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The Chlorella variabilis NC64A Genome Reveals Adaptation to Photosymbiosis, Coevolution with Viruses, and Cryptic Sex
Virology Papers
  • Guillaume Blanc, Aix-Marseille Université
  • Garry A. Duncan, Nebraska Wesleyan University
  • Irina Agarkova, University of Nebraska-Lincoln
  • Mark Borodovsky, Georgia Institute of Technology - Main Campus
  • James Gurnon, University of Nebraska at Lincoln
  • Alan Kuo, Department of Energy Joint Genome Institute
  • Erika Lindquist, Department of Energy Joint Genome Institute
  • Susan Lucas, Department of Energy Joint Genome Institute
  • Jasmyn Pangilinan, Department of Energy Joint Genome Institute
  • Juergen Polle, Brooklyn College of the City University of New York
  • Asaf Salamov, Department of Energy Joint Genome Institute
  • Astrid Terry, Department of Energy Joint Genome Institute
  • Takashi Yamada, Hiroshima University
  • David D Dunigan, Ph. D., University of Nebraska-Lincoln
  • Igor V. Grigoriev, Department of Energy Joint Genome Institute
  • Jean-Michel Claverie, Aix-Marseille Université
  • James L Van Etten, University of Nebraska - Lincoln
Date of this Version
9-1-2010
Citation

The Plant Cell, Vol. 22: 2943–2955, September 2010;

Comments

Copyright 2010 American Society of Plant Biologists. Used by permission.

Abstract

Chlorella variabilis NC64A, a unicellular photosynthetic green alga (Trebouxiophyceae), is an intracellular photobiont of Paramecium bursaria and a model system for studying virus/algal interactions. We sequenced its 46-Mb nuclear genome, revealing an expansion of protein families that could have participated in adaptation to symbiosis. NC64A exhibits variations in GC content across its genome that correlate with global expression level, average intron size, and codon usage bias. Although Chlorella species have been assumed to be asexual and nonmotile, the NC64A genome encodes all the known meiosis-specific proteins and a subset of proteins found in flagella. We hypothesize that Chlorella might have retained a flagella-derived structure that could be involved in sexual reproduction. Furthermore, a survey of phytohormone pathways in chlorophyte algae identified algal orthologs of Arabidopsis thaliana genes involved in hormone biosynthesis and signaling, suggesting that these functions were established prior to the evolution of land plants. We show that the ability of Chlorella to produce chitinous cell walls likely resulted from the capture of metabolic genes by horizontal gene transfer from algal viruses, prokaryotes, or fungi. Analysis of the NC64A genome substantially advances our understanding of the green lineage evolution, including the genomic interplay with viruses and symbiosis between eukaryotes.

Citation Information
Guillaume Blanc, Garry A. Duncan, Irina Agarkova, Mark Borodovsky, et al.. "The Chlorella variabilis NC64A Genome Reveals Adaptation to Photosymbiosis, Coevolution with Viruses, and Cryptic Sex" (2010)
Available at: http://works.bepress.com/david_dunigan/18/