Fig. 3From: Selection of reference genes for diurnal and developmental time-course real-time PCR expression analyses in lettuceDetermination of the optimal number of reference targets required for normalization. a Pairwise variation (V) of candidate reference genes in diurnal timecourse samples. b V of candidate reference genes in developmental timecourse samples. The pairwise variation (Vn/Vn+1) was analyzed between the normalization factors NFn and NFn+1 by the geNorm software to determine the optimal number of reference genes required for qRT-PCR data normalization. The dashed line indicates the 0.15 thresholdBack to article page