Transgenic potato overproducing l-ascorbic acid resisted an increase in methylglyoxal under salinity stress via maintaining higher reduced glutathione level and glyoxalase enzyme activity

Abstract

Salt-tolerance was studied in transgenic potato. It was conferred by overexpression of ascorbate pathway enzyme (D-galacturonic acid reductase, GalUR). As genetic engineering of the GalUR gene in potato enhances its ascorbic acid content (L-AsA), and subsequently plants suffered minimal oxidative stress-induced damage, we now report on the comprehensive aptness of this engineering approach for enhanced salt tolerance in transgenic potato (Solanum tuberosum L. cv. Taedong Valley). Potatoes overexpressing GalUR grew and tuberized in continuous presence of 200 mM of NaCl. The transgenic plants maintained a higher reduced to oxidized glutathione (GSH:GSSG) ratio together with enhanced activity of glutathione dependent antioxidative and glyoxalase enzymes under salinity stress. The transgenics resisted an increase in methylglyoxal that increased radically in untransformed control plants under salinity stress. This is the first report of genetic engineering of ascorbate pathway gene in maintaining higher level of GSH homeostasis along with higher glyoxalase activity inhibiting the accumulation in methylglyoxal (a potent cytotoxic compound) under salt stress. These results suggested the engineering of ascorbate pathway enzymes as a major step towards developing salinity tolerant crop plants.

Transgenic peanut overexpressing mtlD gene confers enhanced salinity stress tolerance via mannitol accumulation and differential antioxidative responses

“…The phenomenon of increased AsA was also reported in other crops including transgenic-GalUR potato (Upadhyaya et al 2011), and DHAR tomato (Li et al 2012) under salt stress conditions.…”

“…This includes lowmolecular-mass non-enzyme antioxidant metabolites, such as ascorbic acid and various antioxidant enzymes such as SOD, CAT, APX, GR and POD (Bhatnagar-Mathur et al 2009;Miller et al 2010;Chaturvedi et al 2014). Ascorbic acid (AsA) is both a secondary metabolite and an antioxidant which interacts enzymatically and non-enzymatically and detoxifies the ROS (Upadhyaya et al 2011). Therefore, AsA is used as a reference compound in a number of studies associated with stress tolerance in plants (Lopez-Munguia et al 2011).…”

Over-expression of l-gulono-γ-lactone oxidase (GLOase) gene leads to ascorbate accumulation with enhanced abiotic stress tolerance in tomato

“…3D). Upadhyaya et al (2011) reported higher activities of antioxidative enzymes in potato transgenic plants over-expressing the strawberry GalUR gene involved in ascorbic acid biosynthesis.…”

Effect of Salinity Stress on Capsicum annuum Callus Growth, Regeneration and Callus Content of Capsaicin, Phenylalanine, Proline and Ascorbic Acid

“…Transforming potato with GalUR gene which enhanced its ascorbic acid content, reduced the damage occurred by salt stress. Thus Upadhyaya et al [30] concluded that engineering of ascorbate pathway enzymes is a major step in the development of salt tolerant crop plants. Pretreatment of lentil seeds with ascorbic acid reduced the effects of salt stress and improved its grain yield [31].…”