title: White mutants of Chlamydomonas reinhardtii are defective in phytoene synthase.
abstract: Carotenoids play an integral and essential role in photosynthesis and photoprotection in plants and algae. A collection of Chlamydomonas reinhardtii mutants lacking carotenoids was characterized for pigment and tocopherol (vitamin E) composition, growth phenotypes under different light conditions, and the molecular basis of their mutant phenotype. The carotenoid-less mutants, or "white" mutants, were also deficient in chlorophylls but had approximately twice the tocopherol content of the wild type. White mutants grew in the dark but were unable to survive in the light, even under very low light conditions on acetate-containing medium. Genetic crosses and recombination tests revealed that all individual white mutants in the collection are alleles of a single gene, lts1, and the white phenotype was closely linked to a marker located in the phytoene synthase gene. DNA sequencing of the phytoene synthase gene from each of the mutants revealed nonsense, missense, frameshift, and splice site mutations. Transformation with a wild-type copy of the phytoene synthase gene was able to complement the lts1-210 mutation. Together, these results show that all the white mutants examined in this work are affected in the phytoene synthase gene.
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, California 94720-3102, USA.
authors.forename: Sarah S
authors.initials: SS
authors.lastname: McCarthy
authors.forename: Marilyn C
authors.initials: MC
authors.lastname: Kobayashi
authors.forename: Krishna K
authors.initials: KK
authors.lastname: Niyogi
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000172:deficiency / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D002338:Carotenoids / Q000096:biosynthesis; D016825:Chlamydomonas reinhardtii / Q000201:enzymology / Q000235:genetics*; D002851:Chromatography, High Pressure Liquid; D005819:Genetic Markers; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase; D008969:Molecular Sequence Data; D009154:Mutation; D010858:Pigmentation / Q000235:genetics* / Q000502:physiology
chemical_list: D005819:Genetic Markers; D002338:Carotenoids; D019883:Alkyl and Aryl Transferases; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase