Comparative proteomic analysis of chestnut blight fungus, Cryphonectria parasitica, under tannicacid-inducing and hypovirus-regulating conditions

Chestnut blight fungus, Cryphonectria parasitica, and its hypovirus present a useful model system for investigating the mechanisms of hypoviral infection. To identify gene products associated with fungal pathogenicity and hypoviral regulation, we attempted a proteomic analysis of the virus-free EP155/2 strain and its isogenic virus-infected UEP1 strain in response to tannic acid (TA), which is abundant in the bark of chestnut trees. In this study, pretreatment of mycelia grown on TA-supplemented media was developed for proteomic analysis. Approximately 704 proteins from the mycelia of the EP155/2 strain were reproducibly present in 3 independent extractions. Among these, 111 and 79 spots were found to be responsive to hypovirus infection and TA supplementation, respectively. The TA-grown UEP1 strain yielded 28 spots showing an expression pattern different from that of untreated UEP1. Thirty protein spots showing considerable differences in spot density were selected for further analysis. Hybrid tandem LC-MS/MS spectrometry of the 30 selected protein spots revealed that 29 were identified while 1 was unidentified. Among the identified 29 proteins, 15 were metabolic enzymes; 5 were stress-related, of which 4 were heat-shock proteins and 1 was glutathione S-transferase; 5 were signaling and cellular process-related proteins; 2 were structural proteins; and 2 matched proteins of hypothetical genes.