Selection and evaluation of reference genes for quantitative gene expression studies in cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae)

An efficient technique for investigating gene expression is the real time quantitative reverse transcription PCR (qRT-PCR). Despite the fact that this technique has been extensively used to explore the gene function in Helicoverpa armigera, stability of the reference genes still requires validation. This research aims to validate the stability of expression of nine potential reference genes under different experimental conditions including temperature, mechanical injury, starvation, photoperiod, and developmental stage. An exhaustive system (RefFinder), available online, was employed to evaluate and grade the studied genes. Appropriateness of the reference genes as endogenous controls was determined through four computational algorithms (Delta Ct, NormFinder, BestKeeper, and geNorm). According to the findings of this study, RPL28 and RPS15 were found to be the most stable reference genes in case of starved larvae, temperature stressed larvae; and different developmental stages. On the other hand, HSP90 and TUBB proved to be highly stable in case of photoperiod stressed larvae. Finally, TUBB and GAPDH were the most stable reference genes in case of larvae subjected to mechanical injury. These results can facilitate development of a standardized qRT-PCR technique and can also prove to be helpful for standard RT-PCR method which need reference gene for normalization. (C) 2015 Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society. Published by Elsevier B.V. All rights reserved.