An Effector Csep087 from Erysiphe Necator Targets Arginine Decarboxylase Vviadc to Regulate Host Immunity in Grapevine

Grapevine has suffered from fungal pathogen powdery mildew, which impacts the grape production around the world. Powdery mildew secrectes a large number of effectors into plant cells and modulates innate immunity system to promote colonization in the infection. There are many studies on the interaction between pathogens and plants, but the working mechanism of effectors in the interaction between powdery mildew and grapevine has not been reported. In this study, we identified an effector CSEP087 from the grapevine powdery mildew isolate, Erysiphe necator NAFU1, which is upregulated during infection and contain a signal peptide used to secrete verified by a yeast secretion assay. Expression of CSEP087 in grape leaves facilitates the powdery mildew growth and suppresses the production of reactive oxygen species (ROS) in grapevine. CSEP087 interactes with an arginine decarboxylase from the grapevine ( Vitis vinifera ), VviADC, which is screened by yeast two-hybrid system. VviADC is a conserved protein in horticultural plants and model plants, especially at the recognition and catalytic sites of the enzyme active center. Expression of VviADC in grape leaves inhibited the powdery mildew growth and promoted the ROS production in plant. VviADC can promote the production of hydrogen peroxide in plant. In addition, VviADC improves the activity of enzymes related to ROS scavenging. Our results demonstrate that powdery mildew effector CSEP087 targets VviADC, which is a regulator of hydrogen peroxide production and plant immunity. This finding advances the understanding the role of effectors in the grapevine-powdery mildew interaction.