The role of peridinin-chlorophyll a-proteins in the photosynthetic light adaption of the marine dinoflagellate, Glenodinium sp.

The marine dinoflagellate, Glenodinium sp., was cultured at a series of light levels and growth, pigmentation, and photosynthetic rates were compared. Under decreasing light conditions, growth rates decreased, cellular chlorophyll a and peridinin content per cell increased, and maximum cellular photosynthetic rates remained unchanged. Pigmentation changes were related to alterations in cellular concentrations of a peridinin-chlorophyll a-protein and an unidentified chlorophyll a component of the chloroplast membrane. Maintenance of photosynthetic rates with decreased irradiance is interpreted as an increase in the number of pigment molecules in the light-harvesting antenna associated with the reaction centers of the photosynthetic apparatus, thus increasing the potential for photon capture for photosynthesis.