PCR protocols for genetic identification of dinoflagellates directly from single cysts and plankton cells

A simple preparation method and PCR protocol are described which allow succ essful PCR amplification of partial ribosomal RNA gene sequences from as li ttle as one dinoflagellate cyst or vegetative cell. Amplification from sing le or small numbers of cysts can be applied to a range of morphologically i dentifiable cyst species and produces rDNA sequence data identical to those obtained from DNA extractions from cultured vegetative cells. Applications of the approach have the potential to aid phylogenetic studies of dinoflag ellates and other microalgae by (1) improving taxonomic sampling of uncultu rable and heterotrophic species, (2) providing data to Link cysts of unknow n affinity with their potential planktonic cell counterparts; and (3) confi rming the identification of cysts that cannot be germinated or are nonviabl e. Examples are presented where this method was used to confirm the identit y and distribution of nonviable microreticulate cysts in coastal marine sed iment samples, such as those of the recently described species Gymnodinium microreticulatum.