THE RESPONSE OF PERIDINIUM GATUNENSE TO DIFFERENT LIGHT REGIMES: ITS PIGMENTATION AND POSSIBLE IMPLICATIONS ON THE LIGHT-SHADE ADAPTATION

The response of Peridinium gatunense (formerly Peridinium cinctum fa.westii) to different light regimes was investigated based on pigment profiles, which were revealed by HPLC analyses, over the ranges of 16.6-250μE·m-2·S-1 Peridinin and diadinoxanthin are the two most important carotenoids, shared about 90% of the total xanthophylls.Cellular chlorophyll a showed an evident drop along the increased irradiance gradients.Evidence was presented to show the role of diadinoxanthin and β-carotene as light protectants, including: l) diadinoxanthin / chlorophyll a ratios increased drastically when Peridinium was exposed to increased light gradients and β-carotene / chlorophyll a ratios also showed an obvious increasing tendency; 2) β-carotene / chlorophyll a ratios under light condition were higher than those under completely dark condition; and 3) diadinoxanthin / chlorophyll a ratios exhibited inter-group differences among high irradiance, low irradiance, high to low and low to high irradiance treatments.Hereby the possible implication for pigment metabolic routes and their limnological behaviour was deduced.