Component of the PI(3,5)P2 regulatory complex that regulates both the synthesis and turnover of phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2) (By similarity). Plays an important role in osmotically-induced vacuole fragmentation (By similarity). Required for cytoplasm to vacuole transport (Cvt) vesicle formation, pexophagy and starvation-induced autophagy (By similarity). Involved in correct ATG9 trafficking to the pre-autophagosomal structure (By similarity). With ATG2, protects ATG8 from ATG4-mediated cleavage (By similarity). Autophagy is required for proper vegetative growth, asexual/sexual reproduction, and full virulence (PubMed:28894236). Autophagy is particularly involved in the biosynthesis of deoxynivalenol (DON), an important virulence determinant (PubMed:28894236). Component of the PI(3,5)P2 regulatory complex (By similarity). Interacts with ATG2 and ATG9 (By similarity). The ATG2-ATG18 complex is essential for autophagosome formation (By similarity). The 377 first amino acids might form a beta-propeller domain involved in specific binding to phosphatidylinositol 3,5-bisphosphate (PIP2), leading to the association of the protein to the membrane (By similarity). Association to the membrane can also occur through binding to phosphatidylinositol 3-monophosphate (PI3P) (By similarity). The L/FRRG motif is essential for the cytoplasm to vacuole transport (Cvt) pathway, for the recruitment of ATG8 and ATG16 to the PAS in nutrient-rich medium, and for its recruitment to and dissociation from the PAS under starvation conditions (By similarity). Does not significantly decrease the growth rate under nutrient-rich conditions (PubMed:28894236). Belongs to the WD repeat PROPPIN family.