Clone, Sequence Analysis And Expression Of PKS Gene In Several Typical Red Tide Algaes

Objective: In order to provide information for the HABs toxins synthesis mechanism, polyketide synthase (PKS) gene were cloned in several typical red tide algaes, such as Prorocentrum donghaiense, Prorocentrum lima, Alexandrium tamarense and Chattonellia marina. The expression of PKS gene in these four algaes were observed. The relationship between the PKS gene and toxins production was analyzed.Methods: Using degenerate primer, PKS gene in Prorocentrum donghaiense, Prorocentrum lima, Alexandrium tamarense and Chattonellia marina was amplified by PCR. The PCR products were cloned into the PMD18-T vector and sequenced. The homology analysis was conducted and phylogenetic tree was constructed with biotic software of Dnastar and Dnaman. The expression of the PKS gene in different red tide algae were observed by reverse transcriptase PCR (RT-PCR).Results: 700 bp bands were amplified from Prorocentrum donghaiense, Prorocentrum lima, Alexandrium tamarense, which were consistant with the references in the size of PCR product of PKS gene. These suggested that the PKS gene existed in Prorocentrum lima, Alexandrium tamarense, but not in Chattonellia marina. The amio acids of PKS in different algaes exhibited high homology of 61.43% among other species. Prorocentrum lima grouped strongly with Prorocentrum micans, Alexandrium tamarense and Pseudomonas belong to a cluster, the Prorocentrum donghaiense tended to far away from the large clade. High expressions of PKS gene were observed in DSP toxin-producing Prorocentrum lima in contrast with no expression in toxin-nonproducing Prorocentrum donghaiense and PSP toxin toxin-producing Alexandrium tamarense.Conclusions: The PKS gene in Prorocentrum donghaiense, Prorocentrum lima, Alexandrium tamarense were obtained successfully. The sequence numbers in Genbank were EF521599, EF521600 and EF521601, respectively. High expressions of PKS gene in Prorocentrum lima and no expressions in Prorocentrum donghaiense, Alexandrium tamarense suggested that the PKS might have an important role in the production of DSP.