Molecular Cloning and Characterization of γ-Glutamyl Cysteine Synthetase (VrγECS) from Roots of Vigna radiata (L.) Wilczek Under Progressive Drought Stress and Recovery

Abstract

Glutathione is an essential redox buffer and an antioxidant in majority of higher plants, imparting tolerance against abiotic stress. The rate-limiting enzyme, gamma-glutamyl cysteine synthetase (γECS), plays an important role in regulation of glutathione biosynthesis under adverse environmental conditions including drought. To understand the role of γECS in an economically important food legume, Vigna radiata (L.) Wilczek, under progressive drought stress, we cloned and derived the full-length cDNA sequence and denoted it as VrγECS. Real-time PCR analysis of VrγECS in the roots of V. radiata, during progressive drought stress and recovery, indicated a stable expression pattern of the gene. However, the VrγECS enzyme activity altered differentially during varying water-deficit conditions and recovery period, reflecting the existence of some post-transcriptional or post-translational regulatory system for the enzyme. Linear regression analysis between H 2O 2 and lipid peroxidation as well as H 2O 2 and VrγECS enzyme activity during drought stress and recovery demonstrates the delicate inter-relationships and putative regulatory mechanisms operating in the root system under adverse conditions. The present study could contribute towards understanding the complex regulation of γECS in glutathione biosynthesis in an important food legume under drought stress. © 2012 Springer-Verlag.