Host and environmental regulation of cercosporin biosynthesis: a genetic perspective

Cercospora zeae-maydis, a hemibiotrophic foliar pathogen of maize, produces cercosporin, a phytotoxic perylenequinone, during the necrotrophic stage of pathogenesis. Although the cercosporin biosynthetic (CTB) gene cluster has been identified, little is known about the molecular regulation of cercosporin production during pathogenesis. Through a combination of forward and reverse genetics, we identified a suite of non-cluster genes that positively or negatively regulate cercosporin biosynthesis. These include genes implicated in environmental sensing, signal transduction, nutrient acquisition, primary metabolism, chromatin remodeling, and the circadian clock. From this information, a new working model describing the regulation of cercosporin biosynthesis has emerged.