Clone Of Wingless Gene In Rice Planthoppers And Its Function Of Regulating Wing Forms In Sogatella Furcifera

Brown planthopper Nilaparvata lugens, small brown planthopper Laodelphax striatellus and the white-backed planthopper Sogatella furcifera are three important pests in rice field of Asia. Adults of rice planthopper are wing dimorphism. However, the genetics of wing dimorphism are still vague. Wingless gene (Wg) plays a vital role in regulating wing imaginal discs, but it is still not known the functions of Wg in the wing dimorphism of rice planthopper.In this study, the full-length or open reading frame (ORF) sequences of Wg in three rice planthoppers were cloned, and the wing forms of white-backed planthoppers (WBPH) were selected. The relative expression of Wg between macropterous and brachypterous lineages of WBPH, as well as among five different tissuses, head, throax, abdomen, legs and wings of macropterous lineage, were detected by qRT-PCR techniques. The fuctions of Wg to control the wing dimorphism of WBPH was also studied using RNAi-mediated gene knockdown method. The main results were summarized as follows:1. After 40 generations of selection for wing forms of WBPHs, the macropterous pure lineage and brachypterous nearly pure lineage of WBPH were obtained. The offsprings in macropterous lineage were long-winged completely after seven genetions of selection. While the short-winged rate in females was about 95% after tween-five generations of selection in the brachypterous lineage. There was a strong response for wing selection in WBPH.2. The cDNA of Wg in S. furcifera and L. striatellus and the ORF region of Wg in N. lugens were obtained by RACE and cloning methods. The full-length cDNA length of Wg in S. furcifera is 1571 bp, which encodes 390 amino acid residues. A full-length cDNA of Wg in L. striatellus is 1443 bp, which encodes 390 amino acid residues too. The Wg of ORF in N. lugens is 1185 bp and encoding 394 amino acid residues. There is a high similarity among these three kinds of Wg protein sequences and the similarity by pairwise comparison of them is more than 96%.3. Wg relative expression level in the 3rd-5th instar nymphs and adults of brachypterous and macropterous lineage of WBPH were checked by qRT-PCR technology. The result showed that Wg was highly expressed in nymphs and was very lower in adult stage. Expression levels of Wg in the macropterous lineage of WBPH from the 3rd to 5th nymphs were higher than in the brachypterous lineage. Wg expression level in wings was the highest than in the head, throax, abdomen and legs.4. The function of Wg in WBPH was studied by RNA interference technology. The results showed that 100 ng/μL of dsWg ingested by nymphs led to the significantly decline of relative expression level of Wg, and also resulted in the lighter body weight and shorter wings of adults. The dsWg caused abnormal winges of WBPH, and these winges were unfolded or curling. When the dsWg concentrations were 200 ng/μL and 400 ng/μL, the adults with short wings only reached to the tip of abdomen were found in the macropterous lineage of WBPH. When the 4000 ng/μL,2000 ng/μL, or 1500 ng/μL of dsWg was injected into the third instar nymphs, a brachypterous adult from the macropterous lineage was obtained. The Wg plays an important role in controling the wing development of WBPH.