Calculation of PCR efficiencies. Real-time PCR efficiencies of reference (ACT, EF1 and UBQ) and target genes (APX and SOD) were determined. Cq was plotted against the log amount of cDNA input. Amplification efficiencies were calculated according to the equation E = 10(-1/slope). ACT, actin; APX, ascorbate peroxidase; EF1, elongation factor 1; SOD, superoxide dismutase; UBQ, ubiquitin; n = 3.