본 연구는 환경요인의 변화, 특히 겨울철 저온이 식물체에 미치는 영향을 정량적으로 밝히기 위해, 저온감수성 식물인 문주란을 대상으로 겨울철 일주기에 있어서 항산화효소 활성과 O-J-I-P곡선의 변화를 조사하였다. 겨울철의 superoxide dismutase와 peroxidase의 활성은 여름철에 비해 다소 증가하였다. 특히, peroxidase는 겨울철 새벽과 밤에 높은 활성을 보였으며 초겨울에만 특이적으로 검출되는 isoenzyme들로 관찰할 수 있

The change of chlorophyll fluorescence parameters, O-J-I-P transients and psbA gene expression were investigated in the leaves of Crinum asiaticum var. japonicum on the natural condition in winter, in order to elucidate physiological responses of photosystem Ⅱ (PSⅡ) activity to winter stresses. The photochemical efficiencies of PSⅡ, Fv/Fm, were significantly low in winter, contrary to its high value in summer. The values of 1-qN and 1-qP were lower in midday than at dawn or night both in summer and winter, although their decrease in midday was less in winter than in summer. In the O-J-I-P transients, the fluorescence intensity of J, I, P-step decreased remarkably depending on temperature drop in winter. And the D1 reaction center protein of PSⅡ decreased in late winter more than in early winter, concomitantly with relatively high content of description products of psbA gene in midday. These results indicate that low temperature in winter causes irreversible damage to PSⅡ and subsequently leads to cell death.