@IJAPSA-2016, All rights Reserved Page 24 EFFECT OF IRON STRESS ON OXIDATIVE METABOLISM IN WHEAT PLANTS (TRITICUM AESTIVUM (L).) IRON STRESS IN WHEAT Laxmi Verma 1 and Nalini Pandey 2 1,2 Plant Nutrition and Stress Physiology Laboratory, Botany Department, University of Lucknow, Lucknow 226007 Abstract Wheat plants (Triticum aestivum L. var. DBW 17) exposed to different concentration of iron(10, 100, 200, 400 μM Fe) in the form of FeEDTA under controlled glass house conditions were quantified for different physiological parameters and antioxidative enzymes as well as antioxidant compounds. At 40 and 60 days of exposure the plants were harvested and growth, active Fe content, lipid peroxidation enzymes and metabolites of the antioxidative metabolism were determined. Plants showed maximum growth at 100 μM Fe supply and this level was treated as control. At 10 μM Fe plants shoewd maximum reduction in growth and choruses in young leaves. Excess of Fe also caused significant inhibition of growth and induced bronzing of older leaves. High concentration of TBARS (indicated lipid peroxidation) and H 2 O 2 content in leaves were detected in Fe deficient and Fe toxic plants (10, 200 and 400 μM Fe) as compared to control. The activities of Fe containing enzymes such as speroxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX) increased with increasing Fe concentration at 40 DAT. A significant enhancement in the activity of GR was also observed with increasing Fe concentration at 40 DAT but the activity of GR as also that of POD and APX reduced at 60 DAT. The ascorbate (ASA) and non- protein thiol (NPT) content in general increased with increasing Fe concentration. The results indicate that under Fe stress condition plants suffer increased oxidative damage, which is regulated by change in the activities of antioxidative enzymes and the contents of the antioxidants ASA and NPT. Key words: Antioxidant enzymes, wheat, Fe stress, oxidative damage, reactive oxygen species (ROS). I. INTRODUCTION Iron is one of the essential micronutrient for plants (Barber, 1984). In the soil iron is the fourth abundant element on earth, but its unavailability for the plants and microorganism is, due to low solubility of minerals which contain iron. Iron is absorbed by the plants in soil when it is converted from insoluble ferric (Fe 3+ ) form to a ferrous (Fe 2+ ) form. Due to its ability to accept and donate electrons, it behaves as a cofactor for many enzymes involved in plant metabolism especially nitrogen and sulfur metabolism, such as nitrate reductase, nitrite reductase, sulfite reductase, and nitrogenase, which use iron-containing prosthetic groups (Briat et al., 2007; Ha¨nsch and Mendel 2009). Iron plays a very crucial role in photosynthesis and respiration, being involved in electron transport chain (Miller et al., 1995). It is also an active cofactor of many enzymes that are necessary for plant hormone synthesis. Approximately 80% of iron is found in photosynthetic cells where it is essential for the biosynthesis of cytochrome, heme molecules, chlorophyll, and construction of Fe-S clusters (Briat et al., 2007).