For determination of relative transcript abundance, the threshold cycle (Ct) for each gene in each cDNA sample was normalized to the reference gene ribosomal protein S9 (RPS9) using the formula Ct(gene of interest) − Ct(RPS9) = delta Ct (Merriman et al., 2017). The delta Ct values for each gene were used for statistical analysis described below. The mean delta Ct (±SE) for each treatment was transformed using the formula 1,000 × 2−delta Ct to report the relative number of transcripts per 1,000 RPS9 transcripts.