Transcriptome-Based Identification and Characterization of Genes Associated with Resistance to Beta-Cypermethrin in Rhopalosiphum padi (Hemiptera: Aphididae)

Abstract

Beta-cypermethrin is one of the most widely used pyrethroid insecticides. However, its continuous and extensive use developed pests’ resistance to beta-cypermethrin. To identify candidate genes for potential resistance phenotypes and facilitate more targeted studies, we screened out a wide range of resistance-related genes by comparing multiple transcripts before and after the induction of multiple agents. In this study, transcriptomes were compared to elucidate the mechanisms and genetic basis of potential resistance between Rhopalosiphum padi (R. padi) sensitive (SS) and resistant (Beta-R) strains to beta-cypermethrin (resistance ratio: 4588.48). These two strains of aphids were treated with a spray solution of lethal beta-cypermethrin concentration (i.e., LC50). To obtain diverse transcripts, we obtained 17,985,440–25,478,353 clean data from different transcript groups, of which 17,183 genes were annotated. Subsequently, these transcripts were divided into multiple groups for comparison purposes to obtain more comprehensive genes related to resistance. There were 178 to 2856 differentially expressed genes (DEGs) in these transcript groups. The DEGs, including the enriched ones, were classified according to the GO and KEGG Pathway databases. Besides, some drug-resistant DEGs were related to cuticle proteins and detoxification metabolic processes. Among them, 17 genes related to cuticle protein were upregulated and 20 were downregulated, 11 genes related to P450 were upregulated and 25 were downregulated, 7 genes related to UGT were upregulated and 15 were downregulated, 2 genes related to ABC transporter were upregulated and 4 were downregulated, 2 genes related to trypsin were upregulated and 1 were downregulated. Finally, qRT-PCR by DEGs confirmed the observed trend in the RNA sequencing expression profile, and most of the results were consistent between qRT-PCR and RNA sequencing (RNA-seq). The results of this study are highly significant in understanding the resistance phenomenon in R. padi and other similar wheat aphids, establishing the valuable basis for further research in the complex mechanism of R. padi resistance to beta-cypermethrin.