Zinc Metalloprotease CsMep is Involved in Zinc Homeostasis and Pathogenicity in <i>Colletotrichum sublineola</i> with Alterations in Aromatic Amino Acid Biosynthesis

Sorghum anthracnose, caused by <i>Colletotrichum sublineola</i>, severely affects leaves, stems, and panicles. This study characterizes CsMep, a zinc-dependent metalloprotease with a conserved HEXXH motif and an N-terminal signal peptide. CsMep localizes to the cell membrane, cytoplasm, and nucleus and suppresses plant programmed cell death in an HEXXH-dependent manner. This suppression was accompanied by reduced ROS accumulation and cell necrosis along with decreased electrolyte leakage in plant tissues. Deletion of CsMep impaired fungal pathogenicity, hindering hyphal growth, sporulation, and appressorium formation, while increasing sensitivity to ZnSO₄ stress. Under zinc treatment, the mutant exhibited modifications in gene expression and metabolite accumulation, including the upregulation of aromatic amino acid biosynthesis along with increased levels of L-tryptophan and protocatechuic acid. These findings indicate that CsMep is crucial for adaptation to zinc stress and for achieving full virulence, thereby highlighting its significance in fungal pathogenesis and its potential as a target for disease control.