Changes in VOCs from a chestnut blight fungus Cryphonectria parasitica by a hypovirus infection: mycoviral infection alters fungal smell for insect vectors

Background: The chestnut blight fungus, Cryphonectria parasitica, and its Cryphonectria hypovirus 1 (CHV1) comprise a useful model system to study fungus–virus interactions. CHV1 infection results in various phenotypic changes in the fungal host, including hypovirulence and other associated symptoms. Many studies have investigated the effects of hypoviral infection and how this infection affects physiological and biochemical states: however, no studies have examined volatile organic compounds (VOCs). Results: This study characterized the global profile of VOCs released from C. parasitica, and by comparing CHV1-free with CHV1-infected isogenic strains, proved that CHV1 infection significantly affects the composition and levels of VOCs. We demonstrated that these VOC alterations were caused by viral regulation of the expression of fungal genes encoding enzymes responsible for the production of VOCs. The changed VOC profile resulting from CHV1 infection was more attractive to insects than the VOC profile from the virus-free strain, suggesting differences in the efficacy of fungal dissemination by the insect vector. Conclusions: We characterized VOCs from C. parasitica and demonstrated that mycovirus (CHV1) infection affects fungal VOCs. We provided evidences that these alterations are caused by the modulation of the corresponding gene expression by CHV1 and resulted in changes in attractiveness to insects, suggesting the improved efficacy of hypovirulent C. parasitica for insect-borne dissemination. Graphical Abstract: (Figure presented.)