【摘要】 南海北部湾海域近年来连年暴发球形棕囊藻赤潮,严重威胁近海生态安全,亟待探明赤潮成因。球形棕囊藻是一种广泛分布于温带至热带海域的有害藻华微藻,具有明显的种下遗传分化。为了解北部湾海域球形棕囊藻的遗传多样性及其对赤潮藻种来源的指示意义,本研究针对分离于北部湾海域赤潮发生期间的4株棕囊藻,以核糖体28S大亚基rRNA基因(28SrDNA)D1—D2区和转录间隔区(ITS区)为靶区构建克隆文库,通过测序分析了北部湾海域球形棕囊藻的遗传多样性。结果表明,从北部湾分离的4株棕囊藻均为球形棕囊藻,但不同年份分离的球形棕囊藻藻株之间存在明显的遗传差异。部分球形棕囊藻藻株(PG2015和PG2017)的不同克隆间也存在遗传差异,这种遗传差异在由单一藻细胞建立的克隆培养系中仍存在,表明遗传差异是来自细胞内多拷贝的基因序列,可能源自不同地理种群球形棕囊藻之间的基因交流。与ITS区相比,28SrDNAD1—D2区能更好地反映球形棕囊藻遗传多样性状况,具有作为分子标记指示球形棕囊藻地理种群的潜力,但仍需深入研究。研究结果深化了对北部湾球形棕囊藻遗传多样性的认识,有望为进一步解析北部湾海域球形棕囊藻赤潮原因种来源提供判据。更多还原

【Abstract】 Red tides of Phaeocystis globosa were recorded in the Beibu Gulf, the South China Sea in the last five years,posing significant impacts on marine environment and ecosystems. P. globosa is a major red-tide causative species,distributes from temperate to tropical waters around the world, and features rich intraspecies genetic diversity. To understand the status of genetic diversity of P. globosa in the Beibu Gulf and its potential role to reveal the origin of red-tide-forming P. globosa, four strains of Phaeocystis were isolated from the gulf during Phaeocystis blooms from 2015 to 2017 and examined. Targeting at the 28 S ribosomal rRNA gene(28 SrDNA) and the ITS region, clone libraries were established for the four strains of P. globosa and sequenced. Based on the phylogenetic analysis of the 28 D1—D2 region and ITS region, all of the four strains of Phaeocystis could be identified as P. globosa, and significant genetic diversity was revealed in P. globosa. Strains isolated at different years from the Beibu Gulf had different genetic information. High genetic diversity was found not only among strains of P. globosa but also within a clone culture established from a single cell of P. globosa. It implies that the genetic diversity of some P. globosa strains exists within multiple copies of targeted genes within a single cell, which is probably due to the gene exchange among different geographical populations of P. globosa. Compared to the ITS region, the 28 SrDNA D1—D2 region is a better choice to represent the intraspecies genetic diversity of P. globosa. The results primarily revealed the genetic diversity of P. globosa in the Beibu Gulf and will provide important clues of the origination of bloom-forming P. globosa in the Beibu Gulf.更多还原