【目的】筛选出Bt毒素诱导后的小菜蛾Plutella xylostella (L.)的实时定量PCR最适内参基因。【方法】选取核糖体18S rRNA (18S rRNA)、 肌动蛋白(ACTB)、 延伸因子(EF1)、3-磷酸甘油醛脱氢酶(GAPDH)、 核糖体蛋白L32 (RPL32)、 核糖体蛋白S13 (RPS13)、 核糖体蛋白S20 (RPS20)和β-微管蛋白(TUB)基因作为候选内参基因, 以geNorm、 Normfinder和BestKeeper软件分析这8个基因在Bt毒素诱导后的小菜蛾不同品系中肠组织中的表达稳定性。并应用筛选出来的内参基因分析小菜蛾氨肽酶2(aminopeptidase N2, APN2)基因的表达水平。【结果】geNorm软件以RPS13和EF1为最稳定内参基因, NormFinder和BestKeeper软件均以RPS13和RPL32为最稳定基因。使用3种不同内参基因分析Bt毒素诱导后的小菜蛾Bt抗性和敏感品系中ANP2表达水平时, 新的内参基因EF1和传统内参基因RPL32表现了良好的稳定性, 二者作为标准化因子, ANP2表达量结果基本一致, 而使用18S rRNA作为内参基因, 却导致部分表达量分析结果有所误差。【结论】筛选出PRS13,RPL32和EF1可以作为小菜蛾某些试验条件下的内参基因, 对小菜蛾基因表达研究奠定了一定基础, 也对其他昆虫内参基因的筛选具有参考价值。
【Aim】 To select the suitable reference genes in Plutella xylostella after exposure to Bt toxin by quantitative real-time PCR. 【Methods】 Eight candidate reference genes, including 18S ribosomal RNA (18S rRNA), beta actin gene (ACTB), elongation factor 1 gene (EF1), glyceraldehyde-3-phosphate dehydrogenase gene (GAPDH), ribosomal protein L32 gene (RPL32), ribosomal protein S13 gene (RPS13), ribosomal protein S20 gene (RPS20) , and β-tubulin gene (TUB), were chosen. The stability of these candidate reference genes was investigated using three softwares (geNorm, NormFinder and BestKeeper). Then, the expression of aminopeptidase N2 gene (APN2) was analyzed by using different reference genes. 【Results】 Based on the results of geNorm analysis RPS13 and EF1 were the most suitable reference genes in P. xylostella after exposure to the Bt toxin Cry1Ac, while based on the results of the NormFinder and BestKeeper analysis RPS13 and RPL32 were the most suitable reference genes. Using new reference gene (EF1) or traditional reference gene (RPL32) for normalization, similar expression levels of APN2 were observed, whereas normalization with the unstable reference gene (18S rRNA) might lead to erroneous interpretations. 【Conclusion】 This work is contributable to the solid foundation for future gene expression studies in the diamondback moth, and may also serve as a resource to screen reference genes for expression studies in other insects.