Genome-wide identification and validation of new reference genes for transcript normalization in developmental and post-harvested fruits of Actinidia chinensis

The appropriate reference genes are important and essential for reliable results of transcript normalization in real-time qRT-PCR. In the current study, we identified 1203 stably expressed genes from 35,286 genes' expression profiles in developmental fruits of Actinidia chinensis. We manually selected six candidate genes and assessed their expression levels, using two sets of fruit samples of A. chinensis: flesh fruits at four developmental stages and post-harvested fruits. The expression stability of these six genes was assessed by three independent algorithms: geNorm, NormFinder, and BestKeeper. Statistical results indicated these six genes can serve as internal control in both developmental and post-harvested fruits. Among these genes, UBQ_CONJ_E2 (Ubiquitin-conjugating enzyme E2 36) and TUB_FCB (Tubulin folding cofactor B) were the two best reference genes identified in this study. The identification and validation of these reference genes can be helpful for elucidating the studies of fruit development and post-harvested fruits' storage in A. chinensis and other fruit crops of Actinidiaceae.