THE SMALLEST DINOFLAGELLATE GENOME IS YET TO BE FOUND: A COMMENT ON LAJEUNESSE ET AL. “SYMBIODINIUM (PYRRHOPHYTA) GENOME SIZES (DNA CONTENT) ARE SMALLEST AMONG DINOFLAGELLATES”1

LaJeunessse and colleagues (LaJeunesse et al. 2005) have recently documented small genome sizes of Symbiodinium and concluded that Symbiodinium is a dinoflagellate lineage with the smallest genome. The conclusion is inconsistent with recent discoveries of picoplanktonic dinoflagellates. The search for the smallest genome and the effort to understand the evolutionary history of dinoflagellate genome should be an area of research in the years to come, which can be greatly aided by an understanding on the current hypotheses regarding mechanisms of genome size evolution. Even the smallest dinoflagellate genome documented to date is too large to be sequenced with current technology, but sequencing of chromosomes or expressed genes of key representative species is feasible and can be very insightful for understanding genome composition and function in this important lineage of eukaryotes.