• Applied Biological Chemistry
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• v.38 no.3
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• pp.202-206
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• 1995

In order to obtain the basic data for clarifing the mechanism of cold tolerance in crops, we analyzed various biochemical changes according to the Uniconazole treatment in Brassica seedling. Peroxidase activity in the root fraction of Brassica seedling was about 3 to 4 times higher than that in hypocotyl fraction, while catalase activity in those fractions showed opposite trend to the peroxidase activity. The content of hydrogen peroxide in root fraction was higher than that of hypocotyl fraction as being a reciprocal proportion with catalase activity. Especially in all fractions, peroxidase· activity of 'Sandongchae' (B. campestris) seedling, known as cold tolerant, was two-fold higher than that of cold sensitive rape(B. napus). The elongation rate of hypocotyl after germination was faster in B. napus than in B. campestris. The application of Uniconazole at 0.3 to 1.0 ppm to B. napus suppressed 43 to 46% of hypocotyl elongation and increased 65 to 73% of peroxidase activity in hypocotyl fraction. The shortening rate of hypocotyl length due to Uniconazole treatment was positively correlated with the increasing rate of peroxidase activity in hypocotyl fraction. Superoxide dismutase was not induced upon Uniconazole treatment and has only 3 isozymes in any fractions. Its activity was observed in the order of cotyledon>root>hypocotyl fraction.

• Applied Biological Chemistry
• /
• v.38 no.3
• /
• pp.207-211
• /
• 1995

In order to determine the mechanism of cold tolerance in crops, changes in biochemical factors related with the biological reduction of molecular oxygen upon cold shock treatment were analyzed at an early stage of Brassica germination. As the cold shocked seedlings were recovered under the normal growth condition for 24 hours, the peroxidase activities in cold sensitive rape(B. napus) and cold tolerant 'Sandongchae'(B. campestris) were considerably increased by 33% and 87% in root fraction and, 84% and 206% in hypocotyl, respectively. The content of superoxide($H_2O_2$) in hypocotyl fraction was dramatically accumulated until 8 hours after recovery and then gradually decreased. The extent of superoxide accumulation was severer in B. napus than B. campestris. At 24 hours after cold shock, $H_2O_2$ content was decreased to the nearly control level in B. campestris but still remained by 38%, in E. napus. Even though $H_2O_2$ content in hypocotyl fraction was decreased only 2% in B. napus during cold shock, while in B. campestris it was severely decreased about 15%. On the other hand, the cold shock at 3 days after Uniconazole treatment was more effective in increase of peroxidase activity than each separate treatment.