Analysis of Gymnodinium catenatum dinophyceae using sequences of the 5.8S rDNA-ITS regions and random amplified polymorphic DNA

The genetic relatedness of the toxigenic dinoflagellate Gymnodinium catenatum Graham from Australia, Japan, Portugal and Spain were examined using sequence comparison of the 5.8S rDNA and internal transcribed spacer (ITS) regions and/or random amplified polymorphic DNA (RAPD) analysis. The sequence analysis showed that the sizes of ITS1, ITS2 and the 5.8S rDNA in six isolates of G. catenatum were conserved and were 192, 223 and 160 bp, respectively. ITS and the 5.8S rDNA regions between all isolates tested were found to be extremely homogeneous and were divergent from several other dinoflagellates. Aligned nucleotide sequences in the 5.8S rDNA region of G. catenatum and several species of dinoflagellates showed the existence of DNA signatures (base pair 90-115) specific to G. catenatum in this region. Therefore, the nuclear ITS spacer regions of G. catenatum provide phylogenetically informative and G. catenatum-specific genetic markers. RAPD patterns revealed the subdivided population of G. catenatum. The isolate from Japan (JP02) exhibited almost the same RAPD patterns as those of the two isolates from Portugal (PR01) and Spain (GC21V) and was clearly discriminated from the four isolates from Australia. Two isolates from Australia (DE06 and DE08) showed similar RAPD patterns. Three other isolates (GPU2, HU02, and HU07) exhibited unique RAPD patterns. This is the first report about the application of RAPDs to discriminate dinoflagellates. RAPD may provide a useful and rapid tool for the genetic differentiation of these organisms at intra-species level.