Drought is among the most destructive abiotic stresses limiting crop growth and yield worldwide. Although most research has focused on the contribution of plant-associated microbial communities to plant growth and disease suppression, far less is known about the microbes involved in drought resistance among desert plants. In the present study, we applied 16S rRNA gene amplicon sequencing to determine the structure of rhizosphere and root endosphere microbiomes of Alhagi sparsifolia. Compared to those of the rhizosphere, endosphere microbiomes had lower diversity but contained several taxa with higher relative abundance; many of these taxa were also present in the roots of other desert plants. We isolated a Pseudomonas strain (LTGT-11-2Z) that was prevalent in root endosphere microbiomes of A. sparsifolia and promoted drought resistance during incubation with wheat. Complete genome sequencing of LTGT-11-2Z revealed 1-aminocyclopropane-1-carboxylate deaminases, siderophore, spermidine, and colanic acid biosynthetic genes, and type VI secretion system genes, which are likely involved in biofilm formation and plant-microbe interactions. Together, these results indicate that drought-enduring plants harbor bacterial endophytes favorable to plant drought resistance, and suggest that novel endophytic bacterial taxa and gene resources may be discovered among these desert plants.

Importance Understanding microbe-mediated plant resistance to drought is important for sustainable agriculture. We performed 16S rRNA gene amplicon sequencing and culture-dependent functional analyses of Alhagi sparsifolia rhizosphere and root endosphere microbiomes, and identified key endophytic bacterial taxa and their genes facilitating drought resistance in wheat. This study improves our understanding of plant drought resistance and provides new avenues for drought resistance improvement in crop plants under field conditions.

干旱是破坏性最强的非生物胁迫之一，在全世界范围内限制着作物的生长和单产。尽管大多数研究都集中在与植物相关的微生物群落对植物生长和疾病抑制的贡献上，但对于沙漠植物中涉及抗旱性的微生物知之甚少。在本研究中，我们应用16S rRNA基因扩增子测序来确定Alhagi sparsifolia的根际和根内微生物群的结构。与根际相比，内球微生物群落的多样性较低，但含有多个相对丰富度的分类单元。这些分类单元中的许多也存在于其他沙漠植物的根中。我们分离出了假单胞菌株（LTGT-11-2Z），这是在根流行endosphere的微生物组A.骆驼刺小麦孵育期间，促进抗旱性。LTGT-11-2Z的完整基因组测序揭示了1-氨基环丙烷-1-羧酸盐脱氨基酶，铁载体，亚精胺和可乐酸的生物合成基因以及VI型分泌系统基因，这些基因可能与生物膜形成和植物-微生物相互作用有关。总之，这些结果表明耐旱植物具有有利于植物抗旱的细菌内生菌，并表明在这些荒漠植物中可能发现了新的内生细菌类群和基因资源。

重要性了解微生物介导的植物抗旱性对于可持续农业至关重要。我们对杂草（Alhagi sparsifolia）的根际和根内微生物群进行了16S rRNA基因扩增子测序和依赖培养的功能分析，并鉴定了关键的内生细菌类群及其促进小麦抗旱的基因。这项研究提高了我们对植物抗旱性的理解，并为田间条件下提高作物抗旱性提供了新途径。