An effector of <i>Erysiphe necator</i> translocates to chloroplasts and plasma membrane to suppress host immunity in grapevine

Abstract

The powdery mildew (<i>Erysiphe necator</i>) is a prevalent pathogen hampering grapevine growth in the vineyard. An arsenal of candidate secreted effector proteins (CSEPs) was encoded in the <i>E. necator</i> genome, but it is largely unclear what role CSEPs plays during the <i>E. necator</i> infection. In the present study, we identified a secreted effector CSEP080 of <i>E. necator</i>, which was located in plant chloroplasts and plasma membrane. Transient expressing <i>CSEP080</i> promotes plant photosynthesis and inhibits INF1-induced cell death in tobacco leaves. We found that <i>CSEP080</i> was a necessary effector for the <i>E. necator</i> pathogenicity, which interacted with grapevine chloroplast protein VviB6f (cytochrome b6-f complex iron-sulfur subunit), affecting plant photosynthesis. Transient silencing VviB6f increased the plant hydrogen peroxide production, and the plant resistance to powdery mildew. In addition, CSEP080 manipulated the VviPE (pectinesterase) to promote pectin degradation. Our results demonstrated the molecular mechanisms that an effector of <i>E. necator</i> translocates to host chloroplasts and plasma membrane, which suppresses with the grapevine immunity system by targeting the chloroplast protein VviB6f to suppress hydrogen peroxide accumulation and manipulating VviPE to promote pectin degradation.