State-transitions facilitate robust quantum yields and cause an over-estimation of electron transport in Dunaliella tertiolecta cells held at the CO2 compensation point and re-supplied with DIC
State-transitions facilitate robust quantum yields and cause an over-estimation of electron transport in Dunaliella tertiolecta cells held at the CO2 compensation point and re-supplied with DIC
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DOI：
10.1007/s11120-013-9937-8
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发表时间：
2014-03-01
影响因子：
3.7
通讯作者：
Silsbe, Greg M.
中科院分区：
文献类型：
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作者：
Ihnken, Sven;Kromkamp, Jacco C.;Silsbe, Greg M.
光合能量消耗和非光合能量猝灭过程具有内在联系。这两个过程都必须由细胞控制，以使细胞维持和生长，同时也避免光损伤。以绿藻Dunaliella terolecta为研究对象，研究了光合和非光合途径的相互调节如何随溶解无机碳（DIC）和光子通量梯度变化。具体来说，细胞被转移到缺乏DIC的介质中，以达到二氧化碳补偿，然后再被提供不同浓度和不同光子通量水平的DIC。在这些实验中，我们使用脉冲振幅调制荧光、析氧、77 K荧光发射光谱和快速重复率荧光法监测和表征了光生理反应。在DIC耗竭条件下，对O-2的吸收没有显著刺激，这表明O-2的产生速率与同化光合作用相对应。基于荧光的相对电子传递速率（rets）测量高估了基于氧的光合作用测量，因为强的状态过渡响应促进了高有效量子产率。采用另一种基于荧光的rETR计算，该计算考虑了状态转换，从而改善了线性氧与rETR的相关性。本研究显示了D. tertiolecta通过灵活调节状态转变来保持稳定有效量子产率的非凡能力。给出了状态转移控制机制的不确定性。
Photosynthetic energy consumption and non-photosynthetic energy quenching processes are inherently linked. Both processes must be controlled by the cell to allow cell maintenance and growth, but also to avoid photodamage. We used the chlorophyte algae Dunaliella tertiolecta to investigate how the interactive regulation of photosynthetic and non-photosynthetic pathways varies along dissolved inorganic carbon (DIC) and photon flux gradients. Specifically, cells were transferred to DIC-deplete media to reach a CO2 compensation before being re-supplied with DIC at various concentrations and different photon flux levels. Throughout these experiments we monitored and characterized the photophysiological responses using pulse amplitude modulated fluorescence, oxygen evolution, 77 K fluorescence emission spectra, and fast-repetition rate fluorometry. O-2 uptake was not significantly stimulated at DIC depletion, which suggests that O-2 production rates correspond to assimilatory photosynthesis. Fluorescence-based measures of relative electron transport rates (rETRs) over-estimated oxygen-based photosynthetic measures due to a strong state-transitional response that facilitated high effective quantum yields. Adoption of an alternative fluorescence-based rETR calculation that accounts for state-transitions resulted in improved linear oxygen versus rETR correlation. This study shows the extraordinary capacity of D. tertiolecta to maintain stable effective quantum yields by flexible regulation of state-transitions. Uncertainties about the control mechanisms of state-transitions are presented.