Comparative Proteomics Studies On Brown Planthopper Responding To Host Rice Resistance

The brown planthopper(BPH)is one of the most destructive pests of rice.Spraying insecticides is one of the most common control methods.However,this method always results in generation of resistant pest,and serious balance destruction of ecosystem in the field.Cultivating and growing resistant rice varieties is an effective and environment-friendly step to manage this pest,exhibiting a potential application in the future.Proteomics has become a powerful tool to investigate the physiological changes at the protein level.Comparative proteomics analyses of BPH will help to find new measures to control BPH.In this work,comparative proteomics analyses of the fourth instar nymphs of biotype Ⅰ and Ⅱ which infested the susceptible rice TN1 plants and the resistant rice Mudgo plants,will be carried out by isobaric tag-based methodology for relative peptide quantification(iTRAQ)technique.The results revealed that 7385 protein fragments were detected,and 696 fragments were quantified.According to the credibility level,total 201 proteins showed obviously different expression levels.These proteins wer expressed differently between the two types of BPH,or the same type BPH feeding on the two rice varieties with different resistant levels.To confirm the expression level of these proteins,27 differentially expressed proteins were selected to investigate the expression level of the corresponding genes by fluorescent quantitative real-time PCR.The results displayed that most of the genes have the same expression trends with their coding proteins.It is noteworthy that three genes(vitellogenin,fatty acid synthase,protein kinase)were expressed at an extremely different pattern.The data showed vitellogenin were expressed at a high level in both biotype Ⅰ and Ⅱ BPH fed with TN1.However,this gene decreased remarkably in biotype Ⅰ BPH after infesting Mudgo,suggesting resistant rice can inhibit the propagation of biotype Ⅰ BPH.The results also indicated that fatty acid synthase regulates biotype formation as well as the acute stress reaction.Because this gene is expressed at a higher level in biotype Ⅰ than that in biotype Ⅱ PBH.And this gene will be expressed in a dramatically high level in nymphs feeding on TN1 regardless of the biotype.On the contrary,this gene will be restrained in biotype Ⅰ BPH after fed with Mudgo,implying that resistant rice suppresses metabolic pathway of fatty acid,then inhibits the synthesis of fatty acid and the body develop.protein kinase is expressed at a higher level in biotype ⅡBPH that in biotype Ⅰ BPH,demonstrating that this gene may be involved in formation and maintaining of a special biotype.This study will help in intensifying the knowledge of the interaction mechanism of BPH and rice,including:① during the acute stress reaction of BPH to host rice resistance,the variation laws of the midgut proteomics,which will indirectly provide some important information about the resistance mechanism of rice;② the discrepancy between different biotype BPH midgut proteomics,which will provide some important information for division of biotype and elucidating the molecular mechanism of the formation of a special biotype.