Figure 2. Determination of the optimal number of reference genes required for effective normalization.

Pairwise variation (V_{n/n +1}) analysis between the normalization factors (NF_n and NF_{n +1}) was performed by the geNorm program to determine the optimal number of reference genes, and carried out for qPCR data normalization in various sample pools. GA: gibberellin; SA: salicylic acid; MeJA: methyl jasmonate; ABA: abscisic acid; Abiotic stress: heat, cold, salt, and drought; Hormone stimuli: SA, GA, ABA, and MeJA; Total: all sample.