Key Laboratory of Aquatic Eutrophication and Control of Harmful Algal Blooms of Guangdong Higher Education Institute, College of Life Science and Technology, Jinan University, Guangzhou 510632, China; College of Food Science and Engineering, Foshan University of Science and Technology, Foshan 528231, China.
Key Laboratory of Aquatic Eutrophication and Control of Harmful Algal Blooms of Guangdong Higher Education Institute, College of Life Science and Technology, Jinan University, Guangzhou 510632, China.
Harmful Algae. 2023 Jul;126:102441. doi: 10.1016/j.hal.2023.102441. Epub 2023 May 3.
Karenia mikimotoi and Prorocentrum shikokuense (also identified as P. donghaiense Lu and P. obtusidens Schiller) are two important harmful algal species which often form blooms in the coasts of China. Studies have shown that the allelopathy of K. mikimotoi and P. shikokuense plays an important role in inter-algal competition, though the underlying mechanisms remain largely unclear. Here, we observed reciprocal inhibitory effects between K. mikimotoi and P. shikokuense under co-cultures. Based on the reference sequences, we isolated RNA sequencing reads of K. mikimotoi and P. shikokuense from co-culture metatranscriptome, respectively. We found the genes involved in photosynthesis, carbon fixation, energy metabolism, nutrients absorption and assimilation were significantly up-regulated in K. mikimotoi after co-cultured with P. shikokuense. However, genes involved in DNA replication and cell cycle were significantly down-regulated. These results suggested that co-culture with P. shikokuense stimulated cell metabolism and nutrients competition activity of K. mikimotoi, and inhibited cell cycle. In contrast, genes involved in energy metabolism, cell cycle and nutrients uptake and assimilation were dramatically down-regulated in P. shikokuense under co-culture with K. mikimotoi, indicating that K. mikimotoi could highly affect the cellular activity of P. shikokuense. In addition, the expression of PLA2G12 (Group XII secretory phospholipase A2) that can catalyze the accumulation of linoleic acid or linolenic acid, and nitrate reductase that may be involved in nitric oxide production were significantly increased in K. mikimotoi, suggesting that PLA2G12 and nitrate reductase may play important roles in the allelopathy of K. mikimotoi. Our findings shed new light on the interspecies competition between K. mikimotoi and P. shikokuense, and provide a novel strategy for studying interspecific competition in complex systems.
米氏凯伦藻和东海原甲藻（也被鉴定为 P. 东海原甲藻 Lu 和 P. 钝角藻 Schiller）是两种在中国沿海经常形成赤潮的重要有害藻类。研究表明，米氏凯伦藻和东海原甲藻的化感作用在种间竞争中起着重要作用，尽管其潜在机制仍在很大程度上不清楚。在这里，我们观察到米氏凯伦藻和东海原甲藻在共培养下的相互抑制作用。根据参考序列，我们从共培养宏转录组中分别分离出米氏凯伦藻和东海原甲藻的 RNA 测序reads。我们发现，与单独培养相比，与东海原甲藻共培养后的米氏凯伦藻中参与光合作用、碳固定、能量代谢、营养吸收和同化的基因显著上调。然而，参与 DNA 复制和细胞周期的基因显著下调。这些结果表明，与东海原甲藻共培养刺激了米氏凯伦藻的细胞代谢和营养竞争活性，并抑制了细胞周期。相比之下，与米氏凯伦藻共培养后的东海原甲藻中，参与能量代谢、细胞周期和营养吸收和同化的基因显著下调，表明米氏凯伦藻对东海原甲藻的细胞活性有很大影响。此外，米氏凯伦藻中催化累积亚麻酸或亚油酸的 PLA2G12（XII 分泌型磷脂酶 A2）和可能参与一氧化氮产生的硝酸盐还原酶的表达显著增加，表明 PLA2G12 和硝酸盐还原酶可能在米氏凯伦藻的化感作用中发挥重要作用。我们的研究结果为米氏凯伦藻和东海原甲藻之间的种间竞争提供了新的见解，并为研究复杂系统中的种间竞争提供了新的策略。
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