Exogenous application of ascorbic acid alleviates oxidative stress in maize

Abstract

One of the most important physiological manifestations of abiotic stress in plants is rapid burst of reactive oxygen species (ROS), which severely damages cell structure and function. In the present study, oxidative stress was induced in field grown maize by application of methyl viologen at the flowering stage. 48 h prior to the induced stress, a set of plants were treated with graded concentrations (0.5, 1.0 and 1.5 mM) of ascorbic acid (AsA). Data for hyper-spectral reflectance and chlorophyll content was recorded post treatment and post stress, while root biomass and grain yield was recorded at harvest. Membrane leakage, total soluble proteins, and specific activities of three key ROS scavenging enzymes viz., superoxide dismutase (SOD), catalase (CAT), and peroxidases (POX) were also determined. AsA treatment led to increase in chlorophyll content, root biomass and grain yield and reduced electrolyte leakage under stress. Biochemical analysis revealed widespread rebalancing of ROS scavenging enzymes after stress and AsA treatment. In control plants, SOD activity decreased upon induction of stress, while in AsA treated plants SOD activity increased significantly. Similarly, AsA application caused remarkable increase in CAT activity, while it did not significantly affect POX activity under stress. The study concludes that AsA is capable of alleviating oxidative stress in maize through increasing activity of antioxidant enzymes like SOD and CAT.