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Ab initio model for the chlorophyll-lutein exciton coupling in the LHCII complex
摘要： 2A_g^- state of lutein plays a crucial role in photoprotection of higher plants. Due to its multiconfigurational nature, accurate description of this electronic state and respective transition properties is a formidable task. In this paper, applicability of various CASSCF and RASSCF formulations for description of the 2A_g^- state is discussed. It is shown that inclusion of the entire π-system of lutein into the active space is required for accurate calculation of transition properties. Exciton coupling in the chlorophyll-lutein dimer involved in non-photochemical quenching in the LHCII complex was calculated to provide a connection between pigment interactions and non-photochemical quenching regulation.
关键词： non-photochemical quenching,MCSCF,Xanthophyll,lutein,exciton coupling,LHCII
更新于2025-09-23 15:23:52
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Spatial Heterogeneity of Cadmium Effects on Salvia sclarea Leaves Revealed by Chlorophyll Fluorescence Imaging Analysis and Laser Ablation Inductively Coupled Plasma Mass Spectrometry
摘要： In this study, for a first time (according to our knowledge), we couple the methodologies of chlorophyll fluorescence imaging analysis (CF-IA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), in order to investigate the effects of cadmium (Cd) accumulation on photosystem II (PSII) photochemistry. We used as plant material Salvia sclarea that grew hydroponically with or without (control) 100 μM Cd for five days. The spatial heterogeneity of a decreased effective quantum yield of electron transport (ΦPSII) that was observed after exposure to Cd was linked to the spatial pattern of high Cd accumulation. However, the high increase of non-photochemical quenching (NPQ), at the leaf part with the high Cd accumulation, resulted in the decrease of the quantum yield of non-regulated energy loss (ΦNO) even more than that of control leaves. Thus, S. sclarea leaves exposed to 100 μM Cd exhibited lower reactive oxygen species (ROS) production as singlet oxygen (1O2). In addition, the increased photoprotective heat dissipation (NPQ) in the whole leaf under Cd exposure was sufficient enough to retain the same fraction of open reaction centers (qp) with control leaves. Our results demonstrated that CF-IA and LA-ICP-MS could be successfully combined to monitor heavy metal effects and plant tolerance mechanisms.
关键词： effective quantum yield (ΦPSII),non-photochemical quenching (NPQ),photoprotective mechanism,photochemical quenching (qp),photosynthetic heterogeneity,phytoremediation,reactive oxygen species (ROS),bioimaging,singlet oxygen (1O2),clary sage
更新于2025-09-11 14:15:04
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Changes in the photosynthesis properties and photoprotection capacity in rice (Oryza sativa) grown under red, blue, or white light
摘要： Non-photochemical quenching (NPQ) of the excited state of chlorophyll a is a major photoprotective mechanism plants utilize to survive under high light. Here, we report the impact of long-term light quality treatment on photosynthetic properties, especially NPQ in rice. We used three LED-based light regimes, i.e., red (648–672 nm), blue (438–460 nm), and “warm” white light (529–624 nm), with the incident photon flux density of 300 μmol photons m?2 s?1, the difference in the absorbed photon flux densities by leaves grown under different light quality being less than 7%. Our results show that blue light, as compared to white light, induced a significant decrease in Fv/Fm, a decreased rate of reduction of P700+ after P700 was completely oxidized; furthermore, blue light also induced higher NPQ with an increased initial speed of NPQ induction, which corresponds to the qE component of NPQ, and a lower maximum quantum yield of PSII, i.e., Y(II). In contrast, rice grown under long-term red light showed decreased Y(II) and increased NPQ, but with no change in Fv/Fm. Furthermore, we found that rice grown under either blue or red light showed decreased transcript abundance of both catalase and ascorbate peroxidase, together with an increased H2O2 content, as compared to rice grown under white light. All these data suggest that even under a moderate incident light level, rice grown under blue or red light led to compromised antioxidant system, which contributed to decreased quantum yield of photosystem II and increased NPQ.
关键词： Non-photochemical quenching of the excited state of chlorophyll a,Effective quantum yield of PSII,Light quality,Quantum yield of regulated energy dissipation in PSII,Oryza sativa,Antioxidant system
更新于2025-09-10 09:29:36
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Advancing Terrestrial Ecosystem Science with a Novel Automated Measurement System for Sun-Induced Chlorophyll Fluorescence for Integration with Eddy Covariance Flux Networks
摘要： Sun-induced chlorophyll fluorescence (SIF) provides critical information on the dynamics of gross primary productivity, a unique role not readily achievable using other methods. Long-term continuous SIF observations have the potential to advance terrestrial ecosystem science. Realizing this potential, however, requires synergistic implementation of SIF measurements within eddy covariance (EC) flux networks. There is a need for SIF systems that can integrate seamlessly with EC instrumentation to maximize synergistic use of obtained data. Here, we introduce the Fluorescence Auto-Measurement Equipment (FAME) and protocol that fulfill such a purpose. FAME is designed specifically for plug-and-play integration with existing EC data acquisition systems. Its innovative hardware and software designs provide versatility, extensibility, autonomous operation, and ease of maintenance for acquiring SIF data of high quality and quantity. A major novel feature of FAME is its synchronized sampling of spectral irradiance and environmental variables, allowing for more precise interpretation of the SIF signal. FAME has been deployed since September 2016 at the Missouri Ozark AmeriFlux site, providing high-quality measurements even when air temperatures approached 40?C. Results reveal that canopy SIF saturated or even slightly decreased at high light, similar to leaf-level photosynthesis. Clear diurnal hysteresis was observed: for the same light, morning SIF was higher than afternoon. Dynamic energy dissipation processes and stress-induced movements of chloroplasts and leaves may explain the observed pattern. The technology and measurement protocol introduced here advances the coordinated observation of SIF and EC fluxes and represents a step change in observational ecosystem and carbon cycle science research.
关键词： canopy photosynthesis,non-photochemical quenching,ecosystem carbon cycle,Instrument design and measurement protocol,gross primary production
更新于2025-09-10 09:29:36