Exogenous application of nitric oxide modulates osmolyte metabolism, antioxidants, enzymes of ascorbate-glutathione cycle and promotes growth under cadmium stress in tomato

Plant and Soil, 39(1), 205-207

Reactive oxygen species (ROS) are produced in plants as byproducts during many metabolic reactions, such as photosynthesis and respiration. Oxidative stress occurs when there is a serious imbalance between the production of ROS and antioxidant defense. Generation of ROS causes rapid cell damage by triggering a chain reaction. Cells have evolved an elaborate system of enzymatic and nonenzymatic antioxidants which help to scavenge these indigenously generated ROS. Various enzymes involved in ROS-scavenging have been manipulated, over expressed or downregulated to add to the present knowledge and understanding the role of the antioxidant systems. The present article reviews the manipulation of enzymatic and nonenzymatic antioxidants in plants to enhance the environmental stress tolerance and also throws light on ROS and redox signaling, calcium signaling, and ABA signaling. Show more

The zinc (Zn) and nickel (Ni) as oxidative stress factors and associated responses of 6-day-old seedlings of two pigeonpea (Cajanus cajan (L.) Millspaugh) cultivars namely LRG30 and ICPL87 were studied. Zinc and Ni exposure increased lipid peroxidation in relation to their concentration. Reduction in dry matter accumulation of roots and shoots was noticed in Zn and Ni treatments. The activities of antioxidative enzymes such as superoxide dismutase, peroxidase and glutathione reductase registered higher values and the activity of catalase and the antioxidative substances such as ascorbic acid and total glutathione contents registered lower values in all the Zn and Ni treatments when compared to their controls. The levels of catalase, peroxidase and glutathione reductase and ascorbic acid and total glutathione contents were high in cv. LRG30 than in cv. ICPL87 in response to Zn and Ni treatments. However, the activity of superoxide dismutase, the major scavenger of O(2)(&z.rad;-) radical registered higher values in cv. ICPL87. The cv. LRG30 is less sensitive to Zn and Ni treatments compared to the cv. ICPL87. Correlation coefficients between the different antioxidant parameters and metal dose level, or dry matter accumulation, were established, assessing for an induced-oxidative stress. Additional evidence was provided by comparing the sensitivity of the two cultivars. Show more