Study On The Mechanism Of Tomato Chlorosis Virus Regulating Host Plant To Influence Whitefly Preference

Tomato chlorotic virus(ToCV)is a phloem-restricted RNA virus,which spreads in a semi-persistent manner by the whitefly and seriously affects the production of tomatoes and other crops.ToCV was first discovered in Taiwan in 2004.Since 2012,it has been spread rapidly to more than 10 regions including Beijing,Shandong,and Hunan.The outbreak of ToCV is closely related to the occurrence of Bemisia tabaci in China.At present,there are few studies on the interaction mechanism between semi-persistent viruses,plants and vectors.To solve this problem,we detected the effect of ToCV on plant nutrition,volatiles,defense and metabolism,and preference of B.tabaci.Furthermore,the P22 protein was found as a key factor of ToCV,and the molecular mechanism was clarified that P22 regulates the host plants to alter vector preference.The result showed that non-viruliferous B.tabaci prefer ToCV-infected plants,while viruliferous B.tabaci prefer healthy plants,and the B.tabaci preference increases with the growth of ToCV in plants.The effects of ToCV on plant chlorophyll,terpenoid volatiles,plant sugars and amino acids nutrition,plant defense and metabolism were studied.It was found that ToCV can affect the preference of B.tabaci by reducing plant chlorophyll content and nutrition,regulating terpenoid volatiles,and inducing SA defense.In addition,after B.tabaci feeding on ToCV-infected plants,the expression of JA synthesis-related genes and terpenoid synthesis-related genes were down-regulated.It indicates that ToCV inhibits JA and JA-induced terpenoid to attract B.tabaci.Furthermore,the ToCV P22 protein was found as a key factor to mediate whitefly preference.P22 interacted with the host protein MYC2,and inhibit JAinduced terpenoid volatiles to attract B.tabaci.In summary,this study clarified the mechanism that ToCV regulates host plants to manipulate B.tabaci preference,and initially explored the molecular mechanism of P22 regulating plant JA-induced terpenoid volatiles to attract B.tabaci.It lays the foundation for the study of the interaction of semi-persistent viruses with host plants and vector insects,and provides new ideas and references for the prevention and control of ToCV in the field.