Appressorium formation is regulated by the Msb2‐ and Sho1‐dependent hierarchical transcriptional network in Colletotrichum gloeosporioides

Abstract

AbstractColletotrichum gloeosporioides, which penetrates the plant hosts via special infection structures called appressoria, causes anthracnose in many plants worldwide. However, the biological mechanism underlying appressorium formation is not fully characterized in this pathogen. In the present study, the overall gene expression pattern of appressorium formation was studied by targeted gene deletion and expression analysis during the conidial germination of wildtype and ΔCgMsb2Sho1 double mutant strains of C. gloeosporioides on hydrophobic surfaces. Significant transcriptional changes were detected for nearly 41.9% and 45.4% of the genes in the wildtype and ΔCgMsb2Sho1 strains, respectively. Two genes encoding the cAMP‐dependent protein kinase regulatory subunit and adenylate cyclase had higher expression in the wild type than in the ΔCgMsb2Sho1 mutant; cAMP then activates the mitogen‐activated protein kinase (MAPK) signalling pathway. However, we revealed that genes involved in the MAPK signalling pathway may inhibit appressorium formation by encoding proteins that disrupt the downstream signal transduction process after recognition of the host by the cell membrane surface receptor proteins mucin (Msb2) and the sensor protein Sho, encoded by CgMsb2 and CgSho1, respectively. Finally, the regulation of transcription factors on lipid metabolism and plant cell wall‐degrading enzymes was affected. The results provide a comprehensive overview of the changes in the expression of important genes during the early stage of appressorium formation, which may be useful for understanding the molecular mechanism of appressorium formation in C. gloeosporioides.