Molecular Analysis of Morphologically Similar Dinoflagellates Cochlodinium polykrikoides, Gyrodinium impudicum and Gymnodinium catenatum Based on Internal Transcribed Spacer and 5.8S rDNA Regions

Algae > Volume 16(1); 2001 > Article

Algae 2001;16(1): 53-57.

Eun Seob Cho, Gi-Young Kim, Yong Chul Cho

Harmful Algal Research Division, National Fisheries Research and Development Institute, Department of Microbiology, Pusan National University

ABSTRACT

The Internal Transcribed Spacers (ITS) of rDNA were sequenced for three dinoflagellates, having morphologically similar features, Cochlodinium polykrikoides, Gyrodinium impudicum and Gymnodinium catenatum to provide characters for phylogenetic analysis and predicted secondary structure. In Cochlodinium polykrikoides, the length of ITS1 was longest than that any other of Gyrodinium impudicum and Gymnodinium catenatum, whereas Gymnodinium catenatum was longest in the length of ITS2 than that any other of C. polykrikoides and Gyrodinium impudicum. In ITS1 and ITS2 regions there were variation and 5.8S was a little. In particular the ITS1 was more variable than ITS2 from these species. The inferred phylogeny using by Neighbor-Joining (NJ) method indicated that Gyrodinium impudicum was more closely related to Gymnodinium catenatum rather than C. polykrikoides. Based on secondary structure analysis, the conserved sequences were found at the loop of domain 1 in Gymnodinium catenatum and Gyrodinium impudicum, while C. polykrikoides did not show the sequence between the stem and loop. These results suggested that ITS regions might play an important role in differentiating C. polykrikoides from Gyrodinium impudicum and Gymnodinium catenatum.

Key words: genetic marker, ITS rDNA sequences genetic marker, molecular analysis, phylogeny, red tide dinoflagellates