Study On Erysiphe Necator Effector EnCSEP087 Targeting Arginine Decarboxylase VviADC In Regulating Grapevine Immune Reaction

Grapevine(Vitis spp.)is one of the most significant fruit trees in the world,but Eurasian grapevines(Vitis vinifera L.)which are widely cultivated are highly susceptible to powdery mildew(PM)caused by Erysiphe necator Schw.This obligate biotrophic fungus is presenting the grape industry with serious challenges.Many studies revealed that pathogens can secrete effectors to interfere with the plant immune system to infect the host cell.Although there are many studies about the interaction between pathogens and plants,the research on the interaction between grapevine and Erysiphe necator effectors is rarely reported.Our research group has identified an effector protein EnCSEP087 from a native PM isolate En.NAFU1.In this experiment,we studied the biological function of EnCSEP087 by agrobacterium?mediated transient transformation in grapevine leaves.Then,we used EnCSEP087 as a bait protein to screen an interacting protein identified as arginine decarboxylase(ADC)by using yeast twohybrid system(Y2H)and analyzed functions preliminarily.The main results are as follows:1.RT-qPCR results showed that the expression of the Erysiphe necator effector gene EnCSEP087 was significantly up-regulated at 24 h after Erysiphe necator infected.In addition,EnCSEP087 is a secreted protein by yeast secretion assay and located in the nucleus and cell membrane by a transient transformation.What’s more,the transient overexpression of EnCSEP087 in Thompson Seedless promoted the hyphal growth of Erysiphe necator and inhibited the accumulation of reactive oxygen species.2.We confirmed that EnCSEP087 interacts with Vvi ADC by yeast two-hybrid assay,luciferase complementation assay,and bimolecular fluorescence complementation assay.3.Vvi ADC was mainly located in the nucleus and cell membrane by transiently overexpressing Vvi ADC in Nicotiana benthamiana leaves.In addition,transient overexpression Vvi ADC in Thompson Seedless leaves resulted that the growth of hyphal was inhibited,and the number of cells producing reactive oxygen species was significantly higher than that of the control group at 5 d.The further results showed that the content of hydrogen peroxide and the activities of CAT,POD,and SOD were improved in the Vvi ADC overexpressed Thompson Seedless leaves.In conclusion,the results of this study indicate that the effector protein EnCSEP087 can be secreted into grapevine cells to target the grapevine arginine decarboxylase Vvi ADC,thereby affecting the function of the grapevine immune system.