The Role of Snx41-Based Pexophagy in Magnaporthe Development

Pexophagy, the degradation of peroxisomes via selective autophagy, depends on Atg20/Snx42 function in Saccharomyces cerevisiae. Besides its role in selective autophagy, Atg20/Snx42 is also involved in an autophagy-independent endosomal retrieval trafficking, in cooperation with two other sorting nexins, Snx41 and Snx4. Recently, we reported that the sorting nexin MoSnx41, which showed high sequence similarity to yeast Snx41 and Snx42/Atg20 proteins, regulates the gamma-glutamyl cycle and GSH production and is essential for conidiation and pathogenicity in Magnaporthe oryzae. Pexophagy was also found to be defective in Mosnx41 Delta mutant. These findings indicate that MoSnx41 likely serves combined functions of Snx42/Atg20 and Snx41 in M. oryzae.. In this study, we performed complementation analyses and demonstrate that MoSnx41 alone serves the dual function of protein sorting (ScSnx41) and pexophagy (ScSnx42/Atg20). To study the potential biological function of pexophagy in fungal pathogenic life cycle, we created deletion mutants of potential pexophagy-specific genes, and characterized them in terms of pexophagy, conidiation and pathogenesis. We identified Pex14 as an essential protein for pexophagy in M. oryzae. Overall, our results show that pexophagy per se is not essential for asexual development or virulence in M. oryzae.