中国近海铜藻ITS与coxⅠ序列相似性分析

Analysis of the Similarity of ITS and cox I Sequences of Sargassum horneri Along the Offshore of China

本研究分别对2016和2017年中国近海10个铜藻(Sargassumhorneri)漂浮地理种群以及3个定生种群的51个采集样本进行了ITS和coxⅠ序列分析及相似性比对。结果显示,51个样本的coxⅠ序列完全一致,ITS序列存在2个变异位点,按基因型的异同可分为4个类型,其中大连龙王塘、烟台大钦岛和南隍城岛的漂浮铜藻基因型相同,青岛金沙滩漂浮型、烟台大钦岛和大连獐子岛的定生铜藻基因型相同,威海俚岛和温州洞头的漂浮铜藻基因型相同,青岛雕塑园、王哥庄、大珠山、威海乳山的漂浮型和枸杞岛定生铜藻基因型相同,而同一种群内部即便是不同年份的个体间基因型并没有差异。基于ITS序列构建的系统树显示,来自中国的所有铜藻样本聚为一支,与来自韩国的铜藻样本有一定的遗传距离。以上结果说明,我国近海漂浮和定生铜藻的不同地理株间ITS和coxⅠ的遗传变异水平较低,漂浮铜藻可能具有不同的来源,为进一步探明中国近海海域铜藻的分子遗传背景提供依据。

Large-scale green tides have broken out annually in the Yellow Sea since2007,which, upon twinning with floating Sargassum horneri,became a new hazard and increased the difficulty of preventing and controlling the green tide in Shandong Peninsula.In this study,the similarity of1TS and coxI sequences were analyzed using S.horneri samples collected from ten free-floating populations and three benthic populations in2016and2017along the offshore of China.The results showed that the coxI sequences of51samples were consistent,while there were two variable nucleotide sites within the ITS sequence.Based on genotypic differences,S.horneri samples could be sorted into four categories,among which the genotype of free-floating samples from Dalian Longwangtang,Daqin Island,and Nanhuangcheng Island of Yantai were identical.Free-floating samples from the Golden Beach of Qingdao and benthic samples from Daqin Island of Yantai and Zhangzi Island of Dalian were identical; free-floating samples from Lidao of Weihai and Dongtou of Wenzhou were identical;and free-floating samples from the Sculpture Garden,Wanggezhuang,Dazhushan of Qingdao,Rushan of Weihai,and benthic samples from Gouqi Island were identical.However,there was no difference in genotype among individuals within the same population,even among those occurring in different years.A phylogenetic tree based on ITS sequences of S.horneri showed that samples from China were clustered.together; however,there was some genetic distance from the Korean samples.It is possible that the genetic variation of1TS and coxI regions is low in different coastal strains of S.horneri,and that drifting population could be of different origins.These findings will provide a basis for further understanding of the molecular genetic background of S.horneri along the offshore of China.