An effector CSEP087 from Erysiphe necator targets arginine decarboxylase VviADC to regulate host immunity in grapevine

Abstract

• It firstly reported that the grapevine powdery mildew, Erysiphe necator NAFU1, effector CSEP087 molecular mechanism in interaction between powdery mildew and grapevine. • CSEP087, which is upregulated during En NAFU1 infection contains a secreted signal peptide 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 a grape arginine decarboxylase VviADC, which is screened by yeast two-hybrid system. • Expression of VviADC in grape leaves inhibited the powdery mildew growth and promoted the ROS production during En NAFU1 infection. Grapevine ( Vitis vinifera ) is suffering from the fungal pathogen powdery mildew, which affects grape production worldwide. Powdery mildew secretes a large number of effectors into plant cells, which modulate the innate immune system to promote colonization of the infection. Many studies have been conducted on the interactions between pathogens and plants, but the working mechanism of the effectors in the interaction between powdery mildew and grapevine has not been reported. In this study, we identified the CSEP087 effector from the grapevine powdery mildew isolate, Erysiphe necator NAFU1, which was upregulated during infection and contained a signal peptide that was secreted into the plant cells as verified by a yeast secretion assay. The expression of CSEP087 in grapevine leaves facilitated the growth of powdery mildew and suppressed the production of reactive oxygen species (ROS). CSEP087 interacted with VviADC, an arginine decarboxylase from grapevine, as screened by a yeast two-hybrid system. VviADC is a conserved protein in horticultural and model plants, particularly localized at the recognition and catalytic sites of the enzyme active center. The expression of VviADC in grapevine leaves inhibited the growth of powdery mildew and promoted ROS production, including hydrogen peroxide in the plants. In addition, VviADC increases the enzymes related to ROS scavenging activities. Our results demonstrate that the powdery mildew effector CSEP087 targeted VviADC, which is a regulator of hydrogen peroxide production and plant immunity. This finding advances our understanding of the role of effectors in the grapevine-powdery mildew interaction.