Biochemical Response Trends of Macrotyloma uniflorum, Lam. Subjected to Dehydration Stress in Different Growth Conditions

Abstract

The mechanismof plant toleranceagainst dehydration is differs according to the growth status of the plant. To understand the similarities and differences in the drought responses of two different growth situations of horse gram, seedlings of normal plants along with regenerated tissue culture were subjected to dehydration stresshave been investigated. Enzymatic and non-enzymatic antioxidants of both seedlings behaved similar albeit minor variations. Activity of antioxidant enzymes of both seedlings compared to their controls showed a similar trend. Peroxidase (POX; EC 1.11.1.7), Superoxide dismutase (SOD; EC 1.15.1.1) and Glutathione reductase (GR; EC 1.6.4.2) were elevated. However, Catalase (CAT; EC 1.11.1.6) was reduced in both stressed seedlings. Also the antioxidants levels in both stressed plantlets exhibited 2 folds elevation of ascorbic acid and ~3 folds of GSH, but the elevation of proline was different where it was 6 folds in callus, while normal seedlings increased by 10 times compared to control. Stress markers hydrogen peroxide and thiobarbeturic acid reactive substances (TBARS) 2 folds increased, these coincides with higher levels of Peroxidase, reflecting a great damage of membrane in both stressed status. These suggest that horse gram seedlings behave in similar manner even if grown in different conditions and circumstances which confirm their similar biochemical resistance mechanism when exposed to water deficiency stress. Abbreviations: PMSF: phenyl methyl sulphonyl fluoride; SGH: reduced glutathione; ROS: Reactive Oxygen Species; ABA: Abscisic Acid