The Molecular Mechanism Of Glutathione Transferase Involving In Sensitivity Difference Of Imidacloprid Between B And Q Bemisia Tabaci

Bemisia tabaci(Gennadius)is a worldwide invasion pest,which has an impact on the China’s agricultural production and resulted in huge economic losses.MED/Q has replaced the MEAM1/B in recent years,which was the main B.tabaci before in China and MED/Q,seriously affecting the farmland ecosystems nowadays,has become the most widely distributed B.tabaci.The ecological mechanism of the replacement was the insecticide overused.However,the molecular mechanism behind it is still vague(for the convenience of description,Q is expressed as MED /Q,and B is expressed as MEAM1/B).As an important detoxification enzyme in the organism,glutathione transferase plays a key role in the insectcide resistance.In this study,the glutathione transferase genes were annotated according to the genomic and transcriptome information.Then,RNA interference was used to elucidate that the specific glutathione transferase gene is invlolved in the process of the B.tabaci B being replaced by B.tabaci Q,To search for putative BtGST genes,the available GST gene sequences from others insect species was used as references to screen the B.tabaci genomic and transcriptomic databases with TBLASTN.It found that the GSTs genes between B and Q B.tabaci were similar in number,sequence and so on.It had 23 GSTs gene in total including 2 microsomal GST and 21 cytoplasmic GST.For the cytoplasmic GST,it had 4 subfamlily,including 12 Delta,6 Sigma,1 Omega,and 1 Zeta.There was no Epsilon and Theta subfamily.In order to clarify the response mechanism of GSTs gene of B and Q B.tabaci to imidacloprid,the expression of GST genes were analyzed by qPCR.It found that the response of GST genes to imidacloprid was different between B and Q B.tabaci.For the Q B.tabaci the expression of BtQGST-d7 was increased by 4.39 times,and the expression of BtQGST-d8 increased by 2.36 times.However,for the B B.tabaci,only one GST gene(BGST-s2)was increased by 2.78 times after imidacloprid treatment for 24 h.The results showed that the different expression of GSTs could play an important role in the susceptibility to imidacloprid between B and Q B.tabaci.In order to further elucidate the function of GST-d7,RNA interference was applied.The bioassay results showed that the mortality rate of Q B.tabaci was significantly increased after the GST-d7 was knockouted;the mortality was increased in 42%(50μg/mL)or 44%(30μg/mL)which was similar to the B B.tabaci.However,the mortality rate was the same with the control for B B.tabaci after the GST-d7 was knockouted.All of the results indicated that the GST genes play a siginificant role in the sensitivity difference of imidacloprid between B and Q B tabaci.