Functional characterization of the Dsc E3 ligase complex in the citrus postharvest pathogen Penicillium digitatum

In this study, five genes, designated PddscA, PddscB, PddscC, PddscD, and PddscE encoding the Dsc E3 ligase complex were characterized to be required for fungicide resistance, ergosterol biosynthesis and CoCl2 tolerance in P. digitatum. Each of the dsc genes was inactivated by target gene disruption and the resulted phenotypes were analyzed and compared. Genetic analysis reveals that, of five Dsc complex components, PddscB is the core subunit gene in P. digitatum. Although the resultant dsc mutants were able to infect citrus fruit and induce maceration lesions as the wild-type, the mutants rarely produced aerial mycelia on affected citrus fruit peels. P. digitatum Dsc proteins regulated not only the expression of genes involved in ergosterol biosynthesis but also that of PdsreA. Yeast two-hybrid assays revealed a direct interaction between the PdSreA protein and the Dsc proteins. Ectopic expression of the PdSreA N-terminus restored fungicide resistance in the dsc mutants. Our results provide important evidence to understand the mechanisms underlying SREBP activation and regulation of ergosterol biosynthesis in plant pathogenic fungi.
Source: Microbiological Research - Category: Infectious Diseases Source Type: research