Although plant roots encounter a plethora of microorganisms in the surrounding soil, at the rhizosphere, plants exert selective forces on their bacterial colonizers. Unlike immune recognition of pathogenic bacteria, the mechanisms by which beneficial bacteria are selected and how they interact with the plant immune system are not well understood. To better understand this process, we studied the interaction of auxin-producing Bacillus velezensis FZB42 with Arabidopsis roots and found that activation of the plant immune system is necessary for efficient bacterial colonization and auxin secretion. A feedback loop is established in which bacterial colonization triggers an immune reaction and production of reactive oxygen species, which, in turn, stimulate auxin production by the bacteria. Auxin promotes bacterial survival and efficient root colonization, allowing the bacteria to inhibit fungal infection and promote plant health. Thus, a feedback loop between bacteria and the plant immune system promotes the fitness of both partners.

尽管植物根系在周围土壤中遇到大量微生物，但在根际，植物对它们的细菌定殖者施加选择力。与病原菌的免疫识别不同，选择有益细菌的机制以及它们如何与植物免疫系统相互作用尚不清楚。为了更好地理解这一过程，我们研究了产生生长素的贝莱斯芽孢杆菌 FZB42与拟南芥的相互作用根并发现植物免疫系统的激活对于有效的细菌定植和生长素分泌是必要的。建立了一个反馈回路，其中细菌定植触发免疫反应和活性氧的产生，进而刺激细菌产生生长素。生长素促进细菌存活和有效的根系定殖，使细菌能够抑制真菌感染并促进植物健康。因此，细菌和植物免疫系统之间的反馈回路促进了双方的健康。