Nuclear basket nucleoporin MoNup50 is essential for fungal development, pathogenicity, and autophagy in Magnaporthe oryzae

Abstract

Autophagy is crucial for appressorium development and host invasion by phytopathogenic fungi, including Magnaporthe oryzae. During appressorium maturation, many organelles, such as nuclei, in the conidia need to be degraded through autophagy to be recycled in appressorium. However, the interplay between autophagy and nuclear membrane systems remains poorly understood. In this study, we functionally characterized MoNup50, a nuclear pore-associated protein. Despite sharing limited sequence identity with human and yeast Nup proteins, MoNup50 contains conserved domains typical of nuclear pore complex proteins. Observation under fluorescence microscopy revealed that MoNup50 localizes at the nuclear membrane in M. oryzae. Deletion of MoNUP50 resulted in reduced hyphal growth, spore production, appressorium formation, and pathogenicity, while increasing sensitivity to osmotic stress and cell wall disruption. Notably, MoNup50 interacts with the key autophagy protein MoAtg7, which regulates MoAtg8-PE synthesis during autophagy. Moreover, MoNUP50 deletion led to elevated autophagy levels and increased phosphorylation of the MAPKs Osm1 and Mps1. These findings suggest that MoNup50 is involved in appressorium morphogenesis and pathogenicity by modulating autophagy and MAPK pathways, highlighting the critical role of nuclear pore proteins in M. oryzae pathogenicity and their potential cross-talk with autophagic and MAPK signaling.