Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 21, 2001
Publication Date: July 21, 2001
Citation: MAHAN, J.R., LIGHT, G.G., HOPPER, N. THE ROLE OF METABOLIC AND ENZYMIC ACTIVITIES IN LOW TEMPERATURE GERMINATION AND EMERGENCE IN SEVERAL COLD TOLERANT COTTON VARIETIES. AMERICAN SOCIETY OF PLANT BIOLOGISTS ANNUAL MEETING. 2001. Supplement 91 #377 Technical Abstract: Several cotton varieties with enhanced germination and seedling growth at low temperatures have been previously identified. Cold tolerance in these lines was determined from a combination of metabolic and imbibitional data. In an effort to more fully define the basis of the enhanced low temperature performance of these varieties, a series of metabolic and enzymatic analyses were carried out. The varieties were compared to a low temperature-sensitive variety commonly grown on the Southern High Plains of Texas. Calorespirometric ratios, indicative of respiratory efficiency, were measured at 15, 20 and 25C. At 20C the highest respiratory efficiencies (lowest calorespirometric ratios) were found in the most cold tolerant varieties while the cold sensitive varieties had lower respiratory efficiencies. The thermal dependencies of malate synthase function, determined in three varieties, two cold tolerant and one cold sensitive, were found to be similar across a 10 to 45C temperature range. This suggests that differences in lipid metabolism in the seedlings are probably not important factors in their differential cold tolerance. In an effort to assess the role of differential antioxidant capabilities in the observed cold tolerance, a variety of antioxidant metabolism indicators was monitored in the cold tolerant and cold sensitive varieties. Antioxidant pools (ascorbate and glutathione), malondialdehyde content (an oxidative by product), and antioxidant enzyme activites (glutathione reductase, ascorbate peroxidase and superoxide dismutase) were determined in seedlings grown at 20 and 30C.