ISHS Acta Horticulturae 620: XXVI International Horticultural Congress: Asian Plants with Unique Horticultural Potential: Genetic Resources, Cultural Practices, and Utilization
CHANGES IN ANTIOXIDANT ENZYMES AND POLYAMINES IN RESPONSE TO LOW TEMPERATURE CHILLING IN WATERMELON PLANTS |
| Authors: | S.W. Kwon, B.R. Ko, D.G. Bai |
| Keywords: | watermelon, chilling, antioxidant enzymes, polyamines, protein, isozymes |
| Abstract:
The changes in antioxidant enzymes and polyamines were investigated in the leaves of watermelon plants in response to a short exposure to chilling temperatures. Chilling temperatures not only reduced biomass but also caused an overall increase in antioxidant enzyme activities and polyamines in the leaves of watermelon. The antioxidant enzyme activities after chilling treatment were higher than those plants grown at 30 °C. The catalase (CAT) and peroxidase (POD) activities in leaves were significantly increased, reaching a maximum at 2 days after chilling treatment, while they decreased slightly after 3 days. The means of antioxidant enzyme activities were higher in the leaves than in shoot apexes. In the native-gel assay of antioxidant enzymes, the low temperature treatment resulted in quantitative changes in CAT and superoxide dismutase (SOD) isozyme profiles, but we could not find any qualitative changes in the isozymes which were induced by chilling. In contrast, low temperatures induced the synthesis of 4 new POD band isozymes in watermelon leaves. Similarly increased polyamine contents of watermelon leaves were found to be associated with antioxidant enzyme activities under the chilling conditions. Exposure to low temperatures caused an increase in spermidine (SPD) and spermine (SPM), but not in putrescine (PUT) levels. One of the possible mechanisms of chilling resistance was an observed increase in polyamines with the marked increases in antioxidant enzyme activities. The results also indicate that SPD and SPM levels in watermelon leaves could have a protective role against chilling-induced active oxygen species. | |
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