Comparing Genomes of Two Algae Strains Highlights Genes for Carbon Capture

Picoeukaryotes are a taxonomically diverse group of organisms less than 2 micrometers in diameter.

The Science

Photosynthetic marine picoeukaryotes in the genus Micromonas thrive in ecosystems ranging from tropical to polar and could serve as sentinel organisms for biogeochemical fluxes of modern oceans during climate change. These broadly distributed primary producers belong to an anciently diverged sister clade to land plants. Although Micromonas isolates have high 18S ribosomal RNA gene identity, we found that genomes from two isolates shared only 90% of their predicted genes. Their independent evolutionary paths were emphasized by distinct riboswitch arrangements as well as the discovery of intronic repeat elements in one isolate, and in metagenomic data, but not in other genomes. Divergence appears to have been facilitated by selection and acquisition processes that actively shape the repertoire of genes that are mutually exclusive between the two isolates differently than the core genes. Analyses of the Micromonas genomes offer valuable insights into ecological differentiation and the dynamic nature of early plant evolution.


Ancestral green algae were of fundamental importance to the eukaryotic greening that shaped the geochemistry of our planet. Scientists from the Monterey Bay Aquarium Research Institute, led by Alexandra Z. Worden, have decoded the genomes of two algal strains, highlighting the genes enabling them to capture carbon and maintain the delicate balance of carbon in the oceans.  The study sampled two geographically diverse isolates of the photosynthetic algal genus Micromonas: one from the South Pacific, the other from the English Channel. Surprisingly, the two isolates had about 90% of their genes in common compared to about 98% for humans and some primates.  Algae such as Micromonas were among the first cells on Earth to acquire the capacity to fix CO2 and use the energy from sunlight to generate biomass (the essential process of photosynthesis).  Worden said that the differences between these algae may make them more resilient compared to more closely related species, enabling them to better survive environmental change and their geographically diverse locations. These results help illuminate cellular processes that could be used to produce algae-derived biofuels. Scientists at DOE’s Joint Genome Institute (JGI) played an essential role in the research by carrying out the DNA sequencing and participating in the interpretation of the results.

Principal Investigator

Alexandra Z. Worden
Monterey Bay Aquarium Research Institute

BER Program Manager

Ramana Madupu

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


Worden, A. Z., J.-H. Lee, T. Mock, P. Rouzé, M. P. Simmons, A. L. Aerts, A. E. Allen, M. L. Cuvelier, E. Derelle, M. V. Everett, E. Foulon, J. Grimwood, H. Gundlach, B. Henrissat, C. Napoli, S. M. McDonald, M. S. Parker, S. Rombauts, A. Salamov, P. Von Dassow, J. H. Badger, P. M. Coutinho, E. Demir, I. Dubchak, C. Gentemann, W. Eikrem, J. E. Gready, U. John, W. Lanier, E. A. Lindquist, S. Lucas, K. F. X. Mayer, H. Moreau, F. Not, R. Otillar, O. Panaud, J. Pangilinan, I. Paulsen, B. Piegu, A. Poliakov, S. Robbens, J. Schmutz, E. oulza, T. Wyss, A. Zelensky, K. Zhou, E. V. Armbrust, D. Bhattacharya, U. S. Goodenough, Y. Van de Peer, and I. V. Grigoriev. 2009. “Green Evolution and Dynamic Adaptations Revealed by Genomes of the Marine Picoeukaryotes Micromonas,” Science 324. DOI:10.1126/science.1167222.