Genome-wide analysis of the bean GST gene family and over-expression of the bean dehydroascorbate reductase 1 (PvDHAR1) gene under drought stress in tobacco (Nicotiana benthamiana)

Glutathione S-transferases (GSTs) are isozymes found in advanced organisms that play an important and pivotal function in eliminating oxygen-containing reactive species. GSTs are involved in both stressors that are abiotic and biotic, providing protection to plants against different types of stress. This study aimed to conduct a genome-wide examination of the GST gene family in Phaseolus vulgaris using bioinformatics tools and to investigate their expression profiles in leaf tissue under conditions of salt and drought stress individually. In addition, it was aimed to investigate the function of DHAR1 gene, a member of the DHAR subfamily of GSTs, in drought stress response by overexpressing this gene in tobacco plants using a transgenic approach. In Phaseolus vulgaris, 55 Pv-GST proteins were identified. These proteins ranged in molecular weight from 15.02 kDa to 47.99 kDa, amino acid counts from 132 to 420, and isoelectric points (theoretically) from 5.03 to 9.61. Phylogenetic analyses were performed with protein sequence information of P. vulgaris, Glycine max and Arabidopsis thaliana species. qRT-PCR was performed with five selected GST genes and expression levels for each of them changed in response to drought, salt and melatonin treatments. In addition, the results obtained by overexpressing the PvDHAR1 gene in tobacco plants under drought stress confirmed that this gene is involved in the response to drought stress. Overexpression lines were found to tolerate the increased H2O2 levels remarkably well. Decreased MDA and EC% values also support these findings. The data obtained from this study are expected to fill the gap in the existing literature on the role of bean DHAR1 gene in drought stress response.