Cellophane surface-induced gene, VdCSIN1, regulates hyphopodium formation and pathogenesis via cAMP-mediated signalling in Verticillium dahliae.

The soil-borne vascular pathogen Verticillium dahliae infects many dicotyledonous plants to cause devastating wilt diseases. During colonization, V. dahliae spores develop hyphae surrounding the roots. Only a few hyphae that adhere tightly to the root surface form hyphopodia at the infection site, which further differentiate into penetration pegs to facilitate infection. The molecular mechanisms controlling hyphopodium formation in V. dahliae remain unclear. Here, we uncovered a cellophane surface-induced gene (VdCSIN1) as a regulator of V. dahliae hyphopodium formation and pathogenesis. Deletion of VdCSIN1 compromises hyphopodium formation, hyphal development and pathogenesis. Exogenous application of cyclic adenosine monophosphate (cAMP) degradation inhibitor or disruption of the cAMP phosphodiesterase gene (VdPDEH) partially restores hyphopodium formation in the VdΔcsin1 mutant. Moreover, deletion of VdPDEH partially restores the pathogenesis of the VdΔcsin1 mutant. These findings indicate that VdCSIN1 regulates hyphopodium formation via cAMP-mediated signalling to promote host colonization by V. dahliae.