Phylogenetic analysis on a strain of Alexandrium tamarense collected from Antarctic Ocean

A PST-toxin producing Alexandrium species was found and successfully isolated from the Antarctic Ocean (Southern Ocean) in 2001 (Ho et al., 2003). The species was identified as Alexandrium tamarense based on their morphological features and thecal plate analysis previously. Mono-culture of this Antarctic Alexandrium strain, designated as Kci, has been successfully kept in our laboratory. In order to gain more insight into the origin of this strain, phylogenetic relationship of this Alexandrium strain to other Alexandrium spp. within the A. tamarense complex was carried out using 28S and ITS rDNA sequences. These are the first such sequences reported for an Alexandrium spp. found in Antarctic Ocean. Based on the ribosomal DNA sequences and phylogenetic analysis, the Antarctic Alexandrium strain was fell within the ribotypes in Group IV of the group-numbering scheme as suggested by Lilly et al. (2007). Interestingly, the Antarctic Alexandrium strain Kci was closely affiliated to Alexandrium isolates from the China Sea.