Photosynthetic response of in vitro guayule plants in low and high lights and the role of non-photochemical quenching in plant acclimation

This paper deals first with the early, although incomplete, history of photoinhibition, of 'non-QA-related chlorophyll (Chl) a fluorescence changes', and the xanthophyll cycle that preceded the discovery of the correlation between non-photochemical quenching of Chl a fluorescence (NPQ) and conversion of violaxanthin to zeaxanthin. It includes the crucial observation that the fluorescence intensity quenching, when plants are exposed to excess light, is indeed due to a change in the quantum yield of fluorescence. The history ends with a novel turn in the direction of research — isolation and characterization of NPQ xanthophyll-cycle mutants of Chlamydomonas reinhardtii Dangeard and Arabidopsis thaliana (L.) Heynh., blocked in conversion of violaxanthin to zeaxanthin, and zeaxanthin to violaxanthin, respectively. In the second part of the paper, we extend the characterization of two of these mutants (npq1, which accumulates violaxanthin, and npq2, which accumulates zeaxanthin) through parallel measurements on growth, and several assays of PSII function: oxygen evolution, Chl a fluorescence transient (the Kautsky effect), the two-electron gate function of PSII, the back reactions around PSII, and measurements of NPQ by pulse-amplitude modulation (PAM 2000) fluorimeter. We show that, in the npq2 mutant, Chl a fluorescence is quenched both in the absence and presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). However, no differences are observed in functioning of the electron-acceptor side of PSII — both the two-electron gate and the back reactions are unchanged. In addition, the role of protons in fluorescence quenching during the 'P-to-S' fluorescence transient was confirmed by the effect of nigericin in decreasing this quenching effect. Also, the absence of zeaxanthin in the npq1 mutant leads to reduced oxygen evolution at high light intensity, suggesting another protective role of this carotenoid. The available data not only support the current model of NPQ that includes roles for both pH and the xanthophylls, but also are consistent with additional protective roles of zeaxanthin. However, this paper emphasizes that we still lack sufficient understanding of the different parts of NPQ, and that the precise mechanisms of photoprotection in the alga Chlamydomonas may not be the same as those in higher plants.

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The role of LHCBM1 in non-photochemical quenching in Chlamydomonas reinhardtii

10.1101/2022.01.13.476201 ◽

2022 ◽

Author(s):

Xin Liu ◽

Wojciech J Nawrocki ◽

Roberta Croce

Keyword(s):

Chlamydomonas Reinhardtii ◽

Protein Complexes ◽

Ph Sensor ◽

High Light ◽

Photochemical Quenching ◽

Knock Out ◽

Photosynthetic Organisms ◽

Pigment Protein Complexes ◽

Non Photochemical Quenching

Non-photochemical quenching (NPQ) is the process that protects photosynthetic organisms from photodamage by dissipating the energy absorbed in excess as heat. In the model green alga Chlamydomonas reinhardtii, NPQ was abolished in the knock-out mutants of the pigment-protein complexes LHCSR3 and LHCBM1. However, while LHCSR3 was shown to be a pH sensor and switching to a quenched conformation at low pH, the role of LHCBM1 in NPQ has not been elucidated yet. In this work, we combine biochemical and physiological measurements to study short-term high light acclimation of npq5, the mutant lacking LHCBM1. We show that while in low light in the absence of this complex, the antenna size of PSII is smaller than in its presence, this effect is marginal in high light, implying that a reduction of the antenna is not responsible for the low NPQ. We also show that the mutant expresses LHCSR3 at the WT level in high light, indicating that the absence of this complex is also not the reason. Finally, NPQ remains low in the mutant even when the pH is artificially lowered to values that can switch LHCSR3 to the quenched conformation. It is concluded that both LHCSR3 and LHCBM1 need to be present for the induction of NPQ and that LHCBM1 is the interacting partner of LHCSR3. This interaction can either enhance the quenching capacity of LHCSR3 or connect this complex with the PSII supercomplex.

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

10.1101/2020.07.10.197483 ◽

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.

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The role of coccoliths in protecting <i>Emiliania huxleyi</i> against stressful light and UV radiation

Biogeosciences ◽

10.5194/bg-13-4637-2016 ◽

2016 ◽

Vol 13 (16) ◽

pp. 4637-4643 ◽

Cited By ~ 14

Author(s):

Juntian Xu ◽

Lennart T. Bach ◽

Kai G. Schulz ◽

Wenyan Zhao ◽

Kunshan Gao ◽

...

Keyword(s):

Solar Radiation ◽

Uv Radiation ◽

Growth Rates ◽

Emiliania Huxleyi ◽

Photochemical Quenching ◽

Visible Radiation ◽

Light Levels ◽

Relative Electron ◽

Non Photochemical Quenching

Abstract. Coccolithophores are a group of phytoplankton species which cover themselves with small scales (coccoliths) made of calcium carbonate (CaCO3). The reason why coccolithophores form these calcite platelets has been a matter of debate for decades but has remained elusive so far. One hypothesis is that they play a role in light or UV protection, especially in surface dwelling species like Emiliania huxleyi, which can tolerate exceptionally high levels of solar radiation. In this study, we tested this hypothesis by culturing a calcified and a naked strain under different light conditions with and without UV radiation. The coccoliths of E. huxleyi reduced the transmission of visible radiation (400–700 nm) by 7.5 %, that of UV-A (315–400 nm) by 14.1 % and that of UV-B (280–315 nm) by 18.4 %. Growth rates of the calcified strain (PML B92/11) were about 2 times higher than those of the naked strain (CCMP 2090) under indoor constant light levels in the absence of UV radiation. When exposed to outdoor conditions (fluctuating sunlight with UV radiation), growth rates of calcified cells were almost 3.5 times higher compared to naked cells. Furthermore, the relative electron transport rate was 114 % higher and non-photochemical quenching (NPQ) was 281 % higher in the calcified compared to the naked strain, implying higher energy transfer associated with higher NPQ in the presence of calcification. When exposed to natural solar radiation including UV radiation, the maximal quantum yield of photosystem II was only slightly reduced in the calcified strain but strongly reduced in the naked strain. Our results reveal an important role of coccoliths in mitigating light and UV stress in E. huxleyi.

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Photoprotective strategies in the motile cryptophyte alga Rhodomonas salina—role of non-photochemical quenching, ions, photoinhibition, and cell motility

Folia Microbiologica ◽

10.1007/s12223-019-00742-y ◽

2019 ◽

Vol 64 (5) ◽

pp. 691-703 ◽

Cited By ~ 2

Author(s):

Radek Kaňa ◽

Eva Kotabová ◽

Barbora Šedivá ◽

Eliška Kuthanová Trsková

Keyword(s):

Cell Motility ◽

Photochemical Quenching ◽

Rhodomonas Salina ◽

Non Photochemical Quenching

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From ecophysiology to phenomics: some implications of photoprotection and shade–sun acclimation in situ for dynamics of thylakoids in vitro

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2012.0072 ◽

2012 ◽

Vol 367 (1608) ◽

pp. 3503-3514 ◽

Cited By ~ 26

Author(s):

Shizue Matsubara ◽

Britta Förster ◽

Melinda Waterman ◽

Sharon A. Robinson ◽

Barry J. Pogson ◽

...

Keyword(s):

Membrane Dynamics ◽

Persea Americana ◽

Physiological Data ◽

Photochemical Quenching ◽

Shade Acclimation ◽

Non Photochemical Quenching ◽

Time Frames ◽

Shade Leaves

Half a century of research into the physiology and biochemistry of sun–shade acclimation in diverse plants has provided reality checks for contemporary understanding of thylakoid membrane dynamics. This paper reviews recent insights into photosynthetic efficiency and photoprotection from studies of two xanthophyll cycles in old shade leaves from the inner canopy of the tropical trees Inga sapindoides and Persea americana (avocado). It then presents new physiological data from avocado on the time frames of the slow coordinated photosynthetic development of sink leaves in sunlight and on the slow renovation of photosynthetic properties in old leaves during sun to shade and shade to sun acclimation. In so doing, it grapples with issues in vivo that seem relevant to our increasingly sophisticated understanding of Δ pH-dependent, xanthophyll-pigment-stabilized non-photochemical quenching in the antenna of PSII in thylakoid membranes in vitro .

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Photoprotective energy dissipation is greater in the lower, not the upper, regions of a rice canopy: a 3D analysis

Journal of Experimental Botany ◽

10.1093/jxb/eraa411 ◽

2020 ◽

Vol 71 (22) ◽

pp. 7382-7392 ◽

Cited By ~ 1

Author(s):

Chuan Ching Foo ◽

Alexandra J Burgess ◽

Renata Retkute ◽

Pracha Tree-Intong ◽

Alexander V Ruban ◽

...

Keyword(s):

Three Dimensional ◽

High Light ◽

Photochemical Quenching ◽

3D Analysis ◽

Low Light ◽

Gene Encoding ◽

Light Intensities ◽

Dimensional Reconstruction ◽

Non Photochemical Quenching

Abstract High light intensities raise photosynthetic and plant growth rates but can cause damage to the photosynthetic machinery. The likelihood and severity of deleterious effects are minimised by a set of photoprotective mechanisms, one key process being the controlled dissipation of energy from chlorophyll within PSII known as non-photochemical quenching (NPQ). Although ubiquitous, the role of NPQ in plant productivity is important because it momentarily reduces the quantum efficiency of photosynthesis. Rice plants overexpressing and deficient in the gene encoding a central regulator of NPQ, the protein PsbS, were used to assess the effect of protective effectiveness of NPQ (pNPQ) at the canopy scale. Using a combination of three-dimensional reconstruction, modelling, chlorophyll fluorescence, and gas exchange, the influence of altered NPQ capacity on the distribution of pNPQ was explored. A higher phototolerance in the lower layers of a canopy was found, regardless of genotype, suggesting a mechanism for increased protection for leaves that experience relatively low light intensities interspersed with brief periods of high light. Relative to wild-type plants, psbS overexpressors have a reduced risk of photoinactivation and early growth advantage, demonstrating that manipulating photoprotective mechanisms can impact both subcellular mechanisms and whole-canopy function.

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