CaSun1, a SUN family protein, governs the pathogenicity of <i>Colletotrichum camelliae</i> by recruiting CaAtg8 to promote mitophagy

<i>Camellia oleifera</i>, a woody oilseed plant native to China, is highly susceptible to anthracnose, a fungal disease that poses a significant threat to its yield and quality. Mitophagy, a specialized form of autophagy that specifically targets dysfunctional mitochondria, is crucial for cellular homeostasis, stress response, and pathogenesis in fungi. The proteins that potentially participate in mitophagy in <i>Colletotrichum camelliae</i> were identified herein using immunoprecipitation-mass spectrometry (IP-MS) by screening for the potential protein interactors of the core autophagy-related protein, CaAtg8. Among the identified mitochondria-associated proteins, CaSun1 was selected for further investigation. Phenotypic analyses revealed that CaSun1 is a critical regulator of vegetative growth, conidiation, and pathogenicity. CaSun1 localized to the mitochondria, consistent with the conserved function of SUN family proteins. Notably, the findings revealed that CaSun1 was essential for mitophagy and colocalized with CaAtg8 during nitrogen starvation. Functional analyses demonstrated that CaSun1-mediated mitophagy is vital for the growth of invasive hyphae and pathogenicity in <i>C. camelliae</i>. In summary, our findings indicated that CaSun1 mediates mitophagy by facilitating the recruitment of CaAtg8 in <i>C. camelliae</i>, thereby contributing to the establishment of anthracnose. This study provided novel insights into the molecular mechanisms underlying the pathogenesis of fungal infections and identified a potential target for disease control.