title: The chloroplast genome of a Symbiodinium sp. clade C3 isolate.
abstract: Dinoflagellate algae of the genus Symbiodinium form important symbioses within corals and other benthic marine animals. Dinoflagellates possess an extremely reduced plastid genome relative to those examined in plants and other algae. In dinoflagellates the plastid genes are located on small plasmids, commonly referred to as 'minicircles'. However, the chloroplast genomes of dinoflagellates have only been extensively characterised from a handful of species. There is also evidence of considerable variation in the chloroplast genome organisation across those species that have been examined. We therefore characterised the chloroplast genome from an environmental coral isolate, in this case containing a symbiont belonging to the Symbiodinium sp. clade C3. The gene content of the genome is well conserved with respect to previously characterised genomes. However, unlike previously characterised dinoflagellate chloroplast genomes we did not identify any 'empty' minicircles. The sequences of this chloroplast genome show a high rate of evolution relative to other algal species. Particularly notable was a surprisingly high level of sequence divergence within the core polypeptides of photosystem I, the reasons for which are currently unknown. This chloroplast genome also possesses distinctive codon usage and GC content. These features suggest that chloroplast genomes in Symbiodinium are highly plastic.
authors: Department of Biochemistry, University of Cambridge, Building O, Downing Site, Tennis Court Road, Cambridge, CB2 1QW, UK. Electronic address: acb18@cam.ac.uk.
authors: Adrian C
authors: AC
authors: Barbrook
authors: Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
authors: Christian R
authors: CR
authors: Voolstra
authors: Department of Biochemistry, University of Cambridge, Building O, Downing Site, Tennis Court Road, Cambridge, CB2 1QW, UK.
authors: Christopher J
authors: CJ
authors: Howe
mesh_terms: D056893:Alveolata / Q000145:classification / Q000235:genetics*; D001482:Base Composition; D016000:Cluster Analysis; D003062:Codon; D018742:DNA, Chloroplast / Q000737:chemistry / Q000235:genetics; D014644:Genetic Variation; D054628:Genome, Chloroplast; D008969:Molecular Sequence Data; D010802:Phylogeny; D017422:Sequence Analysis, DNA
chemical_list: D003062:Codon; D018742:DNA, Chloroplast
keywords: Symbiodinium; chloroplast genome; dinoflagellate; diversity.; minicircle