Molecular cloning and characterization of <i>Cu/Zn-SOD</i> and <i>DREB3</i> gene fragments reveal drought tolerance in tomato

Understanding the abiotic stress tolerance of tomatoes is crucial for ensuring sustainable yields. In this study, two distinct genotypes, ‘EC-317-6-1’ (drought-tolerant) and ‘Kashi Amrit’ (susceptible), identified based on physicochemical criteria in a prior study, were selected to characterize the genetic polymorphism in response to drought stress. Specifically, the study focused on two abiotic stress-responsive genes, Cu/Zn-SOD and DREB3, by conducting partial cloning and expression analysis. The cDNA fragments of Cu/Zn-SOD and DREB3 genes were found to encode proteins of 152 and 264 amino acids, respectively, with sequences belonging to plant SOD and AP2/ERF, respectively. Bioinformatics analysis revealed significant sequence similarity among the cloned genes of tomato genotypes and related crop plants, suggesting conservation in the evolutionary process. The amino acid sequences exhibited significant homology with known proteins, suggesting similar biological activities in crop plants. Expression analysis demonstrated polymorphism in Cu/Zn-SOD and DREB3 gene expression between the drought-tolerant and susceptible genotypes. Notably, these genes exhibited significant upregulation in the drought-tolerant genotype (EC-317-6-1) compared to the susceptible one (Kashi Amrit). This up-regulation substantiates the potential of the EC-317-6-1 genotype for drought stress tolerance, emphasizing its suitability for integration into varietal development programs aimed at enhancing drought tolerance in tomatoes.