Exogenous Proline and Betaine-induced Upregulation of Glutathione Transferase and Glyoxalase I in Lentil (<i>Lens culinaris</i>) under Drought Stress</span>

Abstract

This study was conducted to investigate the proline (Pro) and betaine (Bet) driven modulation of glutathione S-transferase (GST) and glyoxalase I (Gly I) in drought stressed lentil seedlings. Among the seven lentil varieties tested, BARI mosur 2 was found have higher activities of GST and Gly 1 which was selected for further time-course investigation. Drought stress resulted in a significant increase in glutathione (GSH), glutathione disulfide (GSSG) and hydrogen peroxide (H2O2) contents and GST and Gly I activities at different period  of the stress, while the GST activity decreased significantly at one and three days drought. However, exogenous application of 15 mM Bet or Pro with drought stress resulted in an increase in GSH content, maintenance of high activities of GST and Gly I as compared to the control and mostly also drought stressed plants, with a concomitant decrease in GSSG content and H2O2 level suggesting important role in protecting cell from the toxic effects of reactive oxygen species (ROS) and methyl glyoxal (MG) detoxification system. The application of Pro and Bet with the stress period revealed that they have important role in upregulating the homeostasis in lentil under stress condition. However, Pro exhibited better protection than Bet under drought stress. These findings suggest that both Pro and Bet provided a protective role in drought induced oxidative stress by reducing H2O2 levels and by increasing the antioxidant defense systems.