Lee Tsung-Yen, Lam Lam, Patel-Tupper Dhruv, Lam Henry E, Niyogi Krishna K, Fleming Graham R
Department of Chemistry, University of California, Berkeley, California 94720, United States.
Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
J Phys Chem Lett. 2025 Jul 24;16(29):7352-7358. doi: 10.1021/acs.jpclett.5c01473. Epub 2025 Jul 14.
Non-photochemical quenching (NPQ) protects plants from excess light by dissipating excitation energy as heat. Limited exciton migration is a key feature of NPQ, reducing the energy flux to reaction centers; however, quantitative evidence for this mechanism in native thylakoid membranes has been lacking. Here, we investigate the correlation between NPQ activity and exciton diffusion length () using mutants with distinct NPQ capacities. NPQ under both light- and dark-acclimated conditions was quantified for each genotype via fluorescence lifetime snapshots, and exciton mobility was probed using transient absorption spectroscopy with exciton-exciton annihilation analysis. By comparing the relationship between chlorophyll fluorescence lifetime and across mutants, we observed that NPQ activation quantitatively limits the spatial range of exciton migration, thereby reducing the access to reaction centers. Our findings provide direct experimental evidence that NPQ modulates the dynamics of energy transport, advancing our understanding of photoprotective regulation in photosynthetic systems.
非光化学猝灭（NPQ）通过将激发能以热的形式耗散来保护植物免受过量光照的影响。有限的激子迁移是NPQ的一个关键特征，它减少了流向反应中心的能量通量；然而，在天然类囊体膜中，这种机制的定量证据一直缺乏。在这里，我们使用具有不同NPQ能力的突变体研究NPQ活性与激子扩散长度（）之间的相关性。通过荧光寿命快照对每种基因型在光适应和暗适应条件下的NPQ进行定量，并使用具有激子 - 激子湮灭分析的瞬态吸收光谱探测激子迁移率。通过比较突变体之间叶绿素荧光寿命与的关系，我们观察到NPQ激活在定量上限制了激子迁移的空间范围，从而减少了对反应中心的能量传递。我们的研究结果提供了直接的实验证据，表明NPQ调节能量传输的动态过程，增进了我们对光合系统中光保护调节的理解。
