Auxilin‐like protein MoSwa2 promotes effector secretion and virulence as a clathrin uncoating factor in the rice blast fungus Magnaporthe oryzae

Abstract

Plant pathogens elaborate the extracellular matrix (ECM) to inhibit host immunity during their interactions with the host. The formation of ECM involves a series of continuous steps of vesicular transport events. To understand how such vesicle trafficking impacts ECM and the virulence in the rice blast fungus Magnaporthe oryzae, we have characterized MoSwa2, a previously identified actin‐regulating kinase MoArk1 interacting protein, as an ortholog of the auxilin‐like clathrin uncoating factor Swa2 of the budding yeast Saccharomyces cerevisiae. We found that MoSwa2 functions as an uncoating factor of the coat protein complex II (COPII) via an interaction with the COPII subunit MoSec24‐2. Loss of MoSwa2 led to a deficiency in the secretion of extracellular proteins, resulting in both restricted growth of invasive hyphae and reduced inhibition of host immunity. Additionally, extracellular fluid (ECF) proteome analysis revealed that MoSwa2‐regulated extracellular proteins include many redox proteins, such as the berberine bridge enzyme‐like (BBE‐like) protein MoSef1. We further found that MoSef1 functions as an apoplastic virulent factor that inhibits the host immune response. Our studies reveal a novel function of a COPII uncoating factor in vesicular transport that is critical in the suppression host immunity and pathogenicity of M. oryzae.