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چکیده
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Bacterial wilt caused by Ralstonia solanacearum is one of the most significant diseases affecting potato plants worldwide. The current study aims to investigate the role of endophytic bacteria, Bacillus safensis Har267, B. pumilus Fer469, B. zhangzhouensis Kh690, B. aerius Kh867, and B. wiedmannii Ah945, for their potential to control wilting development. The effects of cell-free culture supernatant (CFCS) from endophytic bacteria on the virulence traits of R. solanacearum cells in vitro, as well as the induction of disease resistance in inoculated plants under greenhouse conditions, were investigated. Two endophytic bacteria, Kh690 and Ah945, significantly reduced wilting symptoms. Moreover, the CFCS of endophytic bacteria significantly reduced various motility behaviors, including swarming, swimming, and twitching, as well as chemotaxis migration toward potato root extract, exopolysaccharide (EPS) production, and biofilm formation by R. solanacearum. GS-MS analysis revealed that the CFCS of endophytic bacteria contains various compounds with potential antibacterial activities. Statistical analysis revealed that colonization of the root and shoot by R. solanacearum was significantly reduced in plants pre-treated by endophytic bacteria. Our results, based on statistical analysis, showed that the endophytic bacteria significantly increased plant defensive enzyme activities such as catalase (CAT), polyphenol oxidase (PPO), and peroxidase (POD), compared to non-inoculated control (Ctrl-). The Kh690 and Ah945 strains significantly upregulated the expression level of NPR1, a defense gene related to plant resistance, suggesting the induction of resistance against pathogen attack.
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