Department of Biochemistry and Center for Plant Biology, Purdue University, West Lafayette, IN, 47907, USA.
Photosynth Res. 2021 Mar;147(3):317-328. doi: 10.1007/s11120-020-00811-1. Epub 2021 Jan 2.
Diatoms are a diverse group of photosynthetic unicellular algae with a plastid of red-algal origin. As prolific primary producers in the ocean, diatoms fix as much carbon as all rainforests combined. The molecular mechanisms that contribute to the high photosynthetic productivity and ecological success of diatoms are however not yet fully understood. Using the model diatom Phaeodactylum tricornutum, here we show rhythmic transcript accumulation of plastid psaA, psbA, petB, and atpB genes as driven by a free running circadian clock. Treatment with the electron transport inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea overrides the circadian signal by markedly downregulating transcription of psaA, petB, and atpB genes but not the psbA gene. Changes in light quantity produce little change in plastid gene transcription while the effect of light quality seems modest with only the psaA gene responding in a pattern that is dependent on the redox state of the plastoquinone pool. The significance of these plastid transcriptional responses and the identity of the underlying genetic control systems are discussed with relevance to diatom photosynthetic acclimation.
硅藻是一类具有红藻起源质体的光合单细胞藻类，种类繁多。作为海洋中生产力极高的初级生产者，硅藻固定的碳量与所有热带雨林加起来一样多。然而，硅藻高光合作用生产力和生态成功的分子机制尚未完全理解。在这里，我们使用模式硅藻三角褐指藻（Phaeodactylum tricornutum）表明，质体 psaA、psbA、petB 和 atpB 基因的转录积累是由自由运行的生物钟驱动的。用电子传递抑制剂 3-(3,4-二氯苯基)-1,1-二甲基脲处理会通过显著下调 psaA、petB 和 atpB 基因的转录而消除生物钟信号，但 psbA 基因不受影响。光量的变化对质体基因转录的影响很小，而光质的影响似乎不大，只有 psaA 基因的反应模式依赖于质体醌库的氧化还原状态。这些质体转录反应的意义以及潜在的遗传控制系统的身份与硅藻光合作用适应有关。
