The Molecular Mechanism Of CYP302A1 And CYP307A1v2 Regulated The Difference Of Sensitivity To Triflumezopyrim In Male And Female Laodelphax Striatellus

The small brown planthopper(SBPH),Laodelphax striatellus(Fallén),belongs to family of hemiptera delphacidae.The nymphs and adults suck the sap from the leaves of rice,corn and other crops,which causes direct damage.Meanwhile,it also transmits a variety of viral diseases such as stripe blight,black-streaked dwarf disease,and corn rough dwarf disease,causes indirect damage.A novel mesoionic insecticide,triflumezopyrim,can control pests by rapidly inhibiting acetylcholine-induced ion currents to block nerve signaling.It is currently the only compound that can inhibit but not activate the nicotinic acetylcholine receptor(n ACh R).It can effectively control all kinds of rice planthoppers.In this paper,it was found that male and female L.striatellus had difference in sensitivity to triflumezopyrim.Further,the role of cytochrome P450 detoxification enzymes in the difference in sensitivity to triflumezopyrim between female and male L.striatellus was researched by silencing related P450 genes with RNAi technology.The main results are as follows:In laboratory strain of L.striatellus,the LC50 of female adault to triflumezopyrim was 2.2-fold than that of male.In field strain,the LC50 of female adault was 2.7-fold higher than that of male.The activity of cytochrome P450 of the laboratory strain of SBPH was determined,the enzymatic activity of female planthopper was significantly higher than that of male.After treating three-instar nymphs and female adults with LC30 triflumezopyrim,the enzyme activity increased significantly relative to that in the control group.It indicated that the difference of P450 enzyme activity probably led to the difference in sensitivity to triflumezopyrim between male and female L.striatellus.In order to explore the difference in the expression of P450 gene in male and female L.striatellus,the expression stability of candidate reference genes was evaluated by ge Norm,Norm Finder and Best Keeper method.the results showed that the β-TUB was suited for q RTPCR in this paper.On the basis of screening stable reference gene,the relative expression of five P450 genes CYP302A1、CYP307A1v2、CYP314A1、CYP315A1 and CYP439A1v3 were detected,and the expression of CYP302A1,CYP307A1v2 and CYP314A1 in female insects was 27,130 and 3-fold than that of male insects,respectively.After treating planthoppers with LC30,the relative expression of CYP302A1,CYP307A1v2 and CYP314A1 in female and nymph increased significantly by 2-3 fold,but there was no significant change in males.The results showed that among the five genes detected,CYP302A1、CYP307A1v2 and CYP314A1 were up-regulated,and it was speculated that these genes may be involved in the mechanism ofsensitivity difference between male and female L.striatellus to triflumezopyrim.CYP302A1 and CYP307A1v2 were silenced with RNAi,and the relative expression decreased by 63.5% and 58% in female L.striatellus.Moreover,the mortality of female L.striatellus in the interference group was significantly increased by 30% and 38.3% respectively compared with that in the control group(ds EGFP).These results showed that the overexpression of CYP302A1 and CYP307A1v2 genes is one of the mechanisms of which male and female L.striatellus have sensitivity differences to triflumezopyrim.