Evaluation and Validation of Reference Genes for Gene Expression Analysis Using qRT-PCR in the Sugarcane Stem Borer Chilo sacchariphagus (Lepidoptera: Pyralidae)

Chilo sacchariphagus (Lepidoptera: Pyralidae) is an economically important sugarcane pest. Although numerous studies were conducted on the physiological responses in C. sacchariphagus, little is known regarding the genes regulating these physiological processes. Gene expression analysis by qRT-PCR can offer a significant indication for functional gene studies. To our knowledge, the reference genes of C. sacchariphagus have not been screened or evaluated, which hinders the functional gene study. In the present study, the stability of seven reference genes (beta-ACT, GAPDH, BTF3, 28S, RPL7, EF1 alpha, and SDHA) was evaluated in C. sacchariphagus under different experimental conditions, including tissues (antenna, head, thorax, abdomen, leg, and wing), temperatures (4 degrees C, 25 degrees C, and 37 degrees C) and sexes (male and female), through RefFinder, which integrates four algorithms (Normfinder, BestKeeper, Delta Ct method, and geNorm). The findings suggested that the combination of beta-ACT and RPL7 is ideal to analyze gene expressions in different tissues and at distinct temperatures, and EF1 alpha and SDHA were suitable reference genes for comparing gene expressions between sexes. Finally, the expression profiles of CsacPBP1 gene were evaluated, and the outcomes further confirm the importance of selecting fitting reference genes for normalization of qRT-PCR data. This study represents the first kind in screening out suitable reference genes for gene expression analysis in C. sacchariphagus. Information from this study is poised to galvanize future inquiry into the gene expression of C. sacchariphagus, an economically important pest of sugarcane.