The histone deacetylase HOS2 controls pathogenicity through regulation of melanin biosynthesis and appressorium formation in Colletotrichum gloeosporioides

The reversible acetylation of histones is effective for controlling chromatin dynamics and plays crucial roles in eukaryotes. In the present study, we identified and characterized a histone deacetylase HOS2 ortholog, designated CgHOS2, in Colletotrichum gloeosporioides . Knocking out CgHOS2 resulted in decreased vegetative growth, impaired conidiation, and reduced stress tolerance. Moreover, the Δ CgHOS2 mutant failed to form appressoria and lost pathogenicity on intact plant leaves. Western blot analysis revealed that CgHOS2 is responsible for the deacetylation of histone H3. Via transcriptomic analysis, a series of candidate genes controlled by CgHOS2 were predicted. Of these candidate genes, the expression of melanin biosynthesis-related enzymes was significantly reduced in vegetative hyphae and especially in appressoria, which led to a decrease in melanin content and failure of appressorium formation. Taken together, these results highlight the role of CgHOS2 in pathogenicity via regulation of melanin biosynthesis in C. gloeosporioides .