Interaction Of Q Bemisia Tabaci Odorant Binding Protein (OBPs) With Tomato Chlorotic Virus (ToCV)

Tomato chlorosis virus(ToCV)is a plant virus that spreads mainly through Bemisia tabaci in a semi-persistent and non-circulating manner.ToCV is widely distributed and has caused serious economic losses to vegetables and horticultural ornamental plants.Monitoring the occurrence and spread of ToCV is of great significance for timely detection of ToCV and implementing appropriate preventive measures.Odor-binding proteins(OBPs),as carriers for transporting odor molecules,play a crucial role in the recognition of olfactory signal molecules such as volatile odorous compounds during the interaction of insects with the host plants.To carry out the role of OBPs in the selection of healthy/infected-ToCV plants,will provides a theoretical basis for the comprehensive control of Q whitefly.In this study,we detected ToCV and whitefly infection in Solanaceae vegetables using RT-PCR.At the same time,the interaction mechanism of whitefly OBPs genes and ToCV was also investigated.The main results are as follows:1.Samples of each of 20 tomatoes,eggplants,peppers and potatoes,which were suspected to be infected with ToCV,collected from the district of vegetable research institute of Hunan province,were detected by RT-PCR.We sequenced the products after purifying RT-PCR amplification,and the results showed that the partial sequence was similar with the Beijing tomato ToCV isolate(KC887999.1)and the similarity reached to 99.0 %.The ToCV-infected rates of tomato,eggplant,pepper and potato samples were100 %,80 %,85 % and 70 %,respectively.ToCV RT-PCR was performed with B.tabaci from the back of the leaves of these four vegetables,and the biotype of B.tabaci was also identified.The resultsshowed that B.tabaci carried ToCV,and the rate of viruliferous B.tabaci was more than 87.5 %,and the biotype of all detected whiteflies were Q.2.RT-qPCR was used to detect the relative expression level of OBPs genes in Q which fed on ToCV-infected tomato plants at different AAPs(24h,48 h,72 h and 96 h),and Q whitefly fed on healthy tomato plants were used as control.The results showed that the change trend of relative expression level of OBP3 gene was similar with the trend of virus load in the process of ToCV acquisition by B.tabaci.That is,with the increase of feeding time,the gene expression increased first and then decreased,and reached the maximum expression at 48 h.3.The condition of RNA interference(RNAi)of Q whitefly was optimized.The results showed that the survival rate of B.tabaci was higher after 2 days of artificial feeding.4.The expression of OBP3 gene was specifically knocked down in Q whitefly by RNAi technology,and the relative expression level of RNAi efficiency and other related OBPs in Q whitefles was analyzed by RT-qPCR.The results showed that the expression of OBP3 gene decreased to 27.1 %after 2 days of RNAi,and the RNAi showed a better effect.After the expression of OBP3 gene was knocked down,the expression level of some OBPs in Q whitefly changed.The relative expression levels of OBP1 and OBP2 genes were significantly up-regulated,and the expression levels of OBP5 and OBP6 genes were significantly down-regulated,while the expression levels of OBP4 and OBP7 were not significantly changed.At the same time,after OBP3 expression was interferenced,the feeding preference of Q whiteflies for healthy/infected-ToCV plants also changed.The nonviruliferous Q whiteflies tended to feed on healthy plants,while the viruliferous Q whiteflies had no obvious preference for healthy/infected-ToCV plants.