher, respectively, than the uninoculated treatment (Fig. 2 b). Inoculation with Pantoea sp. SPM1 (T3) did not differ statistically from the control. For root length (RL), all inoculated treatments showed higher means than the control; however, only Brevibacillus sp. UPT4 exhibited a significant increase of 43.40% (Fig. 3 a). All inoculated treatments increased the root volume (RV) of cucumber seedlings compared to the control, with increments ranging from 92.86% to 117.86% (Fig. 3 b). For shoot biomass allocation (SBA), all inoculated treatments showed lower mean values compared to the control (Fig. 4a). Conversely, inoculation resulted in a higher percentage of biomass allocation to the roots (RBA) compared to the control (Fig. 4b). Pantoea sp. SPM1 exhibited the greatest increase (194.86%), followed by the microbial consortium (141.94%) and Brevibacillus sp. UPT4 (110.69%). Redundancy analysis (RDA) enabled the correlation of the functional profile of the strains with the evaluated phytometric parameters, explaining 83.3% and 16.7% of the variance along the first (RDA1) and second (RDA2) axes, respectively (Fig. 4). The results revealed that the greatest variability in RV, SD, RL, and SL was associated with the ability of the strains to produce indole-3-acetic acid (IAA). Moreover, asymbiotic nitrogen fixation capacity exhibited a positive correlation with root biomass allocation values, whereas SBA displayed distinct distribution patterns compared to the other parameters. Discussion Arid and semi-arid regions are often characterized by stress conditions such as high temperatures, low relative air humidity, and reduced water availability. These factors modulate plant microbiome interactions, favoring the presence of microorganisms capable of assisting in nutrient uptake and stress responses, thereby promoting plant development (Yang et al. 2023; López-Hernández et al. 2020). Phyllosphere microorganisms are exposed to extreme climatic fluctuations, which compel them to develop biochemical and physiological strategies that ensure their adaptability to hostile conditions. The formulation of inoculants based on microorganisms from the phyllosphere of semi-arid regions represents a promising biotechnological tool. Studies have shown that the genetic repertoire of epiphytic bacteria from cacti in such regions includes various mechanisms associated with phytohormone synthesis, nitrogen fixation, and stress tolerance (López-Hernández et al. 2020). Similarly, Li et al. (2023) emphasizes that epiphytic bacteria from desert plants possess specialized functional capabilities, serving as sources of metabolites and mechanisms applicable to agriculture. A specialized functional profile was identified in the present study, as both strains exhibited tolerance to abiotic stresses, including high salinity and low water activity. These findings are consistent with reports of phyllosphere microorganisms adapted to harsh environments, such as those associated with Tillandsia landbeckii Phil. in the Atacama Desert (Hakobyan et al. 2023 ) and phytobacteria associated with rice cultivars (Devarajan et al. 2020). The results of this study indicate that strains isolated from T. inamoena possess potential for agricultural application, particularly in cropping systems subjected to environmental stresses. The high IAA production observed suggests that the strains have potential for plant growth promotion (Table 1 ). The adverse conditions of the semi-arid climate exert selective pressure on the phyllosphere microbiota, triggering osmotic stress and inducing the expression of genes related to IAA production (Etesami and Glick 2024 ). As a result, tryptophan present in foliar exudates is assimilated by epiphytic communities, which secrete the phytohormone and stimulate plant development (Saleem and Paul 2015 ), as verified in this study. Mechanisms associated with mineral nutrient availability were also identified. Potassium solubilization, observed in Pantoea sp. SPM1, represents an important trait in plant growth promotion, enhancing photosynthesis and activating key enzymes (Pandey and Saharan 2025 ). In addition, the asymbiotic nitrogen fixation observed in both strains may integrate into the set of nutritional mechanisms available to cropping systems. The assimilation of atmospheric nitrogen in the phyllosphere, as reported for Methylobacterium symbioticum , may serve as an alternative in environments with low nutrient availability, while also reducing the need for chemical fertilizers (Valente et al. 2024 ). Although neither strain exhibited phosphorus solubilization capacity, this result did not compromise the plant growth gains observed. On the contrary, it suggests that other mechanisms, such as IAA production and nitrogen fixation, were more decisive, as observed on RDA. This finding reinforces that the potential of PGPB is not necessarily linked to the presence of all classical mechanisms, but rather to the functional effectiveness of those most relevant under specific environmental and physiological conditions. In this context, it is essential to consider the identification and selection of elite microorganisms, i.e., strains that, even with a limited set of traits, display high agronomic efficiency and functional plasticity across different cropping systems. In cucumber assays, significant increases in shoot growth were observed in treatments inoculated with the microbial consortium and with Brevibacillus sp. UPT4, particularly in SL and SD. These results suggest a possible synergistic action between IAA production and nitrogen fixation, promoting greater structural development and biomass allocation. Similar findings were reported in tomato and pepper seedlings inoculated with Brevibacillus brevis FJAT-0809-GLX, which showed significant increases in growth parameters after 14 days of cultivation (Che et al. 2018 ). The root system showed superior development in inoculated plants compared to the control. Increases in root architecture are strongly associated with IAA synthesis, which directly influences root growth. A more robust root system enhances water and nutrient uptake, thereby increasing crop resilience under conditions of water and nutrient limitation (Dias et al. 2020). In studies with maize (Maulina et al. 2023) and cotton (Nehra et al. 2018), inoculation with Brevibacillus spp. also resulted in significant gains in root length and biomass, reinforcing the ecological and functional plasticity of these microorganisms, even when originating from the phyllosphere. The effects observed with the microbial consortium may indicate advantages over single-strain formulations, as the combination of different microorganisms can broaden the spectrum of benefits to crops (Mir et al. 2019). Studies with common bean (Verma et al., 2018 ), millet (Kushwaha et al. 2020 ), and pearl millet (Kaur et al. 2023) have shown that microbial consortia improve growth, biomass, and chlorophyll content. The present study also revealed differences in shoot and root biomass allocation. Inoculated plants displayed greater root biomass allocation compared to the control, consistent with findings by Awasthi et al. ( 2024 ) in Bacopa monnieri (L.) Wettst inoculated with Pantoea sp. MTP17. In this study, the higher root allocation rate observed with Pantoea sp. SPM1 may be related to its high IAA production and potassium solubilization, traits that favor biomass accumulation in roots. RDA confirmed the association between the responses obtained in vitro and the phenotypic performance in vivo, suggesting that the functional traits of the strains were decisive for the differences among treatments. The contrasting distribution of SBA and RBA likely reflects distinct biomass allocation strategies induced by each strain. The dissociation of SBA from the other variables in the RDA suggests the occurrence of an adaptive trade-off. In this strategy, the plant reduces biomass allocation to the shoot and prioritizes root growth, ensuring greater efficiency in water and nutrient acquisition under stress conditions, albeit at the expense of immediate shoot growth (Chieb and Gachomo 2023 ; Grover et al. 2021 ; Bektas et al. 2023 ) The positive correlation between asymbiotic nitrogen fixation and root variables reinforces the role of these bacteria in plant nutrition, while the association between IAA and RL, SL, and SD highlights the direct contribution of the phytohormone to cucumber growth under the tested conditions, identifying the inoculated treatments with the greatest agronomic potential. Nevertheless, as this study was conducted at an early stage under controlled conditions, further field trials are necessary to validate these effects and confirm strain efficiency across different environments and cropping systems. Conclusion These results highlight the potential of the phyllosphere of native semi-arid plants as a source for the development of new technologies aimed at sustainable agriculture. The integration of epiphytic microorganisms represents a promising tool to address the challenges posed by population growth and climate change. Brevibacillus sp. UPT4 exhibited the greatest improvements in cucumber vegetative development, promoting increases in shoot and root system length, thereby enhancing plant efficiency and resilience, particularly under water and salt stress conditions. Declarations Funding The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. Competing Interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Author Contributions All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Ellie José Pereira and Vinícius de Souza. The first draft of the manuscript was written by Ellie José Pereira and Vinícius de Souza, and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Data Availability The authors confirm that the data supporting the findings of this study are available within the article. Ethics approval and consent to participate Not applicable. References Agbodjato NA, Babalola OO (2024). Promoting sustainable agriculture by exploiting plant growth-promoting rhizobacteria (PGPR) to improve maize and cowpea crops. PeerJ. 12:e16836. doi: https://doi.org/10.7717/peerj.16836 Alzate Zuluaga MY, Fattorini R, Cesco S, Pii Y (2024). Plant-microbe interactions in the rhizosphere for smarter and more sustainable crop fertilization: the case of PGPR-based biofertilizers. Front Microbiol. 15. doi: https://doi.org/10.3389/fmicb.2024.1440978 Arun KD, Sabarinathan KG, Gomathy M, Kannan R, Balachandar D (2020). Mitigation of drought stress in rice crop with plant growth‐promoting abiotic stress‐tolerant rice phyllosphere bacteria. J Basic Microbiol. 60(9):768–786. doi: https://doi.org/10.1002/jobm.202000011 Awasthi A, Soni SK, Laxmi, Bajpai A (2024). Indole-3-acetic acid-producing Pantoea strain MTP 17 and Glomus mosseae synergistically improve the growth, yield and bacoside content of Bacopa monnieri. Discov Plants. 1(1). doi: https://doi.org/10.1007/s44372-024-00015-0 Bahloul H (2021). Effect of foliar spray with some growth stimulants on growth, productivity and quality of cucumber plants grown under greenhouse conditions. Ann Agric Sci Moshtohor. 59(5):975–986. doi: https://doi.org/10.21608/assjm.2021.214961 Bektas H, Hohn CE, Lukaszewski AJ, Waines JG (2023). On the Possible Trade-Off between Shoot and Root Biomass in Wheat. Plants. 12(1):2513. doi: https://doi.org/10.3390/plants12132513 Che J, Liu B, Liu G, et al (2018). Effect of optimized application technology on tomato and pepper seedling growth of Brevibacillus brevis FJAT-0809-GLX. China Veg. 1(4):43–47. Chieb M, Gachomo EW (2023). The role of plant growth promoting rhizobacteria in plant drought stress responses. BMC Plant Biol. 23(1): 407. doi: https://doi.org/10.1186/s12870-023-04403-8 Devarajan AK, Muthukrishanan G, Truu J, Truu M, Ostonen I, Kizhaeral S, Panneerselvam P, Gopalasubramanian SK (2021). The foliar application of rice phyllosphere bacteria induces drought-stress tolerance in Oryza sativa (L.). Plants. 10(2):387. doi: https://doi.org/10.3390/plants10020387 Dias AC, Alves GC, Silva TFR, Reis VM (2023). Inoculation effects of growth-promoting bacteria on corn root architecture: influence of nitrogen levels, bacterial populations, and plant genotypes. Rev Bras Cienc Solo. 47. doi: https://doi.org/10.36783/18069657rbcs20230059 Etesami H, Glick BR (2024). Bacterial indole-3-acetic acid: a key regulator for plant growth, plant-microbe interactions, and agricultural adaptive resilience. Microbiol Res. 281:127602. doi: https://doi.org/10.1016/j.micres.2024.127602 Flores-Núñez VM, Fonseca-García C, Desgarennes D, Eloe-Fadrosh E, Woyke T, Partida-Martínez LP (2020). Functional signatures of the epiphytic prokaryotic microbiome of Agaves and Cacti. Front Microbiol. 10:3044. doi: https://doi.org/10.3389/fmicb.2019.03044 Flores-Núñez VM, Fonseca-García C, Desgarennes D, Partida-Martínez LP (2025). The Agave and Cacti microbiome: models for a planet under global warming. Metagenomics. p. 421–460. doi: https://doi.org/10.1016/b978-0-323-91631-8.00010-x Gordon SA, Weber RP (1951). Colorimetric estimation of indoleacetic acid. Plant Physiol. 26(1):192. doi: https://doi.org/10.1104/pp.26.1.192 Grover M, Bodhankar S, Sharma A, Sharma P, Singh J, Nain L (2021). PGPR Mediated Alterations in Root Traits: Way Toward Sustainable Crop Production. Front. Sustain. Food Syst. 4(1). doi: https://doi.org/10.3389/fsufs.2020.618230 Hakobyan A, et al (2023). Tillandsia landbeckii phyllosphere and laimosphere as refugia for bacterial life in a hyperarid desert environment. Microbiome. 11(1):246. doi: https://doi.org/10.1186/s40168-023-01684-x Hallsworth JE, Nomura Y, Iwahara M (1998). Ethanol-induced water stress and fungal growth. J Ferment Bioeng. 86(5):451–456. doi: https://doi.org/10.1016/s0922-338x(98)80150-5 Kaur M, Sharma P (2021). Recent advances in cucumber ( Cucumis sativus L.). J Hortic Sci Biotechnol. 97(1):3–23. doi: https://doi.org/10.1080/14620316.2021.1945956 Kaur T, Devi R, Kumar S, Kour D, Yadav AN (2022). Plant growth promotion of pearl millet ( Pennisetum glaucum L.) by novel bacterial consortium with multifunctional attributes. Biologia. 78(2):621–631. doi: https://doi.org/10.1007/s11756-022-01291-5 Khosravi H, Khoshru B, Nosratabad AF, Mitra D (2024). Exploring the landscape of biofertilizers containing plant growth-promoting rhizobacteria in Iran: progress and research prospects. Curr Res Microb Sci. 7:100268. doi: https://doi.org/10.1016/j.crmicr.2024.100268 Kushwaha P, Kashyap PL, Srivastava AK, Tiwari RK (2020). Plant growth promoting and antifungal activity in endophytic Bacillus strains from pearl millet ( Pennisetum glaucum ). Braz J Microbiol. 51:229–241. doi: https://doi.org/10.1007/s42770-019-00172-5 Liu J, Sun X, Zuo Y, Hu Q, He X (2023). Plant species shape the bacterial communities on the phyllosphere in a hyper-arid desert. Microbiol Res. 269:127314. doi: https://doi.org/10.1016/j.micres.2023.127314 Mallick PK (2022). Evaluating potential importance of cucumber ( Cucumis sativus L. - Cucurbitaceae): a brief review. Int J Appl Sci Biotechnol. 10(1):12–15. doi: https://doi.org/10.3126/ijasbt.v10i1.44152 Marson M, Saccone D (2023). Fed with import and starved by war: estimating the consequences of the Russia-Ukraine conflict on cereals trade and global hunger. Int Econ Econ Policy. 20(3):413–423. doi: https://doi.org/10.1007/s10368-023-00564-x Maulina NMI, Suprapta DN, Temaja IGRM, Adnyana IM, Suriani NL (2022). Rhizobacteria of Bali with obvious growth-promoting properties on corn ( Zea mays L.). Front Sustain Food Syst. 6. doi: https://doi.org/10.3389/fsufs.2022.899736 Nehra V, Saharan BS, Choudhary M (2016). Evaluation of Brevibacillus brevis as a potential plant growth promoting rhizobacteria for cotton ( Gossypium hirsutum) crop. SpringerPlus. 5(1). doi: https://doi.org/10.1186/s40064-016-2584-8 Organisation for Economic Co-operation and Development (OECD), Food and Agriculture Organization of the United Nations (FAO) (2024). OECD-FAO agricultural outlook 2024–2033. Paris (FR): OECD Publishing. doi: https://doi.org/10.1787/4c5d2cfb-en Pandey K, Saharan BS (2025). Potassium-solubilizing endophytes: mechanisms and applications in enhancing sustainable agriculture and plant resilience. Symbiosis. 95(3):291–305. doi: https://doi.org/10.1007/s13199-025-01052-3 R Core Team (2024). R: a language and environment for statistical computing. Vienna (AT): R Foundation for Statistical Computing. Remus-Emsermann MNP, Schlechter RO (2018). Phyllosphere microbiology: at the interface between microbial individuals and the plant host. New Phytol. 218(4):1327–1333. doi: https://doi.org/10.1111/nph.15054 Safi L, Mujeeb M, Sahak K, Mushwani H, Hashmi SK (2024). Climate change impacts and threats on basic livelihood resources, food security and social stability in Afghanistan. GeoJournal. 89(2). doi: https://doi.org/10.1007/s10708-024-11077-8 Saleem B, Paul PK (2015). Phytohormones from phylloplane microbes: a review. Trends Biosci. 8(17):4450–4458. Sands RD, Meade B, Seale JL Jr, Robinson S, Seeger R. (2023). Scenarios of global food consumption: implications for agriculture. doi: https://doi.org/10.22004/ag.econ.338943 Shahwar D, Mushtaq Z, Mushtaq H, Alqarawi AA, Park Y, Alshahrani TS, Faizan S (2023). Role of microbial inoculants as biofertilizers for improving crop productivity: a review. Heliyon. 9(6):e16134. doi: https://doi.org/10.1016/j.heliyon.2023.e16134 Sharath S, Triveni S, Nagaraju Y, Latha PC, Vidyasagar B (2021). The role of phyllosphere bacteria in improving cotton growth and yield under drought conditions. Front Agron. 3. doi: https://doi.org/10.3389/fagro.2021.68 Srivastava RM, Joshih S (2021). Integrated pest management for cucurbits in cucumber ( Cucumis sativus L.). In: Cucumber economic values and its cultivation and breeding. doi: https://doi.org/10.5772/intechopen.97123 Valente F, Panozzo A, Bozzolin F, Barion G, Bolla PK, Bertin V, Potestio S, Visioli G, Wang Y, Vamerali T (2024). Growth, photosynthesis and yield responses of common wheat to foliar application of Methylobacterium symbioticum under decreasing chemical nitrogen fertilization. Agriculture. 14(10):1670. doi: https://doi.org/10.3390/agriculture14101670 Verma JP, Jaiswal DK, Krishna R, Prakash S, Yadav J, Singh V (2018). Characterization and screening of thermophilic Bacillus strains for developing plant growth promoting consortium from hot spring of Leh and Ladakh region of India. Front Microbiol. 9:1293. doi: https://doi.org/10.3389/fmicb.2018.01293 Wilson PW, Knight SG (1952). Experiments in bacterial physiology. 3rd ed. Minneapolis (MN): Burgess Publishing Co. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 03 Mar, 2026 Read the published version in International Microbiology → Version 1 posted Editorial decision: Revision requested 12 Dec, 2025 Reviews received at journal 05 Dec, 2025 Reviewers agreed at journal 24 Nov, 2025 Reviews received at journal 24 Nov, 2025 Reviewers agreed at journal 14 Nov, 2025 Reviewers invited by journal 30 Oct, 2025 Editor assigned by journal 30 Oct, 2025 Submission checks completed at journal 26 Oct, 2025 First submitted to journal 23 Oct, 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-7935575","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":542188828,"identity":"97d96495-c2d7-4a00-a165-51301f3af01c","order_by":0,"name":"Ellie José Pereira","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+0lEQVRIiWNgGAWjYDACduaGAxAWYwMDQwWQZmZuwK+FmRFZyxmICEEtCA5jG0wvHsDPzNh44OMOm3x+9ua2Dz/n1UbztwO1/KjYhlOLZDNjw8GZZ9IsZ/YcbJ7Zu+147ozDjA2MPWdu49RiAFRwmLftsIHBjcRmBt5tx3IbgCLMjG24tdiDtPxt+29gf/9hM+PfOcdy5xPSYgD0/mHGtgMGBhKMzcy8DTW5GwhpkQAqONh7JtlA4kxiM7PMsQO5G0Ei+PzC3958+MPPHXYG/O3HHzO+qanLnXf+8MEHPypwawEDpIg4DCYP4FePqqWOoOJRMApGwSgYeQAAywJghhVfIroAAAAASUVORK5CYII=","orcid":"","institution":"State University of Bahia","correspondingAuthor":true,"prefix":"","firstName":"Ellie","middleName":"José","lastName":"Pereira","suffix":""},{"id":542188829,"identity":"3e68d2bb-701e-4efe-b4f0-fbcabe31e7f2","order_by":1,"name":"Vinícius Souza","email":"","orcid":"","institution":"State University of Bahia","correspondingAuthor":false,"prefix":"","firstName":"Vinícius","middleName":"","lastName":"Souza","suffix":""},{"id":542188830,"identity":"1522b924-61ae-402c-af58-6078cb7e37e0","order_by":2,"name":"Caliane Silva Braulio","email":"","orcid":"","institution":"State University of Bahia","correspondingAuthor":false,"prefix":"","firstName":"Caliane","middleName":"Silva","lastName":"Braulio","suffix":""},{"id":542188831,"identity":"2d83f8c5-f722-4036-bf8a-6b3f6254277a","order_by":3,"name":"Adailson Feitoza Jesus Santos","email":"","orcid":"","institution":"State University of Bahia","correspondingAuthor":false,"prefix":"","firstName":"Adailson","middleName":"Feitoza Jesus","lastName":"Santos","suffix":""}],"badges":[],"createdAt":"2025-10-24 00:23:04","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7935575/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7935575/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10123-026-00778-4","type":"published","date":"2026-03-03T15:58:06+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":95571332,"identity":"caf7fc44-3e76-4570-b052-411778c19250","added_by":"auto","created_at":"2025-11-10 17:01:00","extension":"tiff","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":44415334,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.1.tiff","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/6238b5e30ab6774a23981660.tiff"},{"id":95571297,"identity":"8cf709fc-41d1-406d-b02e-382d25098e67","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":6716892,"visible":true,"origin":"","legend":"","description":"","filename":"Manuscript.docx","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/0f2e6f3fddde4ec0e90fd88d.docx"},{"id":95654696,"identity":"eb390a5c-9eae-4e4b-94f1-770db34adfbe","added_by":"auto","created_at":"2025-11-11 16:12:46","extension":"tiff","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2105076,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.2a.tiff","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/d0052bf6e4f8fc505664f36e.tiff"},{"id":95571296,"identity":"6e5245bb-7f37-4eb1-91d6-f69143ec9659","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"tiff","order_by":3,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2105076,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.2b.tiff","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/b58e217a94ed868fc124bec4.tiff"},{"id":95571299,"identity":"487ac9db-6b1e-43d8-87ee-2bb1f39b5371","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"tiff","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2105076,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.3a.tiff","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/051ba5fce4520724d51924e6.tiff"},{"id":95655819,"identity":"c497ec72-bf53-4c5d-98dc-5cd021437bdc","added_by":"auto","created_at":"2025-11-11 16:17:01","extension":"tiff","order_by":5,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2105076,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.3b.tiff","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/c541fdeb7c3f2ccc14c540d4.tiff"},{"id":95571295,"identity":"4f64aa7e-c5d2-4be9-9945-94ea845068a8","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"tiff","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2105076,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.4a.tiff","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/9b2bfd8792b154219707fc82.tiff"},{"id":95571307,"identity":"825e4e38-5741-4617-ba4f-089bb53c427d","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"tiff","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2105076,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.4b.tiff","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/2d720eb0ebc0350cc0e7f73f.tiff"},{"id":95655614,"identity":"0deffd6f-060d-4ee4-a79a-2ba83694d2b1","added_by":"auto","created_at":"2025-11-11 16:16:33","extension":"tiff","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":4347192,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.5.tiff","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/507167fb4751f28a712960fb.tiff"},{"id":95655598,"identity":"e1e9a9b8-3f64-475a-980b-d6e31ae931f3","added_by":"auto","created_at":"2025-11-11 16:16:32","extension":"json","order_by":9,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":5736,"visible":true,"origin":"","legend":"","description":"","filename":"be98067b6f3d4752bbf829c35afdef59.json","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/99f9abb7769c6ac1408e5856.json"},{"id":95655913,"identity":"2d87163e-b943-4d46-8d0d-c4268458ef43","added_by":"auto","created_at":"2025-11-11 16:17:13","extension":"xml","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":96327,"visible":true,"origin":"","legend":"","description":"","filename":"be98067b6f3d4752bbf829c35afdef591enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/1936a7301ee40fccbe2fe0c2.xml"},{"id":95571330,"identity":"cd5659ba-159a-4cd6-8fbf-416a65645570","added_by":"auto","created_at":"2025-11-10 17:01:00","extension":"tiff","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":44415334,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.1.tiff","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/bcfff544cf79cd36b9c42087.tiff"},{"id":95571320,"identity":"04d4ccdc-d734-4e6b-afec-3c5560b1268d","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"tiff","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2105076,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.2a.tiff","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/0bf76e709a9d4fb7195f2ae8.tiff"},{"id":95655854,"identity":"7a052173-b9eb-4fda-ac51-1e0bc4462232","added_by":"auto","created_at":"2025-11-11 16:17:03","extension":"tiff","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2105076,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.2b.tiff","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/8e0f7446631802ef0985ee59.tiff"},{"id":95571302,"identity":"38d3002c-5b8b-40e6-86be-27e28f6a6579","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"tiff","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2105076,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.3a.tiff","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/866f857c381de8091f6f8e9a.tiff"},{"id":95656325,"identity":"f172b4c7-c1dd-4c68-a237-7c83e0303cf7","added_by":"auto","created_at":"2025-11-11 16:18:27","extension":"tiff","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2105076,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.3b.tiff","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/5fc6a90c3a87b4efd58e6bfd.tiff"},{"id":95571328,"identity":"d3baffb7-1600-4d35-a21a-61aa9b651c8a","added_by":"auto","created_at":"2025-11-10 17:01:00","extension":"tiff","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2105076,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.4a.tiff","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/6df1b867ae064d01ef2df428.tiff"},{"id":95656176,"identity":"671dd3b9-358b-4abf-9809-80fa3dd132d3","added_by":"auto","created_at":"2025-11-11 16:17:56","extension":"tiff","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2105076,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.4b.tiff","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/04587badd293deab94a589bf.tiff"},{"id":95654830,"identity":"a1a7fe0b-777f-4684-a180-cc8ff6b26baa","added_by":"auto","created_at":"2025-11-11 16:13:17","extension":"tiff","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":4347192,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.5.tiff","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/5b45d15abafef1ce24ebdf4b.tiff"},{"id":95571327,"identity":"6592b74f-543a-45bf-888c-e1cf8cade9eb","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"jpeg","order_by":19,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":970048,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/a9944e98ac38c3626e49707d.jpeg"},{"id":95655612,"identity":"337cdc9f-2806-4508-87e4-7c3fa83f17ec","added_by":"auto","created_at":"2025-11-11 16:16:33","extension":"jpeg","order_by":20,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1074,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/30d13236d509ddb3a3d5be95.jpeg"},{"id":95571318,"identity":"cb57a9a5-da32-4245-b506-6aa63e077b10","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"jpeg","order_by":21,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1074,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/c0d50fff1a25dcb797e095a5.jpeg"},{"id":95655841,"identity":"f69c62ed-ae9e-48de-ae69-f47b2fe644d0","added_by":"auto","created_at":"2025-11-11 16:17:02","extension":"jpeg","order_by":22,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":301209,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/5df721f1291c7d0dbab76b84.jpeg"},{"id":95656326,"identity":"1ea9b957-23ce-4f07-8acc-8229598297b5","added_by":"auto","created_at":"2025-11-11 16:18:27","extension":"jpeg","order_by":23,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":4347192,"visible":true,"origin":"","legend":"","description":"","filename":"Fig.5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/0435cc951a06d4c474d4d2a4.jpeg"},{"id":95571324,"identity":"b4aa08ed-9db9-439f-9bce-b66ecb8a3e9f","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"jpeg","order_by":24,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":19136,"visible":true,"origin":"","legend":"","description":"","filename":"groupimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/0909782f23b1bed2136bca25.jpeg"},{"id":95656015,"identity":"9a36cb62-a774-43fb-a0ba-6c29d802cd62","added_by":"auto","created_at":"2025-11-11 16:17:33","extension":"jpeg","order_by":25,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":20670,"visible":true,"origin":"","legend":"","description":"","filename":"groupimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/9515c221a1a72c23eccd8d5e.jpeg"},{"id":95655220,"identity":"0b5ae6da-fa7b-4745-aff6-cdfb97bd6a30","added_by":"auto","created_at":"2025-11-11 16:14:46","extension":"png","order_by":26,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":377762,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig.1.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/e73b830952ad4099d48f5091.png"},{"id":95655825,"identity":"2516fe8e-ac5d-499b-ad29-7fe930c17270","added_by":"auto","created_at":"2025-11-11 16:17:01","extension":"png","order_by":27,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":10468,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig.2a.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/ba7b34e45a598d613e09ec94.png"},{"id":95571306,"identity":"e0d09a71-50da-42b5-ba9a-547e45939fba","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"png","order_by":28,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":10741,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig.2b.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/6cf485b180ab1e1b26098f05.png"},{"id":95571312,"identity":"17469db0-55dc-4264-a88d-88cb930487c0","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"png","order_by":29,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":10589,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig.3a.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/a28390a6a09f5cc4366dd83f.png"},{"id":95656235,"identity":"072541f9-e1ef-4303-84fc-c427bb63f937","added_by":"auto","created_at":"2025-11-11 16:18:05","extension":"png","order_by":30,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":10351,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig.3b.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/081573731541707538b5329e.png"},{"id":95656049,"identity":"c9e4868a-8e74-42a6-ac91-160d9559eb36","added_by":"auto","created_at":"2025-11-11 16:17:41","extension":"png","order_by":31,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":11519,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig.4a.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/a7513394e1c941c7a3c5af2d.png"},{"id":95571313,"identity":"8b85cddf-d496-4234-a15f-28d14c5cdd76","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"png","order_by":32,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":10892,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig.4b.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/b94bb9dd28a32e60652a6253.png"},{"id":95655932,"identity":"a9b23ac0-cb73-45f8-8fdc-2108cbe00b86","added_by":"auto","created_at":"2025-11-11 16:17:20","extension":"png","order_by":33,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":13091,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig.5.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/22d3d86879a59303fbcbf04b.png"},{"id":95571321,"identity":"0b49960d-1eef-4b95-8410-426748876ce9","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"png","order_by":34,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":115916,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/3ae4fef0cd30ad95a497d7fa.png"},{"id":95655340,"identity":"2a139620-0b9e-4a06-811a-877532c1cd3f","added_by":"auto","created_at":"2025-11-11 16:15:29","extension":"png","order_by":35,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":935,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/d0db9990572001086533cdea.png"},{"id":95655938,"identity":"18c961c2-1242-4d58-95c1-61a34a2bdd32","added_by":"auto","created_at":"2025-11-11 16:17:21","extension":"png","order_by":36,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":935,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/5254175341b5ef2f9730954f.png"},{"id":95571326,"identity":"53d76cae-e88f-4c2e-9d30-ddaea915925b","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"png","order_by":37,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":45144,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/df1cc12c4ad6757fbdcd43bb.png"},{"id":95654894,"identity":"ed0ce353-6a4d-4480-bdcc-96ac4165b66d","added_by":"auto","created_at":"2025-11-11 16:13:42","extension":"png","order_by":38,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":13091,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/44645b2a0314710e118fd6c9.png"},{"id":95571325,"identity":"698976e8-e7b7-4392-9689-9c7dbc054469","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"png","order_by":39,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":6075,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinegroupimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/3f5bc2483538828dc8aefe7d.png"},{"id":95571337,"identity":"f2612db4-94c1-4be6-98fa-458d0166cc51","added_by":"auto","created_at":"2025-11-10 17:01:00","extension":"png","order_by":40,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":5819,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinegroupimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/a4cad20d104321eb2e96450c.png"},{"id":95571336,"identity":"cc7cf4b8-8c98-4625-938f-5c6e11286e7b","added_by":"auto","created_at":"2025-11-10 17:01:00","extension":"xml","order_by":41,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":95269,"visible":true,"origin":"","legend":"","description":"","filename":"be98067b6f3d4752bbf829c35afdef591structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/4f8683ed45cbff4c9738d8c3.xml"},{"id":95571329,"identity":"2e6481a3-b1e2-43e6-bedd-cf7159c5a3b9","added_by":"auto","created_at":"2025-11-10 17:01:00","extension":"html","order_by":42,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":105200,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/067fb63a5bdadda755d691c6.html"},{"id":95571290,"identity":"31e70740-6a91-4b40-a374-3abaf08de380","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":202252,"visible":true,"origin":"","legend":"\u003cp\u003eCucumber seedlings inoculated with epiphytic bacterial isolated from the Caatinga biome. (a) Comparison between treatments. (b) Cucumber inoculated with bacterial consortium, and (c) cucumber inoculated with \u003cem\u003eBrevibacillus\u003c/em\u003e sp. UPT4.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/99cbea2853c7d4e8bf55629f.png"},{"id":95655779,"identity":"fc3ba982-5efc-4bb4-b425-fae48f538b95","added_by":"auto","created_at":"2025-11-11 16:16:54","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":37910,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of epiphytic bacterial from \u003cem\u003eT. inamoena\u003c/em\u003eon (a) shoot length (SL) and (b) stem diameter (SD) of cucumber seedlings.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/788b3a1a3f4940664c66453c.png"},{"id":95571292,"identity":"c1e0684a-5de4-43a8-b2a9-d02a224fa8f8","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":38376,"visible":true,"origin":"","legend":"\u003cp\u003eInfluence of inoculated treatments on (a) root length (RL) and (b) root volume (RV) of cucumber seedlings.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/9617cbdb4394b39401fce367.png"},{"id":95571293,"identity":"3e81be13-685a-41bd-b332-da59612dfb65","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":48788,"visible":true,"origin":"","legend":"\u003cp\u003eBiomass allocation in cucumber seedlings inoculated with epiphytic bacteria from \u003cem\u003eT. inamoena\u003c/em\u003e: percentage of (a) shoot biomass allocation (SBA) and (b) root biomass allocation (RBA).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/6122466c21e3fab5dfbecb00.png"},{"id":95571294,"identity":"abb8ed8d-7651-49c9-b882-54db37edb8f5","added_by":"auto","created_at":"2025-11-10 17:00:59","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":34350,"visible":true,"origin":"","legend":"\u003cp\u003ePrincipal component analysis (PCA) showing the correlation between the observed functional traits and the results obtained in the cucumber experiment.\u003c/p\u003e\n\u003cp\u003eNotes: IAA = Indole-3-acetic acid production; ANF = Asymbiotic nitrogen fixation; K = Potassium solubilization; P = Phosphorus solubilization; Aw = Growth under reduced water activity; NaCl = Salinity tolerance; SL= Shoot length; SD= Stem diameter; RL= Root length; RV= Root volume; ABA= Aboveground biomass allocation; RBA= Root biomass allocation.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/d2d288b1875047c610b0ddc7.png"},{"id":104251529,"identity":"3d6cf20e-fa2b-47a4-9a8a-bf72fc2477c2","added_by":"auto","created_at":"2026-03-09 16:13:44","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1097714,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7935575/v1/70b6cb86-7eb7-4964-af92-0edbabf91dfc.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Epiphytic bacteria from Tacinga inamoena (K. Schum.) N.P. Taylor \u0026 Stuppy improve plant growth in cucumber seedlings","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe rapid growth of the global population poses significant challenges to food security, with projections estimating approximately 10\u0026nbsp;billion inhabitants by 2050. It is anticipated that population expansion, combined with changes in consumption patterns and increased per capita income, will raise global food demand by around 44% (OECD-FAO 2024; Sands et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Concurrently, economic and territorial conflicts, together with the escalating climate crisis, exacerbate global food insecurity (Safi et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Marson and Sacconel 2023).\u003c/p\u003e\u003cp\u003eIn Brazil, vegetable production plays a strategic role in food security. Within this context, cucumber (\u003cem\u003eCucumis sativus\u003c/em\u003e L.) stands out due to its high domestic demand and market acceptance, despite its pronounced susceptibility to phytopathogens and adverse environmental conditions. This susceptibility often leads to the intensive use of chemical pesticides and fertilizers to ensure crop productivity (Mallick \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). However, the indiscriminate application of these inputs negatively affects soil and water quality, generates toxic residues in the environment, and disrupts the composition and dynamics of microbial communities associated with crops (Kaur and Sharma 2022).\u003c/p\u003e\u003cp\u003eIn this scenario, biofertilizers based on plant growth-promoting bacteria (PGPB) emerge as promising tools for developing ecologically sustainable agriculture in the face of climate change. These microorganisms act through multiple mechanisms, including phytohormone production, biological nitrogen fixation (BNF), nutrient solubilization, and induction of systemic resistance (ISR), thereby supporting crop development under stress conditions (Srivastava and Joshih \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Bahloul \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Shahwayr et al. 2023; Alzate Zuluaga et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e\u003cp\u003ePlants naturally exposed and adapted to conditions of water scarcity and high solar radiation, such as Cactaceae species, may harbor in their phyllosphere microbial communities resilient to environmental adversities (Liu et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Flores-Nu\u0026ntilde;ez et al. 2024). Studies have demonstrated the potential of these microorganisms to promote the growth of various agricultural crops, integrating innovative approaches for the development of new agricultural technologies (Devarajan et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Sharath et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Agbodiato and Babalola 2024; Khosravi et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThus, to contribute to the development of efficient biostimulants and foster sustainable agricultural practices, this study aimed to evaluate the effects of phyllosphere bacteria from \u003cem\u003eTacinga inamoena\u003c/em\u003e (K. Schum.) N.P. Taylor \u0026amp; Stuppy on the vegetative growth of cucumber seedlings.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eMicroorganisms\u003c/h2\u003e\u003cp\u003e\u003cem\u003eBrevibacillus\u003c/em\u003e sp. UPT4 and \u003cem\u003ePantoea\u003c/em\u003e sp. SPM1 were isolated from the surface of \u003cem\u003eT. inamoena\u003c/em\u003e cladodes and deposited in the microbial collection of the Laboratory of Microbial Ecology and Biotechnology of the Semi-Arid Region, State University of Bahia (LEBIMS \u0026ndash; UNEB), Paulo Afonso, Bahia state, Brazil. \u003cem\u003eBrevibacillus\u003c/em\u003e sp. UPT4 was isolated in Serra do Umbuzeiro (Latitude: \u0026minus;\u0026thinsp;9.58103091088262; Longitude: \u0026minus;\u0026thinsp;38.2047843933105), Paulo Afonso, Bahia state, Brazil. \u003cem\u003ePantoea\u003c/em\u003e sp. SPM1 was isolated in Environmental Protection Area Serra Branca (Latitude: \u0026minus;\u0026thinsp;9.945193254158575; Longitude: \u0026minus;\u0026thinsp;38.57322551035467), located in the municipality of Jeremoabo, Bahia state, Brazil.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eEvaluation of plant growth-promoting potential and tolerance to abiotic stresses\u003c/h3\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003eIndole-3-acetic acid (IAA) production\u003c/h2\u003e\u003cp\u003eBacterial cultures (OD\u003csub\u003e600nm\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.3) were inoculated into tryptic soy broth (TSB) supplemented with L-tryptophan (5 mM) and incubated under constant agitation (150 rpm) at 28\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C for 72 h. Cultures were centrifuged at 10,000 rpm for 10 min, and the cell-free supernatant was transferred to tubes containing Salkowski reagent (2% FeCl₃ in 35% HClO₄) (1:1), following Gordon and Weber (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e1951\u003c/span\u003e). The mixture was incubated in the dark for 30 min, and IAA concentration was determined spectrophotometrically at 530 nm, using a standard curve of IAA.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eAsymbiotic nitrogen fixation\u003c/h3\u003e\n\u003cp\u003eBacterial cultures (OD\u003csub\u003e600nm\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.3) were inoculated into tubes containing semi-solid nitrogen-free Burk\u0026rsquo;s medium (Wilson and Knight \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e1952\u003c/span\u003e) with the following composition (g L⁻\u0026sup1;): glucose (10), agar (1.8), K₂HPO₄ (0.52), KH₂PO₄ (0.41), CaCl₂ (0.2), MgSO₄\u0026middot;7H₂O (0.1), Na₂SO₄ (0.05), FeSO₄\u0026middot;7H₂O (0.005), and Na₂MoO₄\u0026middot;2H₂O (0.0025), pH adjusted to 7.0. Tubes were incubated at 28\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C for 7 days, and the formation of a sub-surface pellicle indicated asymbiotic nitrogen fixation capacity.\u003c/p\u003e\n\u003ch3\u003ePhosphorus (P) and potassium (K) solubilization\u003c/h3\u003e\n\u003cp\u003eBacterial colonies were streaked onto Pikovskaya\u0026rsquo;s agar (TM Media\u0026reg;) and Aleksandrow agar (TM Media\u0026reg;) plates for the determination of phosphorus and potassium solubilization capacity, respectively. Plates were incubated at 28\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C for 15 days, and solubilization activity was evidenced by halo formation around the bacterial colonies.\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eGrowth under reduced water activity (Aw)\u003c/h2\u003e\u003cp\u003eStrains were streaked onto tryptic soy agar (TSA) supplemented with different concentrations of sorbitol (285, 405, 520, and 780 g L⁻\u0026sup1;), corresponding to water activity (Aw) values of 0.957, 0.919, 0.897, and 0.807, respectively (Hallworth et al. 1998). Plates were incubated at 28\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C for 48 h, and tolerance to water stress was determined based on bacterial growth at each Aw level.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eSalt tolerance\u003c/h3\u003e\n\u003cp\u003eStrains were streaked onto TSA supplemented with NaCl at concentrations of 0, 2, 4, 6, 8, and 10%. Plates were incubated at 28\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C for 48 h, and salt tolerance was evaluated based on bacterial growth at each concentration.\u003c/p\u003e\n\u003ch3\u003eEvaluation of plant growth promotion in cucumber\u003c/h3\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eExperimental design\u003c/h2\u003e\u003cp\u003eThe experiment was conducted in a greenhouse covered with polyethylene film and sidewalls protected with 30% shade cloth, under natural photoperiod, with average temperatures of 36\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C (day) and 24\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C (night), at the State University of Bahia (UNEB), Campus VIII, Paulo Afonso, Bahia, Brazil, in December 2024.\u003c/p\u003e\u003cp\u003eCucumber seeds were surface-sterilized with 70% ethanol (1 min), 1% NaOCl (3 min), and rinsed three times with sterile distilled water. Seeds were then microbiolized by immersion in bacterial inoculum adjusted to OD\u003csub\u003e600nm\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;1.0 with xanthan gum (0.1%) as an adhesive agent. The control treatment consisted of seeds immersed only in 0.1% xanthan gum solution.\u003c/p\u003e\u003cp\u003eThe experimental design was a completely randomized block design with four treatments and five replicates, totaling 20 experimental units. Treatments included: (T1) uninoculated control, (T2) co-inoculation of \u003cem\u003ePantoea\u003c/em\u003e sp. SPM1 and \u003cem\u003eBrevibacillus\u003c/em\u003e sp. UPT4, (T3) inoculation with \u003cem\u003ePantoea\u003c/em\u003e sp. SPM1, and (T4) inoculation with \u003cem\u003eBrevibacillus\u003c/em\u003e sp. UPT4. Seeds were sown in pots containing 2 kg of soil with the following chemical characteristics: pH 7.91; 89.5 mg/dm\u0026sup3; P (Mehlich-1); 0.64 cmolc/dm\u0026sup3; K+; 9.99 cmolc/dm\u0026sup3; calcium (Ca\u003csup\u003e2+\u003c/sup\u003e); and electrical conductivity of 1.00 dS/m. Plants were irrigated daily to maintain adequate soil water content, which was monitored by daily weighing of the pots in the late afternoon, considering both plant fresh mass and soil mass.\u003c/p\u003e\u003cp\u003eEvaluations were performed 25 days after emergence (DAE). Shoots were cut at the cotyledonary node, separating roots and shoots. Stem diameter was measured in millimeters using a digital caliper. Shoot length (SL) and root length (RL) were measured with a graduated ruler. Root volume (RV) was determined by water displacement in a graduated cylinder. Shoots and roots were placed in paper bags and oven-dried at 60\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C until constant weight, which was used to determine shoot biomass allocation (SBA) and root biomass allocation (RBA).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eData were subjected to analysis of variance (ANOVA) using the F-test (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). When significant differences were detected, means were compared using the Scott-Knott test at the 5% probability level. Relationships between in vitro assay parameters and cucumber growth experiment variables were assessed by Redundancy Analysis (RDA) based on Pearson\u0026rsquo;s correlation matrix. Statistical analyses were performed in RStudio software (v. 4.3.3) (R Core Team \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cb\u003eFunctional profile of Brevibacillus sp. UPT4 and Pantoea sp. SPM1 indicates potential for plant growth promotion and tolerance to abiotic stresses\u003c/b\u003e\u003c/p\u003e\u003cp\u003eBoth strains exhibited multiple traits associated with plant growth promotion and tolerance to abiotic stresses (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). \u003cem\u003eBrevibacillus\u003c/em\u003e sp. UPT4 and \u003cem\u003ePantoea\u003c/em\u003e sp. SPM1 demonstrated the ability to produce indole-3-acetic acid (IAA), with concentrations of 58.93 and 53.19 \u0026micro;g/mL, respectively. Similarly, both strains displayed the capacity for asymbiotic nitrogen fixation.\u003c/p\u003e\u003cp\u003eRegarding the solubilization of mineral nutrients, only \u003cem\u003ePantoea\u003c/em\u003e sp. SPM1 exhibited potassium-solubilizing ability, whereas neither strain demonstrated phosphorus-solubilizing capacity. With respect to growth under abiotic stress conditions, both strains were able to grow under low water availability as well as under saline stress. \u003cem\u003ePantoea\u003c/em\u003e sp. SPM1 sustained growth at NaCl concentrations of up to 8%, while \u003cem\u003eBrevibacillus\u003c/em\u003e sp. UPT4 tolerated up to 4% NaCl.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eFunctional traits associated with plant growth promotion and tolerance to abiotic stresses exhibited by \u003cem\u003eBrevibacillus\u003c/em\u003e sp. UPT4 and \u003cem\u003ePantoea\u003c/em\u003e sp. SPM1.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSTRAIN\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eIAA\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eANF\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eK\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eAw\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNaCl\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003ePantoea\u003c/em\u003e sp. SPM1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e53.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.957\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e8%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eBrevibacillus\u003c/em\u003e sp. UPT4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e58.93\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.957\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e4%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"7\"\u003eNotes: IAA\u0026thinsp;=\u0026thinsp;Indole-3-acetic acid production (\u0026micro;g/mL); ANF\u0026thinsp;=\u0026thinsp;Asymbiotic nitrogen fixation; K\u0026thinsp;=\u0026thinsp;Potassium solubilization; P\u0026thinsp;=\u0026thinsp;Phosphorus solubilization; Aw\u0026thinsp;=\u0026thinsp;Growth under reduced water activity; NaCl\u0026thinsp;=\u0026thinsp;Salinity tolerance.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\u003ch2\u003eEpiphytic strains from T. inamoena modulate growth, root architecture, and biomass allocation in cucumber seedlings\u003c/h2\u003e\u003cp\u003eThe experiment demonstrated a significant effect (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) of strain inoculation on cucumber growth. For shoot length (SL), distinct responses were observed among the treatments (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea), with the bacterial consortium (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb) and \u003cem\u003eBrevibacillus\u003c/em\u003e sp. UPT4 (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec) standing out, promoting increases of 38.52% and 56.59%, respectively, compared to the control treatment (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea). Similarly, for stem diameter (SD), co-inoculation and inoculation with \u003cem\u003eBrevibacillus\u003c/em\u003e sp. UPT4 resulted in values 13.58% and 20.20% higher, respectively, than the uninoculated treatment (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb). Inoculation with \u003cem\u003ePantoea\u003c/em\u003e sp. SPM1 (T3) did not differ statistically from the control.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFor root length (RL), all inoculated treatments showed higher means than the control; however, only \u003cem\u003eBrevibacillus\u003c/em\u003e sp. UPT4 exhibited a significant increase of 43.40% (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea). All inoculated treatments increased the root volume (RV) of cucumber seedlings compared to the control, with increments ranging from 92.86% to 117.86% (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFor shoot biomass allocation (SBA), all inoculated treatments showed lower mean values compared to the control (Fig.\u0026nbsp;4a). Conversely, inoculation resulted in a higher percentage of biomass allocation to the roots (RBA) compared to the control (Fig.\u0026nbsp;4b). \u003cem\u003ePantoea\u003c/em\u003e sp. SPM1 exhibited the greatest increase (194.86%), followed by the microbial consortium (141.94%) and \u003cem\u003eBrevibacillus\u003c/em\u003e sp. UPT4 (110.69%).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eRedundancy analysis (RDA) enabled the correlation of the functional profile of the strains with the evaluated phytometric parameters, explaining 83.3% and 16.7% of the variance along the first (RDA1) and second (RDA2) axes, respectively (Fig.\u0026nbsp;4). The results revealed that the greatest variability in RV, SD, RL, and SL was associated with the ability of the strains to produce indole-3-acetic acid (IAA). Moreover, asymbiotic nitrogen fixation capacity exhibited a positive correlation with root biomass allocation values, whereas SBA displayed distinct distribution patterns compared to the other parameters.\u003c/p\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eArid and semi-arid regions are often characterized by stress conditions such as high temperatures, low relative air humidity, and reduced water availability. These factors modulate plant microbiome interactions, favoring the presence of microorganisms capable of assisting in nutrient uptake and stress responses, thereby promoting plant development (Yang et al. 2023; L\u0026oacute;pez-Hern\u0026aacute;ndez et al. 2020). Phyllosphere microorganisms are exposed to extreme climatic fluctuations, which compel them to develop biochemical and physiological strategies that ensure their adaptability to hostile conditions.\u003c/p\u003e\u003cp\u003eThe formulation of inoculants based on microorganisms from the phyllosphere of semi-arid regions represents a promising biotechnological tool. Studies have shown that the genetic repertoire of epiphytic bacteria from cacti in such regions includes various mechanisms associated with phytohormone synthesis, nitrogen fixation, and stress tolerance (L\u0026oacute;pez-Hern\u0026aacute;ndez et al. 2020). Similarly, Li et al. (2023) emphasizes that epiphytic bacteria from desert plants possess specialized functional capabilities, serving as sources of metabolites and mechanisms applicable to agriculture.\u003c/p\u003e\u003cp\u003eA specialized functional profile was identified in the present study, as both strains exhibited tolerance to abiotic stresses, including high salinity and low water activity. These findings are consistent with reports of phyllosphere microorganisms adapted to harsh environments, such as those associated with \u003cem\u003eTillandsia landbeckii\u003c/em\u003e Phil. in the Atacama Desert (Hakobyan et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) and phytobacteria associated with rice cultivars (Devarajan et al. 2020). The results of this study indicate that strains isolated from \u003cem\u003eT. inamoena\u003c/em\u003e possess potential for agricultural application, particularly in cropping systems subjected to environmental stresses.\u003c/p\u003e\u003cp\u003eThe high IAA production observed suggests that the strains have potential for plant growth promotion (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The adverse conditions of the semi-arid climate exert selective pressure on the phyllosphere microbiota, triggering osmotic stress and inducing the expression of genes related to IAA production (Etesami and Glick \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). As a result, tryptophan present in foliar exudates is assimilated by epiphytic communities, which secrete the phytohormone and stimulate plant development (Saleem and Paul \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), as verified in this study.\u003c/p\u003e\u003cp\u003eMechanisms associated with mineral nutrient availability were also identified. Potassium solubilization, observed in \u003cem\u003ePantoea\u003c/em\u003e sp. SPM1, represents an important trait in plant growth promotion, enhancing photosynthesis and activating key enzymes (Pandey and Saharan \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). In addition, the asymbiotic nitrogen fixation observed in both strains may integrate into the set of nutritional mechanisms available to cropping systems. The assimilation of atmospheric nitrogen in the phyllosphere, as reported for \u003cem\u003eMethylobacterium symbioticum\u003c/em\u003e, may serve as an alternative in environments with low nutrient availability, while also reducing the need for chemical fertilizers (Valente et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eAlthough neither strain exhibited phosphorus solubilization capacity, this result did not compromise the plant growth gains observed. On the contrary, it suggests that other mechanisms, such as IAA production and nitrogen fixation, were more decisive, as observed on RDA. This finding reinforces that the potential of PGPB is not necessarily linked to the presence of all classical mechanisms, but rather to the functional effectiveness of those most relevant under specific environmental and physiological conditions. In this context, it is essential to consider the identification and selection of elite microorganisms, i.e., strains that, even with a limited set of traits, display high agronomic efficiency and functional plasticity across different cropping systems.\u003c/p\u003e\u003cp\u003eIn cucumber assays, significant increases in shoot growth were observed in treatments inoculated with the microbial consortium and with \u003cem\u003eBrevibacillus\u003c/em\u003e sp. UPT4, particularly in SL and SD. These results suggest a possible synergistic action between IAA production and nitrogen fixation, promoting greater structural development and biomass allocation. Similar findings were reported in tomato and pepper seedlings inoculated with \u003cem\u003eBrevibacillus brevis\u003c/em\u003e FJAT-0809-GLX, which showed significant increases in growth parameters after 14 days of cultivation (Che et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe root system showed superior development in inoculated plants compared to the control. Increases in root architecture are strongly associated with IAA synthesis, which directly influences root growth. A more robust root system enhances water and nutrient uptake, thereby increasing crop resilience under conditions of water and nutrient limitation (Dias et al. 2020). In studies with maize (Maulina et al. 2023) and cotton (Nehra et al. 2018), inoculation with \u003cem\u003eBrevibacillus\u003c/em\u003e spp. also resulted in significant gains in root length and biomass, reinforcing the ecological and functional plasticity of these microorganisms, even when originating from the phyllosphere.\u003c/p\u003e\u003cp\u003eThe effects observed with the microbial consortium may indicate advantages over single-strain formulations, as the combination of different microorganisms can broaden the spectrum of benefits to crops (Mir et al. 2019). Studies with common bean (Verma et al., \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), millet (Kushwaha et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), and pearl millet (Kaur et al. 2023) have shown that microbial consortia improve growth, biomass, and chlorophyll content.\u003c/p\u003e\u003cp\u003eThe present study also revealed differences in shoot and root biomass allocation. Inoculated plants displayed greater root biomass allocation compared to the control, consistent with findings by Awasthi et al. (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) in \u003cem\u003eBacopa monnieri\u003c/em\u003e (L.) Wettst inoculated with \u003cem\u003ePantoea\u003c/em\u003e sp. MTP17. In this study, the higher root allocation rate observed with \u003cem\u003ePantoea\u003c/em\u003e sp. SPM1 may be related to its high IAA production and potassium solubilization, traits that favor biomass accumulation in roots.\u003c/p\u003e\u003cp\u003eRDA confirmed the association between the responses obtained in vitro and the phenotypic performance in vivo, suggesting that the functional traits of the strains were decisive for the differences among treatments. The contrasting distribution of SBA and RBA likely reflects distinct biomass allocation strategies induced by each strain. The dissociation of SBA from the other variables in the RDA suggests the occurrence of an adaptive trade-off. In this strategy, the plant reduces biomass allocation to the shoot and prioritizes root growth, ensuring greater efficiency in water and nutrient acquisition under stress conditions, albeit at the expense of immediate shoot growth (Chieb and Gachomo \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Grover et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Bektas et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2023\u003c/span\u003e)\u003c/p\u003e\u003cp\u003eThe positive correlation between asymbiotic nitrogen fixation and root variables reinforces the role of these bacteria in plant nutrition, while the association between IAA and RL, SL, and SD highlights the direct contribution of the phytohormone to cucumber growth under the tested conditions, identifying the inoculated treatments with the greatest agronomic potential. Nevertheless, as this study was conducted at an early stage under controlled conditions, further field trials are necessary to validate these effects and confirm strain efficiency across different environments and cropping systems.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThese results highlight the potential of the phyllosphere of native semi-arid plants as a source for the development of new technologies aimed at sustainable agriculture. The integration of epiphytic microorganisms represents a promising tool to address the challenges posed by population growth and climate change. \u003cem\u003eBrevibacillus\u003c/em\u003e sp. UPT4 exhibited the greatest improvements in cucumber vegetative development, promoting increases in shoot and root system length, thereby enhancing plant efficiency and resilience, particularly under water and salt stress conditions.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that no funds, grants, or other support were received during the preparation of this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Ellie José Pereira and Vinícius de Souza. The first draft of the manuscript was written by Ellie José Pereira and Vinícius de Souza, and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors confirm that the data supporting the findings of this study are available within the article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAgbodjato NA, Babalola OO (2024). Promoting sustainable agriculture by exploiting plant growth-promoting rhizobacteria (PGPR) to improve maize and cowpea crops. PeerJ. 12:e16836. doi: https://doi.org/10.7717/peerj.16836\u003c/li\u003e\n\u003cli\u003eAlzate Zuluaga MY, Fattorini R, Cesco S, Pii Y (2024). Plant-microbe interactions in the rhizosphere for smarter and more sustainable crop fertilization: the case of PGPR-based biofertilizers. Front Microbiol. 15. doi: https://doi.org/10.3389/fmicb.2024.1440978\u003c/li\u003e\n\u003cli\u003eArun KD, Sabarinathan KG, Gomathy M, Kannan R, Balachandar D (2020). Mitigation of drought stress in rice crop with plant growth‐promoting abiotic stress‐tolerant rice phyllosphere bacteria. J Basic Microbiol. 60(9):768\u0026ndash;786. doi: https://doi.org/10.1002/jobm.202000011\u003c/li\u003e\n\u003cli\u003eAwasthi A, Soni SK, Laxmi, Bajpai A (2024). Indole-3-acetic acid-producing \u003cem\u003ePantoea\u003c/em\u003e strain MTP 17 and \u003cem\u003eGlomus mosseae\u003c/em\u003e synergistically improve the growth, yield and bacoside content of Bacopa monnieri. Discov Plants. 1(1). doi: https://doi.org/10.1007/s44372-024-00015-0\u003c/li\u003e\n\u003cli\u003eBahloul H (2021). Effect of foliar spray with some growth stimulants on growth, productivity and quality of cucumber plants grown under greenhouse conditions. Ann Agric Sci Moshtohor. 59(5):975\u0026ndash;986. doi: https://doi.org/10.21608/assjm.2021.214961\u003c/li\u003e\n\u003cli\u003eBektas H, Hohn CE, Lukaszewski AJ, Waines JG (2023). On the Possible Trade-Off between Shoot and Root Biomass in Wheat. Plants. 12(1):2513. doi: https://doi.org/10.3390/plants12132513\u003c/li\u003e\n\u003cli\u003eChe J, Liu B, Liu G, et al (2018). Effect of optimized application technology on tomato and pepper seedling growth of \u003cem\u003eBrevibacillus brevis\u003c/em\u003e FJAT-0809-GLX. China Veg. 1(4):43\u0026ndash;47.\u003c/li\u003e\n\u003cli\u003eChieb M, Gachomo EW (2023). The role of plant growth promoting rhizobacteria in plant drought stress responses. BMC Plant Biol. 23(1): 407. doi: https://doi.org/10.1186/s12870-023-04403-8\u003c/li\u003e\n\u003cli\u003eDevarajan AK, Muthukrishanan G, Truu J, Truu M, Ostonen I, Kizhaeral S, Panneerselvam P, Gopalasubramanian SK (2021). The foliar application of rice phyllosphere bacteria induces drought-stress tolerance in \u003cem\u003eOryza sativa\u003c/em\u003e (L.). Plants. 10(2):387. doi: https://doi.org/10.3390/plants10020387\u003c/li\u003e\n\u003cli\u003eDias AC, Alves GC, Silva TFR, Reis VM (2023). Inoculation effects of growth-promoting bacteria on corn root architecture: influence of nitrogen levels, bacterial populations, and plant genotypes. Rev Bras Cienc Solo. 47. doi: https://doi.org/10.36783/18069657rbcs20230059\u003c/li\u003e\n\u003cli\u003eEtesami H, Glick BR (2024). Bacterial indole-3-acetic acid: a key regulator for plant growth, plant-microbe interactions, and agricultural adaptive resilience. Microbiol Res. 281:127602. doi: https://doi.org/10.1016/j.micres.2024.127602\u003c/li\u003e\n\u003cli\u003eFlores-N\u0026uacute;\u0026ntilde;ez VM, Fonseca-Garc\u0026iacute;a C, Desgarennes D, Eloe-Fadrosh E, Woyke T, Partida-Mart\u0026iacute;nez LP (2020). Functional signatures of the epiphytic prokaryotic microbiome of Agaves and Cacti. Front Microbiol. 10:3044. doi: https://doi.org/10.3389/fmicb.2019.03044\u003c/li\u003e\n\u003cli\u003eFlores-N\u0026uacute;\u0026ntilde;ez VM, Fonseca-Garc\u0026iacute;a C, Desgarennes D, Partida-Mart\u0026iacute;nez LP (2025). The Agave and Cacti microbiome: models for a planet under global warming. Metagenomics. p. 421\u0026ndash;460. doi: https://doi.org/10.1016/b978-0-323-91631-8.00010-x\u003c/li\u003e\n\u003cli\u003eGordon SA, Weber RP (1951). Colorimetric estimation of indoleacetic acid. Plant Physiol. 26(1):192. doi: https://doi.org/10.1104/pp.26.1.192\u003c/li\u003e\n\u003cli\u003eGrover M, Bodhankar S, Sharma A, Sharma P, Singh J, Nain L (2021). PGPR Mediated Alterations in Root Traits: Way Toward Sustainable Crop Production. Front. Sustain. Food Syst. 4(1). doi: https://doi.org/10.3389/fsufs.2020.618230\u003c/li\u003e\n\u003cli\u003eHakobyan A, et al (2023). Tillandsia landbeckii phyllosphere and laimosphere as refugia for bacterial life in a hyperarid desert environment. Microbiome. 11(1):246. doi: https://doi.org/10.1186/s40168-023-01684-x\u003c/li\u003e\n\u003cli\u003eHallsworth JE, Nomura Y, Iwahara M (1998). Ethanol-induced water stress and fungal growth. J Ferment Bioeng. 86(5):451\u0026ndash;456. doi: https://doi.org/10.1016/s0922-338x(98)80150-5\u003c/li\u003e\n\u003cli\u003eKaur M, Sharma P (2021). Recent advances in cucumber (\u003cem\u003eCucumis sativus\u003c/em\u003e L.). J Hortic Sci Biotechnol. 97(1):3\u0026ndash;23. doi: https://doi.org/10.1080/14620316.2021.1945956\u003c/li\u003e\n\u003cli\u003eKaur T, Devi R, Kumar S, Kour D, Yadav AN (2022). Plant growth promotion of pearl millet (\u003cem\u003ePennisetum glaucum\u003c/em\u003e L.) by novel bacterial consortium with multifunctional attributes. Biologia. 78(2):621\u0026ndash;631. doi: https://doi.org/10.1007/s11756-022-01291-5\u003c/li\u003e\n\u003cli\u003eKhosravi H, Khoshru B, Nosratabad AF, Mitra D (2024). Exploring the landscape of biofertilizers containing plant growth-promoting rhizobacteria in Iran: progress and research prospects. Curr Res Microb Sci. 7:100268. doi: https://doi.org/10.1016/j.crmicr.2024.100268\u003c/li\u003e\n\u003cli\u003eKushwaha P, Kashyap PL, Srivastava AK, Tiwari RK (2020). Plant growth promoting and antifungal activity in endophytic \u003cem\u003eBacillus\u003c/em\u003e strains from pearl millet (\u003cem\u003ePennisetum glaucum\u003c/em\u003e). Braz J Microbiol. 51:229\u0026ndash;241. doi: https://doi.org/10.1007/s42770-019-00172-5\u003c/li\u003e\n\u003cli\u003eLiu J, Sun X, Zuo Y, Hu Q, He X (2023). Plant species shape the bacterial communities on the phyllosphere in a hyper-arid desert. Microbiol Res. 269:127314. doi: https://doi.org/10.1016/j.micres.2023.127314\u003c/li\u003e\n\u003cli\u003eMallick PK (2022). Evaluating potential importance of cucumber (\u003cem\u003eCucumis sativus\u003c/em\u003e L. - Cucurbitaceae): a brief review. Int J Appl Sci Biotechnol. 10(1):12\u0026ndash;15. doi: https://doi.org/10.3126/ijasbt.v10i1.44152\u003c/li\u003e\n\u003cli\u003eMarson M, Saccone D (2023). Fed with import and starved by war: estimating the consequences of the Russia-Ukraine conflict on cereals trade and global hunger. Int Econ Econ Policy. 20(3):413\u0026ndash;423. doi: https://doi.org/10.1007/s10368-023-00564-x\u003c/li\u003e\n\u003cli\u003eMaulina NMI, Suprapta DN, Temaja IGRM, Adnyana IM, Suriani NL (2022). Rhizobacteria of Bali with obvious growth-promoting properties on corn (\u003cem\u003eZea mays\u003c/em\u003e L.). Front Sustain Food Syst. 6. doi: https://doi.org/10.3389/fsufs.2022.899736\u003c/li\u003e\n\u003cli\u003eNehra V, Saharan BS, Choudhary M (2016). Evaluation of Brevibacillus brevis as a potential plant growth promoting rhizobacteria for cotton (\u003cem\u003eGossypium hirsutum) \u003c/em\u003ecrop. SpringerPlus. 5(1). doi: https://doi.org/10.1186/s40064-016-2584-8\u003c/li\u003e\n\u003cli\u003eOrganisation for Economic Co-operation and Development (OECD), Food and Agriculture Organization of the United Nations (FAO) (2024). OECD-FAO agricultural outlook 2024\u0026ndash;2033. Paris (FR): OECD Publishing. doi: https://doi.org/10.1787/4c5d2cfb-en\u003c/li\u003e\n\u003cli\u003ePandey K, Saharan BS (2025). Potassium-solubilizing endophytes: mechanisms and applications in enhancing sustainable agriculture and plant resilience. Symbiosis. 95(3):291\u0026ndash;305. doi: https://doi.org/10.1007/s13199-025-01052-3\u003c/li\u003e\n\u003cli\u003eR Core Team (2024). R: a language and environment for statistical computing. Vienna (AT): R Foundation for Statistical Computing.\u003c/li\u003e\n\u003cli\u003eRemus-Emsermann MNP, Schlechter RO (2018). Phyllosphere microbiology: at the interface between microbial individuals and the plant host. New Phytol. 218(4):1327\u0026ndash;1333. doi: https://doi.org/10.1111/nph.15054\u003c/li\u003e\n\u003cli\u003eSafi L, Mujeeb M, Sahak K, Mushwani H, Hashmi SK (2024). Climate change impacts and threats on basic livelihood resources, food security and social stability in Afghanistan. GeoJournal. 89(2). doi: https://doi.org/10.1007/s10708-024-11077-8\u003c/li\u003e\n\u003cli\u003eSaleem B, Paul PK (2015). Phytohormones from phylloplane microbes: a review. Trends Biosci. 8(17):4450\u0026ndash;4458.\u003c/li\u003e\n\u003cli\u003eSands RD, Meade B, Seale JL Jr, Robinson S, Seeger R. (2023). Scenarios of global food consumption: implications for agriculture. doi: https://doi.org/10.22004/ag.econ.338943\u003c/li\u003e\n\u003cli\u003eShahwar D, Mushtaq Z, Mushtaq H, Alqarawi AA, Park Y, Alshahrani TS, Faizan S (2023). Role of microbial inoculants as biofertilizers for improving crop productivity: a review. Heliyon. 9(6):e16134. doi: https://doi.org/10.1016/j.heliyon.2023.e16134\u003c/li\u003e\n\u003cli\u003eSharath S, Triveni S, Nagaraju Y, Latha PC, Vidyasagar B (2021). The role of phyllosphere bacteria in improving cotton growth and yield under drought conditions. Front Agron. 3. doi: https://doi.org/10.3389/fagro.2021.68\u003c/li\u003e\n\u003cli\u003eSrivastava RM, Joshih S (2021). Integrated pest management for cucurbits in cucumber (\u003cem\u003eCucumis sativus\u003c/em\u003e L.). In: Cucumber economic values and its cultivation and breeding. doi: https://doi.org/10.5772/intechopen.97123\u003c/li\u003e\n\u003cli\u003eValente F, Panozzo A, Bozzolin F, Barion G, Bolla PK, Bertin V, Potestio S, Visioli G, Wang Y, Vamerali T (2024). Growth, photosynthesis and yield responses of common wheat to foliar application of Methylobacterium symbioticum under decreasing chemical nitrogen fertilization. Agriculture. 14(10):1670. doi: https://doi.org/10.3390/agriculture14101670\u003c/li\u003e\n\u003cli\u003eVerma JP, Jaiswal DK, Krishna R, Prakash S, Yadav J, Singh V (2018). Characterization and screening of thermophilic \u003cem\u003eBacillus\u003c/em\u003e strains for developing plant growth promoting consortium from hot spring of Leh and Ladakh region of India. Front Microbiol. 9:1293. doi: https://doi.org/10.3389/fmicb.2018.01293\u003c/li\u003e\n\u003cli\u003eWilson PW, Knight SG (1952). Experiments in bacterial physiology. 3rd ed. Minneapolis (MN): Burgess Publishing Co.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"international-microbiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"intm","sideBox":"Learn more about [International Microbiology](https://www.springer.com/journal/10123)","snPcode":"10123","submissionUrl":"https://submission.nature.com/new-submission/10123/3","title":"International Microbiology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Agriculture, Bioinputs, Caatinga, Crops, Phyllosphere","lastPublishedDoi":"10.21203/rs.3.rs-7935575/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7935575/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eUnder stress conditions, the phyllosphere of host plants harbors microorganisms with potential for the development of agricultural bioinputs. In this study, the potential of \u003cem\u003eBrevibacillus\u003c/em\u003e sp. UPT4 and \u003cem\u003ePantoea\u003c/em\u003e sp. SPM1, two epiphytic strains from \u003cem\u003eTacinga inamoena\u003c/em\u003e isolated from the Caatinga biome, was assessed through in vitro assays and a greenhouse experiment. The experiment was conducted in a randomized block design with four treatments (individual strains, bacterial consortium, and control) and five replicates. Biometric parameters (shoot and root length, stem diameter, root volume, and biomass allocation to shoot and root) were measured and analyzed by the Scott-Knott test at a probability level of 5%, as well as Redundancy Analysis (RDA). The strains exhibited auxin production, nitrogen fixation, and tolerance to abiotic stresses, showing significant increases (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) in shoot and root parameters (13.58% to 194.86%) compared to the control. RDA indicated that most of the variability observed in the parameters was associated with auxin production and stress tolerance. These findings highlight the potential of epiphytic bacteria isolated from the Caatinga biome as promising tools to address challenges posed by climate change.\u003c/p\u003e","manuscriptTitle":"Epiphytic bacteria from Tacinga inamoena (K. Schum.) N.P. Taylor \u0026amp; Stuppy improve plant growth in cucumber seedlings","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-10 17:00:54","doi":"10.21203/rs.3.rs-7935575/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-12-12T10:39:24+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-05T15:09:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"305841442434667871554253525015325079033","date":"2025-11-24T15:24:02+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-24T08:37:25+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"3260601782282111692724319499656857080","date":"2025-11-14T10:04:40+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-30T13:42:42+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-30T13:41:24+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-26T23:24:23+00:00","index":"","fulltext":""},{"type":"submitted","content":"International Microbiology","date":"2025-10-24T00:07:21+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"international-microbiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"intm","sideBox":"Learn more about [International Microbiology](https://www.springer.com/journal/10123)","snPcode":"10123","submissionUrl":"https://submission.nature.com/new-submission/10123/3","title":"International Microbiology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"7f823baf-db98-48cd-a3a6-8d3c83251930","owner":[],"postedDate":"November 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-03-09T16:09:18+00:00","versionOfRecord":{"articleIdentity":"rs-7935575","link":"https://doi.org/10.1007/s10123-026-00778-4","journal":{"identity":"international-microbiology","isVorOnly":false,"title":"International Microbiology"},"publishedOn":"2026-03-03 15:58:06","publishedOnDateReadable":"March 3rd, 2026"},"versionCreatedAt":"2025-11-10 17:00:54","video":"","vorDoi":"10.1007/s10123-026-00778-4","vorDoiUrl":"https://doi.org/10.1007/s10123-026-00778-4","workflowStages":[]},"version":"v1","identity":"rs-7935575","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7935575","identity":"rs-7935575","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}