Comparative transcriptome analysis of Cytospora mali QH2 reveals its response mechanisms to the biocontrol agent Bacillus velezensis L-1

Bacillus velezensis L-1 was identified as an effective biocontrol agent against various postharvest fruit pathogens in previous work. However, little is known about its controlling effects on apple valsa canker (AVC) and the underlying mechanisms. So, the changes in cell structure and gene expression level in C. mali QH2 upon challenged with B. velezensis L-1 were observed. B. velezensis L-1 impaired the membrane formation, cell stability, autophagy of C. mali QH2. and reduced the expressions of virulence genes related secondary metabolites in C. mali QH2, including gene encoding non-ribosomal peptide synthesis, cytochrome P450, pectinases, and Acetyl-CoA. B. velezensis L-1 treated C. mali QH2 enhanced the antioxidation and detoxification through up-regulating genes related to superoxide dismutase, peroxidase, multicopper oxidase, monocarboxylate transporters, ABC transporter, and glutathione S-transferase. Overall, our results showed that B. velezensis L-1 was capable of efficiently controlling AVC and provided a theoretical basis for identifying the response mechanism of C. mali QH2 under biotic stress conditions.