北部湾卡盾藻(Chattonella spp.)种类鉴定

2018年9月在北部湾海域分离得到3株卡盾藻，采用光学显微镜对其进行形态学初步鉴定，并通过核糖体大亚基LSU rDNA和ITS基因进行系统进化分析。结果表明，卡盾藻北部湾株符合海洋卡盾藻形态学典型特征:藻体黄褐色，细胞呈纺锤形，无黏液泡，尾部具尖端，细胞平均长（57.8±9.1）μm。系统发育树上北部湾卡盾藻分别以96%（LSU rDNA）和99%（ITS）的自展支持率与不同来源的海洋卡盾藻、古老卡盾藻、卵圆卡盾藻、小型卡盾藻聚在同一大分支上。通过遗传距离分析发现，北部湾3株卡盾藻与不同来源的海洋卡盾藻、古老卡盾藻、卵圆卡盾藻、小型卡盾藻亲缘关系较近，LSU和ITS遗传距离分别为0.0000~0.0016和0.0000~0.0235；而与盐生卡盾藻亲缘关系较远，遗传距离分别为0.0415~0.0490和0.0733~0.0750。因此，综合形态学和分子生物学结果可以确定北部湾3株卡盾藻为海洋卡盾藻/海洋卡盾藻的变种。研究结果可为我国卡盾藻藻华藻种库的构建和卡盾藻北部湾株生理生态学的研究提供基础数据。

Identification of strains of Chattonella spp. from the Beibu Gulf

Three strains of Chattonella spp. were isolated from the Beibu Gulf in September 2018 and were identified using light microscopy and phylogenetic analysis based on LSU rDNA and ITS gene sequencing. Results show that the Chattonella spp. strains from the Beibu Gulf are yellowish-brown; the cells are spindle-shaped with a pointed posterior end, and mucocysts are absent; the average cell length is (57.8±9.1) μm. These characteristics are consistent with the typical morphological characteristics of C. marina. In phylogenetic trees, the strains from the Beibu Gulf were clustered with C. marina, C. antiqua, C. ovata, and C. minima, with bootstrap value of 96% and 99% for LSU rDNA and ITS, respectively. Genetic distance analysis demonstrated that the three Chattonella spp. strains in the Beibu Gulf were closely related to C. marina, C. antiqua, C. ovata, and C. minima with genetic distances of 0.0000~0.0016 and 0.0000~0.0235, while being distantly related to C. subsalsa with genetic distances of 0.0415~0.0490 and 0.0733~0.0750 for LSU rDNA and ITS, respectively. Therefore, our comprehensive morphological and molecular biology methods suggested that the three strains of Chattonella spp. in the Beibu Gulf belonged to C. marina/C. marina var. antiqua/C. marina var. ovata. This study is helpful for Chattonella collection in the Beibu Gulf and will support further ecophysiological studies.