The ArfGAP protein MoGlo3 regulates the development and pathogenicity of Magnaporthe oryzae

Abstract

The ADP ribosylation factor (Arf) and the coat protein complex I (COPI) are both involved in vesicle transport. Together with GTPase-activating proteins (ArfGAPs) and guanine exchange factors (ArfGEFs) that regulate the activity of Arf, they govern vesicle formation, COPI trafficking, and the maintenance of the Golgi complex. In an ongoing effort to study the role of membrane trafficking in pathogenesis of the rice blast fungus Magnaporthe oryzae, we identified MoGlo3 as an ArfGAP protein that is homologous to Glo3p of the budding yeast Saccharomyces cerevisiae. As suspected, MoGlo3 partially complements the function of yeast Glo3p. Consistent with findings in S. cerevisiae, MoGlo3 is localized to the Golgi and that the localization is dependent on the conserved BoCCS domain. We found that MoGlo3 is highly expressed during conidiation and early infection stages, and is required for vegetative growth, conidial production, and sexual development. We further found that the ΔMoglo3 mutant is defective in endocytosis, scavenging of the reactive oxygen species (ROS), and in the response to endoplasmic reticulum (ER) stress. The combined effects result in failed appressorium function and decreased pathogenicity. Moreover, we provided evidence showing that the domains including the GAP, BoCCS and GRM are all important for normal MoGlo3 functions. Our studies further illustrate the importance of normal membrane trafficking in the physiology and pathogenicity of the rice blast fungus.

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 .…”

System-Wide Characterization of MoArf GTPase Family Proteins and Adaptor Protein MoGga1 Involved in the Development and Pathogenicity of Magnaporthe oryzae

“…cerevisiae Arl1 is Golgi localized (53, 54), we tested whether the punctate colocalizes with the Golgi. To do this, we introduced the Golgi marker protein MoSft2-RFP (MoSft2-red fluorescent protein) (36, 55) and found that the green fluorescence punctate indeed colocalized with MoSft2-RFP in conidia, germ tubes, appressoria, and the vegetative and invasive hyphae (Fig. 5).…”

“…We previously found that ArfGAP protein MoGlo3, mediating endocytosis and vesicle trafficking, regulates growth, conidiation, and pathogenesis in the blast fungus (36). Intriguingly, interactions between MoGlo3 and all MoArf proteins cannot be established by the Y2H assay (data not shown).…”

“…Previously, we demonstrated that ArfGAP protein MoGlo3 is involved in vesicle trafficking and pathogenicity in M. oryzae (36). We also previously characterized dynamin GTPase superfamily proteins and showed that MoDnm1 mediates peroxisomal and mitochondrial fission regulating vesicle trafficking and pathogenicity of the blast fungus (37).…”

ArfGAPs; Depletion or Overexpression?

“…Although Arf6•GTP levels increased by depletion of ACAP3, the shRNA of Arf6 also decreased neurite outgrowth. As the fast cycling mutant of Arf6, T157A rescued the phenotype of ACAP3 knockdown, but not GDP-and GTP-locked mutant of Arf6, Q67L and T44N, Miura et al [33] concluded that the cycle of Arf6 is required for neurite outgrowth. Although the consequences of depletion of ArfGAPs in terms of Arf•GTP levels should be addressed carefully, accumulating evidence [33][34][35][36][37][38][39][40] shows that ArfGAPs are able to positively regulate biological processes.…”