Symbiodinium (Pyrrhophyta) genome sizes (DNA content) are smallest among dinoflagellates

Todd C. LaJeunesse, Georgina Lambert, Robert A. Andersen, Mary Alice Coffroth, David W. Galbraith

Research output: Contribution to journalArticlepeer-review

190 Scopus citations


Using flow cytometric analysis of fluorescence, we measured the genome sizes of 18 cultured "free-living" species and 29 Symbiodinium spp. isolates cultured from stony corals, gorgonians, anemones, jellyfish, and giant clams. Genome size directly correlated with cell size, as documented previously for most eukaryotic cell lines. Among the smallest of dinoflagellates, Symbiodinium spp. (6-15 μm) possessed the lowest DNA content that we measured (1.5-4.8 pg · cell-1). Bloom-forming or potentially harmful species in the genera Alexandrium, Karenia, Pfiesteria, and Prorocentrum possessed genomes approximately 2 to 50 times larger in size. A phylogenetic analysis indicated that genome/cell size has apparently increased and decreased repeatedly during the evolution of dinoflagellates. In contrast, genome sizes were relatively consistent across distantly and closely related Symbiodinium spp. This may be the product of intracellular host habitats imposing strong selective pressures that have restricted symbiont size.

Original languageEnglish (US)
Pages (from-to)880-886
Number of pages7
JournalJournal of Phycology
Issue number4
StatePublished - Aug 2005

All Science Journal Classification (ASJC) codes

  • Aquatic Science
  • Plant Science


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