Nonphotochemical Chlorophyll Fluorescence Quenching: Mechanism and Effectiveness in Protecting Plants from Photodamage

Abstract

We review the mechanism underlying nonphotochemical chlorophyll fluorescence quenching (NPQ) and its role in protecting plants against photoinhibition. This review includes an introduction to this phenomenon, a brief history of major milestones in our understanding of NPQ, definitions, and a discussion of quantitative measurements of NPQ. We discuss the current knowledge and unknown aspects in the NPQ scenario, including the following: DpH, the proton gradient (trigger); lightharvesting complex II (LHCII), PSII light harvesting antenna (site); and changes in the antenna induced by DpH (change), which lead to the creation of the quencher. We conclude that the minimum requirements for NPQ in vivo are DpH, LHCII complexes, and the PsbS protein. We highlight the most important unknown in the NPQ scenario, the mechanism by which PsbS acts upon the LHCII antenna. Finally, we describe a novel, emerging technology for assessing the photoprotective "power" of NPQ and the important findings obtained through this technology.

Connection of the Photochemical Reflectance Index (PRI) with the Photosystem II Quantum Yield and Nonphotochemical Quenching Can Be Dependent on Variations of Photosynthetic Parameters among Investigated Plants: A Meta-Analysis

“…The stressors decrease the probability of survival and productivity of plants; in particular, they damage the photosynthetic process [12]. Early monitoring of these damages plays an important role in precision agriculture and ecological monitoring.…”

“…This index, which is related to the fast transition in the xanthophyll cycle, is based on the rapid decrease of reflectance at 531 nm that is caused by the dissipation of light energy associated with xanthophyll de-epoxidation [26,36]. It is known that the de-epoxidation of xanthophylls plays an important role in the increase of nonphotochemical quenching of fluorescence of chlorophyll (NPQ) under stress conditions [12,37]. Thus, it can be expected that PRI is strongly connected with NPQ (and other photosynthetic parameters) under different environmental conditions.…”

UV-B photoreceptor-mediated protection of the photosynthetic machinery in Chlamydomonas reinhardtii

“…To avoid photodamage, photosynthetic light harvesting is regulated by nonphotochemical quenching (NPQ), which allows dissipation of harmful excess energy as heat through its qE (energy-dependent nonphotochemical quenching) component (1)(2)(3)(4)(5)(6). Specialized members of the light harvesting complex (LHC) protein family, such as Photosystem II Subunit S (PSBS) in higher plants or members of the LHC Stress-Related (LHCSR) family in mosses and algae, are central to qE (7)(8)(9)(10)(11).…”

Light-harvesting antenna complexes in the moss Physcomitrella patens: implications for the evolutionary transition from green algae to land plants

“…Surprisingly, the localizations of PpLHCSR and PpPsbS appear to be exclusive of each other in P. patens thylakoid membranes, where the former is found mostly in grana margin and stroma lamellae, and the latter is localized only in grana [56 ]. It has been suggested that PpLHCSR can associate with both PSI and PSII to activate qE under excess light conditions [56 ], while PpPsbS interacts with the moderately-bound major LHCII in the PSII supercomplex [57 ], as similarly suggested in A. thaliana [30]. The dual mechanisms of PpLHCSR and PpPsbS to induce qE clearly imply the requirement for conquering newly experienced light environments during plant terrestrialization.…”

“…[30]). The molecular details of the qE mechanism are still debated, but the development of the transmembrane pH gradient across thylakoid membrane (DpH) is known to be the trigger.…”