Department of Environmental and Prevention Sciences, University of Ferrara, Ferrara.
Physiol Plant. 2022 Jan;174(1):e13604. doi: 10.1111/ppl.13604. Epub 2021 Dec 6.
The Lycophyte Selaginella martensii efficiently acclimates to diverse light environments, from deep shade to full sunlight. The plant does not modulate the abundance of the Light Harvesting Complex II, mostly found as a free trimer, and does not alter the maximum capacity of thermal dissipation (NPQ). Nevertheless, the photoprotection is expected to be modulatable upon long-term light acclimation to preserve the photosystems (PSII, PSI). The effects of long-term light acclimation on PSII photoprotection were investigated using the chlorophyll fluorometric method known as "photochemical quenching measured in the dark" (qP ). Singularly high-qP values at relatively low irradiance suggest a heterogeneous antenna system (PSII antenna uncoupling). The extent of antenna uncoupling largely depends on the light regime, reaching the highest value in sun-acclimated plants. In parallel, the photoprotective NPQ (pNPQ) increased from deep-shade to high-light grown plants. It is proposed that the differences in the long-term modulation in the photoprotective capacity are proportional to the amount of uncoupled LHCII. In deep-shade plants, the inconsistency between invariable maximum NPQ and lower pNPQ is attributed to the thermal dissipation occurring in the PSII core.
石松属植物石松能有效地适应从深荫到阳光充足的各种光照环境。该植物不会调节光捕获复合物 II 的丰度，该复合物主要以游离三聚体的形式存在，也不会改变热耗散（NPQ）的最大容量。然而，预计在长期的光驯化过程中，光保护是可以调节的，以保护光系统（PSII、PSI）。使用称为“黑暗中测量的光化学猝灭”（qP）的叶绿素荧光方法研究了长期光驯化对 PSII 光保护的影响。在相对低的辐照度下，单高-qP 值表明存在不均匀的天线系统（PSII 天线解偶联）。天线解偶联的程度在很大程度上取决于光照条件，在阳光驯化的植物中达到最高值。同时，在从深荫到高光生长的植物中，光保护 NPQ（pNPQ）增加。据推测，长期光保护能力的调节差异与解偶联 LHCII 的数量成正比。在深荫植物中，不变的最大 NPQ 和较低的 pNPQ 之间的不一致性归因于 PSII 核心中的热耗散。
