title: Identification and validation of reference genes for quantitative real-time PCR studies in Hedera helix L.
abstract: Reference gene evaluation and selection are necessary steps in gene expression analysis, especially in new plant varieties, through reverse transcription quantitative real-time PCR (RT-qPCR). Hedera helix L. is an important traditional medicinal plant recorded in European Pharmacopoeia. Research on gene expression in H. helix has not been widely explored, and no RT-qPCR studies have been reported. Thus, it is important and necessary to identify and validate suitable reference genes to for normalizing RT-qPCR results. In our study, 14 candidate protein-coding reference genes were selected. Their expression stability in five tissues (root, stem, leaf, petiole and shoot tip) and under seven abiotic stress conditions (cold, heat, drought, salinity, UV-C irradiation, abscisic acid and methyl jasmonate) were evaluated using geNorm and NormFinder. This study is the first to evaluate the stability of reference genes in H. helix. The results show that different reference genes should be chosen for normalization on the basis of various experimental conditions. F-box was more stable than the other selected genes under all analysis conditions except ABA treatment; 40S was the most stable reference gene under ABA treatment; in contrast, EXP and UBQ were the most unstable reference genes. The expressions of HhSE and Hhβ-AS, which are two genes related to the biosynthetic pathway of triterpenoid saponins, were also examined for reference genes in different tissues and under various cold stress conditions. The validation results confirmed the applicability and accuracy of reference genes. Additionally, this study provides a basis for the accurate and widespread use of RT-qPCR in selecting genes from the genome of H. helix.
authors.affiliation: Horticulture & Landscape College, Hunan Agricultural University, Changsha, Hunan 410128, China.
authors.forename: Hua-Peng
authors.initials: HP
authors.lastname: Sun
authors.affiliation: Horticulture & Landscape College, Hunan Agricultural University, Changsha, Hunan 410128, China; National Center for Citrus Improvement, Changsha, Hunan 410128, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Li
authors.affiliation: Horticulture & Landscape College, Hunan Agricultural University, Changsha, Hunan 410128, China.
authors.forename: Qin-Mei
authors.initials: QM
authors.lastname: Ruan
authors.affiliation: Horticulture & Landscape College, Hunan Agricultural University, Changsha, Hunan 410128, China. Electronic address: xh-zhong@163.com.
authors.forename: Xiao-Hong
authors.initials: XH
authors.lastname: Zhong
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D000085:Acetates / Q000494:pharmacology; D003517:Cyclopentanes / Q000494:pharmacology; D017931:DNA Primers; D055864:Droughts; D020869:Gene Expression Profiling / Q000379:methods / Q000592:standards; D017343:Genes, Plant; D035981:Hedera / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D054883:Oxylipins / Q000494:pharmacology; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods / Q000592:standards*; D012015:Reference Standards; D054712:Salinity; D013312:Stress, Physiological / Q000235:genetics; D014466:Ultraviolet Rays
chemical_list: D000085:Acetates; D003517:Cyclopentanes; D017931:DNA Primers; D054883:Oxylipins; D000040:Abscisic Acid; C072239:methyl jasmonate
keywords: Abiotic stress; Differential expression; Hedera helix L.; RT-qPCR; Reference gene