CHLOROPHYLL-A' AND PHEOPHYTIN-A, AS DETERMINED BY HPLC, IN PHOTOSYNTHESIS MUTANTS AND DOUBLE MUTANTS OF CHLAMYDOMONAS-REINHARDTII

HPLC analysis of chlorophyll (Chl) a′ and pheophytin (Pheo) a content was run for wild type Chlamydomonas reinhardtii and seven mutants with impaired photosynthetic functions. Four of them had no or little Photosystem II (PS II) activity. Two had no Photosystem I (PS I) activity and no P-700. In the seventh mutant, both photosystems were present but the main light-harvesting antenna (the chlorophyll-protein complex corresponding to PS II: CP II) was totally lacking because of the absence of Chl b. In mutants impaired in PS II activity, Pheo a is either lacking or found in only low amounts in direct relation with the loss in PS II activity. These results are in agreement with the well-known role of Pheo a as a primary electron acceptor in PS II. In mutants impaired in PS II activity the Chl a′ level is normal. In mutants impaired in PS I activity (P-700 less mutants), only half of the normal content of Chl a′ is present. So Chl a′ is associated exclusively with PS I as demonstrated before by Watanabe (Watanabe, T., Kobayashi, M., Hongu, A., Nakazato, M., Hiyama, T. and Murata, N. (1985) FEBS Lett. 191, 252-256). But only half the Chl a′ content could be P-700. This last result contradicts Watanabe's conclusion that the whole Chl a′ constitutes P-700. On the other hand, there is no relation between the presence of Chl a′ and the second Chl a-protein complex of PS I: CP 0a. The possible function of Chl a′ related to PS I activity is discussed. © 1990.