Evidence for a role of exogenous glycinebetaine and proline in antioxidant defense and methylglyoxal detoxification systems in mung bean seedlings under salt stress

Abstract

In mung bean seedlings, salt stress (300 mM NaCl) caused a significant increase in reduced glutathione (GSH) content within 24 h of treatment as compared to control whereas a slight increase was observed after 48 h of treatment. Highest oxidized glutathione (GSSG) content was observed after 48 h to treatment with a concomitant decrease in glutathione redox state. Glutathione peroxidase, glutathione S-transferase, and glyoxalase II enzyme activities were significantly elevated up to 48 h, whereas glutathione reductase and glyoxalase I activities were increased only up to 24 h and then gradually decreased. Application of 15 mM proline or 15 mM glycinebetaine resulted in an increase in GSH content, maintenance of a high glutathione redox state and higher activities of glutathione peroxidase, glutathione S-transferase, glutathione reductase, glyoxalase I and glyoxalase II enzymes involved in the ROS and methylglyoxal (MG) detoxification system for up to 48 h, compared to those of the control and mostly also salt stressed plants, with a simultaneous decrease in GSSG content, H 2 O 2 and lipid peroxidation level. The present study suggests that both proline and glycinebetaine provide a protective action against saltinduced oxidative damage by reducing H 2 O 2 and lipid peroxidation level and by enhancing antioxidant defense and MG detoxification systems.

Up-regulation of antioxidant and glyoxalase systems by exogenous glycinebetaine and proline in mung bean confer tolerance to cadmium stress

“…To our knowledge, currently there is no information available on the possible beneficial effects of exogenous application of betaine and proline on MG detoxification system in plants grown under Cd stress. Although our previous study showed that both betaine and proline improve salinity tolerance in mung bean seedlings by enhancing antioxidant and MG detoxification systems (Hossain and Fujita 2010). In this study, we investigated the possible beneficial effects of exogenous proline and betaine on lipid peroxidation, intracellular ROS accumulation, and components of antioxidant defense and MG detoxification systems in mung bean seedlings subjected to Cd stress.…”

“…The natural accumulation of proline/ betaine, however, is not high enough to protect plants from stress-induced damage (Subbarao et al 2001;Okuma et al 2002;Tamura et al 2003;Tamas et al 2008). Under such condition their exogenous application may help to reduce the adverse effects of various environmental stresses including Cd stress (Yang and Lu 2005;Kumar and Yadav 2009;Huang et al 2009;Islam et al 2010;Hossain and Fujita 2010). In addition to their roles as osmoprotectants, proline and betaine contribute to the protection of membranes, proteins and enzymes from the damaging effect of various stresses (Ashraf and Foolad 2007;Hossain and Fujita 2010).…”

“…Under such condition their exogenous application may help to reduce the adverse effects of various environmental stresses including Cd stress (Yang and Lu 2005;Kumar and Yadav 2009;Huang et al 2009;Islam et al 2010;Hossain and Fujita 2010). In addition to their roles as osmoprotectants, proline and betaine contribute to the protection of membranes, proteins and enzymes from the damaging effect of various stresses (Ashraf and Foolad 2007;Hossain and Fujita 2010). Furthermore, betaine and proline provide protection against oxidative stress by maintaining redox homeostasis Hossain and Fujita 2010).…”

“…In addition to their roles as osmoprotectants, proline and betaine contribute to the protection of membranes, proteins and enzymes from the damaging effect of various stresses (Ashraf and Foolad 2007;Hossain and Fujita 2010). Furthermore, betaine and proline provide protection against oxidative stress by maintaining redox homeostasis Hossain and Fujita 2010). Recently, it has been reported that betaine and proline alleviates Cd toxicity by detoxifying ROS and increasing antioxidant activity and GSH content in Solanum and tobacco BY-2 cells (Xu et al 2009;Islam et al 2010).…”

“…In this study, we investigated the possible beneficial effects of exogenous proline and betaine on lipid peroxidation, intracellular ROS accumulation, and components of antioxidant defense and MG detoxification systems in mung bean seedlings subjected to Cd stress. In addition, we compared these results from Cd-stressed seedlings with our previous results from salinity stress (Hossain and Fujita 2010).…”