College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Key Laboratory of Marine Environment and Ecology, Ocean University of China, Qingdao 266100, China.
College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
Sci Total Environ. 2024 Feb 10;911:168759. doi: 10.1016/j.scitotenv.2023.168759. Epub 2023 Nov 21.
Phosphorus (P) is an essential macronutrient impacting bloom formation of marine dinoflagellates. The dinoflagellate Alexandrium pacificum is a cosmopolitan species known to frequently cause dense blooms in estuarine and coastal waters worldwide, while the physiological and molecular responses of A. pacificum to P utilization are still not well understood. Herein, the growth, P utilization, toxin production and transcriptomes of A. pacificum grown under P-deficient, inorganic P-replete, and organic P-replete conditions were compared. The results indicated that P-deficient adversely affected the growth of A. pacificum and significantly down-regulated the expression of genes related to P transport and material metabolism, but enhanced the production of toxin. On the other hand, no significant differences were observed in growth and toxin production between the organic and inorganic P-replete treatments. However, genes involved in P transport, utilization and TCA cycle were significantly changed in the organic P-replete compared with the inorganic P-replete group, and the mechanisms underlying the use of various organic P compounds were different. These findings suggested that A. pacificum evolved diverse organic P utilization strategies to adapt to low P conditions, which might be a crucial factor driving bloom formation in a low inorganic P environment.
磷（P）是一种必需的大量营养素，会影响海洋甲藻的繁殖。太平洋甲藻是一种世界性的物种，已知其在全球的河口和沿海水域中经常引发密集的繁殖，而太平洋甲藻对 P 利用的生理和分子反应仍未得到很好的理解。在此，比较了在缺磷、无机磷充足和有机磷充足条件下生长的太平洋甲藻的生长、P 利用、毒素产生和转录组。结果表明，缺磷会对太平洋甲藻的生长产生不利影响，并显著下调与 P 运输和物质代谢相关的基因表达，但会增强毒素的产生。另一方面，在有机磷充足和无机磷充足处理之间，生长和毒素产生没有明显差异。然而，与无机磷充足组相比，有机磷充足组中与 P 运输、利用和 TCA 循环相关的基因发生了显著变化，并且利用各种有机 P 化合物的机制不同。这些发现表明，太平洋甲藻进化出了多种有机 P 利用策略来适应低 P 条件，这可能是在低无机 P 环境中形成繁殖的关键因素。
