A <i>Colletotrichum fructicola</i> dual specificity phosphatase CfMsg5 is regulated by the CfAp1 transcription factor during oxidative stress and promotes virulence on <i>Camellia oleifera</i>

Anthracnose, caused by <i>Colletotrichum</i> species, induces significant economic damages to crop plants annually, especially for <i>Camellia oleifera</i>. During infection, the counter-defence mechanisms of plant pathogens against ROS-mediated resistance, however, remain poorly understood. By employing Weighted Gene Co-expression Network Analysis (WGCNA), we identified ACTIVATOR PROTEIN-1 (AP-1), a bZIP transcription factor, as significant to infection. And deletion of <i>CfAP1</i> inhibited aerial hyphae formation and growth under oxidative stress. Furthermore, RNA-seq analysis post H₂O₂ treatment revealed 33 significantly down-regulated genes in the AP-1 deficient strain, including A12032, a dual specificity phosphatase (DSP) homologous to MSG5 from <i>Saccharomyces cerevisiae</i>. This Δ<i>Cfmsg5</i> strain showed enhanced oxidative tolerance, reduced ROS scavenging, and negative regulation of the CWI MAPK cascade under oxygen stress, suggesting its involvement in oxidative signal transduction. Importantly, we provide evidence that CfMsg5 regulates growth, endoplasmic reticulum stress, and several unfolded protein response genes upregulated in Δ<i>Cfmsg5</i>. Collectively, this study identified core components during <i>C. fructicola</i> infection and highlights a potential regulatory module involving CfAp1 and CfMsg5 in response to host ROS bursts. It provides new insights into fungal infection mechanisms and potential targets like <i>CfAP1</i> and <i>CfMSG5</i> for managing anthracnose diseases.