基于核糖体DNA大亚基片断序列探讨中国东海海域赤潮原甲藻的分子分类

Identification of Prorocentrum donghaiense in Genus Prorocentrum from the East China Sea Based on Partial LSU rDNA

采用PCR扩增技术对分类上有争议的中国东海赤潮原因种(被称为东海原甲藻,本文简称:东海株系)的基因组DNA进行了核糖体DNA大亚基片断(LSU rDNA)的扩增和测序,并与一同扩增的来自美国CCMP的被称为具齿原甲藻(本文简称:CCMP株系)的同源序列进行分析比较.结果表明,两者710 bp的LSU rDNA同源序列中仅存在7个碱基的差异,遗传相似度高达99.01%,遗传差异为0.99%.进一步与Genebank其他3种原甲藻即P.mexicanum、P.micans和P.minimum的同源序列进行比较,发现其他3种原甲藻两两间的种间遗传相似度在91.1%～95.5%之间,而P.micans和P.minimum种内不同株系的遗传相似度为99.4%～99.9%,均为99%以上.综合这些数据说明东海株系与CCMP株系之间的0.99%的遗传差异应视为种内差异,原甲藻的东海株系与CCMP株系当属异名同种.因此本试验结果从分子水平支持了被称为东海原甲藻的原甲藻与被称为具齿原甲藻(P.dentatum)的原甲藻同为一种的观点.

The redtide causative organism Prorocentrum donghaiense from the East China Sea (Donghai strain) and P.dentatum from Culture Center of Marine Phytoplankton(CCMP) were analyzed by amplifying and sequencing the part of region of the large-subunit ribosomal DNA gene(LSU rDNA).The results showed that of 710 base pairs(bp) within LSU rDNA,only 5 bps were different between them.Both strains showed 99.01% genetic homology and 0.99% genetic differences.At the same time,the homologous sequences of another three species(P.mexicanum,P.micans,P.minimum) in genus Prorocentrum were downloaded from Genbank and analyzed by software.There were 99.4%~99.9% (up to 99.0%) homology between different strains within specie,and 91.1%~95.5% homology between different species in genus Prorocentrum.It was suggested that the genetic differences between Donghai strain and CCMP strain (0.99%) should be considered as variation within species,and Donghai strain and CCMP strain should be the same morphotype.This study supported the conclusion that Donghai strain and CCMP strain is actually the same species based on molecular data.