Botrytis cinerea alcohol dehydrogenase mediates fungal development, environmental adaptation and pathogenicity

Abstract

Botrytis cinerea is an economically critical necrotrophic fungus that infecting many types of plants species. Although the lifestyle adaptations and genetic foundations of several enzymes and metabolites involved in B. cinerea virulence during host plant infection are well studied, the role of B. cinerea alcohol dehydrogenase (ADH) enzymes in these processes is poorly understood. Herein, we identified a significant up-regulation of the transcriptional levels of the BcADH1 gene during the tomato – B. cinerea strain B0510 interaction and at the early stage of infection. Substantially, we used a recent approach for replacement of gene by utilizing homologous recombination to generate knock-out mutants (Δbcadh1) and their effective complementary strains (Δbcadh1/C). A strong difference in the morphology of Δbcadh1 mutants from the wild type (WT) was detected, with respect to the conidiospore, conidial germination, and formation of branches, sporulation and sclerotia. In addition, the Δbcadh1 mutants showed significant differences in their virulence on tomato leaves relative to the WT. Moreover, the Δbcadh1 mutants appeared to have higher sensitivity to oxygen limitation (hypoxia) and reactive oxygen species, and had lost their ability of alcoholic fermentation compared with the WT and complementary strains. These results provide strong evidence for the requirement of the ADH1 gene for fungal development, environmental adaptation and its ability for full pathogenicity. Communicated by Ramaswamy H. Sarma