|
|
||||||||
|
First published online April 22, 2005; 10.1104/pp.104.056069 Plant Physiology 138:490-515 (2005) © 2005 American Society of Plant Biologists Genome-Based Examination of Chlorophyll and Carotenoid Biosynthesis in Chlamydomonas reinhardtii1,[w]Institut für Allgemeine Botanik Johannes Gutenberg-Universität, 55099 Mainz, Germany (M.L.); and The Carnegie Institution Department of Plant Biology, Stanford, California 84305 (C.-S.I., A.R.G.)
The unicellular green alga Chlamydomonas reinhardtii is a particularly important model organism for the study of photosynthesis since this alga can grow heterotrophically, and mutants in photosynthesis are therefore conditional rather than lethal. The recently developed tools for genomic analyses of this organism have allowed us to identify most of the genes required for chlorophyll and carotenoid biosynthesis and to examine their phylogenetic relationships with homologous genes from vascular plants, other algae, and cyanobacteria. Comparative genome analyses revealed some intriguing features associated with pigment biosynthesis in C. reinhardtii; in some cases, there are additional conserved domains in the algal and plant but not the cyanobacterial proteins that may directly influence their activity, assembly, or regulation. For some steps in the chlorophyll biosynthetic pathway, we found multiple gene copies encoding putative isozymes. Phylogenetic studies, theoretical evaluation of gene expression through analysis of expressed sequence tag data and codon bias of each gene, enabled us to generate hypotheses concerning the function and regulation of the individual genes, and to propose targets for future research. We have also used quantitative polymerase chain reaction to examine the effect of low fluence light on the level of mRNA accumulation encoding key proteins of the biosynthetic pathways and examined differential expression of those genes encoding isozymes that function in the pathways. This work is directing us toward the exploration of the role of specific photoreceptors in the biosynthesis of pigments and the coordination of pigment biosynthesis with the synthesis of proteins of the photosynthetic apparatus.
1 This work was supported by the Deutsche Forschungsgemeinschaft (grant no. LO840/11 to M.L.). A.R.G. would like to thank the National Science Foundation for supporting genomic research using Chlamydomonas reinhardtii (grant no. MCB 0235878). C.-S.I. was supported by the National Science Foundation (grant no. IBN 0084189 awarded to A.R.G.). 2 These authors contributed equally to the paper. [w] The online version of this article contains Web-only data. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.104.056069. * Corresponding author; e-mail lohr{at}uni-mainz.de; fax 4961313923075. Received November 5, 2004; returned for revision February 3, 2005; accepted February 8, 2005. This article has been cited by other articles:
|
|||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ASPB Publications | PLANT PHYSIOLOGY | THE PLANT CELL | |
|---|---|---|---|