Overexpression of Glutathione S-Transferase Genes in Field λ-Cyhalothrin-Resistant Population of <i>Cydia pomonella</i>: Reference Gene Selection and Expression Analysis

Abstract

Analysis of the glutathione S-transferase (GST) gene expression in an insecticide-resistant strain of <i>Cydia pomonella</i> using real-time quantitative polymerase chain reaction is a key step toward more mechanism studies that require suitable reference genes with stable expression. Here, nine commonly used reference genes were selected, and their expression stabilities were analyzed. Results showed that <i>EF-1</i>α was the most stable reference gene in all of the experimental sets. The combinations of <i>EF-1</i>α and <i>18S</i>, <i>EF-1</i>α and <i>RPL1</i>2, and <i>EF-1</i>α and <i>GAPDH</i> were sufficient for normalization of gene expression analysis accurately in developmental stages, tissues, and larvae exposed to sublethal dose of λ-cyhalothrin, respectively. Additionally, the suitability of particular reference genes was verified by analyzing the spatiotemporal and insecticide-induced expression profiles of <i>CpGSTe3</i>, <i>CpGSTd3</i>, and <i>CpGSTd4</i>, which were overexpressed in a λ-cyhalothrin-resistant population from northeast China. These genes were used to confer the practicability of reference genes chosen in this study.