Biochemical Changes in Brassica Seedlings Due to Uniconazole Treatment

Brassica속 작물 유묘에서 생장억제제 Uniconazole 처리에 따른 생화학적 변화

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.

작물 내한성 기작구명을 위한 기초자료를 얻고자 우선 Brassica속 작물의 발아초기단계에서 생장억제제인 Uniconazole 처리에 따른 생화학적 변화를 분석해 본 결과, 발아초기의 peroxidase 활성도는 뿌리부위가 배축부위에 비해 $3{\sim}4$배 정도 더 높았으며 특히 내한성이 강한 산동채가 내한성이 약한 유채보다 모든 부위에서 2배 정도 더 높은 효소 활성도를 보였다. 그러나, catalase 활성도는 뿌리보다 배축부위가 $3{\sim}4$배 정도 더 높아 peroxidase와는 상반된 결과를 보였으며 $H_2O_2$ 함량은 catalase 활성도에 거의 반비례하여 매축보다 뿌리부위가 더 높았고, 배축장은 내한성이 약한 유채가 산동채 보다 훨씬 더 길었다. 한편, 유채 3일유묘에 $0.3{\sim}1.0ppm$의 Uniconazole처리는 처리 3일후의 배축장을 약 $43{\sim}46%$ 억제시켜 배축부위의 peroxidase 활성도를 $65{\sim}73%$ 증가시켰고, Uniconazole 처리농도에 따른 배축장 단축율과 배축부위의 peroxidase 활성도 증가율과는 정의 유의상관을 보였다. 그러나, superoxide dismutase의 활성화는 관찰할 수 없었고, 단지 활성도가 자엽>뿌리>배축의 순서를 보이며 3개의 동위효소가 존재함을 확인하였다.