values distribution of candidate reference genes in different species. The values are given as real-time PCR quantification cycle (Cq) values. The boxes represent the lower and upper quartiles with medians; the whiskers illustrate the 10-90 percentiles of the samples. All Cq values significantly differed between species (one-way ANOVA). (W) = wheat samples (60 samples), (B) = barley samples (60 samples), (O) = oat samples (60 samples).