The rhizosheath is a layer of soil around the root that provides a favorable environment for soil microbe enrichment and root growth. Rice (Oryza sativa) roots form rhizosheaths under moderate soil drying (MSD) conditions, but how the rhizosheath forms associations with microbes is unclear. To investigate rice rhizosheath formation under MSD, we employed a multiphasic approach, integrating data from high-throughput sequencing and root-bacteria interactions. Rice roots formed a pronounced rhizosheath under MSD, but not under continuous flooding regimens. Plant growth-promoting rhizobacteria of the Enterobacteriaceae were enriched in rhizosheaths of two different rice varieties, ‘Gaoshan 1’ (drought tolerant) and ‘Nipponbare’ (drought sensitive). RNA-sequencing analysis revealed that the ethylene pathway was induced in the rhizosheath-root system under MSD. Enterobacter aerogenes, a bacterium isolated from the rhizosheath, degrades the ethylene precursor 1-aminocyclopropane-1-carboxylate, thereby increasing rhizosheath formation. Furthermore, a 1-aminocyclopropane-1-carboxylate deaminase-deficient mutant of E. aerogenes failed to enhance rice rhizosheath formation. Our results suggest that root-bacteria associations substantially contribute to rhizosheath formation in rice under MSD conditions by mechanisms that involve the ethylene response. These data inform strategies to reduce water consumption in rice production, one of the most water-intensive human activities.

根茎是根周围的一层土壤，为土壤微生物的富集和根的生长提供了有利的环境。水稻（水稻根在中等土壤干燥（MSD）条件下会形成根茎，但不清楚根茎如何与微生物形成关联。为了研究MSD下的水稻根瘤菌形成，我们采用了一种多相方法，整合了高通量测序和根细菌相互作用的数据。在MSD下，水稻的根部形成了明显的根状茎，但在连续淹没的情况下却没有。肠杆菌科的促进植物生长的根瘤菌富含两个不同水稻品种的根际，“高山1号”（耐旱）和“日本晴”（对干旱敏感）。RNA测序分析表明，MSD诱导根茎系统中的乙烯途径被诱导。产气肠杆菌从根瘤菌中分离出的细菌，使乙烯前体1-氨基环丙烷-1-羧酸盐降解，从而增加了根瘤菌的形成。此外，的1-氨基环丙烷-1-羧酸脱氨酶缺陷型突变产气肠杆菌未能提高米饭rhizosheath形成。我们的结果表明，根与细菌的结合在MSD条件下通过参与乙烯反应的机制在水稻根际形成中起重要作用。这些数据提供了减少稻米生产中水消耗的策略，这是人类最耗水的活动之一。