Regulation of Non-Photochemical Quenching of Chlorophyll Fluorescence in Plants

1995 ◽  
Vol 22 (2) ◽  
pp. 221 ◽  
Author(s):  
AV Ruban ◽  
P Horton
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosystem Ii ◽  
Excited States ◽  
Light Harvesting ◽  
Structure And Function ◽  
Photochemical Quenching ◽  
Dynamic Nature ◽  
Dissipation Of Energy ◽  
And Function ◽  
Non Photochemical Quenching

Non-photochemical quenching of chlorophyll fluorescence indicates the de-excitation of light-generated excited states in the chlorophyll associated with photosystem II (PSII). The principle process contributing to this quenching is dependent on the formation of the thylakoid proton gradient and is an important mechanism for protecting PSII from photodamage. Evidence points to the importance of the light-harvesting chlorophyll proteins as the site of dissipation of energy, and suggests that the structure and function of these proteins are regulated by protonation and the ratio of zeaxanthin to violaxanthin. The minor light-harvesting proteins may have a particularly important role as the primary sites of proton binding and because of their enrichment in xanthophyll cycle carotenoids. The dynamic nature of the light-harvesting system is an important part of the process by which plants are able to adapt to different light environments.

scholarly journals Changes in Photo-Protective Energy Dissipation of Photosystem II in Response to Beneficial Bacteria Consortium in Durum Wheat under Drought and Salinity Stresses

2020 ◽  
Vol 10 (15) ◽  
pp. 5031 ◽  
Author(s):  
Mohammad Yaghoubi Khanghahi ◽  
Sabrina Strafella ◽  
Carmine Crecchio
Keyword(s):  
Chlorophyll Fluorescence ◽  
Energy Dissipation ◽  
Quantum Yield ◽  
Photosystem Ii ◽  
Excitation Energy ◽  
Durum Wheat ◽  
Photochemical Quenching ◽  
Plant Growth Promoting Bacteria ◽  
Psii Photochemistry ◽  
Non Photochemical Quenching

The present research aimed at evaluating the harmless dissipation of excess excitation energy by durum wheat (Triticum durum Desf.) leaves in response to the application of a bacterial consortium consisting of four plant growth-promoting bacteria (PGPB). Three pot experiments were carried out under non-stress, drought (at 40% field capacity), and salinity (150 mM NaCl) conditions. The results showed that drought and salinity affected photo-protective energy dissipation of photosystem II (PSII) increasing the rate of non-photochemical chlorophyll fluorescence quenching (NPQ (non-photochemical quenching) and qCN (complete non-photochemical quenching)), as well as decreasing the total quenching of chlorophyll fluorescence (qTQ), total quenching of variable chlorophyll fluorescence (qTV) and the ratio of the quantum yield of actual PSII photochemistry, in light-adapted state to the quantum yield of the constitutive non-regulatory NPQ (PQ rate). Our results also indicated that the PGPB inoculants can mitigate the adverse impacts of stresses on leaves, especially the saline one, in comparison with the non-fertilized (control) treatment, by increasing the fraction of light absorbed by the PSII antenna, PQ ratio, qTQ, and qTV. In the light of findings, our beneficial bacterial strains showed the potential in reducing reliance on traditional chemical fertilizers, in particular in saline soil, by improving the grain yield and regulating the amount of excitation energy.

scholarly journals Allosteric regulation of the light-harvesting system of photosystem II

2000 ◽  
Vol 355 (1402) ◽  
pp. 1361-1370 ◽  
Author(s):  
Peter Horton ◽  
Alexander V. Ruban ◽  
Mark Wentworth
Keyword(s):  
Photosystem Ii ◽  
Xanthophyll Cycle ◽  
Light Harvesting ◽  
Allosteric Regulation ◽  
Photochemical Quenching ◽  
Protein Subunit ◽  
Ps Ii ◽  
Non Photochemical Quenching

Non–photochemical quenching of chlorophyll fluorescence (NPQ) is symptomatic of the regulation of energy dissipation by the light–harvesting antenna of photosystem II (PS II). The kinetics of NPQ in both leaves and isolated chloroplasts are determined by the transthylakoid ΔpH and the de–epoxidation state of the xanthophyll cycle. In order to understand the mechanism and regulation of NPQ we have adopted the approaches commonly used in the study of enzyme–catalysed reactions. Steady–state measurements suggest allosteric regulation of NPQ, involving control by the xanthophyll cycle carotenoids of a protonationdependent conformational change that transforms the PS II antenna from an unquenched to a quenched state. The features of this model were confirmed using isolated light–harvesting proteins. Analysis of the rate of induction of quenching both in vitro and in vivo indicated a bimolecular second–order reaction; it is suggested that quenching arises from the reaction between two fluorescent domains, possibly within a single protein subunit. A universal model for this transition is presented based on simple thermodynamic principles governing reaction kinetics.

Role of electron-transfer quenching of chlorophyll fluorescence by carotenoids in non-photochemical quenching of green plants

2005 ◽  
Vol 33 (4) ◽  
pp. 858-862 ◽  
Author(s):  
A. Dreuw ◽  
G.R. Fleming ◽  
M. Head-Gordon
Keyword(s):  
Electron Transfer ◽  
Chlorophyll Fluorescence ◽  
Charge Transfer ◽  
Excited States ◽  
Quantum Chemical ◽  
Photochemical Quenching ◽  
Quenching Mechanism ◽  
High Level ◽  
Non Photochemical Quenching

NPQ (non-photochemical quenching) is a fundamental photosynthetic mechanism by which plants protect themselves against excess excitation energy and the resulting photodamage. A discussed molecular mechanism of the so-called feedback de-excitation component (qE) of NPQ involves the formation of a quenching complex. Recently, we have studied the influence of formation of a zeaxanthin–chlorophyll complex on the excited states of the pigments using high-level quantum chemical methodology. In the case of complex formation, electron-transfer quenching of chlorophyll-excited states by carotenoids is a relevant quenching mechanism. Furthermore, additionally occurring charge-transfer excited states can be exploited experimentally to prove the existence of the quenching complex during NPQ.

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