Understanding the role of chemotaxis in ecological interactions between plants and microbes in the rhizosphere is necessary to optimize biocontrol strategies targeting plant soil-borne diseases. Therefore, we examined and profiled the antagonistic endophytic bacteria (AEB) population with chemotaxis potential in the medicinal plant Panax notoginseng using a cheA gene-based approach coupled with 16S rRNA sequencing. Phylogenetic analysis of the chemotactic AEB (CAEB) community in P. notoginseng enabled the identification of 56 CAEB strains affiliated with 30 species of Actinobacteria, Firmicutes, and Proteobacteria; Firmicutes, especially Bacillus, were predominant. We then systematically quantified the chemotactic response profiles of CAEB toward five organic acid (OA) attractants: citric acid, fumaric acid (FA), malic acid, oxalic acid, and succinic acid. Further hierarchical cluster analysis revealed that the chemotaxis of CAEB to the same attractant exhibited different patterns among not only genera but also species and even strains of the same species. Following chemotaxis and hierarchical analysis, we selected the strongest chemoattractant, fumaric acid (FA), as the target for evaluating the effects of OAs on the representative CAEB strain Bacillus amyloliquefaciens subsp. plantarum YP1. Application of FA significantly stimulated the chemotaxis ability and growth of YP1, and increased the transcript levels of cheA and biocontrol-related genes in YP1. This is the first study to characterise the diversity of chemotaxis profiles toward OAs in natural bacterial assemblages of P. notoginseng and to highlight how FA promotes the biocontrol-related traits of P. notoginseng-associated CAEB.

了解趋化性在植物和根际微生物之间生态相互作用中的作用对于优化针对植物土传病害的生物防治策略是必要的。因此，我们使用基于cheA基因的方法结合 16S rRNA 测序检查并分析了药用植物三七中具有趋化潜力的拮抗性内生细菌 (AEB) 种群。通过对三七趋化 AEB (CAEB) 群落的系统发育分析，鉴定了隶属于 30 种放线菌、厚壁菌门和变形菌门的 56 种 CAEB 菌株；厚壁菌，尤其是芽孢杆菌，占主导地位。然后，我们系统地量化了 CAEB 对五种有机酸 (OA) 引诱剂的趋化反应曲线：柠檬酸、富马酸 (FA)、苹果酸、草酸和琥珀酸。进一步的层次聚类分析表明，CAEB 对同一引诱剂的趋化性不仅在属之间表现出不同的模式，而且在同一物种的物种甚至菌株之间也表现出不同的模式。在趋化性和层次分析之后，我们选择了最强的趋化剂富马酸 (FA) 作为评估 OA 对代表性 CAEB 菌株解淀粉芽孢杆菌亚种的影响的目标。植物YP1。FA 的应用显着刺激了 YP1 的趋化能力和生长，并增加了YP1 中的 cheA和生物防治相关基因。这是第一项研究，以表征三七天然细菌组合中对 OA 的趋化性特征的多样性，并强调 FA 如何促进三七相关 CAEB的生物防治相关性状。