Pigmentation traits in Chlamydomonas are known to be controlled cooper
atively by nuclear and chloroplast genes. A method for obtaining mutan
ts without chlorophyll b was developed, which offers a possibility for
genetic analysis of chlorophyll b synthesis. Meiotic analysis of muta
nts selected for increased protoporphyrin IX content revealed a mutant
chlorplast gene allele that affects the activity of aminolevulinate-s
ynthesizing enzymes. Polyploids of Chlamydomonas reinhardtii, first is
olated by us, were used for genetic analysis of pigment mutations. The
discovery of phytoene in green photosensitive mutants of Chlamydomona
s allowed investigations of the genetic control of phytoene desaturase
(a key enzyme in carotenoid biosynthesis). Future studies on the mole
cular and genetic nature of the above mutations are outlined.