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.

• 오순자(제주대학교 생명과학과·기초과학연구소) | Soonja Oh
• 고석찬(제주대학교 생명과학과·기초과학연구소) | Seok Chan Koh Corresponding Author