The Chlorella variabilis NC64A genome reveals adaptation to photosymbiosis, coevolution with viruses, and cryptic sex

Guillaume Blanc, Garry Duncan, Irina V Agarkova, Mark Borodovsky, James Gurnon, Alan Kuo, Erika Lindquist, Susan Lucas, Jasmyn Pangilinan, Juergen Polle, Asaf Salamov, Astrid Terry, Takashi Yamada, David D Dunigan, Igor V. Grigoriev, Jean Michel Claverie, James L Van Etten

Research output: Contribution to journalArticle

294 Citations (Scopus)

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.

Original languageEnglish (US)
Pages (from-to)2943-2955
Number of pages13
JournalPlant Cell
Volume22
Issue number9
DOIs
StatePublished - Jan 1 2010

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Chlorella
coevolution
Phycodnaviridae
Genome
Viruses
viruses
genome
Symbiosis
Flagella
gender
flagellum
algae
symbiosis
Embryophyta
Paramecium
Horizontal Gene Transfer
Chlorophyta
Proteins
Plant Growth Regulators
proteins

ASJC Scopus subject areas

  • Plant Science
  • Cell Biology

Cite this

The Chlorella variabilis NC64A genome reveals adaptation to photosymbiosis, coevolution with viruses, and cryptic sex. / Blanc, Guillaume; Duncan, Garry; Agarkova, Irina V; Borodovsky, Mark; Gurnon, James; Kuo, Alan; Lindquist, Erika; Lucas, Susan; Pangilinan, Jasmyn; Polle, Juergen; Salamov, Asaf; Terry, Astrid; Yamada, Takashi; Dunigan, David D; Grigoriev, Igor V.; Claverie, Jean Michel; Van Etten, James L.

In: Plant Cell, Vol. 22, No. 9, 01.01.2010, p. 2943-2955.

Research output: Contribution to journalArticle

Blanc, G, Duncan, G, Agarkova, IV, Borodovsky, M, Gurnon, J, Kuo, A, Lindquist, E, Lucas, S, Pangilinan, J, Polle, J, Salamov, A, Terry, A, Yamada, T, Dunigan, DD, Grigoriev, IV, Claverie, JM & Van Etten, JL 2010, 'The Chlorella variabilis NC64A genome reveals adaptation to photosymbiosis, coevolution with viruses, and cryptic sex', Plant Cell, vol. 22, no. 9, pp. 2943-2955. https://doi.org/10.1105/tpc.110.076406
Blanc, Guillaume ; Duncan, Garry ; Agarkova, Irina V ; Borodovsky, Mark ; Gurnon, James ; Kuo, Alan ; Lindquist, Erika ; Lucas, Susan ; Pangilinan, Jasmyn ; Polle, Juergen ; Salamov, Asaf ; Terry, Astrid ; Yamada, Takashi ; Dunigan, David D ; Grigoriev, Igor V. ; Claverie, Jean Michel ; Van Etten, James L. / The Chlorella variabilis NC64A genome reveals adaptation to photosymbiosis, coevolution with viruses, and cryptic sex. In: Plant Cell. 2010 ; Vol. 22, No. 9. pp. 2943-2955.
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