Drought stress is a key factor limiting crop growth and production. Although a variety of crops can improve their survival and drought resistance as a result of interactions with their rhizosphere microbiota, the mechanisms related to plant–rhizosphere microbiota interactions under drought stress are not fully understood, especially regarding the mechanisms in habitats with droughts. Here, the molecular mechanisms involving the E. ulmoides rhizosphere microbiota in response to drought stress were systematically analyzed using pot experiments, metagenomic sequencing, and assessment of plant physiological indexes. The results showed that the composition and co-occurrence patterns of the E. ulmoides rhizosphere microbiota were altered under drought stress, and the phylogenetic diversity of the core microbes was increased. Moreover, Betaproteobacteria and Opitutae were significantly enriched in the rhizosphere and their relative abundances were significantly correlated with the levels of superoxide dismutase (SOD) and soluble sugar (SS) in E. ulmoides. Kyoto Encyclopedia of Genes and Genomes (KEGG) functional analysis showed that two-component system, biosynthesis of amino acids, ABC transporters, and ribosome became more abundant in the rhizosphere under drought stress, and were significantly correlated with SOD and SS levels. Similarly, genes encoding Carbohydrate Active Enzymes (CAZymes) activities that auxiliary activities and glycosyl transferases became more abundant and were significantly correlated with SOD and SS levels. In conclusion, the relative abundances of KEGG functions and CAZymes classes in the E. ulmoides rhizosphere microbiota were altered by enrichment of Betaproteobacteria and Opitutae, which in turn affected the host physiological indexes to improve the host’s adaptability to drought. These findings are of great significance for improving plant drought tolerance in order to increase sustainable crop production.

干旱胁迫是限制作物生长和生产的关键因素。尽管多种作物通过与根际微生物群的相互作用可以提高其生存率和抗旱性，但在干旱胁迫下植物-根际微生物群相互作用的相关机制尚不完全清楚，尤其是关于干旱栖息地的机制。在这里，使用盆栽实验、宏基因组测序和植物生理指标评估系统分析了涉及 E. ulmoides 根际微生物群响应干旱胁迫的分子机制。结果表明，干旱胁迫下栉根际微生物群的组成和共生模式发生改变，核心微生物的系统发育多样性增加。此外，Betaproteobacteria 和 Opitutae 在根际显著富集，其相对丰度与 E. ulmoides 中超氧化物歧化酶 （SOD） 和可溶性糖 （SS） 水平显著相关。京都基因与基因组百科全书 （KEGG） 功能分析显示，干旱胁迫下，双组分系统、氨基酸生物合成、ABC 转运蛋白和核糖体在根际变得更加丰富，并且与 SOD 和 SS 水平显著相关。同样，编码辅助活性和糖基转移酶活性的碳水化合物活性酶 （CAZymes） 活性的基因变得更加丰富，并且与 SOD 和 SS 水平显著相关。总之，E 中 KEGG 函数和 CAZymes 类的相对丰度。 β变形菌门和Opitutae的富集改变了根际菌群，进而影响宿主的生理指标，提高了宿主对干旱的适应能力。这些发现对于提高植物耐旱性以提高可持续作物生产具有重要意义。