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

BACKGROUND AND

aimsPlants 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 in desert ecosystems remains limited. In this study, we asked: how does the succession of rhizosphere bacterial communities align with stage-specific nutrient demands in the desert plant Leymus racemosus?

methodsWe used 16 S rRNA high-throughput sequencing to analyze the rhizosphere bacterial communities and nutrient contents of the desert plant Leymus racemosus at three growth stages (seedling, flowering, maturity) in the Kalamaili Nature Reserve, Xinjiang, China. For each stage, ten 5 × 5 m quadrats (20 m apart) were established; 6-10 healthy plants were sampled per quadrat, and rhizosphere soil from each quadrat was pooled into one composite sample (n = 10 per stage).

resultsArthrobacter, identified as a core taxon, was associated with the stability of hydrolyzable nitrogen across all growth stages. Bacillus became the dominant genus during the flowering stage, based on correlation and functional prediction, it may contribute to nutrient supply, reflecting a potential "investment" strategy. At maturity, enhanced microbial cooperation (inferred from co-occurrence and correlation analyses) combined with reduced plant demand was associated with the accumulation of rhizosphere nutrients, possibly facilitating energy storage for subsequent growth. These findings provide a potential answer to our question, suggesting that the plant recruits distinct microbial alliances at different phenological phases-a persistent Arthrobacter-based system for nitrogen buffering, a transient Bacillus-enriched community for rapid nutrient mobilization at flowering, and a synergistic network at maturity for delayed nutrient accumulation.

conclusionsThis study reveals the developmental dynamics of rhizosphere bacterial community assembly and nutrient regulation in L. racemosus and provides a theoretical basis for further elucidating plant-microbe interactions in desert ecosystems. However, the proposed functional roles of specific taxa are primarily derived from correlation and predictive analyses; experimental validation (e.g., strain isolation, inoculation tests, and metabolomics) is needed to establish causality.