Changes in Relative Thylakoid Protein Abundance Induced by Fluctuating Light in the Diatom Thalassiosira pseudonana

One of the hallmarks of marine diatom biology is their ability to cope with rapid changes in light availability due to mixing of the water column and the lens effect. We investigated how irradiance fluctuations influence the relative abundance of key photosynthetic proteins in the centric diatom Thalassiosira pseudonana by means of mass-spectrometry-based approaches for relative protein quantitation. Most notably, fluctuating-light conditions lead to a substantial overall up-regulation of light-harvesting complex proteins as well as several subunits of photosystems II and I. Despite an initial delay in growth under FL, there were no indications of FL-induced photosynthesis limitation, in contrast to other photosynthetic organisms. Our findings further strengthen the notion that diatoms use a qualitatively different mechanism of photosynthetic regulation in which chloroplast–mitochondria interaction has overtaken crucial regulatory processes of photosynthetic light reactions that are typical for the survival of land plants, green algae, and cyanobacteria.海洋硅藻生物学的标志性特征之一，是其能够应对因水体混合与透镜效应导致的辐照度快速变化。本研究采用基于质谱的相对蛋白定量技术，探究了辐照度波动对中心硅藻假微型海链藻（Thalassiosira pseudonana）内关键光合蛋白相对丰度的影响。尤为值得关注的是，波动辐照条件会全面显著上调光捕获复合体蛋白，以及光系统II与光系统I的多个亚基。尽管在波动辐照（FL，fluctuating light）条件下初始生长存在延迟，但与其他光合生物不同，本研究未观测到波动辐照诱导的光合受限迹象。本研究结果进一步佐证了这一论点：硅藻采用了本质迥异的光合调控机制——其叶绿体-线粒体相互作用已取代了陆生植物、绿藻与蓝藻维持生存所必需的典型光合光反应调控过程。