Differential changes in antioxidants, proteases, and lipid peroxidation in flag leaves of wheat genotypes under different levels of water deficit conditions

Changes in enzymatic antioxidants and oxidative injury were evaluated in flag leaves of seven wheat genotypes under well watered (WW), medium watered (MW), low watered (LW) and soil stored moisture (SSM) conditions maintained in lysimeters through neutron moisture prob. Genotypes behaved differentially in terms of antioxidant response and stress induced injury under above indicated water deficit levels. In general, antioxidant enzymes were rarely enhanced under MW condition, often increased under LW condition while remained unchanged, elevated or diminished under SSM condition (severe stress). Higher CAT and POD activities were observed in NR-234 and in Pfau followed by FD-83 respectively under LW conditions. Under SSM condition, APX and POD increased significantly in Nesser and Pfau and CAT in NR-234, Nesser and Pfau, while remained at control level or decreased in other genotypes. In NR-234, SOD activity enhanced only under LW condition. However, SOD rose in Nesser, FD-83 and Sarsabz while remained unaffected in NR-241, Sitta and Pfau under all water deficit conditions. Lipid peroxidation increased significantly in FD-83 only under MW condition along with raised protease activity and protein contents. However, peroxidation of lipids was significantly enhanced in all genotypes under LW and SSM conditions. It was concluded that response of genotypes vary under different levels of water deficit. Hydrogen peroxide scavenging system was more actively involved in detoxification of oxidative stress induced by water deficit. Raised antioxidants (CAT, POD) resulting in comparatively lower lipid peroxidation in Pfau under SSM condition and in Sitta under LW condition confer stress tolerance in these genotypes. (C) 2010 Elsevier Masson SAS. All rights reserved.