Silencing Of Nilaparvata Lugens Genes Through DsRNA Feeding On Artificial Diet And Transgenic Plants

Rice is the staple food of almost half the world’s population, it is an enduring topic that how to increase rice yields of per unit area to meet the human need. The brown planthopper, Nilaparvata lugens Stal (Hemiptera:Delphacidae), is the most destructive insect of rice crops. The brown planthopper damages rice plants by directly sucking the rice phloem sap and by acting as a vector for the transmission of the rice grassy stunt virus. At present, the main tactic to control brown planthopper is to combine insecticide with insect-resistant varieties. Although insecticide control of brown planthopper has been a convenient option, indiscriminate usage has resulted in resistance, leading to a resurgence of the insect besides creating serious environment pollution.Hence, genetic improvement of rice host resistance is a preferred alternative. Plant-mediated RNAi has been reported in lepidopteran and coleopteran plant pests. Therefore, the target of this study is selecting important genes in brown planthopper through feeding on dsRNAs with an artificial diet, then transform the RNAi vectors of thesee genes into rice to develop a new way for rice brown planthopper resistance. The main results of this study are as follows:1. Based on rice pest transcriptome database, seven genes involving growth in brown planthopper named dsl, ds2, ds3, ds5, ds6, ds7and ds10were selected.2. Synthesized the dsRNAs of five target genes (ds1、ds2、ds3、ds6and ds10) and two controlled genes (GFP1和GFP2). Lethal phenotypic effects were observed when nymphs were fed on an artificial diet including the dsRNA; the results based on the quantitative real-time PCR analyses showed that the expression level of the targeted genes in N. lugens were reduced simultaneously.3. Seven RNAi vectors were introduced into Zhonghua11. All the transgenic plants were identified by PCR detection, Southern blotting analysis, the gene expression level detection and homozygous strains selection. The reduction of target genes was observed only in a few strains after the nymphs were fed on rice plant materials expressing dsRNAs by quantitative real-time PCR analyses; however, lethal phenotypic effects were not observed. Although generated dsRNA transgenic rice haven’t shown lethal phenotypic effect, it indicated potential of practicability on cultivating transgenic rice resisting to brown planthopper depends on techinical improvement.