Characterization of new strains of nonphotosynthetic mutants of Chlamydomonas reinhardtii I. Fluorescence, photochemical activities, chlorophyll-protein complexes

Thirty-six new strains of nonphotosynthetic mutants of Chlamydomonasreinhardtii, which had been induced by UV irradiation then screenedphotographically for strong chlorophyll fluorescence of theircolonies, were characterized with respect to pigment contents,photochemical activities of Hill and Mehler reactions and chlorophyllfluorescence induction, and by SDS-polyacrylamide gel electrophoresisof the chlorophyllprotein complexes. Eight strains did not show any Photosystem II activity and fiveshowed only very weak activity. Analysis of the chloroplastmembranes of ten of these strains showed that all containedboth complexes CP I and CP II. In the case of one of these mutants,Fl 50, which was totally unable to perform the Hill reactionfrom H₂O, addition of DPC restored about 25% of the DCIP photoreductionactivity. This could be interpreted tentatively in terms ofan impaired accessibility of the Photosystem II centers to electrondonors and acceptors. Ten other mutants showed the following anomalies: no PhotosystemI activity, lack of complex CP I, and higher chlorophyll fluorescenceyield and lower Chl a/Chl b ratio than the wild type. Thesefeatures appeared to be related. (Received February 8, 1979; )