Acclimation of photosynthetic properties in ice algae

点击翻译按钮获取中文摘要

Ice algae and diatoms perform highly efficient photosynthesis, in spite of these very severe environments. We investigated how their light-harvesting systems or photosystems acclimate to very low irradiance to achieve efficient photosynthesis. The way of acclimation was very unique, which was opposite to that of higher plants or green algae. In ice algae, the accessory pigments and also RubisCO were decreased and the ratio of photosystem I (PSI) to PS II was lowered in lower irradiance. And photosynthetic systems acclimated highly to very low irradiance were protected by functional diadinoxanthin cycle, equivalent to the xanthophylls cycle of higher plant, against higher irradiance.The maximum photosysthetic rate was also retained at the same level and photo inhibition could not be observed under illumination up to -800 uEm-2s-1. These properties may indicate that the efficient light-energy utilization and functioning of photosystems of the diatom cells under large variation of irradiance at short time-scale relative to their generation time such as in the ice.