Author (Gurmeen Rakhra, Arun Dev Sharma, Jatinder Singh)
Drought is one of most important abiotic stress that affects plant growth and productivity. Various antioxidants are known to maintain oxidative stress induced-ROS at sub-lethal levels in plants under abiotic stress conditions, but, studies documenting how drought regulates boiling soluble antioxidants at vegetative phase is still a matter of conjuncture. In this study, changes in total Chlorophyll content and its different fractions(Chl a and Chl b), total protein content (TPC), relative water content (RWC), H2O2,O2.-, malondialdehyde (MDA), Membrane injury index(MII), membrane stability index(MSI) and ROS scavenging boiling soluble antioxidants were studied in the shoots of two cultivars (PBW 175 and PBW 621) of wheat at different stages of development. Simultaneous analysis of ROS induced oxidative damage and activities of ROS-scavenging boiling soluble antioxidants gave an integrative view of physiological state and detoxifying potential under conditions of sensitivity and tolerance. Drought stress increased TPC in a developmental stage dependent manner and decreased RWC in both the cultivars of wheat. H2O2 and O2.- content increased considerably under drought stress in both the cultivars. As a result, MDA content, a product of lipid peroxidation along with MII also increased in both the cultivars. There was a differential response of boiling soluble antioxidants in both the cultivars under stress. The BsSOD activity declined considerably in the cv. PBW 621, whereas in the cv. PBW 175, BsSOD activity remained unchanged upon water imposition. The BsAPX activity declined considerably in both the cultivars under drought stress, with a sharper decrease in the cv. PBW 621. The BsGPX activity increased in response to elevated ROS levels in both the cultivars in a developmental stage dependent manner. The BsCAT activity showed negligible values upon water imposition in the cvs. PBW 175 and PBW 621. Based upon our results, it can be inferred that tolerant cv. PBW 175 have more of a biological antioxidative capacity to combat drought- induced oxidative stress.