Con7 is a key transcription regulator for conidiogenesis in the plant pathogenic fungus .

Unlabelled: The mycelium of the plant pathogenic fungus exhibits distinct structures for vegetative growth, asexual sporulation, sexual development, virulence, and chlamydospore formation. These structures are vital for the survival and pathogenicity of the fungus, necessitating precise regulation based on environmental cues. Initially identified in , the transcription factor Con7p regulates conidiation and infection-related morphogenesis, but not vegetative growth. We characterized the Con7p ortholog Con7, and deletion of resulted in severe defects in conidium production, virulence, sexual development, and vegetative growth. The mycelia of the deletion mutant transformed into chlamydospore-like structures with high chitin level accumulation. Notably, boosting expression partially alleviated developmental issues in the deletion mutant. Chromatin immunoprecipitation (ChIP)-quantitative PCR (qPCR) analysis confirmed a direct genetic link between and . Furthermore, the chitin synthase gene (FGSG_06550) showed significant upregulation in the deletion mutant, and altering expression affected cell wall integrity. Further research will focus on understanding the behavior of the chitin synthase gene and its regulation by Con7 in . This study contributes significantly to our understanding of the genetic pathways that regulate hyphal differentiation and conidiation in this plant pathogenic fungus.

Importance: The ascomycete fungus is the primary cause of head blight disease in wheat and barley, as well as ear and stalk rot in maize. Given the importance of conidia and ascospores in the disease cycle of , precise spatiotemporal regulation of these biological processes is crucial. In this study, we characterized the Con7p ortholog and discovered that Con7 significantly influences various crucial aspects of fungal development and pathogenicity. Notably, overexpression of partially restored developmental defects in the deletion mutant. ChIP-qPCR analysis confirmed a direct genetic link between and . Furthermore, our research revealed a clear correlation between Con7 and chitin accumulation and the expression of chitin synthase genes. These findings offer valuable insights into the genetic mechanisms regulating conidiation and the significance of mycelial differentiation in this plant pathogenic fungus.