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KMID : 0613820080180121705
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Journal of Life Science
2008 Volume.18 No. 12 p.1705 ~ p.1711
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Response of Ascorbate Peroxidase and Dehydroascorbate Reductase in Lettuce (Lactuca sativa L.) Leaves Exposed to Cold Stress
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Kang Sang-Jae
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Abstract
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To investigate the relationship between cold stress and the activity of ascorbate peroxidase(APX), dehydroascorbate reductase (DHAR), mRNA expression level of two enzymes, hydrogen peroxide content was studied in lettuce leaves under stress condition imposed by cold stress at 4℃ for 24 hr in the dark and following recovery at 20℃ from cold stress. Hydrogen peroxide content increased gradually in lettuce leaves during cold stress, but decreased slightly following recovery from cold stress. Soluble protein content, however, decreased gradually during cold stress, and then rapidly returned to normal levels following recovery. Total chlorophyll content decreased gradually during cold stress, and then keep constant following recovery. The patterns of chlorophyll a and b content similar to that of total chlorophyll content, and carotenoid content didn’t change. The ratio of chlorophyll a and total chlorophyll was increased during cold stress, but decreased with rapid during cold stress, and then the ratio returned to normal levels following recovery. During cold stress, the activity of APX and DHAR in the lettuce leaves increased dramatically, and also transcript levels of mRNA of APX and DHAR, as determined by probing 32P-labeled single stranded RNA of APX and DHAR, highly increased and returned to normal levels following recovery, respectively. Relationship between APX and DHAR activity and hydrogen peroxide highly related (R²=0.8715 and 0.8643), whereas between hydrogen peroxide and total chlorophyll content and soluble content related reversely (R²=0.5021 and 0.8915).
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KEYWORD
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Ascorbate peroxidase, cold stress, dehydroascorbate reductase, hydrogen peroxide, lettuce
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