Study On Taxonomy And Phylogenetics Of Several Important Dinoflagellate Species In Coastal Area Of China

In this research, Prorocentrum donghaiense and Prorocentrum dentatumwere selected as target algae to be identified by molecular techniques. High variationdomains (D1 and D2) of large subunit ribosomal DNA, small subunit ribosomal DNAand internal transcribed spacers (ITS) were sequenced. And their divergences ofsequences were analyzed. Then cell parameters were acquired by flow cytometory.The similarity and divergence of P. donghaiense and P. dentatum were comparedthrough molecular and flow cytometory parameters. According to hypothesis ofmorphological evolution of dinoflagellates, the evolution of dinoflagellates wereanalyzed including morphological characteristics and estimating evolutional distanceof different species. The phylogenetic tree of 17 dinoflagellates were reconstructedbased on their 18S rDNA sequences and their phylogenetic analysis were reported. The results showed that the similarity of their ITS sequences, the 18S rDNAsequence and the 28S rDNA D1 and D2 domains were 100%, 98.7% and 99.9%respectively. But they had different growth characteristics. These results implied that P.donghaiense and P. dentatum were the same species. The difference of their growthcharacteristics and 1.3% 18S rDNA sequence divergence were the representation ofdifferent adaptation features and the genetic divergence of P. donghaiense and P.dentatum effected by environmental factors. Phylogenetic trees were reconstructed based on 18S rDNA sequences of seventeendinoflagellates. Results showed that planktonic Prorocentrum were assembled to onegroup while benthic Prorocentrum were assembled to another group. The percentagesof the bootstrap values were higher than 95%. The results demonstrated that theplanktonic and benthic Prorocentrum should belong to different genus. Furthermore, the resulting phlogenetic structure showed the percentages of thebootstrap values (98%-100%) of Alexandrium in NJ and ML trees were significantlevers and belong to one group, divergently with genus Gonyaulax. The results 3硕士毕业论文 中国近海几种重要赤潮甲藻分类学及其系统发育学研究indicated that Alexandrium and Gonyaulax have divergence and were in goodconsistence with morphology features of the previous studies. In the phylogeneticstructure, Gymnodinium was related to planktonic Prorocenrum. In the research, the integrated study on P. donghaiense and P. dentatum, which weredispute in classification, was established by molecular technology and flowcytometory for the first time. This work not only provides new methods foridentification of HAB dinoflagellates quickly and also offered foundational materialsfor diversity investigation of microalgae.