Effects Of α-glucosidase On Transmission Of Tomato Chlorosis Virus By Bemisia Tabaci

Tomato chlorosis virus(ToCV)cannot be transmitted by friction and can only be transmitted by insect vectors.ToCV is exclusively transmitted by whiteflies such as Bemisia tabaci,Trialeurodes vaporariorum,Trialerudodes abutilonea and mainly by Bemisia tabaci in China.Our transcriptomic analyses showed that the expression of Bta11975,anα-glucosidase,was significantly elevated in B.tabaci when they were fed on ToCV-infected plants.Our study showed that accumulation of ToCV in B.tabaci MED is closely related to Bta11975 gene by RT-qPCR.We hypothesized that α-glucosidase played an important role in the process of ToCV transmission in B.tabaci.To test this hypothesis,we conducted the following experiments: 1)we compared Bta11975 gene expression and AGLU activity in B.tabaci with and without ToCV;2)we determined the relationship between amount of ToCV and the expression of Bta11975 gene in B.tabaci;3)we determined how Bta11975 dsRNA affected acquisition and transmission of ToCV by B.tabaci;4)we determined how acarbose affected acquisition and transmission of ToCV by B.tabaci.The main results are as follows:1.At most sampling times,there were differences in Bta11975 relative gene expression and AGLU activity in ToCV-infected and healthy B.tabaci.Bta11975 relative gene expression in B.tabaci after an acquisition access period(AAP)of 24-72 h was twice that of healthy B.tabaci;AGLU activity in B.tabaci 24 h AAP was 0.70-fold higher than that of healthy B.tabaci.Bta11975 is highly expressed in primary salivary gland and gut.2.Our study showed that accumulation of ToCV in B.tabaci is closely related to Bta11975 gene.The relative gene expression of Bta11975 in B.tabaci increased as the amount of ToCV in B.tabaci increased.3.At most sampling times,Bta11975 gene expression was significantly lower in B.tabaci fed a nutrient solution containing Bta11975 dsRNA rather than GFP dsRNA.At 48 h and 72 h,acquisition rate of ToCV and ToCV accumulation gradually decreased.Transmission rate of ToCV by 25 and 50 whiteflies,the number of tomato plants infected with ToCV could be effectively controlled,and ToCV accumulation was significantly reduced.4.After a 48-h feeding period,compared with B.tabaci fed only with sucrose solution,B.tabaci mortality increased and AGLU activity in B.tabaci decreased with the concentration of enzyme inhibitors in the nutrient solution.AGLU activity in B.tabaci decreased with feeding time than sugar solution,the acquisition and accumulation of B.tabaci was significantly lower than with control.These results suggested that α-glucosidase played an important role in the transmission of ToCV in B.tabaci.Thereby,RNA interference agents designed for this gene could inhibit the expression of α-glucosidase,and enzyme inhibitors could inhibit the enzyme activity,which eventually lead to the death of B.tabaci and ToCV could be effectively controlled.The results could be used to the control of B.tabaci in agriculture and to reduce the occurrence of tomato chlorosis virus disease.