Extensive regulation of pH-responsive transcription factor PacC on secondary metabolism contributes to development and virulence of Botrytis cinerea

Botrytis cinerea is one of the most important postharvest pathogens and causes huge economic losses worldwide. Ambient pH is a critical factor influencing virulence of B. cinerea. In this study, BcpacC, a crucial gene encoding a pH-responsive transcription factor, was knocked out in B. cinerea strain B05.10. Deletion of BcpacC resulted in pH-dependent reduction in mycelial growth, sporulation, and virulence in apple and tomato fruit, and romaine lettuce leaves. An iTRAQ based proteomic analysis identified 70 differential proteins involved in various biological processes between wildtype (WT) and Delta BcpacC mutant under pH 6 condition, including 18 proteins related to secondary metabolism. Gene expression analysis indicates that 37 of all the 42 secondary metabolism key enzyme encoding genes were regulated by BcPacC. Further, three PacC-regulated polyketide synthase encoding genes, Bcpks4, Bcpks5 and Bcpks11, were knocked out and first proved to contribute to sporulation and virulence in B. cinerea. Our results revealed that the extensive regulation of BcPacC on secondary metabolism might play crucial roles in development and pathogenicity of B. cinerea during adaption to ambient pH.

Automated summary

This study found that the deletion of the crucial gene BcpacC in Botrytis cinerea strain B05.10 resulted in pH-dependent reduction in mycelial growth, sporulation, and virulence in apple and tomato fruit, and romaine lettuce leaves. Proteomic analysis identified 70 differential proteins involved in various biological processes, including 18 proteins related to secondary metabolism. Gene expression analysis revealed that 37 out of 42 secondary metabolism key enzyme encoding genes were regulated by BcPacC. Additionally, three PacC-regulated polyketide synthase encoding genes were found to contribute to sporulation and virulence in B. cinerea. The extensive regulation of BcPacC on secondary metabolism plays crucial roles in the development and pathogenicity of B. cinerea during adaption to ambient pH.