Gu Haifeng, Huang Shuning, Krock Bernd, Leaw Chui Pin, Lim Po Teen, Kassim Nur Shazwani, Shin Hyeon Ho, Roeroe Kakaskasen Andreas, Yuan Hao, Hosny Shimaa, Sasai Rimi, Takahashi Kazuya, Thoha Hikmah, Hamzah Faisal, Ha Dao Viet, Potisarn Nantapak, Lirdwitayaprasit Thaithaworn, Iwataki Mitsunori
Key Laboratory of Marine Ecological Conservation and Restoration, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China; Nansha Islands Coral Reef Ecosystem National Observation and Research Station, Guangzhou 510300, Guangdong Province, China.
Key Laboratory of Marine Ecological Conservation and Restoration, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China.
Harmful Algae. 2025 Nov;149:102934. doi: 10.1016/j.hal.2025.102934. Epub 2025 Jul 23.
The dinoflagellate genus Amphidinium encompasses several toxic species known to cause harmful algal blooms. Despite their ecological significance, the diversity within this genus may be underestimated due to the morphological similarities among species. In this study, we established 82 strains of Amphidinium by isolating single cells from the Asia-Pacific region. We examined their morphology using light and transmission electron microscopy. Additionally, we obtained partial sequences of the large subunit ribosomal (LSU) DNA and/or internal transcribed spacer regions for all strains. Furthermore, DNA metabarcoding targeting the LSU D1-D2 region was employed to detect species in the Bohai Sea, Yellow Sea, Mediterranean Sea, and Red Sea, where strain data is limited. The 82 strains were classified into 13 Amphidinium species. Among these were four undescribed species, provisionally named Amphidinium sp. 1 to Amphidinium sp. 4, as well as A. cupulatisquama, A. fijiensis, A. gibbosum, A. massartii, A. operculatum, A. pseudomassartii, A. thermaeum, A. tomasii, and A. trulla, based on both morphological and molecular analyses. DNA metabarcoding detected nine Amphidinium species. While Amphidinium gibbosum and A. tomasii are confined to tropical and warm subtropical waters, the other species exhibit a broader distribution. Molecular phylogenetic analysis revealed two distinct clades within the genus Amphidinium. Species in clade A, including A. uduigamense, A. stirisquamtum, A. operculatum, Amphidinium sp. 1, and Amphidinium sp. 2, share a characteristic sulcus that originates in the posterior one-third of the hypocone. In contrast, species in clade B are characterized by a sulcus that originates in the anterior or middle part of the cell. Additionally, amphidinol analysis was conducted on ten strains of five Amphidinium species using liquid chromatography-tandem mass spectrometry (LC-MS/MS), but amphidinols were below the detection limit. However, one strain of A. massartii produces a new amphidinol variant with a molecular mass of 1402.7 Da (34.47 fg cell) and hemolysis assays suggest the potential presence of novel amphidinols or related compounds in A. operculatum. Our findings underscore the significant diversity and potential risk posed by Amphidinium species in the Asia-Pacific region and beyond.
扁藻属（Amphidinium）的甲藻包含几种已知会引发有害藻华的有毒物种。尽管它们具有生态重要性，但由于物种间形态相似，该属内的多样性可能被低估。在本研究中，我们通过从亚太地区分离单细胞建立了82株扁藻。我们使用光学显微镜和透射电子显微镜检查了它们的形态。此外，我们获得了所有菌株的大亚基核糖体（LSU）DNA和/或内部转录间隔区的部分序列。此外，针对LSU D1-D2区域的DNA宏条形码技术被用于检测渤海、黄海、地中海和红海的物种，这些地区的菌株数据有限。这82株菌株被分为13种扁藻。其中有4个未描述的物种，暂命名为扁藻1号至扁藻4号，以及基于形态学和分子分析的杯状扁藻（A. cupulatisquama）、斐济扁藻（A. fijiensis）、驼背扁藻（A. gibbosum）、马萨尔蒂扁藻（A. massartii）、有盖扁藻（A. operculatum）、假马萨尔蒂扁藻（A. pseudomassartii）、温泉扁藻（A. thermaeum）、托马西扁藻（A. tomasii）和粗短扁藻（A. trulla）。DNA宏条形码技术检测到9种扁藻。虽然驼背扁藻和托马西扁藻局限于热带和温暖的亚热带水域，但其他物种分布更广。分子系统发育分析揭示了扁藻属内两个不同的进化枝。进化枝A中的物种，包括乌迪加门扁藻（A. uduigamense）、条纹扁藻（A. stirisquamtum）、有盖扁藻、扁藻1号和扁藻2号，具有一个共同特征，即沟起源于下锥的后三分之一处。相比之下，进化枝B中的物种的特征是沟起源于细胞的前部或中部。此外，使用液相色谱-串联质谱（LC-MS/MS）对5种扁藻的10株菌株进行了扁藻毒素分析，但扁藻毒素低于检测限。然而，一株马萨尔蒂扁藻产生了一种新的扁藻毒素变体，分子量为1402.7 Da（每细胞34.47 fg），溶血试验表明有盖扁藻中可能存在新的扁藻毒素或相关化合物。我们的研究结果强调了亚太地区及其他地区扁藻物种的显著多样性和潜在风险。
