Davis Geoffry A, Rutherford A William, Kramer David M
Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA.
Cell and Molecular Biology Graduate Program, Michigan State University, East Lansing, MI 48824, USA.
Philos Trans R Soc Lond B Biol Sci. 2017 Sep 26;372(1730). doi: 10.1098/rstb.2016.0381.
There is considerable interest in improving plant productivity by altering the dynamic responses of photosynthesis in tune with natural conditions. This is exemplified by the 'energy-dependent' form of non-photochemical quenching (), the formation and decay of which can be considerably slower than natural light fluctuations, limiting photochemical yield. In addition, we recently reported that rapidly fluctuating light can produce field recombination-induced photodamage (FRIP), where large spikes in electric field across the thylakoid membrane (Δ) induce photosystem II recombination reactions that produce damaging singlet oxygen (O). Both and FRIP are directly linked to the thylakoid proton motive force (), and in particular, the slow kinetics of partitioning into its ΔpH and Δ components. Using a series of computational simulations, we explored the possibility of 'hacking' partitioning as a target for improving photosynthesis. Under a range of illumination conditions, increasing the rate of counter-ion fluxes across the thylakoid membrane should lead to more rapid dissipation of Δ and formation of ΔpH. This would result in increased rates for the formation and decay of while resulting in a more rapid decline in the amplitudes of Δ-spikes and decreasing O production. These results suggest that ion fluxes may be a viable target for plant breeding or engineering. However, these changes also induce transient, but substantial mismatches in the ATP : NADPH output ratio as well as in the osmotic balance between the lumen and stroma, either of which may explain why evolution has not already accelerated thylakoid ion fluxes. Overall, though the model is simplified, it recapitulates many of the responses seen , while spotlighting critical aspects of the complex interactions between components and photosynthetic processes. By making the programme available, we hope to enable the community of photosynthesis researchers to further explore and test specific hypotheses.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'.
通过调整光合作用的动态响应以适应自然条件来提高植物生产力引起了人们的广泛关注。这一点在非光化学猝灭的“能量依赖”形式（）中得到了体现，其形成和衰减速度可能比自然光波动慢得多，从而限制了光化学产量。此外，我们最近报道，快速波动的光会产生场重组诱导的光损伤（FRIP），其中类囊体膜上的电场大幅峰值（Δ）会诱导光系统II重组反应，产生具有破坏性的单线态氧（O）。和FRIP都与类囊体质子动力势（）直接相关，特别是，向其ΔpH和Δ组分分配的缓慢动力学。通过一系列计算模拟，我们探索了“破解”分配作为改善光合作用目标的可能性。在一系列光照条件下，增加跨类囊体膜的抗衡离子通量速率应会导致Δ更快地耗散和ΔpH的形成。这将导致形成和衰减的速率增加，同时导致Δ峰值幅度更快下降并减少O的产生。这些结果表明离子通量可能是植物育种或工程的一个可行目标。然而，这些变化也会在ATP:NADPH输出比率以及类囊体腔和基质之间的渗透平衡中引起短暂但显著的不匹配，这两者都可能解释为什么进化尚未加速类囊体离子通量。总体而言，尽管该模型较为简化，但它概括了许多观察到的响应，同时突出了组分与光合过程之间复杂相互作用的关键方面。通过提供该程序，我们希望能让光合作用研究人员群体进一步探索和测试具体假设。本文是主题为“提高作物光合作用：改进目标”特刊的一部分。
