MoEnd3 regulates appressorium formation and virulence through mediating endocytosis in rice blast fungus Magnaporthe oryzae

Abstract

Eukaryotic cells respond to environmental stimuli when cell surface receptors are bound by environmental ligands. The binding initiates a signal transduction cascade that results in the appropriate intracellular responses. Studies have shown that endocytosis is critical for receptor internalization and signaling activation. In the rice blast fungus Magnaporthe oryzae, a non-canonical G-protein coupled receptor, Pth11, and membrane sensors MoMsb2 and MoSho1 are thought to function upstream of G-protein/cAMP signaling and the Pmk1 MAPK pathway to regulate appressorium formation and pathogenesis. However, little is known about how these receptors or sensors are internalized and transported into intracellular compartments. We found that the MoEnd3 protein is important for endocytic transport and that the ΔMoend3 mutant exhibited defects in efficient internalization of Pth11 and MoSho1. The ΔMoend3 mutant was also defective in Pmk1 phosphorylation, autophagy, appressorium formation and function. Intriguingly, restoring Pmk1 phosphorylation levels in ΔMoend3 suppressed most of these defects. Moreover, we demonstrated that MoEnd3 is subject to regulation by MoArk1 through protein phosphorylation. We also found that MoEnd3 has additional functions in facilitating the secretion of effectors, including Avr-Pia and AvrPiz-t that suppress rice immunity. Taken together, our findings suggest that MoEnd3 plays a critical role in mediating receptor endocytosis that is critical for the signal transduction-regulated development and virulence of M. oryzae.

The endosomal recycling of FgSnc1 by FgSnx41–FgSnx4 heterodimer is essential for polarized growth and pathogenicity in Fusarium graminearum

“…To further uncover the functional mechanism of the FgSnx41–FgSnx4 dimer, we next investigated whether FgSnx41–FgSnx4‐mediated vesicular trafficking is required for endocytosis, which is a form of active transport of extracellular macromolecules into the cell and is known to be important for fungal polarized growth and virulence (Fuchs et al ., ; Shaw et al ., ; Bielska et al ., ; Liu et al ., ; Li L et al ., ; Li X et al ., ). We did this by staining the hyphae of ΔFgsnx41 and ΔFgsnx4 mutants with FM4‐64.…”

MoPpe1 partners with MoSap1 to mediate TOR and cell wall integrity signalling in growth and pathogenicity of the rice blast fungus Magnaporthe oryzae

“…Three independent experiments were replicated that showed similar results. C. Mps1 phosphorylation level analysis with proteins extracted from appressoria incubated on hydrophobic surfaces for 24 h (Li et al ., ). The phosphorylation levels of Mps1 (44 kDa) were detected using the phosphor‐MAPK antibody (upper panel).…”

“…Previously, studies in M. oryzae showed that the nuclear division is critical in appressorium function (Marroquin‐Guzman et al ., ). To further understand whether the deletion of MoPPE1 caused a nuclear division defect that may account for restricted invasion, a histone H1 protein fused to a red fluorescent protein (H1‐RFP) construct was introduced into the wild‐type strain and Δ Moppe1 mutant (Li et al ., ,b; Marroquin‐Guzman et al ., ). However, the nuclear number were of no significant difference between the Δ Moppe1 mutant and the wild‐type strains at 0, 4, 12, 24 h and infection phase when observed, suggesting that MoPpe1 may be dispensable for nuclear division which was in coordination with cell growth (Supporting Information Fig.…”

VPS9 domain‐containing proteins are essential for autophagy and endocytosis in Pyricularia oryzae

“…graminearum have been verified to be involved in endocytosis and pathogenicity (Dou et al ., ; Zhang et al ., ). Through functional analysis of endocytic proteins such as the ArfGAP protein MoGlo3 (Zhang et al ., ), the class V myosin MoMyo5 (Tang et al ., ), the capping protein MoCap (Li et al ., ), the verprolin protein MoVrp1 (Huang et al ., ), the ADP‐ribosylation factor Arf6 (Zhu et al ., ), the actin‐regulating kinase homologue MoArk1 (Wang et al ., ) and an early endocytic protein‐MoEnd3 (Li et al ., ), it was revealed that endocytosis is essential for conidiogenesis, appressorium formation and pathogenicity in P . oryzae .…”