Sorting nexin (MoVps17) is required for fungal development and plant infection by regulating endosome dynamics in the rice blast fungus

Abstract

Vps17 is a sorting nexin (SNX) and a component of the retromer, a protein complex mediating retrograde vesicle transport between endosomes and the trans-Golgi network. However, its role in the development and pathogenicity of filamentous fungi such as the rice blast fungus (Magnaporthe oryzae) remains unclear. We investigate the functional relationship between the SNX and the cargo-selective complex (CSC) of the fungal retromer by genetic analysis, live cell imaging and immunological assay. Our data show that the MoVps17 null mutation causes defects in growth, development and pathogenicity in M. oryzae. MoVps17 is localized to endosomes depending on the activity of phosphatidylinositol 3-kinase (PI3K), a key enzyme for fungal development and infection. Both PX and BAR domains of MoVps17 are essential for its endosomal localization and function. Furthermore, our yeast two-hybrid assays show that MoVps17 and MoVps5 can interact. Lastly, live cell imaging suggests that MoVps17 can regulate early endosome fusion and budding as well as endocytosis. Taken together, our results suggest that MoVps17 specifically functions as a retromer component with CSC and also plays a distinct role in the regulation of endosome dynamics during fungal development and plant infection.

Small GTPase Rab7-mediated FgAtg9 trafficking is essential for autophagy-dependent development and pathogenicity in Fusarium graminearum

“…For autophagy assay, 4×10 4 /ml conidial suspension were cultured in liquid CM medium for 16 h. Mycelia were harvested and washed twice with water and then transferred to nitrogen-limiting medium (MM-N) in the presence of 2 mM PMSF for 8 h. GFP-FgAtg8 were visualized and total proteins were extracted at 0 h and 8 h after starvation. For immunoblot analysis of GFP-fusion-proteins from cellular extracts, equal concentrations of total proteins were isolated and analyzed by immunoblot detection with the anti-GFP (GFP-Tag Mouse mAb, Abmart, China) and anti-actin antibodies (Actin-Tag Mouse mAb, Abmart, China) following a previous report [ 66 ]. For immunoprecipitation, total proteins were isolated and incubated with 30 μL of GFP-Trap_A beads according to the manufacturer’s instructions.…”

Current opinions on autophagy in pathogenicity of fungi

“…Kim et al showed that TOR regulates some effectors for cellular survival in Aspergillus nidulans undergoing rapamycin-induced and carbon starvation-induced autophagy [15]. Furthermore, an increasing amount of research indicates that the autophagy and endocytosis pathways are also essential for conidial and appressorium formation [16][17][18][19].…”

“…In mammals, Rab1, Rab5, and Rab11 play important roles in the regulation of autophagy by regulating mTOR activity; specifically, these three proteins are involved in autophagosome formation and autophagosome-lysosome fusion [41]. Recent studies have also demonstrated that some endocytosisrelated genes, including MoYpt7, PoVps35, PoVps26, PoVps17, MoVps41, and MoEnd3, are involved in autophagy in M. oryzae [17,37,42,53].…”

“…Regulates infection-associated autophagy [60] MoVPS35 Magnaporthe oryzae Impaired generation of appressorium turgor Involved in conidial autophagic cell death [42] MoVPS17 Magnaporthe oryzae Impaired growth and conidiation Involved in conidiation and conidial morphology [17] MoYPT7 Magnaporthe oryzae Impaired growth and conidiation Required for membrane fusion in autophagy [37] FgRAB7 Fusarium graminearum Impaired vegetative growth Essential for autophagy-dependent development…”

“…Many studies have researched several pathogenic pathways in rice blast fungi, including cAMP signaling, which is associated with surface recognition and appressorium formation, and the Pmk1 pathway, which is essential for appressorium formation and plant invasion [55]. Recent research shows that the endocytosis pathway is required and plays a major role in rice blast fungal morphogenesis, vacuole fusion, stress resistance and pathogenicity [17,19,35]. However, until recently, few studies have elaborated on the crosstalk between these signaling pathways in pathogenic fungi.…”