RNA Interference Of Odorant Binding Proteins And NADPH-Cytochrome P450 Reductase Of Rice Planthoppers

Odorant binding proteins (OBPs) are capable of binding odorants near the environment and transport them to olfactory receptor (OR) localized on olfactory neuron dendrites membrane. It is the first step to mediate physiological responses. NADPH-cytochrome P450 reductase (CPR) serves as the electron donor for cytochrome P450s, which can transfer electrons from Nicotinamide Adenine Dinucleotide Phosphate (NADPH) to the P450 heme center.In this thesis, I chose two notorious insect pest on rice-Sogatella furcifera (Horvath) and Nilaparvata lugens (Stal) as study objects, investigated the function of OBP and CPR genes in these two pests respectively. Our research may provide some new potential for the control of planthoppers. The results are as followings:First, ten OBP genes were coloned from S. furcifera genome DNA. In Among them, three OBP genes were successfully expressed in the prokaryotic expression system. DNA sequences encoding mature SfOBP1 and SfOBP2 were ligated into pET22b vector and transfered into Escherichia coli OrigamiB (DE3) cells for expression. The expressed products were inclusion. DNA sequences encoding mature SfOBP5 was ligated into pET-30a vector and transfered into Escherichia coli BL (DE3) cells for expression. The expressed product was a soluble protein and then pure recombinant protein was purified by Ni ion-exchange chromatography. These results paved the essential for the subsequent research on physiological functions of OBP and screening efficient security attractions or repellents.Second, two genes (SfOBP1 and SfOBP2) of S. furcifera were detected by RT-PCR and indicated that they specifically expressed in the antennae, suggesting that these two genes may play an important role in perception of rice volatiles. RNA interference experiment was performed by injecting dsS/OBP1 and dsSfOBP2. Forty eight hours after injection, the mRNA levels of these two genes were significantly decreased, but the survival rates of insect were not affected. Selective Experimental results show that at the time of 0.5 h, the localization ability of WBPH nymphs decreased. Tne result may indicate that SfOBP1 plays an important role in the perception process of rice volatiles.Third, a cDNA sequence encoding the CPR from N.lugens, named it NlCPR was cloned and NlCPR gene was detected abundantly expressed in different body parts and at different development stages. Injection of nymphs of N. lugens with double-strand RNA target to NlCPR sharply reduced the transcription level of the gene. Silencing of NlCPR resulted in increasing susceptibility for N. lugens nymphs to beta-cypermethrin and imidacloprid, implying CPR may be involved in insecticide detoxification of N. lugens.