Background: Quantitative real-time PCR (qRT-PCR) is one of the preferred methods for analyzing gene expression, and selecting suitable internal reference genes is an important prerequisite for the application of this technology. However, no systematic studies have been conducted on reference genes in luffa, resulting in limited investigations of luffa gene expression.
Results: In this study, seven reference genes ( ACT , TUA , TUB , EF-1α , GAPDH , UBQ , and 18S ) were selected, and their expression levels in luffa plants exposed to various simulated abiotic stresses [i.e., cold, drought, heat, salt, H 2 O 2 , and abscisic acid (ABA) treatments] were analyzed by qRT-PCR. The stability of the reference gene expression levels was validated using the geNorm, NormFinder, BestKeeper, and RefFinder algorithms. The results indicated that EF-1α was the most stably expressed and suitable reference gene overall and for the heat, cold, and ABA treatments. Additionally, UBQ expression was stable following the salt treatment, whereas TUB was identified as a suitable reference gene for H 2 O 2 and drought treatments. In contrast, GAPDH was revealed as an unsuitable reference gene overall and for the heat, salt, H 2 O 2 , ABA, and drought treatments. Regarding the cold treatment, TUA was identified as an unsuitable reference gene. The reliability of the selected reference genes was verified by analyzing the expression of copper/zinc superoxide dismutase ( Cu/Zn-SOD ) gene in luffa. When the most unstable reference genes were used for data normalizations, the resulting expression patterns had obvious biases when compared with the expression patterns for the most ideal reference genes used alone or combined.
Conclusions: The study data were used to compile a list of suitable reference genes for qRT-PCR analyses of the gene expression in luffa plants exposed to abiotic stresses. This work may provide the basis for future qRT-PCR-based investigations of the transcription of important functional genes in luffa.