Fig 4. The use of different reference genes to normalize the expression level of the target gene HSP90 under three temperature treatments was investigated.

The expression level was normalized by different candidate reference genes: RPS15; RPS15 and RPL28; RPS13; and GAPDH. The reference genes were selected based on expression stability across three temperature treatments. Data represent the means±SEM of three biological replicates. The comparisons were analyzed using one-way ANOVA, and different letters (a,b) denote significant differences between normalization strategies determined by Tukey test (P < 0.05).