Study On The Function Of Achaete-scute Homologue And Target Of Rapamycin In Brown Planthopper

Nilarpavata lugens(St?l)(Hemiptera: Delphacidae) is an important migratory pest in rice grown area, possessing the capacity of long-distance migration capacity. There are many bristles on raw in forewing veins of brown planthopper adult, and the function and molecular mechanism of the bristles are not clear. When the brown planthopper is migrating, ovarian development is inhibited, which is a short-lived phenomenon of reproductive diapause. Achaete-scute Complex(AS-C) encodes b HLH transcription factors, and functions in bristle development. The molecular mechanism of reproductive diapause is unclear and we assumed that this phenomenon is regulated by nutrient signaling pathways. The Target of Rapamycin(TOR) signal pathway constitutes a specialized regulatory module coordinating cell growth with its local nutritional environment. So achaete-scute homologue(ASH) and Target of Rapamycin(TOR) gene were cloned and the function was studied using RNAi method on BPH. The results are as follows:Study on the function of achaete-scute homologue in Brown planthopper1. In the present study, we have cloned the achaete-scute homologue(Nl ASH) from N. lugens, Nl ASH encoded 233 amino acid residues. Phylogenetic analysis using coding region of Nl ASH was examined for evolutionary pattern among insects. The Nl ASH was found most closely related to ASH of Apis mellifera and Nasonia vitripennis. 2. The expression level of Nl ASH was higher in nymphs than that in adults. They highly expressed in the wing pads of third- nymphs. 3. Knockdown of Nl ASH expression in vivo generated phenotypic defects in the wing(lose-of–bristles, twisted wing or erected wing). When nymphs at 3rd-instar were treated with ds ASH, the survival rate was significantly decreased compared to those treated with ds GFP, and ds ASH causes lethality.Study on the function of Target of Rapamycin in Brown planthopper1. The experiment was conduct to observe the effect of NITOR gene on different stages of Brachypterous(BS) and Macropterous(MS) strains. The results showed that Nl TOR expressed in both nymph and adult stage of brown planthopper. BS was more effected than MS. Adults at 1, 2 and 4 d of BS were effected by Nl TOR expression and significantly higher than that of the MS. 2. After the injection of ds TOR, the BPHs were observed continuously for 15 days, and no eggs were found on the spawning rice stem. After the dissection ovary of female adults, ovarian development has been inhibited, and eggs were not formed. Besides, ovarian tubules and the oviduct development were suppressed. 3. The silence of NITOR prolongs the period from nymph to adult and decreases the expression levels of Nl E74B(Ecdysone-induced protein 74B) and Nl Ec R(Ecdysteroid receptor)..NITOR regulates the development of ovary by control the expression of Nl Fo XO(Forkhead-box O) and Nl Vg(vitellogenin).In conclusion, this study shows that NIASH was involved in the development of bristles on forewing veins of brown planthopper and plays a key role. Nl TOR genes were involved in the regulation of ovarian development of brown planthopper. Silencing Nl TOR leaded to the inhibition of ovarian development, and eggs could not be generated. The difference between the expression of Nl TOR within Brachypterous and Macropterous strains was significantly different, indicating that Nl TOR may be involved in the regulation of reproductive diapause in brown planthopper when migrating.