FUNCTIONAL-CHANGES IN THE PHOTOSYNTHETIC APPARATUS DURING LIGHT ADAPTATION OF THE GREEN-ALGA CHLORELLA-FUSCA

Cells of the unicellular green alga Chlorella fusca adapt to a low intensity (5 W m-2) of white light or to blue light (DAL 444 nm filter; 7.5-mu-mol m-2 s-2) by increasing the amount of chlorophyll and lowering the photosynthetic capacity and respiration rate in comparison with cells adapted to a high intensity (20 W m-2) of white light or red light (AL 683 nm filter; 7.5-mu-mol m-2 s-2) respectively. The change in adaptation of the alga from one light condition to the other takes about 8 h. Changes in molecular organization of the photocynthetic apparatus of cells adapting to low intensities of white light result in doubling the photosystem I and II units, whereas adaptation to blue light increases the light-harvesting complex of photosystem II preferentially. These results confirm the findings with Scenedesmus.