Unraveling the genomic mosaic of a ubiquitous genus of marine cyanobacteria

Alexis Dufresne, Martin Ostrowski, David J. Scanlan, Laurence Garczarek, Sophie Mazard, Brian P. Palenik, Ian T. Paulsen, Nicole Tandeau de Marsac, Patrick Wincker, Carole Dossat, Steve Ferriera, Justin Johnson, Anton F. Post, Wolfgang R. Hess, Frédéric Partensky*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    265 Citations (Scopus)
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    Background: The picocyanobacterial genus Synechococcus occurs over wide oceanic expanses, having colonized most available niches in the photic zone. Large scale distribution patterns of the different Synechococcus clades (based on 16S rRNA gene markers) suggest the occurrence of two major lifestyles ('opportunists'/'specialists'), corresponding to two distinct broad habitats ('coastal'/'open ocean'). Yet, the genetic basis of niche partitioning is still poorly understood in this ecologically important group. Results: Here, we compare the genomes of 11 marine Synechococcus isolates, representing 10 distinct lineages. Phylogenies inferred from the core genome allowed us to refine the taxonomic relationships between clades by revealing a clear dichotomy within the main subcluster, reminiscent of the two aforementioned lifestyles. Genome size is strongly correlated with the cumulative lengths of hypervariable regions (or 'islands'). One of these, encompassing most genes encoding the light-harvesting phycobilisome rod complexes, is involved in adaptation to changes in light quality and has clearly been transferred between members of different Synechococcus lineages. Furthermore, we observed that two strains (RS9917 and WH5701) that have similar pigmentation and physiology have an unusually high number of genes in common, given their phylogenetic distance. Conclusion: We propose that while members of a given marine Synechococcus lineage may have the same broad geographical distribution, local niche occupancy is facilitated by lateral gene transfers, a process in which genomic islands play a key role as a repository for transferred genes. Our work also highlights the need for developing picocyanobacterial systematics based on genome-derived parameters combined with ecological and physiological data.

    Original languageEnglish
    Article numberR90
    Pages (from-to)1-16
    Number of pages16
    JournalGenome Biology
    Issue number5
    Publication statusPublished - 28 May 2008

    Bibliographical note

    Copyright 2008 Dufresne et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


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