Nitrogen fixation is an important biological process in terrestrial ecosystems and for global crop production. Legume nodulation and N₂ fixation have been improved using nodule‐enhancing rhizobacteria (NER) under both regular and stressed conditions. The positive effect of NER on legume–rhizobia symbiosis can be facilitated by plant growth‐promoting (PGP) mechanisms, some of which remain to be identified. NER that produce aminocyclopropane‐1‐carboxylic acid deaminase and indole acetic acid enhance the legume–rhizobia symbiosis through (i) enhancing the nodule induction, (ii) improving the competitiveness of rhizobia for nodulation, (iii) prolonging functional nodules by suppressing nodule senescence and (iv) upregulating genes associated with legume–rhizobia symbiosis. The means by which these processes enhance the legume–rhizobia symbiosis is the focus of this review. A better understanding of the mechanisms by which PGP rhizobacteria operate, and how they can be altered, will provide opportunities to enhance legume–rhizobial interactions, to provide new advances in plant growth promotion and N₂ fixation.

中文翻译：

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促进植物生长的根瘤菌增强豆科植物根瘤菌共生的机制。

固氮是陆地生态系统和全球作物生产中的重要生物过程。豆科植物结瘤和N ₂在正常和压力条件下，均使用结节增强的根瘤菌（NER）改善了固定。植物生长促进（PGP）机制可促进NER对豆类-根瘤菌共生的积极作用，其中一些机制尚待确定。产生氨基环丙烷-1-羧酸脱氨酶和吲哚乙酸的NER通过（i）增强根瘤诱导，（ii）改善根瘤菌对结瘤的竞争力，（iii）通过抑制结节衰老来延长功能性结节来增强豆类-根瘤菌共生。 （iv）上调与豆科植物-根瘤菌共生相关的基因。这些过程增强豆类-根瘤菌共生的方法是本综述的重点。更好地了解PGP根瘤菌的运作机制及其变化方式，₂注视。