DOE-JGI Sequences Genome of Chlamydomonas reinhardtii, CO2 Capturing Green Alga

The Science

Chlamydomonas reinhardtii is a model system for studying a major form of photosynthesis, the process of fixing CO2 and converting it to biomass, as well as the structure, assembly, and function of whip-like flagella. Chlamy (as it is commonly known to its friends) is a one-celled, soil-dwelling green alga whose lineage diverged from land plants over 1 billion years ago. The DOE-Joint Genome Institute (DOE-JGI) sequenced the ~121,000,000 base pair nuclear genome of C. reinhardtii and analyzed its 17 chromosomes containing its genetic parts list of over 15,000 predicted genes (humans have an estimated 22,000 genes). With multiple (energy-generating) mitochondria, two front-located flagella for motility and mating, and a chloroplast that houses the photosynthetic apparatus and critical metabolic pathways, Chlamy is heavily used to study higher-level photosynthesis because, unlike flowering plants, it grows in the dark on an organic carbon source while maintaining a functional photosynthetic apparatus. Chlamy research is also being actively developed for bioremediation purposes and the potential generation of biofuels starting with sunlight and CO2.


Chlamydomonas reinhardtii is a unicellular green alga whose lineage diverged from land plants over 1 billion years ago. It is a model system for studying chloroplast-based photosynthesis, as well as the structure, assembly, and function of eukaryotic flagella (cilia), which were inherited from the common ancestor of plants and animals, but lost in land plants. Researchers sequenced the approximately 120-megabase nuclear genome of Chlamydomonas and performed comparative phylogenomic analyses, identifying genes encoding uncharacterized proteins that are likely associated with the function and biogenesis of chloroplasts or eukaryotic flagella. Analyses of the Chlamydomonas genome advance the scientific community’s understanding of the ancestral eukaryotic cell, reveal previously unknown genes associated with photosynthetic and flagellar functions, and establish links between ciliopathy and the composition and function of flagella.

BER Program Manager

Ramana Madupu

U.S. Department of Energy, Biological and Environmental Research (SC-33)
Biological Systems Science Division
[email protected]


Merchant, S. S., et al. 2007. “The Chlamydomonas Genome Reveals the Evolution of Key Animal and Plant Functions,” Science 318. DOI:10.1126/science.1143609.