Bacillus amyloliquefaciens Induces Resistance in Tobacco Against Powdery Mildew Pathogen Erysiphe cichoracearum

The beneficial interactions between plant and endophytes can enormously improve plant resistance against phytopathogens. Endophytic bacteria are well known for their plant propitious attributes. A tobacco seed endophyte Bacillus amyloliquefaciens YN201732 can enhance the ability of tobacco plants to resist powdery mildew, but the mechanisms operating at molecular level are highly elusive. In this study, transcriptome of YN201732-treated and non-treated tobacco leaves were compared under pathogen challenge and control conditions. Overall, analysis elucidates that DEGs related to biosynthesis of secondary metabolites, plant hormone signal transduction, phenylpropanoid biosynthesis, flavonoid biosynthesis, metabolic pathways, immune system process, and disease resistance-related biological functions were enriched in endophyte-treated diseased plant. The key genes of JA/ET pathway were significantly upregulated in tobacco plant after endophyte YN201732 treatment, which indicates the activation of JA/ET-mediated disease resistance against powdery mildew. Additionally, chitinase gene and synthesis of lignin and flavonoids were increased in diseased plant upon endophyte treatment which could help plant to resist pathogen infection. In conclusion, the study provides the molecular dissection of B. amyloliquefaciens YN201732-induced resistance in tobacco plant against powdery mildew and lays a theoretical foundation of employing endophytic bacteria against plant diseases.