Selection and Verification of Appropriate Reference Genes for Expression Normalization in Cryptomeria fortunei under Abiotic Stress and Hormone Treatments.

Abstract

Cryptomeria fortunei has become one of the main timber afforestation species in subtropical high-altitude areas of China due to its fast growth, good material quality, and strong adaptability, showing broad application prospects. Quantitative real-time PCR (qRT-PCR) is the most accurate and widely used gene expression evaluation technique, and selecting appropriate reference genes (RGs) is essential for normalizing qRT-PCR results. However, suitable RGs for gene expression normalization in C. fortunei have not been reported. Here, we tested the expression stability for 12 RGs in C. fortunei under various experimental conditions (simulated abiotic stresses (cold, heat, drought, and salinity) and hormone treatments (methyl jasmonate, abscisic acid, salicylic acid, and gibberellin) and in different tissues (stems, tender needles, needles, cones, and seeds) using four algorithms (delta Ct, geNorm, NormFinder, and BestKeeper). Then, geometric mean rankings from these algorithms and the RefFinder program were used to comprehensively evaluate RG stability. The results indicated CYP, actin, UBC, and 18S as good choices for studying C. fortunei gene expression. qRT-PCR analysis of the expression patterns of three target genes (CAT and MAPK1/6) further verified that the selected RGs were suitable for gene expression normalization. This study provides an important basis for C. fortunei gene expression standardization and quantification.