2.10. Expression Analysis of Antioxidant and Stress-Related Genes

Quantitative real-time PCR analysis was used to determine the expression of antioxidant enzymes genes (CAT, SOD, POD, GST) and stress-tolerant genes (GhERF2, GhNAC3, GhRD22, GhDREB1A, GhDREB1B, GhDREB1C) in wild type and T₃ StDREB2-overexpressing cotton lines grown under normal and drought conditions. Isolation of RNA and synthesis of cDNA from plant tissues were carried out as mentioned above. qRT-PCR reactions were performed in triplicates (three biological and three technical replicates) using a QuantiTect SYBR Green PCR kit according to the manufacturer protocols. qRT-PCR condition was adjusted as described by Hao et al. [41]. The primers previously designed for the genes assayed [41] were used in amplification. Small-subunit rRNA was used as an internal control [41]. Relative gene expression level was estimated using 2^−ΔΔCt method.