The Gene Clone And Rnai Function Analysis Of NADPH-Cytocyrome P450 Reductise Of Laodelphax Striatellus (Fallen)

The small brown planthopper Laodelphax striatellus (Fallen) is a pest which had brought serious harm to grain crops, such as rice and wheat. It is not only spreading the virus between crops, but also sucking the gramineous plants. It rarely occurred before twenty-first century, but the L. striatellus populations broke out frequently in china especially in Jiangsu province after 2005. The misuse of pesticides was the important reason for resistance occurrencing in the field. Several papers had showed that the insecticide resistance was an important reason for frequent occurrence of the L. striatellus. Therefore, insecticide resistance management strategies must be developed to prevent further increase in resistance of L. striatellus. Nowadays, searching an efficient method to control this notorious pest is necessary. In this study, we firstly cloned the potential target gene NADPH-Cytochrome P450 reductase of L. striatellus (LSCPR), then explored the phenotypic variation after RNAi, and all the results would provide a new basis for better management of insecticide resistance and the development of new pesticides.1. The full-length gene clone and sequence analysis of NADPH-cytochrome P450 reductase in L. striatellus.We firstly gained the 1550bp segments of LSCPR. Then the rapid amplification of cDNA ends (RACE) technique was utilized to gain the full-length sequence of LSCPR. The results showed that the ORF of LSCPR was 2040 bp, encoding sequences of 679 aa in size. Comparison of the LSCPR sequence with orther insect CPRs indicated that it possessed these characteristics shared in many insect NADPH-Cytochrome P450 reductase genes (CPRs), including the membrane anchor, conserved binding domains (Flavodoxin, FAD binding and NADP binding region), FAD binding motif (ArgxTyrSer) and catalytic residues (Ser-Cys-Asp-Trp). So we preliminarily concluded that the LSCPR was the CPR gene in L. striatellus.2. The RNAi function analysis on NADPH-cytochrome P450 reductase of Laodelphax striatellus (Fallen)We firstly synthesized the 338bp length double strain fragment of LSCPR as the RNA interference (RNAi) aim in this part content, and the GFP served as the control. The concentration of dsRNA was designated as doses at 500 ng/μL for LSCPR and GFP, respectively. qPCR was used to evaluate the expression difference of LSCPR after ingestion of the dsRNA on the fifth day, and the transcript level of LSCPR was significantly increased 50% or so. At the same time, mortalities and retardation were also detected in the LSCPR RNAi when compared with the control. The results showed that LSCPR played a very important role in the growing development of L. striatellus, but the reason for increase expression quantity after RNAi deserved further research.