Chlorophyll fluorescence, non-photochemical quenching and light harvesting complex as alternatives to color measurement, in classifying tomato fruit according to their maturity stage at harvest and in monitoring postharvest ripening during storage

2020 ◽  
Vol 161 ◽  
pp. 111036 ◽  
Author(s):  
Dimitrios S. Kasampalis ◽  
Pavlos Tsouvaltzis ◽  
Anastasios S. Siomos
Keyword(s):  
Chlorophyll Fluorescence ◽  
Light Harvesting ◽  
Tomato Fruit ◽  
Color Measurement ◽  
Photochemical Quenching ◽  
Maturity Stage ◽  
Light Harvesting Complex ◽  
Postharvest Ripening ◽  
Non Photochemical Quenching

scholarly journals Identification of parallel pH- and zeaxanthin-dependent quenching of excess energy in LHCSR3 in Chlamydomonas reinhardtii

2020 ◽  
Author(s):  
Julianne M. Troiano ◽  
Federico Perozeni ◽  
Raymundo Moya ◽  
Luca Zuliani ◽  
Kwangryul Baek ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Light Harvesting ◽  
Complex Stress ◽  
Excess Energy ◽  
Photochemical Quenching ◽  
Light Harvesting Complexes ◽  
Light Harvesting Complex ◽  
Non Photochemical Quenching

AbstractUnder high light conditions, oxygenic photosynthetic organisms avoid photodamage by thermally dissipating excess absorbed energy, which is called non-photochemical quenching (NPQ). In green algae, a chlorophyll and carotenoid-binding protein, light-harvesting complex stress-related (LHCSR3), detects excess energy via pH and serves as a quenching site. However, the mechanisms by which LHCSR3 functions have not been determined. Using a combined in vivo and in vitro approach, we identify two parallel yet distinct quenching processes, individually controlled by pH and carotenoid composition, and their likely molecular origin within LHCSR3 from Chlamydomonas reinhardtii. The pH-controlled quenching is removed within a mutant LHCSR3 that lacks the protonable residues responsible for sensing pH. Constitutive quenching in zeaxanthin-enriched systems demonstrates zeaxanthin-controlled quenching, which may be shared with other light-harvesting complexes. We show that both quenching processes prevent the formation of damaging reactive oxygen species, and thus provide distinct timescales and mechanisms of protection in a changing environment.

scholarly journals Photoprotective qH in Arabidopsis occurs in the light-harvesting complex II trimer

2021 ◽  
Author(s):  
Pierrick Bru ◽  
Collin J. Steen ◽  
Soomin Park ◽  
Cynthia L. Amstutz ◽  
Emily J. Sylak-Glassman ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Light Harvesting ◽  
Single Photon ◽  
Photochemical Quenching ◽  
Average Lifetime ◽  
Wild Type ◽  
Photosynthetic Membrane ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Light Harvesting Complex Ii

Excess light can induce photodamage to the photosynthetic machinery, therefore plants have evolved photoprotective mechanisms such as non-photochemical quenching (NPQ). Different NPQ components have been identified and classified based on their relaxation kinetics and molecular players. The NPQ component qE is induced and relaxed rapidly (seconds to minutes), whereas the NPQ component qH is induced and relaxed slowly (hours or longer). Molecular players regulating qH have recently been uncovered, but the photophysical mechanism of qH and its location in the photosynthetic membrane have not been determined. Using time-correlated single-photon counting analysis of the Arabidopsis thaliana suppressor of quenching 1 mutant (soq1), which displays higher qH than the wild type, we observed shorter average lifetime of chlorophyll fluorescence in leaves and thylakoids relative to wild type. Comparison of isolated photosynthetic complexes from plants in which qH was turned ON or OFF revealed a chlorophyll fluorescence decrease specifically in the trimeric light-harvesting complex II (LHCII) fraction when qH was ON. LHCII trimers are composed of Lhcb1, 2 and 3 proteins, so CRISPR-Cas9 edited and T-DNA insertion lhcb1, lhcb2 and lhcb3 mutants were crossed with soq1. In soq1 lhcb1, soq1 lhcb2, and soq1 lhcb3, qH was not abolished, indicating that no single major Lhcb isoform is necessary for qH. Using transient absorption spectroscopy of isolated thylakoids, no spectral signatures for chlorophyll-carotenoid excitation energy quenching or charge transfer quenching were observed, suggesting that qH may occur through chlorophyll-chlorophyll excitonic interaction.

scholarly journals Identification of pH-sensing Sites in the Light Harvesting Complex Stress-related 3 Protein Essential for Triggering Non-photochemical Quenching inChlamydomonas reinhardtii

2016 ◽  
Vol 291 (14) ◽  
pp. 7334-7346 ◽  
Author(s):  
Matteo Ballottari ◽  
Thuy B. Truong ◽  
Eleonora De Re ◽  
Erika Erickson ◽  
Giulio R. Stella ◽  
...  
Keyword(s):  
Light Harvesting ◽  
Complex Stress ◽  
Photochemical Quenching ◽  
Ph Sensing ◽  
Light Harvesting Complex ◽  
Non Photochemical Quenching

The evolution of the photoprotective antenna proteins in oxygenic photosynthetic eukaryotes

2018 ◽  
Vol 46 (5) ◽  
pp. 1263-1277 ◽  
Author(s):  
Vasco Giovagnetti ◽  
Alexander V. Ruban
Keyword(s):  
Vascular Plants ◽  
Light Harvesting ◽  
Current Knowledge ◽  
Complex Stress ◽  
Photochemical Quenching ◽  
Light Harvesting Complex ◽  
Photosynthetic Organisms ◽  
Photosynthetic Eukaryotes ◽  
Non Photochemical Quenching ◽  
Energy Dependent

Photosynthetic organisms require rapid and reversible down-regulation of light harvesting to avoid photodamage. Response to unpredictable light fluctuations is achieved by inducing energy-dependent quenching, qE, which is the major component of the process known as non-photochemical quenching (NPQ) of chlorophyll fluorescence. qE is controlled by the operation of the xanthophyll cycle and accumulation of specific types of proteins, upon thylakoid lumen acidification. The protein cofactors so far identified to modulate qE in photosynthetic eukaryotes are the photosystem II subunit S (PsbS) and light-harvesting complex stress-related (LHCSR/LHCX) proteins. A transition from LHCSR- to PsbS-dependent qE took place during the evolution of the Viridiplantae (also known as ‘green lineage’ organisms), such as green algae, mosses and vascular plants. Multiple studies showed that LHCSR and PsbS proteins have distinct functions in the mechanism of qE. LHCX(-like) proteins are closely related to LHCSR proteins and found in ‘red lineage’ organisms that contain secondary red plastids, such as diatoms. Although LHCX proteins appear to control qE in diatoms, their role in the mechanism remains poorly understood. Here, we present the current knowledge on the functions and evolution of these crucial proteins, which evolved in photosynthetic eukaryotes to optimise light harvesting.

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.

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