Abstract
This study was carried out to realize the effect of gibberllic acid$(GA_3)$, 1-naphthaleneacetic acid(NAA) and indole-3-acetic acid(IAA) on the biosynthesis of vitamin C. The relation between carbohydrate metabolism and vitamin C production in soybean sprouts was also investigated. Growth, vitamin C content, protein, galactonolactone dehydrogenase(GLD), ribulose diphosphate carboxylase(RuDpCO) and RNA level in the plastid and cytoplasm were determined. The effects of protein and respiratory inhibitors on the growth and vitamin C production were also examined. The most favourable growth of soybean sprouts was observed at the level of NAA $10^{-8}M,\;IAA10^{-6}M\;and\;GA_3\;10^{-5}M$ in the single treatment, respectively, and also favourable at levels of $GA_3\;10^{-5}M+NAA\;10^{-9}M\;and\;GA_3\;10^{-5}M+IAA\;10^{-9}M$ in the case of mixed treatment. The excellent growth was observed at the level IAA $10^{-6}M$ among all the single and mixed treatments. When the soybean sprouts were treated with NAA $10^{-8}M,\;IAA\;10^{-6}M\;GA_3\;10^{-5}M,\;GA_3\;10^{-8}M+IAA\;10^{-6}M,\;and\;GA_3\;10^{-5}M+IAA\;10^{-9}M$, the maximum growth rate was observed at the level of IAA $10^{-6}M$ and the conten of vitamin C was 24.26mg% which was 1.6 times higher than that of the control. RuDpCO was inhibited by the chloramphenicol at the concentration that did not inhibit the growth but the activities of NADP-GDH, GLD and vitamin C content were not affected. These results showed that the biosynthesis of viamin C had nothing to do with the activity of chloroplastic RNA but with cytoplasm. The highest vitamin C content was found at the the level of IAA $10^{-6}M$, where the GLD activity increased up 1.8 times of the control. The concentration of IAA $10^{-6}M$ promoted the biosynthesis of RNa and protein both in chloroplast and cytoplasm, especially in the cytoplasm. Thus it suggeted that IAA affected vitamin C biosynthesis by regulating RNA level in the cytoplasm. 2,4-Dinitrophenol as an uncoupler of oxidative phosphorylation did not inhibit the vitamin C biosynthesis, however, all of the respiratory inhibitors severely inhibited the growth and vitamin C biosynthesis.
비타민C의 급원식품인 콩나물의 생장과 비타민C의 함량을 식물 생장조절제에 의하여 조절할 목적으로 gibberellic acid$(GA_3)$, indole-3-acetic acid(IAA) 및 1-naphthaleneacetic acid(NAa)의 단독 및 혼합 처리를 하였을때 가장 적당한 식물 생장조절제의 종류 및 그 농도를 찾고 이 생장조절제가 비타민C의 생합성에 미치는 영향 및 당대사와 비타민C 생성과의 관계를 검토한 결과를 요약하면 다음과 같다. 콩나물의 생장은 NAA는 $10^{-8}M$, IAA 는 $10^{-6}M$, $GA_3$는 $10^{-5}M$에서 각각 가장 양호하였다. $GA_3$와 NAA 혼합처리의 경우는 $GA_3\;10^{-5}M+NAA\;10^{-9}M$에서, $GA_3$와 IAA 혼합처리의 경우는 $GA_3,\;10^{-5}M+IAA\;$10^{-9}M$에서 양호하였고, 단독처리가 혼합처리에 비하여 양호하였으며 특히 IAA $10^{-6}M$ 처리에서 가장 좋았다. 생장이 비교적 양호한 NAA $10^{-8}M, IAA\;10^{-6}M,\;GA_3\;10^{-5}M,\;GA_3\;10^{-8}M+IAA\;10^{-6}M$ 및 $GA_3\;10^{-5}M+IAA\;10^{-9}M$의 각 처리구에서 비타민C의 생성 정도를 조사한 결과 콩나물 생장이 가장 양호하였던 IAA $10^{-6}M$ 에서 24.26mg%로서 그 함량이 가장 높았으며 대조구의 1.6배였다. 생장이 저해되지 않는 농도의 chloramphenicol(CAP) 처리에 의하여 ribulose diphosphate carboxylase(RuDpCO)는 저해되었으나 nicotineamide adenine dinucleotide phosphate-glyceraldhyde-3-phosphate dehydrogenase (NADP-GDH), galactonolactone dehydrogenase (GLD)의 활성 및 비타민C 함량은 저해되지 않았다. 따라서 비타민C의 생합성은 chloroplast RNA의 작용과는 직접적인 관련은 없고 cytoplasm과 밀접한 관련이 있다고 생각되었다. $IAA\;10^{-6}M$ 처리에 의하여 GLD 활성은 대조구의 1.8배로 촉진되었다. IAA $10^{-6}M$은 chloroplast와 cytoplasm RNA와 단백질의 생합성을 크게 촉진하였으며 cytoplasm에서 더욱 활발하였다. 따라서 IAA는 cytoplasm RNA를 조절하므로 여기서 지배되는 GLD의 생합성을 촉진시킨 결과 비타민C의 생합성이 증가된 것으로 생각되었다. 산화적 인산화 반응의 짝풀림 물질이 2,4+dinitrophenol 처리로 비타민C의 생합성은 저해되지 않았으나, 해당 저해제인 monoiodoacetate와 NaF 및 TCA 회로 저해제인 $NaN_3$와 KCN은 다같이 콩나물의 생장과 비타민C의 생합성을 크게 저해하였다