Autophagy-Related Proteins (ATGs) Are Differentially Required for Development and Virulence of Sclerotinia sclerotiorum

<i>Sclerotinia sclerotiorum</i> is a devastating fungal pathogen that can colonize numerous crops. Despite its economic importance, the regulation of its development and pathogenicity remains poorly understood. From a forward genetic screen in <i>S. sclerotiorum</i>, six UV mutants were identified with loss-of-function mutations in <i>SsATG1</i>, <i>SsATG2</i>, <i>SsATG4</i>, <i>SsATG5</i>, <i>SsATG9</i>, and <i>SsATG26</i>. Functional validation through gene knockouts revealed that each <i>ATG</i> is essential for sclerotia formation, although the morphology of appressoria was not significantly altered in the mutants. Different levels of virulence attenuation were observed among these mutants. Autophagy, monitored using GFP-ATG8, showed dynamic activities during sclerotia development. These findings suggest that macroautophagy and pexophagy contribute to sclerotia maturation and virulence processes. Future work will reveal how autophagy controls target organelle or protein turnover to regulate these processes.