Photosynthetic acclimation and photoprotective mechanism of Haematococcus pluvialis (Chlorophyceae) during the accumulation of secondary carotenoids at elevated irradiation

Abstract The photosynthetic acclimation of Haematococcus pluvialis Flotow to elevated irradiance and its photoprotective mechanisms were investigated. High light caused a remarkable increment in carotenoid content per cell. Cellular and volumetric chlorophyll contents were significantly increased after four days of high light treatment. Net photosynthesis of high light treated cells was decreased but their dark respiration was increased during the accumulation of secondary carotenoids (SC). The inactivation of reaction centers was observed in high light treated cells, and their normalized complementary area and turnover number were higher than those under low light. The PS II activity of red cells from high light was decreased by 17% compared with green cells from low light but their PS I activity was significantly increased. The K-step could not be observed in the fluorescence transients of red cells, indicating that the oxygen-evolving complex was not affected during SC accumulation. Haematococcus pluvi...