University of Hamburg, Institute of Plant Science and Microbiology, Aquatic Ecophysiology and Phycology, Hamburg, Germany.
Alfred-Wegener-Institute Helmholtz-Centre for Polar and Marine Research, Scientific Computing, Bremerhaven, Germany.
Sci Rep. 2019 Jul 22;9(1):10559. doi: 10.1038/s41598-019-47041-7.
Light is a key environmental regulator in all photosynthetic organisms. Many studies focused on the physiologic response to changes in light availability of species from the Zygnematophyceae, but the impact of the absence of light and the molecular acclimation process on the other side have been poorly understood. Here we present transcriptomic analyses of Cosmarium crenatum from a polar habitat exposed to darkness. The algae were cultured in dark for one week; cell number and quantum yield of photosystem II (Fv/Fm) were monitored. Cell number was stable, but the Fv/Fm decreased in both groups, darkness-treated and control. Gene expression analysis revealed a strong repression of transcripts associated with photosynthesis, photorespiration and cell wall development. General carbohydrate and lipid metabolism were differentially regulated, but starch is shown to be the primary energy source in these conditions. Additionally, C. crenatum induced mRNA responsible for epigenetic modifications which may be a specific response to an adaption and acclimation to polar conditions. Our study sheds light on the molecular acclimation process to darkness and provides ecological implications for new perspectives in this specialized group of green algae.
光是所有光合生物的关键环境调节因子。许多研究都集中在研究来自绿藻门物种对光照变化的生理反应，但对光照缺失的影响以及分子适应过程的了解甚少。在这里，我们展示了来自极地生境的 Cosmarium crenatum 在黑暗中暴露的转录组分析。藻类在黑暗中培养了一周；监测了细胞数量和光系统 II 的量子产量 (Fv/Fm)。细胞数量保持稳定，但两组（黑暗处理组和对照组）的 Fv/Fm 均下降。基因表达分析显示，与光合作用、光呼吸和细胞壁发育相关的转录物受到强烈抑制。一般碳水化合物和脂质代谢受到不同程度的调节，但淀粉在这些条件下被证明是主要的能量来源。此外，C. crenatum 诱导了与表观遗传修饰相关的 mRNA，这可能是对适应和适应极地条件的特定反应。我们的研究阐明了对黑暗的分子适应过程，并为这个特殊的绿藻群体提供了新的生态见解。
