Ma Xiao, Qin Zhen, Johnson Kevin B, Sweat L Holly, Dai Sheng, Li Gang, Li Chaolun
Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.
Guangdong Province Key Laboratory of Applied Marine Biology, Guangzhou, China.
Front Microbiol. 2024 Aug 14;15:1437274. doi: 10.3389/fmicb.2024.1437274. eCollection 2024.
Light and nitrogen availability are basic requirements for photosynthesis. Changing in light intensity and nitrogen concentration may require adaptive physiological and life process changes in phytoplankton cells. Our previous study demonstrated that two species exhibited, respectively, distinctive physiological responses to light and nitrogen stresses. Transcriptomic analyses were employed to investigate the mechanisms behind the different physiological responses observed in two diatom species of the genus . The results indicate that the congeneric species are different in their cellular responses to the same shifting light and nitrogen conditions. When conditions changed to high light with low nitrate (HLLN), the large-celled was photodamaged. Thus, the photosynthesis pathway and carbon fixation related genes were significantly down-regulated. In contrast, the small-celled sacrificed cellular processes, especially amino acid metabolisms, to overcome the photodamage. When changing to high light with high nitrate (HLHN) conditions, the additional nitrogen appeared to compensate for the photodamage in the large-celled , with the tricarboxylic acid cycle (TCA cycle) and carbon fixation significantly boosted. Consequently, the growth rate of increased, which suggest that the larger-celled species is adapted for forming post-storm algal blooms. The impact of high light stress on the small-celled was not mitigated by elevated nitrate levels, and photodamage persisted.
光照和氮素供应是光合作用的基本需求。光照强度和氮浓度的变化可能需要浮游植物细胞进行适应性的生理和生命过程改变。我们之前的研究表明，两个物种分别对光照和氮胁迫表现出独特的生理反应。采用转录组分析来探究在该属的两种硅藻中观察到的不同生理反应背后的机制。结果表明，同属物种在对相同的光照和氮条件变化的细胞反应上存在差异。当条件变为高光低硝酸盐（HLLN）时，大细胞的 受到光损伤。因此，光合作用途径和碳固定相关基因显著下调。相比之下，小细胞的 牺牲细胞过程，尤其是氨基酸代谢，以克服光损伤。当转变为高光高硝酸盐（HLHN）条件时，额外的氮似乎补偿了大细胞 的光损伤，三羧酸循环（TCA循环）和碳固定显著增强。因此， 的生长速率增加，这表明较大细胞的物种适合在风暴后形成藻华。高光胁迫对小细胞 的影响并未因硝酸盐水平升高而减轻，光损伤持续存在。
