Stage-specific rhizosphere microbial succession drives nutrient cycling in the desert plant Leymus racemosus (Lam.) tzvelev

Stage-specific rhizosphere microbial succession drives nutrient cycling in the desert plant Leymus racemosus (Lam.) tzvelev | 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 Stage-specific rhizosphere microbial succession drives nutrient cycling in the desert plant Leymus racemosus (Lam.) tzvelev Yufang Sun, Jinfeng Tang, Sijie Ma, Ailijiang Maimaiti, Jun Liu, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8973487/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 15 You are reading this latest preprint version Abstract Background and aims: Plants regulate nutrient uptake and growth by recruiting rhizosphere microorganisms via root exudates. However, a systematic understanding of how the rhizosphere core and functional microbiota jointly regulate the dynamics of carbon, nitrogen, phosphorus, and potassium across the entire plant life cycle remains limited. Methods We used 16S rRNA high-throughput sequencing to analyze the rhizosphere bacterial communities and nutrient contents of the desert plant Leymus racemosus at different growth stages in the Kalamaili Nature Reserve, Xinjiang, China. Results Arthrobacter , as a core taxon, maintained nitrogen stability across all growth stages. Bacillus became the dominant genus during the flowering stage, ensuring nutrient supply and reflecting an “investment” strategy. At maturity, enhanced microbial cooperation combined with reduced plant demand promoted the accumulation of rhizosphere nutrients, thereby facilitating energy storage for subsequent growth. Conclusions This study reveals the developmental dynamics of rhizosphere bacterial community assembly and nutrient regulation in L. racemosus . It provides a theoretical basis for further elucidating plant–microbe interactions in desert ecosystems. Future research should focus on isolating key bacterial strains and integrating metabolomics to clarify the underlying mechanisms. Leymus racemosus rhizosphere microbiome growth stage nutrient cycling microbial succession Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Introduction The plant rhizosphere microbiome comprises specific microbial communities, including primarily bacteria and fungi, that colonize the root surface and the surrounding soil zone [ 1 ]. Often referred to as the plant's “second genome”, these microbes collectively form a complex rhizosphere system [ 2 ]. Through close interactions with plants, rhizosphere microorganisms directly or indirectly regulate plant growth and development [ 2 , 3 ]. Acting as biotransformers of soil nutrients, rhizosphere microbes drive the transformation and cycling of key elements such as carbon, nitrogen, phosphorus, and potassium through their metabolic activities. Moreover, they play indispensable roles in organic matter decomposition, as well as nutrient solubilization and immobilization [ 4 , 5 ]. Consequently, these microorganisms strongly influence soil nutrient bioavailability, thereby affecting plant nutrient uptake, growth, and development [ 6 ]. Numerous studies have shown that plant developmental stage is a key driver of rhizosphere microbial community succession [ 7 , 8 ]. As plants transition from the vegetative seedling stage to the reproductive flowering stage, they actively recruit specific microbial taxa through mechanisms such as root exudation to facilitate the acquisition of nutrients required at each developmental phase [ 9 , 10 ]. For example, during periods of vigorous vegetative growth, microbial taxa associated with nitrogen fixation and transformation may be preferentially enriched. In contrast, functional microbial groups with high efficiency in phosphorus and potassium solubilization may be favored during the reproductive stage [ 7 , 11 – 15 ]. This “on-demand” recruitment model highlights plants' strong capacity for precise regulation of the rhizosphere microenvironment. Although previous studies have provided insight into microbial functional traits associated with individual growth stages, it is still unknown how the core and functional microbiota interact across the entire plant life cycle, or how their synergy co-regulates dynamic changes in nutrients such as nitrogen, phosphorus, and potassium [ 11 ]. Leymus racemosus (Lam.) Tzvelev, a perennial grass species typical of the Junggar Desert in Xinjiang, China [ 16 , 17 ], exhibits distinct phenological stages, including the seedling stage in May, the flowering stage in June, and the maturity stage in July. In this study, L. racemosus was used as a model to systematically analyze the structural succession of the rhizosphere microbial community across three key developmental stages. By integrating microbial community dynamics with changes in soil carbon, nitrogen, phosphorus, and potassium, we aimed to elucidate the potential division of labor and cooperative mechanisms between the core and functional microbiota in nutrient cycling. The findings are expected to advance our understanding of plant strategies for regulating rhizosphere microbes and nutrient cycling processes. Materials and methods Sample collection Samples were collected from May to early July 2024 in a typical desert area of the Kalamaili Mountain Ungulate Wildlife Nature Reserve, located in the Junggar Basin of northern Xinjiang (89.082322°E, 45.246486°N), one of the main distribution areas of Leymus racemosus . This species is listed as a Class II protected plant in the Xinjiang Uygur Autonomous Region, and all necessary permissions for the collection of plant material in this field study were obtained from the Administration of the Kalamaili Mountain Ungulate Wildlife Nature Reserve, with the approval of the local government. The research complied with all relevant institutional, national, and international guidelines and regulations concerning plant collection and access to protected areas. The plant species was formally identified by Professor Juan Qiu based on morphological characteristics. A voucher specimen (Accession Number: 202407-SYS21) has been deposited in the Herbarium of Xinjiang Agricultural University. L. racemosus grows in patchy populations across sandy habitats and is considered a dominant species in this region. A uniform patch with consistent growth vigor and similar plant cluster size was selected as the standardized sampling site. To accurately characterize the rhizosphere microbial community at each developmental stage and avoid interference among successive sampling events, independent and randomly distributed quadrats were established for each stage: seedling ( S ), flowering ( F ), and maturity ( M ). During each sampling event, ten 5 m × 5 m quadrats were arranged at 20 m intervals, and 6–10 healthy individuals were selected from each quadrat for sampling. During sampling, root systems were carefully excavated, and loosely attached non-rhizosphere soil was gently shaken off, while tightly adhering rhizosphere soil was retained. The intact rhizosphere samples were placed in sterile sealed bags, immediately stored in ice-filled containers, and transported to the laboratory. Under aseptic conditions, rhizosphere soil was gently separated from the roots to obtain rhizosphere soil samples [ 18 , 19 ]. For each quadrat, rhizosphere soil from all sampled plants was pooled into one composite sample. Each composite sample was divided into two portions: one was flash-frozen in liquid nitrogen and stored at − 80°C for microbial diversity analysis, and the other was used to determine soil physicochemical properties. High-throughput sequencing Total microbial genomic DNA was extracted from the rhizosphere soil samples using an E.Z.N.A.® Soil DNA Kit (Omega Bio-Tek, Norcross, GA, U.S.), according to the manufacturer's instructions. The quality and concentration of the extracted DNA were assessed by 1.0% agarose gel electrophoresis and a NanoDrop2000 spectrophotometer (ThermoFisher Scientific, United States), respectively. Qualified DNA samples were stored at -80°C for subsequent analysis. The hypervariable V3-V4 region of the bacterial 16S rRNA gene was amplified using the primer pair 338F (5'-ACTCCTACGGGAGGCAGCAG-3') and 806R (5'-GGACTACHVGGGTWTCTAAT-3') on a T100 Thermal Cycler PCR system (Bio-Rad, USA) [ 20 ]. The resulting amplicons were purified, pooled in equimolar concentrations, and subjected to paired-end sequencing on an Illumina NextSeq2000 platform (Illumina, San Diego, USA) [ 21 ]. All sequencing procedures were performed by Majorbio Bio-Pharm Technology Co., Ltd. (Shanghai, China) following standard operational protocols. The raw sequencing data have been deposited in the NCBI Sequence Read Archive (SRA) under BioProject number PRJNA1241221 (accession numbers SRR35918480-SRR35918497). Analysis of soil physicochemical properties Soil organic carbon (OC) was determined using the potassium dichromate oxidation method. Total nitrogen (TN) was measured by acid digestion followed by the Kjeldahl method (ATN-300). Available nitrogen (AN) was quantified using the alkali-hydrolyzed diffusion method. Available phosphorus (AP) was extracted with sodium bicarbonate and measured using the molybdenum-antimony anti-spectrophotometric method. Total potassium (TK) was analyzed by alkali fusion followed by flame photometry (FP6431). Available potassium (AK) was extracted with ammonium acetate and measured using flame photometry (FP6431) [ 22 , 23 ]. Statistical analysis Raw FASTQ files were initially demultiplexed using a custom Perl script. Sequence reads were then processed with fastp (v0.19.6) [ 24 ] for quality control and filtering, and assembled using FLASH (v1.2.7) [ 25 ]. High-quality sequences were clustered into operational taxonomic units (OTUs) at a 97% similarity threshold using the UPARSE algorithm (v7.1) [ 26 ]. The most abundant sequence within each OTU was selected as the representative sequence. An OTU table was constructed and curated by removing chloroplast-derived sequences across all samples. To reduce bias caused by uneven sequencing depth, the dataset was rarefied to 20,000 sequences per sample, which maintained an average Good’s coverage of 99.09%, indicating sufficient sequencing depth. Taxonomic classification of representative OTU sequences was performed using the RDP Classifier (v2.2) against the 16S rRNA gene database with a confidence threshold of 0.7 [ 27 ]. Based on the OTU data, rarefaction curves were generated, and alpha diversity indices (e.g., Simpson, Chao, Ace, and Shannon index) were calculated using Mothur (v1.30.1) [ 28 ]. Similarity among microbial communities in different samples was determined by principal coordinate analysis (PCoA) based on Bray-Curtis dissimilarity using the Vegan package (v2.5-3). Ordination was used to visualize similarities in microbial community structure among samples. Permutational multivariate analysis of variance (PERMANOVA), implemented in the same Vegan package, was applied to quantify the proportion of variation in community composition explained by soil type as well as to assess statistical significance. To visualize abundance dynamics of shared bacterial genera across plant growth stages, a co-occurrence network was constructed using Cytoscape [ 29 ]. The Kruskal–Wallis H test was used to identify taxa with significant differences in abundance among developmental stages. Redundancy analysis (RDA) was performed using the Vegan package (v2.4-3) in R (v3.3.1) to assess relationships between soil nutrient profiles and microbial community structure [ 30 ]. In addition, a heatmap based on Pearson correlation analysis was generated to visualize the strength and direction of associations between specific microbial taxa and soil nutrient factors. All data analyses were conducted using the online tools available on the Majorbio Cloud Platform ( https://www.majorbio.com/tools ). Results Rhizosphere Soil Nutrient Contents Across Different Growth Stages The rhizosphere soil of L. racemosus exhibited significantly higher concentrations of hydrolyzable nitrogen (HN), AP, organic matter (OM), and OC than the bulk soil (Fig. 1 ). However, rhizosphere TN, OM, and AK decreased significantly ( p < 0.05) during the flowering stage. In contrast, AP, AK, OM, and OC increased significantly at the maturity stage (Fig. 1 ). Notably, HN remained unchanged throughout the entire L. racemosus growth period (Fig. 1 a). Rhizosphere microbial community diversity across different growth stages Bacterial diversity in the L. racemosus rhizosphere was assessed at the seedling, flowering, and maturity stages. After quality control and chimera removal, a total of 1,216,512 high-quality sequences were obtained from the assembled reads. These sequences were then clustered into OTUs at a 97% similarity threshold. Rarefaction based on the smallest sample size yielded 13,640 OTUs. Taxonomic classification identified 39 phyla, 126 classes, 297 orders, 507 families, and 1,006 genera. Alpha diversity analysis showed that rhizosphere bacterial diversity varied among plant growth stages. The Shannon and Simpson indices indicated that bacterial diversity at the flowering and maturity stages was significantly higher than at the seedling stage (Kruskal-Wallis H test, p = 0.00469;Shannon: p = 0.00011; Simpson: p = 0.00022; Fig. 2 A, B). In contrast, both the Chao and Ace indices demonstrated that bacterial richness at the maturity stage was significantly higher than at either the seedling and flowering stages (Kruskal-Wallis H test, p = 0.00469; Chao: p = 0.00268; Ace: p = 0.00268; Fig. 2 C, D), whereas no significant difference was observed between the seedling and flowering stages ( p > 0.05; Fig. 2 C, D), indicating a significant accumulation of rhizosphere bacteria at the maturity stage. PCoA based on OTU-level data showed that rhizosphere bacterial communities from the seedling, flowering, and maturity stages formed distinct clusters, indicating high within-stage similarity. Meanwhile, bacterial community composition differed significantly among stages (ANOSIM, p = 0.001; Fig. 3 A), demonstrating a clear shift in rhizobacterial structure during development. This pattern was further supported by PERMANOVA (R² = 0.207, p = 0.0001; Fig. 3 B), confirming that plant growth stage plays a key role in shaping rhizosphere bacterial community assembly. Dynamics of key bacterial taxa across different growth stages Analysis of the rhizobacterial community composition of L. racemosus across different growth stages showed that Arthrobacter was the dominant genus at all three stages (Fig. 4 A, B). The relative abundance of this genus was highest at the seedling stage (20.3%), declined to 7.2% at the flowering stage, and then slightly increased to 9.7% at maturity, with an overall mean relative abundance of 12.7%. Despite the pronounced decline during flowering, Arthrobacter remained at notably high relative abundance. The decrease in Arthrobacter abundance at the flowering stage coincided with a significant increase in the abundance of Bacillus , which rose from 3.1% at the seedling stage to 10.9%, establishing it as a major dominant genus during this period. The abundance of Bacillus subsequently decreased significantly to 1.5% at the maturity stage (Fig. 4 A, B). Species-level analysis of Arthrobacter and Bacillus revealed distinct temporal dynamics across plant developmental stages. Within the genus Arthrobacter , an unclassified species ( unclassified_g__Arthrobacter ) dominated the community at the seedling, flowering, and maturity stages, accounting for more than 80% of the relative abundance (Fig. 4 C). Arthrobacter agilis and Arthrobacter citreus were also present at relatively high proportions (Fig. 4 C). In contrast, the increase in Bacillus abundance during the flowering stage was primarily driven by a marked increase in an unclassified Bacillus species ( unclassified_g__Bacillus ). Meanwhile, Bacillus aryabhattai , Bacillus filamentosus , and Bacillus simplex maintained relatively stable abundances across all stages (Fig. 4 D). Co-occurrence network analysis further revealed growth stage-dependent variations in the abundance of bacterial genera (Fig. 5 ). Consistent with earlier results, Arthrobacter maintained high relative abundance throughout the seedling, flowering, and maturity stages, confirming its role as a stable dominant genus in the L. racemosus rhizosphere. Bacillus reached its peak abundance during the flowering stage. At the same time, the abundances of Pantoea and Massilia also increased significantly, accounting for 3.0% and 1.9% of the community, respectively. Analysis of differentially abundant taxa further showed that Arthrobacter consistently exhibited high abundance across all developmental stages, with its relative abundance at the seedling stage being significantly higher than at the flowering or maturity stages. In addition, Pedobacter , TM7a , and Planomicrobium were significantly more abundant at the seedling stage than at the other two stages. During the flowering stage, in addition to Bacillus , the abundances of Pantoea , Massilia , and Sphingomonas were significantly elevated, establishing them as dominant taxa for this period. In contrast, the maturity stage was characterized by sustained high relative abundances of Arthrobacter , norank_f__JG30-KF-CM45 , Sphingomonas , Devosia , and the Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium group (Fig. 6 ). Functional characterization of key bacterial communities at different growth stages FAPROTAX-based functional profiling identified aerobic chemoheterotrophy, chemoheterotrophy, and nitrate reduction as the core functions of the bacterial community (Fig. 7 A). In addition, ureolysis was significantly more abundant during the flowering stage than during the seedling and maturity stages. As mentioned, the genus Arthrobacter dominated the rhizosphere community across growth stages. Notably, the core function of the Arthrobacter genus was nitrate reduction, followed by arsenate detoxification and reduction (Fig. 7 B). In contrast, Bacillus abundance increased significantly at the flowering stage. Functional prediction for the Bacillus genus revealed not only a strong potential for nitrate reduction but also a significant enhancement of aerobic chemoheterotrophy and chemoheterotrophy at the flowering stage (Fig. 7 C). Associations between microbial communities and soil factors To further explore relationships between the rhizosphere microbial community and soil nutrient conditions, RDA and Spearman correlation analysis were performed. The RDA results (Fig. 8 ) showed that samples from the maturity stage were closely aligned with the vectors for AP, AK, TN, and soil organic carbon (SOC). This alignment indicates a strong association between the rhizobacterial community structure at the maturity stage and the enrichment of these soil nutrients. To further elucidate the roles of specific bacterial genera in nutrient dynamics, Spearman correlation analysis was conducted on the top 30 most abundant genera (Fig. 9 ). The results showed that the abundance of Bacillus was significantly negatively correlated with AP, AK, and SOC. This pattern is consistent with the sharp decline in Bacillus abundance after the flowering stage, coinciding with the onset of soil nutrient accumulation. In contrast, under the elevated nutrient conditions at the maturity stage, the abundances of Sphingomonas , Mycobacterium , Kribbella , and Aeromicrobium were significantly positively correlated with AP and AK. In addition, Kribbella and Aeromicrobium were also significantly positively correlated with SOC (Fig. 9 ). Discussion Arthrobacter as a core beneficial taxon and stabilizer of the L. racemosus rhizosphere Actinobacteriota are widely distributed in soil environments characterized by low water content, high organic matter, and slightly alkaline conditions [ 31 , 32 ], and they play key roles in nitrogen cycling. In this study, Actinobacteriota were significantly enriched in the L. racemosus rhizosphere, indicating that this group may contribute to plant growth and environmental adaptation. Within this phylum, Arthrobacter has been reported as a dominant rhizosphere taxon of desert plants [ 33 ]. Members of this genus exhibit broad carbon source utilization and strong environmental adaptability. Many strains are recognized as plant growth-promoting rhizobacteria (PGPR), with functions that include phosphorus solubilization, nitrogen fixation, potassium release, ACC deaminase production, antibiotic synthesis, and phytohormone secretion [ 34 – 36 ]. Of particular importance is their extensive nitrogen metabolic capacity. Certain strains can decompose and mineralize organic nitrogen (e.g., proteins and amino acids) through extracellular enzyme secretion, directly supplying plants with absorbable ammonium (NH₄⁺) [ 37 – 39 ]. In addition, some strains participate in nitrification and denitrification and may even possess nitrogen-fixing potential, thereby regulating nitrogen forms through multiple pathways to support plant nitrogen nutrition [ 37 , 40 , 41 ]. Our results showed that Arthrobacter maintained dominance in the L. racemosus rhizosphere across all growth stages. This pattern may be associated with the persistently high and stable level of HN in the rhizosphere throughout the growth period. At the seedling stage, the absolute dominance of Arthrobacter , combined with its strong aerobic chemoheterotropic, chemoheterotrophic, and nitrate reduction capacities, likely constituted a core mechanism supporting a steady nitrogen supply and the establishment of a basic nutrient cycle. At the flowering stage, although its relative abundance declined, Arthrobacter likely maintained functional importance through its versatile metabolism of both organic and inorganic nitrogen (e.g., nitrate), together with its potential nitrogen-fixing capacity, enabling persistence under shifting nitrogen forms. By the maturity stage, Arthrobacter , as a persistent keystone taxon, likely acted synergistically with other nutrient-mobilizing genera such as Sphingomonas and Devosia [ 42 , 43 ], continuing to promote nitrogen release via chemoheterotrophy and nitrate reduction. As plant nitrogen demand declined at this stage, sustained microbial activity probably contributed to the observed rhizosphere nutrient enrichment. Based on these findings, we propose that a core bacterial microbiome centered on Arthrobacter forms a robust microbial buffering system. This system mitigates nitrogen fluctuations driven by plant uptake and extreme environmental variability in desert soils through rapid transformation of organic and inorganic nitrogen sources, thereby maintaining dynamic stability of available nitrogen in the L. racemosus rhizosphere. This mechanism may represent a key ecological strategy supporting stable nitrogen supply in harsh desert environments. Flowering-stage enrichment of Bacillus and its role in strategic nutrient allocation Bacillus , a genus within the phylum Firmicutes, exhibits strong environmental adaptability, allowing it to survive under stress conditions such as nutrient limitation, drought, and high temperatures. It plays an important role in global biogeochemical cycles, including carbon and nitrogen cycling [ 44 ]. As typical PGPR, many Bacillus strains can synthesize and secrete phytohormones such as auxins and cytokinins, which stimulate cell division and elongation and thereby enhance root and shoot growth [ 45 ]. In addition, Bacillus species contribute to plant nutrition by fixing atmospheric nitrogen, solubilizing inorganic phosphorus, and mobilizing potassium, converting immobilized soil nutrients into plant-available forms [ 46 , 47 ]. Specifically, Bacillus species solubilize inorganic phosphorus through the secretion of organic acids and acid phosphatases and mineralize organic phosphorus via phytase secretion, leading to rapid increases (within days to weeks) in available phosphorus (H₂PO₄⁻/HPO₄²⁻) [ 48 , 49 ]. Concurrently, metabolites such as organic acids and amino acids released by Bacillus can weather potassium-bearing minerals and release plant-available potassium ions (K⁺) [ 50 , 51 ]. In the nitrogen cycle, Bacillus is a key driver in the transformation of organic nitrogen to inorganic forms, as secreted proteases efficiently degrade organic nitrogen and rapidly generate ammonium (NH₄⁺), thereby increasing soil available nitrogen [ 47 , 52 ]. In this study, a significant increase in the relative abundance of Bacillus was observed in the L. racemosus rhizosphere during the flowering stage, followed by a marked decline at maturity. This dynamic pattern is likely linked to the elevated nutrient demand during flowering and reduced uptake during maturation. The flowering stage represents a critical phase of the L. racemosus life cycle, characterized by peak demand for nitrogen, phosphorus, and potassium. This may drive the plant to actively recruit specific rhizobacteria, such as Bacillus , which function as a microbial “rapid-response force”. These microorganisms employ metabolic strategies including aerobic chemoheterotrophy and chemoheterotrophy to mobilize soil nutrients, thereby supporting the high nutrient requirements of L. racemosus during flowering. Despite the enrichment of Bacillus , no significant changes in available nitrogen or available phosphorus were detected in the L. racemosus rhizosphere during flowering. In contrast, both available potassium and total nitrogen decreased significantly, resulting in an overall decline in total rhizosphere nutrient levels. We hypothesize that this pattern reflects the high nutrient demand during flowering, whereby nutrients mobilized by microorganisms are rapidly taken up by the plant, creating a nutrient-limited rhizosphere and preventing nutrient accumulation. Thus, the enrichment of Bacillus during flowering likely represents a demand-driven recruitment strategy by L. racemosus , functioning as a temporary and highly efficient microbial support system. Notably the flowering-stage rhizosphere of L. racemosus was enriched not only in Bacillus , but also in genera such as Pantoea , Massilia , and Sphingomonas . Previous studies have shown that many Pantoea strains possess phosphorus-solubilizing capacity, whereas Sphingomonas can enhance nitrogen and phosphorus cycling in the rhizosphere [ 53 , 54 ]. These findings suggest that a multispecies microbial consortium may act synergistically to support the high-intensity nutrient demands of L. racemosus during flowering. Microbially driven nutrient accumulation during the maturation stage Upon entering the maturation stage, marked shifts occurred in both rhizosphere microbial community structure and nutrient accumulation dynamics. Although the relative abundance of Bacillus decreased sharply and that of Arthrobacter showed only a slight recovery, the contents of available phosphorus, available potassium, and organic carbon increased significantly, indicating a pronounced nutrient enrichment in the rhizosphere. We propose that this pattern is driven by two main mechanisms. First, the extensive proliferation and metabolic activity of Bacillus during the flowering stage may have exerted a lasting influence on the rhizosphere microenvironment, creating favorable conditions for the colonization and functional expression of other microorganisms. This is supported by our results showing that, during the maturation stage, taxa such as norank_f__JG30-KF-CM45 , Sphingomonas , Devosia , and the Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium group maintained relatively high abundances. Moreover, correlation analysis indicated that Devosia was significantly positively correlated with available phosphorus and organic matter, while Sphingomonas was also significantly positively correlated with available phosphorus. These taxa likely form a functionally complementary microbial network that collectively promotes sustained nutrient activation and accumulation during maturation, reflecting a lagged effect of microbial function on nutrient availability. Second, as the plant transitions into the maturation stage, its physiological and metabolic activities slow, leading to reduced nutrient uptake demand and rate. As a result, nutrients mobilized by the microbial community are no longer rapidly absorbed by the plant and are more likely to accumulate within the rhizosphere, ultimately producing the observed nutrient enrichment. Nutrient-microbe interplay in the L. racemosus rhizosphere: Integrated model and future directions Based on the results described above, we developed a conceptual model (Fig. 10 ) illustrating distinct functional stages in the L. racemosus rhizosphere. The seedling stage represents a “foundation phase”, during which a rhizosphere system centered on Arthrobacter establishes a basic nutrient cycling framework that maintains nitrogen stability. As the plant enters the flowering stage, nutrient demand increases sharply, initiating an “investment phase”. This stage is characterized by the pronounced recruitment of Bacillus , which actively mobilizes soil nutrients to support reproductive growth, leading to rapid depletion of the soil nutrient pool and a marked decline in rhizosphere nutrient content. The maturation stage can be viewed as a “harvest phase”, during which plant nutrient demand declines and microbial communities act synergistically to enhance nutrient accumulation beyond plant uptake, resulting in pronounced nutrient enrichment in the rhizosphere. However, we acknowledge several limitations of the present study. First, our interpretation of rhizosphere microbial functions is largely based on bioinformatic predictions and evidence from the existing literature. In addition, the precise taxonomic identities and ecological functions of two key taxa ( unclassified_g__Arthrobacter and unclassified_g__Bacillus ) in the extreme desert environment remain unclear. Therefore, future studies will combine metagenomic approaches with conventional isolation and cultivation methods to more systematically elucidate the relationships between rhizosphere microbial community dynamics and nutrient fluctuations during the growth and development of L. racemosus . Conclusion This study systematically analyzed the rhizosphere microecosystem of Leymus racemosus across different growth stages, elucidating the characteristics of rhizosphere microbial community succession and nutrient dynamics, as well as their potential interrelationships. The main conclusions are as follows: Firstly, the rhizosphere microbial community structure underwent significant succession throughout the entire growth cycle of L. racemosus . Specifically, Arthrobacter was the dominant genus at the seedling stage. Upon entering the flowering stage, Bacillus was substantially enriched and became the core population. By the maturity stage, the community structure shifted again, with Arthrobacter re-emerging as the dominant genus, while the abundance of Bacillus decreased significantly. Secondly, rhizosphere soil nutrient contents exhibited distinct stage-specific characteristics as the growth period progressed. Hydrolyzable nitrogen (HN) remained at a relatively high level throughout the entire growth period. In contrast, the contents of total nitrogen (TN), organic matter (OM), and available potassium (AK) decreased significantly during the flowering stage. At the maturity stage, the contents of available phosphorus (AP), available potassium (AK), organic matter (OM), and organic carbon (OC) showed a significant increase. Finally, correlation analyses revealed a close potential relationship between the dynamics of rhizosphere microorganisms and nutrient cycling in L. racemosus . The core genus Arthrobacter may play a key role in maintaining the stability of rhizosphere available nitrogen. Meanwhile, the specific enrichment of the functional genus Bacillus during the flowering stage might represent a plant-mediated recruitment strategy in response to the high nutrient demand at this critical phenological phase. Overall, during the growth cycle of L. racemosus , microbial community succession and nutrient changes exhibited certain regularities. Based on these findings, future research should focus on isolating key bacterial strains for inoculation experiments and systematically analyzing the dynamics of root exudates using metabolomics approaches. This will help to more directly elucidate the intrinsic driving mechanisms of plant-microbe-soil interactions. Abbreviations S Seedling F Flowering M Maturity OC Soil organic carbon TN Total nitrogen AN Available nitrogen AP Available phosphorus TK Total potassium AK Available potassium SOC Soil organic carbon OTUs Operational taxonomic units RDA Redundancy analysis R Rhizosphere Soil B Bulk soil PCoA Principal Co-ordinates Analysis PERMANOVA Permutational Multivariate Analysis Of Variance FAPROTAX Functional Annotation of Prokaryotic Taxa PGPR Plant growth-promoting rhizobacteria ACC Acetyl - CoA carboxylase Declarations Ethics approval and consent to participate : Not applicable. Consent for publication: Not applicable. Competing Interests: The authors have no relevant financial or non-financial interests to disclose. Funding: This work was sponsored by the Xinjiang Key Laboratory for Ecological Adaptation and Evolution of Extreme Environment Organisms, College of Life Sciences, Xinjiang Agricultural University, Ürümqi 830052, China (grant number: XKLEAEEEO-03). Further funding was provided by the Special Fund of the Xinjiang Key Laboratory of Soil and Plant Ecological Processes (grant number: 23XJTRZW20). Author Contribution Yufang Sun: Writing – review & editing, Writing – original draft, Conceptualization, Visualization, Software, Investigation, Formal analysis, Data curation. Jinfeng Tang: Investigation, Methodology, Conceptualization, Validation, Formal analysis, Data curation. Sijie Ma: Software, Data curation, Validation. Ailijiang Maimaiti: Visualization, Software, Formal analysis, Validation . Juan Qiu: Validation. Jun Liu: Supervision, Validation. Jie Ge: Supervision, Validation, Conceptualization. All authors read and approved the final manuscript. Acknowledgement The authors wish to acknowledge Professor Tan Dunyan for his expert guidance in shaping the research direction. We also sincerely thank the management of the Kalamaili Nature Reserve for granting permission to conduct sample collection at the site. Data Availability Datasets generated during the current study are available in the NCBI repository under Bioproject number PRJNA1241221 ( https://dataview.ncbi.nlm.nih.gov/object/PRJNA1241221 ; accessed 1 November 2025). The corresponding accession numbers for this submission are SRR35918480-SRR35918497. References Philippot L, Raaijmakers JM, Lemanceau P, Van Der Putten WH. Going back to the roots: the microbial ecology of the rhizosphere. Nat Rev Microbiol. 2013;11(11):789–99. https://doi.org/10.1038/nrmicro3109 . Spence C, Bais H. Probiotics for plants: Rhizospheric microbiome and plant fitness. In: De Bruijn FJ, editor. Molecular microbial ecology of the rhizosphere. 1 ed. Wiley; 2013. pp. 713–21. Akram M, Ishaque MRM, Afridi M, Soonmin H. Review on plant microbiome with particular emphasis on rhizospheric biome and its importance. Afr J Biomed Res. 2025;28(1S):1825–31. https://doi.org/10.53555/AJBR.v28i1S.6525 . Sindhu SS, Phour M, Choudhary SR, Chaudhary D. 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J Appl Microbiol. 2011;110(5):1151–65. https://doi.org/10.1111/j.1365-2672.2011.04968.x . Sørensen SR, Ronen Z, Aamand J. Isolation from agricultural soil and characterization of a Sphingomonas sp. able to mineralize the phenylurea herbicide isoproturon. Appl Environ Microbiol. 2001;67(12):5403–9. https://doi.org/10.1128/AEM.67.12.5403-5409.2001 . Additional Declarations No competing interests reported. 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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-8973487","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":607775897,"identity":"07813b3a-973e-409b-939a-cc8cb258a7da","order_by":0,"name":"Yufang Sun","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAy0lEQVRIiWNgGAWjYBAC+/bmgw8k//2T42dvIFKLAc+xZAMLtgPGkj0HiNUikaMmUcF2IHHDjQQitZgz5LBJ3OC5Yyw58/HGGww1NtEEtVg2nD1sOUPimRy/dFqxBcOxtNwGgnoO9iXeljBgNpacnWMmwdhwmAgth3kMpP8kMCduuHmGSC0Gx3iMJCQOHAZ6n4dILZI9bMkGkg1pwEAG+iWBGL/wyz8GRmWDDTAqD2+88aHGhgi/IDtSIoEU5RAtpOoYBaNgFIyCkQEAwwpCo4Za04kAAAAASUVORK5CYII=","orcid":"","institution":"Xinjiang Agricultural University","correspondingAuthor":true,"prefix":"","firstName":"Yufang","middleName":"","lastName":"Sun","suffix":""},{"id":607775899,"identity":"6769b238-d939-4e87-ae0f-56be43afd27a","order_by":1,"name":"Jinfeng Tang","email":"","orcid":"","institution":"Xinjiang Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Jinfeng","middleName":"","lastName":"Tang","suffix":""},{"id":607775902,"identity":"88c334df-dcf1-4ea0-b22a-e8a4af404389","order_by":2,"name":"Sijie Ma","email":"","orcid":"","institution":"Xinjiang Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Sijie","middleName":"","lastName":"Ma","suffix":""},{"id":607775903,"identity":"843f79c2-7ede-4bce-adfb-fb27f63e2a54","order_by":3,"name":"Ailijiang Maimaiti","email":"","orcid":"","institution":"Xinjiang Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Ailijiang","middleName":"","lastName":"Maimaiti","suffix":""},{"id":607775905,"identity":"e18b9e2a-247c-4477-86ed-350350abe60a","order_by":4,"name":"Jun Liu","email":"","orcid":"","institution":"Xinjiang Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Jun","middleName":"","lastName":"Liu","suffix":""},{"id":607775910,"identity":"04c91b98-0a2d-41e9-a05a-00373676c4a0","order_by":5,"name":"Juan Qiu","email":"","orcid":"","institution":"Xinjiang Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Juan","middleName":"","lastName":"Qiu","suffix":""},{"id":607775911,"identity":"4a171e46-5e1c-4ade-9d74-292f124993be","order_by":6,"name":"Jie Ge","email":"","orcid":"","institution":"Xinjiang Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Jie","middleName":"","lastName":"Ge","suffix":""}],"badges":[],"createdAt":"2026-02-26 05:23:26","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8973487/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8973487/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105087628,"identity":"19b90d74-a27d-4a91-a929-4b4ba1736401","added_by":"auto","created_at":"2026-03-20 20:35:16","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":930097,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eNutrient contents at different \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eLeymus racemosus\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e \u003c/em\u003e\u003cstrong\u003egrowth stages. \u003c/strong\u003e(A) Hydrolyzable Nitrogen (HN) and Available Phosphorus (AP). (B) Total Nitrogen (TN) and Available Potassium (AK). (C) Organic Matter (OM) and Organic Carbon (OC). Different letters above the curves indicate statistically significant differences. S, seedling; F, flowering; M, maturity; R,\u003cstrong\u003e \u003c/strong\u003eRhizosphere Soil; B, Bulk soil.\u003c/p\u003e","description":"","filename":"figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8973487/v1/1f4d300de73946792d130aa2.jpg"},{"id":105087629,"identity":"7b9ef583-7a57-452d-a771-18ae10476184","added_by":"auto","created_at":"2026-03-20 20:35:16","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1342340,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eAlpha diversity of \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eLeymus racemosus\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e rhizosphere bacterial communities at different developmental stages\u003c/strong\u003e. S, seedling; F, flowering; M, maturity. *\u003cem\u003ep \u003c/em\u003e\u0026lt; 0.05; **\u003cem\u003ep \u003c/em\u003e\u0026lt; 0.01; ***\u003cem\u003ep \u003c/em\u003e\u0026lt; 0.001\u003c/p\u003e","description":"","filename":"figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-8973487/v1/ed2a8bf9def209993574b653.png"},{"id":105563356,"identity":"f5af830e-aabb-4fda-8efa-21dca7e425d2","added_by":"auto","created_at":"2026-03-27 12:46:47","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1884324,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eBeta diversity of \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eLeymus racemosus\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003erhizosphere bacterial communities at different developmental stages.\u003c/strong\u003e (A) Principal coordinate analysis (PCoA). (B) Statistical significance of differences among growth stages. The \"Between\" box represents the distance values for inter-group differences, while the remaining boxes represent intra-group differences. The y-axis indicates the magnitude of the distance. High “Between” distance values indicate significant inter-group differences. S, seedling; F, flowering; M, maturity.\u003c/p\u003e","description":"","filename":"figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-8973487/v1/bc180fecd4e081676c002ac5.png"},{"id":105087631,"identity":"156099c6-9a2c-40c5-8465-6ad9c8e3d5f0","added_by":"auto","created_at":"2026-03-20 20:35:16","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":188210,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eAnalysis of \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eLeymus racemosus\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003erhizosphere microbial composition at different growth stages.\u003c/strong\u003e(A) Bacterial community composition at the genus level during the seedling (S), flowering (F), and maturity (M) stages. (B) Mean relative abundance of core bacterial genera across the growth cycle. (C)\u003cstrong\u003e \u003c/strong\u003eRelative abundance of \u003cem\u003eArthrobacter\u003c/em\u003especies. (D)\u003cstrong\u003e \u003c/strong\u003eRelative abundance of \u003cem\u003eBacillus \u003c/em\u003especies. Different colors represent different taxa, and bar lengths or slice areas indicate the relative abundance of each taxon.\u003c/p\u003e","description":"","filename":"Picture4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8973487/v1/9b8eb4f6ff4396bea034e880.jpg"},{"id":105563044,"identity":"83f5be10-1612-40a2-b606-64a8a6097733","added_by":"auto","created_at":"2026-03-27 12:45:46","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":8874630,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCo-occurrence network illustrating the relative abundances of bacterial genera in the \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eLeymus racemosus\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e rhizosphere across the seedling (S), flowering (F), and maturity (M) stages.\u003c/strong\u003e Each node represents a bacterial genus. Colored sectors within each node indicate the relative abundance at each growth stage: purple for S, green for F, and yellow for M.\u003c/p\u003e","description":"","filename":"figure5.png","url":"https://assets-eu.researchsquare.com/files/rs-8973487/v1/eccefbd9b41d97c6f1eaf397.png"},{"id":105563043,"identity":"8e9e9c03-da56-497d-9a6f-ca208056f275","added_by":"auto","created_at":"2026-03-27 12:45:46","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":279487,"visible":true,"origin":"","legend":"\u003cp\u003eDifferentially abundant \u003cem\u003eLeymus racemosus \u003c/em\u003erhizosphere bacterial genera across the seedling (S), flowering (F), and maturity (M) stages.\u003c/p\u003e","description":"","filename":"figure6.png","url":"https://assets-eu.researchsquare.com/files/rs-8973487/v1/f14f08408e3c533de31a8dec.png"},{"id":105087638,"identity":"19f9235d-6858-401f-a94f-87a8214cbc9c","added_by":"auto","created_at":"2026-03-20 20:35:17","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":4933011,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFAPROTAX-based functional prediction of the \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eLeymus racemosus\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e rhizosphere microbiota.\u003c/strong\u003e (A) The relative abundance of predicted functional groups across the seedling (S), flowering (F), and maturity (M) stages. (B)\u003cstrong\u003e \u003c/strong\u003eFunctional prediction of the genus \u003cem\u003eArthrobacter\u003c/em\u003e. (C) Functional prediction of the genus \u003cem\u003eBacillus\u003c/em\u003e. The color gradient depicts variation in the abundance of different functions across samples.\u003c/p\u003e","description":"","filename":"figure7.png","url":"https://assets-eu.researchsquare.com/files/rs-8973487/v1/cf05d9d7db755d3435093785.png"},{"id":105563369,"identity":"4166a180-48b0-4633-905d-9e29fa969ed9","added_by":"auto","created_at":"2026-03-27 12:46:48","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":201257,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRedundancy analysis (RDA) of the \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003eLeymus racemosus\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e rhizosphere bacterial community in relation to soil nutrient variables\u003c/strong\u003e. Samples from the seedling (S), flowering (F), and maturity (M) stages are shown in different colors. Red arrows represent soil nutrients, with arrow length indicating the magnitude of their influence on community distribution and direction indicating correlation with sample distribution. OC, Organic carbon; OM, Organic matter. HN, Hydrolyzable nitrogen; TN, Total nitrogen; AN, Available nitrogen; TP, Total phosphorus; AP, Available phosphorus; TK, Total potassium; AK, Available potassium.\u003c/p\u003e","description":"","filename":"figure8.png","url":"https://assets-eu.researchsquare.com/files/rs-8973487/v1/c299312cb4299f190568854a.png"},{"id":105087636,"identity":"3dd580de-f3e0-46b8-a2ed-b7926d5e38b5","added_by":"auto","created_at":"2026-03-20 20:35:16","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":511676,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eHeatmap of correlations between the top 30 bacterial genera and soil nutrients.\u003c/strong\u003e The heatmap depicts correlations between microbial taxa and soil nutrients. The x-axis and y-axis represent taxa and soil nutrients, respectively. The color intensity in each cell corresponds to the Pearson correlation coefficient (R value). OC, Organic carbon; OM, Organic matter. HN, Hydrolyzable nitrogen; TN, Total nitrogen; AN, Available nitrogen; TP, Total phosphorus; AP, Available phosphorus; TK, Total potassium; AK, Available potassium. *0.01 \u0026lt; \u003cem\u003ep\u003c/em\u003e ≤ 0.05; **0.001 \u0026lt; \u003cem\u003ep\u003c/em\u003e ≤ 0.01; ***\u003cem\u003e p\u003c/em\u003e ≤ 0.001.\u003c/p\u003e","description":"","filename":"figure9.png","url":"https://assets-eu.researchsquare.com/files/rs-8973487/v1/79d8d841093f5da3d3c0d8ae.png"},{"id":105087639,"identity":"33bf3c08-4eeb-4a96-9c96-cccafe4eb657","added_by":"auto","created_at":"2026-03-20 20:35:17","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":4864290,"visible":true,"origin":"","legend":"\u003cp\u003eConceptual model illustrating the dynamics of \u003cem\u003eLeymus racemosus\u003c/em\u003e rhizosphere microbial communities and soil nutrients across different developmental stages.\u003c/p\u003e","description":"","filename":"figure10.png","url":"https://assets-eu.researchsquare.com/files/rs-8973487/v1/4acf5ce66e806aa2f0513d22.png"},{"id":105568499,"identity":"9eb684a3-bf94-4146-b6ab-73ce80f8f059","added_by":"auto","created_at":"2026-03-27 13:09:01","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":24837049,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8973487/v1/81a7926e-447b-4ec6-838c-b2c23f0832b5.pdf"},{"id":105087633,"identity":"5f1af864-6fcb-42dc-a059-57f22ecd51cb","added_by":"auto","created_at":"2026-03-20 20:35:16","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":407872,"visible":true,"origin":"","legend":"","description":"","filename":"supplementaryfile1.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8973487/v1/64da13be757125a88ddef44f.pdf"},{"id":105087637,"identity":"1470f1a5-14fa-48ff-a92b-bd62edbc1dea","added_by":"auto","created_at":"2026-03-20 20:35:16","extension":"jpg","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":3753337,"visible":true,"origin":"","legend":"","description":"","filename":"supplementaryfile2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8973487/v1/71e7e34e29ada85d24fabec7.jpg"}],"financialInterests":"No competing interests reported.","formattedTitle":"Stage-specific rhizosphere microbial succession drives nutrient cycling in the desert plant Leymus racemosus (Lam.) tzvelev","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe plant rhizosphere microbiome comprises specific microbial communities, including primarily bacteria and fungi, that colonize the root surface and the surrounding soil zone [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Often referred to as the plant's \u0026ldquo;second genome\u0026rdquo;, these microbes collectively form a complex rhizosphere system [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Through close interactions with plants, rhizosphere microorganisms directly or indirectly regulate plant growth and development [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Acting as biotransformers of soil nutrients, rhizosphere microbes drive the transformation and cycling of key elements such as carbon, nitrogen, phosphorus, and potassium through their metabolic activities. Moreover, they play indispensable roles in organic matter decomposition, as well as nutrient solubilization and immobilization [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Consequently, these microorganisms strongly influence soil nutrient bioavailability, thereby affecting plant nutrient uptake, growth, and development [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eNumerous studies have shown that plant developmental stage is a key driver of rhizosphere microbial community succession [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. As plants transition from the vegetative seedling stage to the reproductive flowering stage, they actively recruit specific microbial taxa through mechanisms such as root exudation to facilitate the acquisition of nutrients required at each developmental phase [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. For example, during periods of vigorous vegetative growth, microbial taxa associated with nitrogen fixation and transformation may be preferentially enriched. In contrast, functional microbial groups with high efficiency in phosphorus and potassium solubilization may be favored during the reproductive stage [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan additionalcitationids=\"CR12 CR13 CR14\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. This \u0026ldquo;on-demand\u0026rdquo; recruitment model highlights plants' strong capacity for precise regulation of the rhizosphere microenvironment.\u003c/p\u003e \u003cp\u003eAlthough previous studies have provided insight into microbial functional traits associated with individual growth stages, it is still unknown how the core and functional microbiota interact across the entire plant life cycle, or how their synergy co-regulates dynamic changes in nutrients such as nitrogen, phosphorus, and potassium [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. \u003cem\u003eLeymus racemosus\u003c/em\u003e (Lam.) Tzvelev, a perennial grass species typical of the Junggar Desert in Xinjiang, China [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], exhibits distinct phenological stages, including the seedling stage in May, the flowering stage in June, and the maturity stage in July. In this study, \u003cem\u003eL. racemosus\u003c/em\u003e was used as a model to systematically analyze the structural succession of the rhizosphere microbial community across three key developmental stages. By integrating microbial community dynamics with changes in soil carbon, nitrogen, phosphorus, and potassium, we aimed to elucidate the potential division of labor and cooperative mechanisms between the core and functional microbiota in nutrient cycling. The findings are expected to advance our understanding of plant strategies for regulating rhizosphere microbes and nutrient cycling processes.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eSample collection\u003c/h2\u003e \u003cp\u003eSamples were collected from May to early July 2024 in a typical desert area of the Kalamaili Mountain Ungulate Wildlife Nature Reserve, located in the Junggar Basin of northern Xinjiang (89.082322\u0026deg;E, 45.246486\u0026deg;N), one of the main distribution areas of \u003cem\u003eLeymus racemosus\u003c/em\u003e. This species is listed as a Class II protected plant in the Xinjiang Uygur Autonomous Region, and all necessary permissions for the collection of plant material in this field study were obtained from the Administration of the Kalamaili Mountain Ungulate Wildlife Nature Reserve, with the approval of the local government. The research complied with all relevant institutional, national, and international guidelines and regulations concerning plant collection and access to protected areas. The plant species was formally identified by Professor Juan Qiu based on morphological characteristics. A voucher specimen (Accession Number: 202407-SYS21) has been deposited in the Herbarium of Xinjiang Agricultural University.\u003c/p\u003e \u003cp\u003e \u003cem\u003eL. racemosus\u003c/em\u003e grows in patchy populations across sandy habitats and is considered a dominant species in this region. A uniform patch with consistent growth vigor and similar plant cluster size was selected as the standardized sampling site. To accurately characterize the rhizosphere microbial community at each developmental stage and avoid interference among successive sampling events, independent and randomly distributed quadrats were established for each stage: seedling (\u003cb\u003eS\u003c/b\u003e), flowering (\u003cb\u003eF\u003c/b\u003e), and maturity (\u003cb\u003eM\u003c/b\u003e). During each sampling event, ten 5 m \u0026times; 5 m quadrats were arranged at 20 m intervals, and 6\u0026ndash;10 healthy individuals were selected from each quadrat for sampling.\u003c/p\u003e \u003cp\u003eDuring sampling, root systems were carefully excavated, and loosely attached non-rhizosphere soil was gently shaken off, while tightly adhering rhizosphere soil was retained. The intact rhizosphere samples were placed in sterile sealed bags, immediately stored in ice-filled containers, and transported to the laboratory. Under aseptic conditions, rhizosphere soil was gently separated from the roots to obtain rhizosphere soil samples [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. For each quadrat, rhizosphere soil from all sampled plants was pooled into one composite sample. Each composite sample was divided into two portions: one was flash-frozen in liquid nitrogen and stored at \u0026minus;\u0026thinsp;80\u0026deg;C for microbial diversity analysis, and the other was used to determine soil physicochemical properties.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eHigh-throughput sequencing\u003c/h3\u003e\n\u003cp\u003eTotal microbial genomic DNA was extracted from the rhizosphere soil samples using an E.Z.N.A.\u0026reg; Soil DNA Kit (Omega Bio-Tek, Norcross, GA, U.S.), according to the manufacturer's instructions. The quality and concentration of the extracted DNA were assessed by 1.0% agarose gel electrophoresis and a NanoDrop2000 spectrophotometer (ThermoFisher Scientific, United States), respectively. Qualified DNA samples were stored at -80\u0026deg;C for subsequent analysis.\u003c/p\u003e \u003cp\u003eThe hypervariable V3-V4 region of the bacterial 16S rRNA gene was amplified using the primer pair 338F (5'-ACTCCTACGGGAGGCAGCAG-3') and 806R (5'-GGACTACHVGGGTWTCTAAT-3') on a T100 Thermal Cycler PCR system (Bio-Rad, USA) [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. The resulting amplicons were purified, pooled in equimolar concentrations, and subjected to paired-end sequencing on an Illumina NextSeq2000 platform (Illumina, San Diego, USA) [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. All sequencing procedures were performed by Majorbio Bio-Pharm Technology Co., Ltd. (Shanghai, China) following standard operational protocols. The raw sequencing data have been deposited in the NCBI Sequence Read Archive (SRA) under BioProject number PRJNA1241221 (accession numbers SRR35918480-SRR35918497).\u003c/p\u003e\n\u003ch3\u003eAnalysis of soil physicochemical properties\u003c/h3\u003e\n\u003cp\u003eSoil organic carbon (OC) was determined using the potassium dichromate oxidation method. Total nitrogen (TN) was measured by acid digestion followed by the Kjeldahl method (ATN-300). Available nitrogen (AN) was quantified using the alkali-hydrolyzed diffusion method. Available phosphorus (AP) was extracted with sodium bicarbonate and measured using the molybdenum-antimony anti-spectrophotometric method. Total potassium (TK) was analyzed by alkali fusion followed by flame photometry (FP6431). Available potassium (AK) was extracted with ammonium acetate and measured using flame photometry (FP6431) [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e].\u003c/p\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eRaw FASTQ files were initially demultiplexed using a custom Perl script. Sequence reads were then processed with fastp (v0.19.6) [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] for quality control and filtering, and assembled using FLASH (v1.2.7) [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. High-quality sequences were clustered into operational taxonomic units (OTUs) at a 97% similarity threshold using the UPARSE algorithm (v7.1) [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. The most abundant sequence within each OTU was selected as the representative sequence. An OTU table was constructed and curated by removing chloroplast-derived sequences across all samples. To reduce bias caused by uneven sequencing depth, the dataset was rarefied to 20,000 sequences per sample, which maintained an average Good\u0026rsquo;s coverage of 99.09%, indicating sufficient sequencing depth. Taxonomic classification of representative OTU sequences was performed using the RDP Classifier (v2.2) against the 16S rRNA gene database with a confidence threshold of 0.7 [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eBased on the OTU data, rarefaction curves were generated, and alpha diversity indices (e.g., Simpson, Chao, Ace, and Shannon index) were calculated using Mothur (v1.30.1) [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Similarity among microbial communities in different samples was determined by principal coordinate analysis (PCoA) based on Bray-Curtis dissimilarity using the Vegan package (v2.5-3). Ordination was used to visualize similarities in microbial community structure among samples. Permutational multivariate analysis of variance (PERMANOVA), implemented in the same Vegan package, was applied to quantify the proportion of variation in community composition explained by soil type as well as to assess statistical significance. To visualize abundance dynamics of shared bacterial genera across plant growth stages, a co-occurrence network was constructed using Cytoscape [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. The Kruskal\u0026ndash;Wallis H test was used to identify taxa with significant differences in abundance among developmental stages. Redundancy analysis (RDA) was performed using the Vegan package (v2.4-3) in R (v3.3.1) to assess relationships between soil nutrient profiles and microbial community structure [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. In addition, a heatmap based on Pearson correlation analysis was generated to visualize the strength and direction of associations between specific microbial taxa and soil nutrient factors. All data analyses were conducted using the online tools available on the Majorbio Cloud Platform (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.majorbio.com/tools\u003c/span\u003e\u003cspan address=\"https://www.majorbio.com/tools\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eRhizosphere Soil Nutrient Contents Across Different Growth Stages\u003c/h2\u003e \u003cp\u003eThe rhizosphere soil of \u003cem\u003eL. racemosus\u003c/em\u003e exhibited significantly higher concentrations of hydrolyzable nitrogen (HN), AP, organic matter (OM), and OC than the bulk soil (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). However, rhizosphere TN, OM, and AK decreased significantly (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) during the flowering stage. In contrast, AP, AK, OM, and OC increased significantly at the maturity stage (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Notably, HN remained unchanged throughout the entire \u003cem\u003eL. racemosus\u003c/em\u003e growth period (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eRhizosphere microbial community diversity across different growth stages\u003c/h3\u003e\n\u003cp\u003eBacterial diversity in the \u003cem\u003eL. racemosus\u003c/em\u003e rhizosphere was assessed at the seedling, flowering, and maturity stages. After quality control and chimera removal, a total of 1,216,512 high-quality sequences were obtained from the assembled reads. These sequences were then clustered into OTUs at a 97% similarity threshold. Rarefaction based on the smallest sample size yielded 13,640 OTUs. Taxonomic classification identified 39 phyla, 126 classes, 297 orders, 507 families, and 1,006 genera.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAlpha diversity analysis showed that rhizosphere bacterial diversity varied among plant growth stages. The Shannon and Simpson indices indicated that bacterial diversity at the flowering and maturity stages was significantly higher than at the seedling stage (Kruskal-Wallis H test, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.00469;Shannon: \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.00011; Simpson: \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.00022; Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA, B). In contrast, both the Chao and Ace indices demonstrated that bacterial richness at the maturity stage was significantly higher than at either the seedling and flowering stages (Kruskal-Wallis H test, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.00469; Chao: \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.00268; Ace: \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.00268; Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC, D), whereas no significant difference was observed between the seedling and flowering stages (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05; Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC, D), indicating a significant accumulation of rhizosphere bacteria at the maturity stage.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003ePCoA based on OTU-level data showed that rhizosphere bacterial communities from the seedling, flowering, and maturity stages formed distinct clusters, indicating high within-stage similarity. Meanwhile, bacterial community composition differed significantly among stages (ANOSIM, p\u0026thinsp;=\u0026thinsp;0.001; Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA), demonstrating a clear shift in rhizobacterial structure during development. This pattern was further supported by PERMANOVA (R\u0026sup2; = 0.207, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0001; Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB), confirming that plant growth stage plays a key role in shaping rhizosphere bacterial community assembly.\u003c/p\u003e\n\u003ch3\u003eDynamics of key bacterial taxa across different growth stages\u003c/h3\u003e\n\u003cp\u003eAnalysis of the rhizobacterial community composition of \u003cem\u003eL. racemosus\u003c/em\u003e across different growth stages showed that \u003cem\u003eArthrobacter\u003c/em\u003e was the dominant genus at all three stages (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA, B). The relative abundance of this genus was highest at the seedling stage (20.3%), declined to 7.2% at the flowering stage, and then slightly increased to 9.7% at maturity, with an overall mean relative abundance of 12.7%. Despite the pronounced decline during flowering, \u003cem\u003eArthrobacter\u003c/em\u003e remained at notably high relative abundance. The decrease in \u003cem\u003eArthrobacter\u003c/em\u003e abundance at the flowering stage coincided with a significant increase in the abundance of \u003cem\u003eBacillus\u003c/em\u003e, which rose from 3.1% at the seedling stage to 10.9%, establishing it as a major dominant genus during this period. The abundance of \u003cem\u003eBacillus\u003c/em\u003e subsequently decreased significantly to 1.5% at the maturity stage (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA, B).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSpecies-level analysis of \u003cem\u003eArthrobacter\u003c/em\u003e and \u003cem\u003eBacillus\u003c/em\u003e revealed distinct temporal dynamics across plant developmental stages. Within the genus \u003cem\u003eArthrobacter\u003c/em\u003e, an unclassified species (\u003cem\u003eunclassified_g__Arthrobacter\u003c/em\u003e) dominated the community at the seedling, flowering, and maturity stages, accounting for more than 80% of the relative abundance (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eC). \u003cem\u003eArthrobacter agilis\u003c/em\u003e and \u003cem\u003eArthrobacter citreus\u003c/em\u003e were also present at relatively high proportions (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eC). In contrast, the increase in \u003cem\u003eBacillus\u003c/em\u003e abundance during the flowering stage was primarily driven by a marked increase in an unclassified \u003cem\u003eBacillus\u003c/em\u003e species (\u003cem\u003eunclassified_g__Bacillus\u003c/em\u003e). Meanwhile, \u003cem\u003eBacillus aryabhattai\u003c/em\u003e, \u003cem\u003eBacillus filamentosus\u003c/em\u003e, and \u003cem\u003eBacillus simplex\u003c/em\u003e maintained relatively stable abundances across all stages (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eD).\u003c/p\u003e \u003cp\u003eCo-occurrence network analysis further revealed growth stage-dependent variations in the abundance of bacterial genera (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). Consistent with earlier results, \u003cem\u003eArthrobacter\u003c/em\u003e maintained high relative abundance throughout the seedling, flowering, and maturity stages, confirming its role as a stable dominant genus in the \u003cem\u003eL. racemosus\u003c/em\u003e rhizosphere. \u003cem\u003eBacillus\u003c/em\u003e reached its peak abundance during the flowering stage. At the same time, the abundances of \u003cem\u003ePantoea\u003c/em\u003e and \u003cem\u003eMassilia\u003c/em\u003e also increased significantly, accounting for 3.0% and 1.9% of the community, respectively.\u003c/p\u003e \u003cp\u003eAnalysis of differentially abundant taxa further showed that \u003cem\u003eArthrobacter\u003c/em\u003e consistently exhibited high abundance across all developmental stages, with its relative abundance at the seedling stage being significantly higher than at the flowering or maturity stages. In addition, \u003cem\u003ePedobacter\u003c/em\u003e, \u003cem\u003eTM7a\u003c/em\u003e, and \u003cem\u003ePlanomicrobium\u003c/em\u003e were significantly more abundant at the seedling stage than at the other two stages. During the flowering stage, in addition to \u003cem\u003eBacillus\u003c/em\u003e, the abundances of \u003cem\u003ePantoea\u003c/em\u003e, \u003cem\u003eMassilia\u003c/em\u003e, and \u003cem\u003eSphingomonas\u003c/em\u003e were significantly elevated, establishing them as dominant taxa for this period. In contrast, the maturity stage was characterized by sustained high relative abundances of \u003cem\u003eArthrobacter\u003c/em\u003e, \u003cem\u003enorank_f__JG30-KF-CM45\u003c/em\u003e, \u003cem\u003eSphingomonas\u003c/em\u003e, \u003cem\u003eDevosia\u003c/em\u003e, and the \u003cem\u003eAllorhizobium-Neorhizobium-Pararhizobium-Rhizobium\u003c/em\u003e group (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eFunctional characterization of key bacterial communities at different growth stages\u003c/h2\u003e \u003cp\u003eFAPROTAX-based functional profiling identified aerobic chemoheterotrophy, chemoheterotrophy, and nitrate reduction as the core functions of the bacterial community (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eA). In addition, ureolysis was significantly more abundant during the flowering stage than during the seedling and maturity stages.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAs mentioned, the genus \u003cem\u003eArthrobacter\u003c/em\u003e dominated the rhizosphere community across growth stages. Notably, the core function of the \u003cem\u003eArthrobacter\u003c/em\u003e genus was nitrate reduction, followed by arsenate detoxification and reduction (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eB). In contrast, \u003cem\u003eBacillus\u003c/em\u003e abundance increased significantly at the flowering stage. Functional prediction for the \u003cem\u003eBacillus\u003c/em\u003e genus revealed not only a strong potential for nitrate reduction but also a significant enhancement of aerobic chemoheterotrophy and chemoheterotrophy at the flowering stage (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eC).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eAssociations between microbial communities and soil factors\u003c/h2\u003e \u003cp\u003eTo further explore relationships between the rhizosphere microbial community and soil nutrient conditions, RDA and Spearman correlation analysis were performed. The RDA results (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e) showed that samples from the maturity stage were closely aligned with the vectors for AP, AK, TN, and soil organic carbon (SOC). This alignment indicates a strong association between the rhizobacterial community structure at the maturity stage and the enrichment of these soil nutrients.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo further elucidate the roles of specific bacterial genera in nutrient dynamics, Spearman correlation analysis was conducted on the top 30 most abundant genera (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e). The results showed that the abundance of \u003cem\u003eBacillus\u003c/em\u003e was significantly negatively correlated with AP, AK, and SOC. This pattern is consistent with the sharp decline in \u003cem\u003eBacillus\u003c/em\u003e abundance after the flowering stage, coinciding with the onset of soil nutrient accumulation.\u003c/p\u003e \u003cp\u003eIn contrast, under the elevated nutrient conditions at the maturity stage, the abundances of \u003cem\u003eSphingomonas\u003c/em\u003e, \u003cem\u003eMycobacterium\u003c/em\u003e, \u003cem\u003eKribbella\u003c/em\u003e, and \u003cem\u003eAeromicrobium\u003c/em\u003e were significantly positively correlated with AP and AK. In addition, \u003cem\u003eKribbella\u003c/em\u003e and \u003cem\u003eAeromicrobium\u003c/em\u003e were also significantly positively correlated with SOC (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003e \u003cb\u003eArthrobacter\u003c/b\u003e \u003cb\u003eas a core beneficial taxon and stabilizer of the\u003c/b\u003e \u003cb\u003eL. racemosus\u003c/b\u003e \u003cb\u003erhizosphere\u003c/b\u003e\u003c/p\u003e \u003cp\u003eActinobacteriota are widely distributed in soil environments characterized by low water content, high organic matter, and slightly alkaline conditions [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e], and they play key roles in nitrogen cycling. In this study, Actinobacteriota were significantly enriched in the \u003cem\u003eL. racemosus\u003c/em\u003e rhizosphere, indicating that this group may contribute to plant growth and environmental adaptation. Within this phylum, \u003cem\u003eArthrobacter\u003c/em\u003e has been reported as a dominant rhizosphere taxon of desert plants [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Members of this genus exhibit broad carbon source utilization and strong environmental adaptability. Many strains are recognized as plant growth-promoting rhizobacteria (PGPR), with functions that include phosphorus solubilization, nitrogen fixation, potassium release, ACC deaminase production, antibiotic synthesis, and phytohormone secretion [\u003cspan additionalcitationids=\"CR35\" citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. Of particular importance is their extensive nitrogen metabolic capacity. Certain strains can decompose and mineralize organic nitrogen (e.g., proteins and amino acids) through extracellular enzyme secretion, directly supplying plants with absorbable ammonium (NH₄⁺) [\u003cspan additionalcitationids=\"CR38\" citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. In addition, some strains participate in nitrification and denitrification and may even possess nitrogen-fixing potential, thereby regulating nitrogen forms through multiple pathways to support plant nitrogen nutrition [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eOur results showed that \u003cem\u003eArthrobacter\u003c/em\u003e maintained dominance in the \u003cem\u003eL. racemosus\u003c/em\u003e rhizosphere across all growth stages. This pattern may be associated with the persistently high and stable level of HN in the rhizosphere throughout the growth period. At the seedling stage, the absolute dominance of \u003cem\u003eArthrobacter\u003c/em\u003e, combined with its strong aerobic chemoheterotropic, chemoheterotrophic, and nitrate reduction capacities, likely constituted a core mechanism supporting a steady nitrogen supply and the establishment of a basic nutrient cycle. At the flowering stage, although its relative abundance declined, \u003cem\u003eArthrobacter\u003c/em\u003e likely maintained functional importance through its versatile metabolism of both organic and inorganic nitrogen (e.g., nitrate), together with its potential nitrogen-fixing capacity, enabling persistence under shifting nitrogen forms. By the maturity stage, \u003cem\u003eArthrobacter\u003c/em\u003e, as a persistent keystone taxon, likely acted synergistically with other nutrient-mobilizing genera such as \u003cem\u003eSphingomonas\u003c/em\u003e and \u003cem\u003eDevosia\u003c/em\u003e [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e], continuing to promote nitrogen release via chemoheterotrophy and nitrate reduction. As plant nitrogen demand declined at this stage, sustained microbial activity probably contributed to the observed rhizosphere nutrient enrichment.\u003c/p\u003e \u003cp\u003eBased on these findings, we propose that a core bacterial microbiome centered on \u003cem\u003eArthrobacter\u003c/em\u003e forms a robust microbial buffering system. This system mitigates nitrogen fluctuations driven by plant uptake and extreme environmental variability in desert soils through rapid transformation of organic and inorganic nitrogen sources, thereby maintaining dynamic stability of available nitrogen in the \u003cem\u003eL. racemosus\u003c/em\u003e rhizosphere. This mechanism may represent a key ecological strategy supporting stable nitrogen supply in harsh desert environments.\u003c/p\u003e \u003cp\u003e \u003cb\u003eFlowering-stage enrichment of\u003c/b\u003e \u003cb\u003eBacillus\u003c/b\u003e \u003cb\u003eand its role in strategic nutrient allocation\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003cem\u003eBacillus\u003c/em\u003e, a genus within the phylum Firmicutes, exhibits strong environmental adaptability, allowing it to survive under stress conditions such as nutrient limitation, drought, and high temperatures. It plays an important role in global biogeochemical cycles, including carbon and nitrogen cycling [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. As typical PGPR, many \u003cem\u003eBacillus\u003c/em\u003e strains can synthesize and secrete phytohormones such as auxins and cytokinins, which stimulate cell division and elongation and thereby enhance root and shoot growth [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]. In addition, \u003cem\u003eBacillus\u003c/em\u003e species contribute to plant nutrition by fixing atmospheric nitrogen, solubilizing inorganic phosphorus, and mobilizing potassium, converting immobilized soil nutrients into plant-available forms [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e]. Specifically, \u003cem\u003eBacillus\u003c/em\u003e species solubilize inorganic phosphorus through the secretion of organic acids and acid phosphatases and mineralize organic phosphorus via phytase secretion, leading to rapid increases (within days to weeks) in available phosphorus (H₂PO₄⁻/HPO₄\u0026sup2;⁻) [\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e, \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e]. Concurrently, metabolites such as organic acids and amino acids released by \u003cem\u003eBacillus\u003c/em\u003e can weather potassium-bearing minerals and release plant-available potassium ions (K⁺) [\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e]. In the nitrogen cycle, \u003cem\u003eBacillus\u003c/em\u003e is a key driver in the transformation of organic nitrogen to inorganic forms, as secreted proteases efficiently degrade organic nitrogen and rapidly generate ammonium (NH₄⁺), thereby increasing soil available nitrogen [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn this study, a significant increase in the relative abundance of \u003cem\u003eBacillus\u003c/em\u003e was observed in the \u003cem\u003eL. racemosus\u003c/em\u003e rhizosphere during the flowering stage, followed by a marked decline at maturity. This dynamic pattern is likely linked to the elevated nutrient demand during flowering and reduced uptake during maturation. The flowering stage represents a critical phase of the \u003cem\u003eL. racemosus\u003c/em\u003e life cycle, characterized by peak demand for nitrogen, phosphorus, and potassium. This may drive the plant to actively recruit specific rhizobacteria, such as \u003cem\u003eBacillus\u003c/em\u003e, which function as a microbial \u0026ldquo;rapid-response force\u0026rdquo;. These microorganisms employ metabolic strategies including aerobic chemoheterotrophy and chemoheterotrophy to mobilize soil nutrients, thereby supporting the high nutrient requirements of \u003cem\u003eL. racemosus\u003c/em\u003e during flowering.\u003c/p\u003e \u003cp\u003eDespite the enrichment of \u003cem\u003eBacillus\u003c/em\u003e, no significant changes in available nitrogen or available phosphorus were detected in the \u003cem\u003eL. racemosus\u003c/em\u003e rhizosphere during flowering. In contrast, both available potassium and total nitrogen decreased significantly, resulting in an overall decline in total rhizosphere nutrient levels. We hypothesize that this pattern reflects the high nutrient demand during flowering, whereby nutrients mobilized by microorganisms are rapidly taken up by the plant, creating a nutrient-limited rhizosphere and preventing nutrient accumulation. Thus, the enrichment of \u003cem\u003eBacillus\u003c/em\u003e during flowering likely represents a demand-driven recruitment strategy by \u003cem\u003eL. racemosus\u003c/em\u003e, functioning as a temporary and highly efficient microbial support system.\u003c/p\u003e \u003cp\u003eNotably the flowering-stage rhizosphere of \u003cem\u003eL. racemosus\u003c/em\u003e was enriched not only in \u003cem\u003eBacillus\u003c/em\u003e, but also in genera such as \u003cem\u003ePantoea\u003c/em\u003e, \u003cem\u003eMassilia\u003c/em\u003e, and \u003cem\u003eSphingomonas\u003c/em\u003e. Previous studies have shown that many \u003cem\u003ePantoea\u003c/em\u003e strains possess phosphorus-solubilizing capacity, whereas \u003cem\u003eSphingomonas\u003c/em\u003e can enhance nitrogen and phosphorus cycling in the rhizosphere [\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e, \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e]. These findings suggest that a multispecies microbial consortium may act synergistically to support the high-intensity nutrient demands of \u003cem\u003eL. racemosus\u003c/em\u003e during flowering.\u003c/p\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eMicrobially driven nutrient accumulation during the maturation stage\u003c/h2\u003e \u003cp\u003eUpon entering the maturation stage, marked shifts occurred in both rhizosphere microbial community structure and nutrient accumulation dynamics. Although the relative abundance of \u003cem\u003eBacillus\u003c/em\u003e decreased sharply and that of \u003cem\u003eArthrobacter\u003c/em\u003e showed only a slight recovery, the contents of available phosphorus, available potassium, and organic carbon increased significantly, indicating a pronounced nutrient enrichment in the rhizosphere. We propose that this pattern is driven by two main mechanisms.\u003c/p\u003e \u003cp\u003eFirst, the extensive proliferation and metabolic activity of \u003cem\u003eBacillus\u003c/em\u003e during the flowering stage may have exerted a lasting influence on the rhizosphere microenvironment, creating favorable conditions for the colonization and functional expression of other microorganisms. This is supported by our results showing that, during the maturation stage, taxa such as \u003cem\u003enorank_f__JG30-KF-CM45\u003c/em\u003e, \u003cem\u003eSphingomonas\u003c/em\u003e, \u003cem\u003eDevosia\u003c/em\u003e, and the \u003cem\u003eAllorhizobium-Neorhizobium-Pararhizobium-Rhizobium\u003c/em\u003e group maintained relatively high abundances. Moreover, correlation analysis indicated that \u003cem\u003eDevosia\u003c/em\u003e was significantly positively correlated with available phosphorus and organic matter, while \u003cem\u003eSphingomonas\u003c/em\u003e was also significantly positively correlated with available phosphorus. These taxa likely form a functionally complementary microbial network that collectively promotes sustained nutrient activation and accumulation during maturation, reflecting a lagged effect of microbial function on nutrient availability.\u003c/p\u003e \u003cp\u003eSecond, as the plant transitions into the maturation stage, its physiological and metabolic activities slow, leading to reduced nutrient uptake demand and rate. As a result, nutrients mobilized by the microbial community are no longer rapidly absorbed by the plant and are more likely to accumulate within the rhizosphere, ultimately producing the observed nutrient enrichment.\u003c/p\u003e \u003cp\u003e \u003cb\u003eNutrient-microbe interplay in the\u003c/b\u003e \u003cb\u003eL. racemosus\u003c/b\u003e \u003cb\u003erhizosphere: Integrated model and future directions\u003c/b\u003e\u003c/p\u003e \u003cp\u003eBased on the results described above, we developed a conceptual model (Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e) illustrating distinct functional stages in the \u003cem\u003eL. racemosus\u003c/em\u003e rhizosphere. The seedling stage represents a \u0026ldquo;foundation phase\u0026rdquo;, during which a rhizosphere system centered on \u003cem\u003eArthrobacter\u003c/em\u003e establishes a basic nutrient cycling framework that maintains nitrogen stability. As the plant enters the flowering stage, nutrient demand increases sharply, initiating an \u0026ldquo;investment phase\u0026rdquo;. This stage is characterized by the pronounced recruitment of \u003cem\u003eBacillus\u003c/em\u003e, which actively mobilizes soil nutrients to support reproductive growth, leading to rapid depletion of the soil nutrient pool and a marked decline in rhizosphere nutrient content. The maturation stage can be viewed as a \u0026ldquo;harvest phase\u0026rdquo;, during which plant nutrient demand declines and microbial communities act synergistically to enhance nutrient accumulation beyond plant uptake, resulting in pronounced nutrient enrichment in the rhizosphere.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eHowever, we acknowledge several limitations of the present study. First, our interpretation of rhizosphere microbial functions is largely based on bioinformatic predictions and evidence from the existing literature. In addition, the precise taxonomic identities and ecological functions of two key taxa (\u003cem\u003eunclassified_g__Arthrobacter\u003c/em\u003e and \u003cem\u003eunclassified_g__Bacillus\u003c/em\u003e) in the extreme desert environment remain unclear. Therefore, future studies will combine metagenomic approaches with conventional isolation and cultivation methods to more systematically elucidate the relationships between rhizosphere microbial community dynamics and nutrient fluctuations during the growth and development of \u003cem\u003eL. racemosus\u003c/em\u003e.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study systematically analyzed the rhizosphere microecosystem of \u003cem\u003eLeymus racemosus\u003c/em\u003e across different growth stages, elucidating the characteristics of rhizosphere microbial community succession and nutrient dynamics, as well as their potential interrelationships. The main conclusions are as follows: Firstly, the rhizosphere microbial community structure underwent significant succession throughout the entire growth cycle of \u003cem\u003eL. racemosus\u003c/em\u003e. Specifically, \u003cem\u003eArthrobacter\u003c/em\u003e was the dominant genus at the seedling stage. Upon entering the flowering stage, \u003cem\u003eBacillus\u003c/em\u003e was substantially enriched and became the core population. By the maturity stage, the community structure shifted again, with \u003cem\u003eArthrobacter\u003c/em\u003e re-emerging as the dominant genus, while the abundance of \u003cem\u003eBacillus\u003c/em\u003e decreased significantly. Secondly, rhizosphere soil nutrient contents exhibited distinct stage-specific characteristics as the growth period progressed. Hydrolyzable nitrogen (HN) remained at a relatively high level throughout the entire growth period. In contrast, the contents of total nitrogen (TN), organic matter (OM), and available potassium (AK) decreased significantly during the flowering stage. At the maturity stage, the contents of available phosphorus (AP), available potassium (AK), organic matter (OM), and organic carbon (OC) showed a significant increase. Finally, correlation analyses revealed a close potential relationship between the dynamics of rhizosphere microorganisms and nutrient cycling in \u003cem\u003eL. racemosus\u003c/em\u003e. The core genus \u003cem\u003eArthrobacter\u003c/em\u003e may play a key role in maintaining the stability of rhizosphere available nitrogen. Meanwhile, the specific enrichment of the functional genus \u003cem\u003eBacillus\u003c/em\u003e during the flowering stage might represent a plant-mediated recruitment strategy in response to the high nutrient demand at this critical phenological phase. Overall, during the growth cycle of \u003cem\u003eL. racemosus\u003c/em\u003e, microbial community succession and nutrient changes exhibited certain regularities. Based on these findings, future research should focus on isolating key bacterial strains for inoculation experiments and systematically analyzing the dynamics of root exudates using metabolomics approaches. This will help to more directly elucidate the intrinsic driving mechanisms of plant-microbe-soil interactions.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSeedling\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eF\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eFlowering\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eM\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMaturity\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eOC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSoil organic carbon\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eTN\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eTotal nitrogen\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eAN\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAvailable nitrogen\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eAP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAvailable phosphorus\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eTK\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eTotal potassium\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eAK\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAvailable potassium\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSOC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSoil organic carbon\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eOTUs\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eOperational taxonomic units\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eRDA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eRedundancy analysis\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eRhizosphere Soil\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eB\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eBulk soil\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePCoA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePrincipal Co-ordinates Analysis\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePERMANOVA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePermutational Multivariate Analysis Of Variance\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eFAPROTAX\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eFunctional Annotation of Prokaryotic Taxa\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePGPR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePlant growth-promoting rhizobacteria\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eACC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAcetyl - CoA carboxylase\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate :\u003c/strong\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication:\u003c/strong\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eCompeting Interests:\u003c/h2\u003e \u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eThis work was sponsored by the Xinjiang Key Laboratory for Ecological Adaptation and Evolution of Extreme Environment Organisms, College of Life Sciences, Xinjiang Agricultural University, \u0026Uuml;r\u0026uuml;mqi 830052, China (grant number: XKLEAEEEO-03). Further funding was provided by the Special Fund of the Xinjiang Key Laboratory of Soil and Plant Ecological Processes (grant number: 23XJTRZW20).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eYufang Sun: Writing \u0026ndash; review \u0026amp; editing, Writing \u0026ndash; original draft, Conceptualization, Visualization, Software, Investigation, Formal analysis, Data curation. Jinfeng Tang: Investigation, Methodology, Conceptualization, Validation, Formal analysis, Data curation. Sijie Ma: Software, Data curation, Validation. Ailijiang Maimaiti: Visualization, Software, Formal analysis, Validation . Juan Qiu: Validation. Jun Liu: Supervision, Validation. Jie Ge: Supervision, Validation, Conceptualization. All authors read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThe authors wish to acknowledge Professor Tan Dunyan for his expert guidance in shaping the research direction. We also sincerely thank the management of the Kalamaili Nature Reserve for granting permission to conduct sample collection at the site.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eDatasets generated during the current study are available in the NCBI repository under Bioproject number PRJNA1241221 ( https://dataview.ncbi.nlm.nih.gov/object/PRJNA1241221 ; accessed 1 November 2025). The corresponding accession numbers for this submission are SRR35918480-SRR35918497.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003ePhilippot L, Raaijmakers JM, Lemanceau P, Van Der Putten WH. Going back to the roots: the microbial ecology of the rhizosphere. 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Appl Environ Microbiol. 2001;67(12):5403\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1128/AEM.67.12.5403-5409.2001\u003c/span\u003e\u003cspan address=\"10.1128/AEM.67.12.5403-5409.2001\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-plant-biology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pbio","sideBox":"Learn more about [BMC Plant Biology](http://bmcplantbiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/pbio/default.aspx","title":"BMC Plant Biology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Leymus racemosus, rhizosphere microbiome, growth stage, nutrient cycling, microbial succession","lastPublishedDoi":"10.21203/rs.3.rs-8973487/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8973487/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground and aims:\u003c/h2\u003e \u003cp\u003ePlants regulate nutrient uptake and growth by recruiting rhizosphere microorganisms via root exudates. However, a systematic understanding of how the rhizosphere core and functional microbiota jointly regulate the dynamics of carbon, nitrogen, phosphorus, and potassium across the entire plant life cycle remains limited.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe used 16S rRNA high-throughput sequencing to analyze the rhizosphere bacterial communities and nutrient contents of the desert plant \u003cem\u003eLeymus racemosus\u003c/em\u003e at different growth stages in the Kalamaili Nature Reserve, Xinjiang, China.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003e \u003cem\u003eArthrobacter\u003c/em\u003e, as a core taxon, maintained nitrogen stability across all growth stages. \u003cem\u003eBacillus\u003c/em\u003e became the dominant genus during the flowering stage, ensuring nutrient supply and reflecting an \u0026ldquo;investment\u0026rdquo; strategy. At maturity, enhanced microbial cooperation combined with reduced plant demand promoted the accumulation of rhizosphere nutrients, thereby facilitating energy storage for subsequent growth.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eThis study reveals the developmental dynamics of rhizosphere bacterial community assembly and nutrient regulation in \u003cem\u003eL. racemosus\u003c/em\u003e. It provides a theoretical basis for further elucidating plant\u0026ndash;microbe interactions in desert ecosystems. Future research should focus on isolating key bacterial strains and integrating metabolomics to clarify the underlying mechanisms.\u003c/p\u003e","manuscriptTitle":"Stage-specific rhizosphere microbial succession drives nutrient cycling in the desert plant Leymus racemosus (Lam.) tzvelev","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-20 20:35:12","doi":"10.21203/rs.3.rs-8973487/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-29T12:57:06+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-28T14:50:58+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-28T11:34:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"240932283715206862476098856411226012210","date":"2026-04-28T11:30:24+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"206919180222567543621953383771582062564","date":"2026-04-27T14:44:16+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"323232046762590844551026326253841838010","date":"2026-04-27T02:39:49+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"211039395656771001378489215102800500925","date":"2026-04-26T02:34:40+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-25T15:54:53+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"277244100186568988966277240993073114179","date":"2026-04-25T15:03:45+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"175054741777564209613912924327662972367","date":"2026-04-24T06:15:49+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-17T17:08:46+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-17T17:07:44+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-09T10:19:48+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-08T15:36:17+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Plant Biology","date":"2026-03-08T15:31:58+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-plant-biology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pbio","sideBox":"Learn more about [BMC Plant Biology](http://bmcplantbiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/pbio/default.aspx","title":"BMC Plant Biology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"8dfedc9e-5437-4587-be99-2a680529af31","owner":[],"postedDate":"March 20th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-18T09:08:09+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-20 20:35:12","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8973487","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8973487","identity":"rs-8973487","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}