Shuang Sheng-Pu, Zhang Jin-Yan, Cun Zhu, Wu Hong-Min, Hong Jie, Chen Jun-Wen
College of Agronomy and Biotechnology, Yunnan Agricultural University, Kunming, China.
Key Laboratory of Medicinal Plant Biology of Yunnan Province, Yunnan Agricultural University, Kunming, China.
Front Plant Sci. 2022 Apr 6;13:819843. doi: 10.3389/fpls.2022.819843. eCollection 2022.
Light intensity is highly heterogeneous in nature, and plants have evolved a series of strategies to acclimate to dynamic light due to their immobile lifestyles. However, it is still unknown whether there are differences in photoprotective mechanisms among different light-demanding plants in response to dynamic light, and thus the role of non-photochemical quenching (NPQ), electron transport, and light energy allocation of photosystems in photoprotection needs to be further understood in different light-demanding plants. The activities of photosystem II (PSII) and photosystem I (PSI) in shade-tolerant species , intermediate species , and sun-demanding species were comparatively measured to elucidate photoprotection mechanisms in different light-demanding plants under dynamic light. The results showed that the NPQ and PSII maximum efficiency ( '/ ') of were higher than the other two species under dynamic high light. Meanwhile, cyclic electron flow (CEF) of sun plants is larger under transient high light conditions since the slope of post-illumination, P700 dark reduction rate, and plastoquinone (PQ) pool were greater. NPQ was more active and CEF was initiated more readily in shade plants than the two other species under transient light. Moreover, sun plants processed higher quantum yield of PSII photochemistry (Φ), quantum yield of photochemical energy conversion [Y(I)], and quantum yield of non-photochemical energy dissipation due to acceptor side limitation (Y(NA), while the constitutive thermal dissipation and fluorescence (Φ) and quantum yield of non-photochemical energy dissipation due to donor side limitation [Y(ND)] of PSI were higher in shade plants. These results suggest that sun plants had higher NPQ and CEF for photoprotection under transient high light and mainly allocated light energy through Φ and Φ, while shade plants had a higher Φ and a larger heat dissipation efficiency of PSI donor. Overall, it has been demonstrated that the photochemical efficiency and photoprotective capacity are greater in sun plants under transient dynamic light, while shade plants are more sensitive to transient dynamic light.
光强在自然界中高度不均一，由于植物固定不动的生活方式，它们进化出了一系列适应动态光照的策略。然而，不同需光植物在响应动态光照时的光保护机制是否存在差异仍不清楚，因此，不同需光植物中光系统的非光化学猝灭（NPQ）、电子传递和光能分配在光保护中的作用有待进一步了解。通过比较耐荫物种、中间型物种和喜光物种中光系统II（PSII）和光系统I（PSI）的活性，以阐明不同需光植物在动态光照下的光保护机制。结果表明，在动态强光下，耐荫物种的NPQ和PSII最大效率（Fv/Fm）高于其他两个物种。同时，在瞬态高光条件下，阳生植物的循环电子流（CEF）更大，因为光照后斜率、P700暗还原率和质体醌（PQ）库更大。在瞬态光照下，耐荫植物的NPQ比其他两个物种更活跃，CEF启动更容易。此外，阳生植物的PSII光化学量子产率（ΦPSII）、光化学能量转换量子产率[Y（I）]和由于受体侧限制导致的非光化学能量耗散量子产率（Y（NA））较高，而耐荫植物中PSI的组成性热耗散和荧光（ΦNO）以及由于供体侧限制导致的非光化学能量耗散量子产率[Y（ND）]较高。这些结果表明，阳生植物在瞬态高光下具有较高的NPQ和CEF用于光保护，主要通过ΦPSII和Y（I）分配光能，而耐荫植物具有较高的ΦNO和PSI供体更大的散热效率。总体而言，已证明在瞬态动态光照下阳生植物的光化学效率和光保护能力更强，而耐荫植物对瞬态动态光照更敏感。
