Petrou Katherina, Kranz Sven A, Doblin Martina A, Ralph Peter J
Plant Functional Biology and Climate Change Cluster and Department of Environmental Sciences, University of Technology, Sydney, PO Box 123, Broadway NSW 2007, AustraliaAlfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, D-27570 Bremerhaven, GermanyPlant Functional Biology and Climate Change Cluster and Department of Environmental Sciences, University of Technology, Sydney, PO Box 123, Broadway NSW 2007, Australia.
J Phycol. 2012 Feb;48(1):127-36. doi: 10.1111/j.1529-8817.2011.01107.x. Epub 2011 Dec 20.
The photosynthetic efficiency and photoprotective capacity of the sea-ice diatom, Fragilariopsis cylindrus (Grunow) W. Krieg., grown in a matrix of nitrogen repletion and depletion at two different temperatures (-1°C and +6°C) was investigated. Temperature showed no significant effect on photosynthetic efficiency or photoprotection in F. cylindrus. Cultures under nitrogen depletion showed enhanced photoprotective capacity with an increase in nonphotochemical quenching (NPQ) when compared with nitrogen-replete cultures. This phenomenon was achieved at no apparent cost to the photosynthetic efficiency of PSII (FV /FM ). Nitrogen depletion yielded a partially reduced electron transport chain in which maximum fluorescence (FM ) could only be obtained by adding 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). reoxidation curves showed the presence of QB nonreducing PSII centers under nitrogen depletion. Fast induction curves (FICs) and electron transport rates (ETRs) revealed slowing of the electrons transferred from the primary (QA ) to the secondary (QB ) quinone electron acceptors of PSII. The data presented show that nitrogen depletion in F. cylindrus leads to the formation of QB nonreducing PSII centers within the photosystem. On a physiological level, the formation of QB nonreducing PSII centers in F. cylindrus provides the cell with protection against photoinhibition by facilitating the rapid induction of NPQ. This strategy provides an important ecological advantage, especially during the Antarctic spring, maintaining photosynthetic efficiency under high light and nutrient-limiting conditions.
研究了在两种不同温度（-1°C和+6°C）下，生长于氮充足和氮缺乏环境中的海冰硅藻——圆柱脆杆藻（Fragilariopsis cylindrus (Grunow) W. Krieg.）的光合效率和光保护能力。温度对圆柱脆杆藻的光合效率或光保护作用没有显著影响。与氮充足的培养物相比，氮缺乏条件下的培养物通过增加非光化学猝灭（NPQ）表现出增强的光保护能力。这种现象在不明显降低PSII光合效率（FV /FM ）的情况下实现。氮缺乏导致电子传递链部分还原，其中只有通过添加3-(3,4-二氯苯基)-1,1-二甲基脲（DCMU）才能获得最大荧光（FM ）。再氧化曲线表明在氮缺乏条件下存在QB非还原型PSII中心。快速诱导曲线（FICs）和电子传递速率（ETRs）显示从PSII的初级（QA ）到次级（QB ）醌电子受体的电子转移减慢。所呈现的数据表明，圆柱脆杆藻中的氮缺乏导致光系统内形成QB非还原型PSII中心。在生理水平上，圆柱脆杆藻中QB非还原型PSII中心的形成通过促进NPQ的快速诱导为细胞提供了免受光抑制的保护。这种策略提供了重要的生态优势，特别是在南极春季，在高光和营养限制条件下维持光合效率。
