Submitted to: American Society of Plant Physiologists Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 6/27/1998
Publication Date: N/A
Technical Abstract: Water and temperature stresses result in the overproduction of reactive oxygen species which can damage plants. Plants contain a variety of compounds and associated enzymes that detoxify these oxidants. The amount and activity of antioxidant compounds in the plant are affected by the presence of oxidants in the environment. Cotton is often grown under water limited conditions and in adverse thermal environments which may result in oxidative damage. Information on the pattern and extent of limitations on antioxidant metabolism that occur in cotton in the field is limited. While alteration of antioxidant levels through molecular manipulation is possible, the lack of information on antioxidant limitations has limited efforts to improve cotton performance by the alteration of antioxidant metabolism. In an effort to identify the pattern and extent of limitations in antioxidant metabolism several aspects of the system have been monitored din cotton over a growing season in the field under three levels of water stress. Leaf water potentials in the three water treatments at maximum water deficits were: 1.5 M Pascals, 2.2 M Pascals and 26 M Pascals for the high, middle and low irrigation treatments respectively. The concentration of malondialdehyde, an oxidative stress product, did not vary among water treatments. Foliar concentrations of the antioxidants glutathione and ascorbate did not vary with water treatment. The activities of glutathione reductase and ascorbate peroxidase did not vary with water treatment. These results indicate that under field conditions antioxidant metabolism is not increased under water stress. It remains to be seen whether the activity is sufficient to manage oxidative stress or if increased antioxidant metabolism would improve plant performance under stress.