Fig. 4
Expression stability of candidate reference genes of ‘Ruegen’ and ‘Monterey’ in combination analyzed by RT-qPCR. To evaluate the expression stability of the RGs, gene-stability measure (M), stability, coefficient of variation (CV), and standard deviation (SD) values were calculated using geNorm (a), BestKeeper (c), NormFinder (d) and Delta CT (e). A lower value indicates greater stability of expression. The RankAggreg package for R was employed to merge the stability measurements obtained from the four tools using a Monte Carlo algorithm and to establish a consensus ranking of the RGs (f). The pairwise variation (Vn/Vn + 1) was calculated to determine the optimal number of RGs for normalization of gene expression (b)