Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, United States.
Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, United States; Department of Biology, Stanford University, Stanford, CA 94305-5020, United States.
Curr Opin Plant Biol. 2017 Oct;39:114-122. doi: 10.1016/j.pbi.2017.06.002. Epub 2017 Jul 7.
Photosynthetic organisms have evolved to modulate their metabolism to accommodate the highly dynamic light and nutrient conditions in nature. In this review we discuss ways in which the green alga Chlamydomonas reinhardtii acclimates to nitrogen and sulfur deprivation, conditions that would limit the anabolic use of excitation energy because of a markedly reduced capacity for cell growth and division. Major aspects of this acclimation process are stringently regulated and involve scavenging the limited nutrient from internal and external sources, and the redirection of fixed carbon toward energy storage (e.g. starch, oil). However, photosynthetic organisms have also evolved mechanisms to dissipate excess absorbed light energy, and to eliminate potentially dangerous energetic electrons through the reduction of O and H to HO; this reduction can occur both through photosynthetic electron transport (e.g. Mehler reaction, chlororespiration) and mitochondrial respiration. Furthermore, algal cells likely exploit other energy management pathways that are currently not linked to nutrient limitation responses or that remain to be identified.
光合生物已经进化出了调节代谢的能力，以适应自然中高度动态的光照和养分条件。在这篇综述中，我们讨论了绿藻莱茵衣藻适应氮和硫缺乏的方式，在这些条件下，由于细胞生长和分裂能力明显下降，会限制合成代谢对激发能的利用。这种适应过程的主要方面受到严格调控，涉及从内部和外部来源中清除有限的养分，并将固定碳重新定向到能量储存（例如淀粉、油）。然而，光合生物也进化出了消耗过量吸收的光能的机制，并通过将 O 和 H 还原为 HO 来消除潜在的危险高能电子；这种还原可以通过光合作用电子传递（例如 Mehler 反应、光呼吸）和线粒体呼吸来实现。此外，藻类细胞可能还利用了其他目前与营养限制反应无关或尚未确定的能量管理途径。
