Studies On Genetic Diversity Of The Typical Toxic Dinoflagellate Alexandrium Tamarense In China

Alexandrium tamarense is a wide-spread species of dinoflagellate causing harmful algal blooms (HABs). It can produce paralytic shellfish poisoning (PSP), which causes severe economic losses in aquaculture and seriously threaten human health. As a typical toxic dinoflagellate in China, A.tamarense distributes all over Chinese coastal water.To explore the origin of A. tamarense in Chinese coastal water, in this study, we analyse the genetic diversity of A. tamarense with different geographical distributions, including 19 European strains,19 Chinese strains and 9 other waters strain by rDNA and microsatellite markers.Results from 5.8S rDNA, internal transcribed spacers (ITS) and large subunit (LSU) rDNA in 47 strains A. tamarense show that:1) the strains assayed in the paper have high homology with A. tamarense complex logined in Genebank; 2) A. tamarense in the world can be divided into at least four lineages:Western Europe, Temperate Asia, Northern America and Mediterranean; the Chinese strains all belong to the type of Temperate Asia. 3) Ribosomal genes may not be the most judicious and accurate molecular markers for analyzing the intraspecific diversity within A. tamarenseMicrosatellite analysis reveal that:1) the gene diversity of the 27 strains of A. tamarense is 0.7576; 2) the A. tamarense from Chinese coastal water can be divided into three lineages; the strains from the East China sea cluster together, while ones from the South China sea separate two groups; the strain ATDH01 clusters together with the four strains such as CCMP115, CCMP1771, CCMP2023 and CCMP2022 from England.3) The genetic distances between the Europe strains and ones from the East China Sea and South China Sea are 0.8762 and 1.1372, repectively. Further, the genetic distances between the East China Sea and South China sea strains is 0.2186.In conclusion, high gentic diversity exists in A. tamarense species complex from Chinese coastal water. The low genetic distance between ATDH01 and the four strains from England suggests the possibility of the foreign strain invasion. However, further studies should be addressed in the future.