Niu Yuxi, Fuente David, Matsubara Shizue, Lazár Dušan, Nedbal Ladislav
Institute of Bio- and Geosciences/Plant Sciences (IBG-2), Jülich, Germany.
Department of Biophysics, Wageningen University and Research, Wageningen, the Netherlands.
Physiol Plant. 2025 Jul-Aug;177(4):e70421. doi: 10.1111/ppl.70421.
The rate of net CO uptake is proportional to dim light and saturates when the light exceeds the plant's assimilation capacity. This simple relationship between constant light and photosynthesis becomes intriguingly complex when the light oscillates. The rates of photosynthesis may differ between the descending and ascending phases of light oscillation. This hysteresis changes with the frequency and amplitude of the light and reports on the dynamics of the photosynthetic reactions and their regulation. Here, we investigated the chlorophyll fluorescence response of Arabidopsis thaliana to light oscillating with three different amplitudes: 100-200, 100-400, and 100-800 μmol photons m s, each with periods ranging from 1 s to 8 min. The light amplitudes and periods were chosen to represent light patterns often appearing in nature. Three genotypes were compared: wild-type Col-0 and npq1 and npq4 mutants that are incapacitated in the rapidly reversible energy-dependent non-photochemical quenching (qE). The experiments identified two major dynamic patterns. One was found in oscillation periods shorter than 30 s, characterized by constitutive hysteresis and non-linearity. The other was mainly formed by regulatory hysteresis, occurring when the oscillation periods were longer than 30 s. The mathematical model simulating the chlorophyll fluorescence dynamics qualitatively reproduced the constitutive and regulatory dynamic patterns observed in the experiments. The model simulations illustrated the dynamics of plastoquinone pool reduction and variables affecting non-photochemical quenching that form the constitutive and regulatory hysteresis types. The model simulations provided mechanistic insights into molecular processes forming the plant response to oscillating light.
净二氧化碳吸收速率与弱光成正比，当光照超过植物的同化能力时达到饱和。当光照振荡时，这种恒定光照与光合作用之间的简单关系变得异常复杂。光合作用速率在光照振荡的下降和上升阶段可能有所不同。这种滞后现象随光照的频率和幅度而变化，并反映了光合反应及其调节的动态过程。在此，我们研究了拟南芥对三种不同幅度振荡光照的叶绿素荧光响应：100 - 200、100 - 400和100 - 800 μmol光子·m⁻²·s⁻¹，每个幅度的周期范围为1秒至8分钟。选择这些光照幅度和周期来代表自然界中经常出现的光照模式。比较了三种基因型：野生型Col - 0以及npq1和npq4突变体，它们在快速可逆的能量依赖性非光化学猝灭（qE）方面存在缺陷。实验确定了两种主要的动态模式。一种出现在振荡周期短于30秒的情况下，其特征是具有组成型滞后和非线性。另一种主要由调节型滞后形成，发生在振荡周期长于30秒时。模拟叶绿素荧光动力学的数学模型定性地再现了实验中观察到的组成型和调节型动态模式。模型模拟说明了质体醌库还原的动态过程以及影响形成组成型和调节型滞后类型的非光化学猝灭的变量。模型模拟为形成植物对振荡光照响应的分子过程提供了机制性见解。
