scholarly journals Greening under High Light or Cold Temperature Affects the Level of Xanthophyll-Cycle Pigments, Early Light-Inducible Proteins, and Light-Harvesting Polypeptides in Wild-Type Barley and theChlorina f2 Mutant

1999 ◽  
Vol 120 (1) ◽  
pp. 193-204 ◽  
Author(s):  
Marianna Król ◽  
Alexander G. Ivanov ◽  
Stefan Jansson ◽  
Klaus Kloppstech ◽  
Norman P.A. Huner
Keyword(s):  
Xanthophyll Cycle ◽  
Light Harvesting ◽  
High Light ◽  
Cold Temperature ◽  
Wild Type ◽  
Xanthophyll Cycle Pigments

scholarly journals Glutathione and zeaxanthin formation during high light stress in foliose lichens

2008 ◽  
Vol 53 (No. 8) ◽  
pp. 340-344 ◽  
Author(s):  
J. Štepigová ◽  
H. Vráblíková ◽  
J. Lang ◽  
K. Večeřová ◽  
M. Barták
Keyword(s):  
Xanthophyll Cycle ◽  
Light Exposure ◽  
Light Stress ◽  
High Light ◽  
Short Term ◽  
Xanthophyll Cycle Pigments ◽  
High Light Stress ◽  
Fluorescence Label ◽  
Thiol Binding ◽  
Pure Acetone

In the presented study, we describe techniques for glutathione and pigment determination in lichens used in our laboratory. Glutathione and xanthophyll cycle pigments, especially zeaxanthin, are important antioxidants protecting plants against various stresses. In our laboratory, the high light stress in lichens has been intensively studied for several years. We extract glutathione in HCl and determine it by thiol-binding fluorescence label monobromobimane. For pigment determination, homogenized lichen thalli are extracted with pure acetone. According to our results, the total amount of glutathione decreases after a short-term high light exposure, while the amount of zeaxanthin increases.

Defensive strategies against high light stress in wild and D1 protein mutant biotypes of Erigeron canadensis

2000 ◽  
Vol 27 (4) ◽  
pp. 325 ◽  
Author(s):  
Éva Darkó ◽  
Gyula Váradi ◽  
Yves Lemoine ◽  
Endre Lehoczki
Keyword(s):  
Electron Transport ◽  
Xanthophyll Cycle ◽  
D1 Protein ◽  
High Light ◽  
Wild Type ◽  
Mutant Plant ◽  
Defensive Strategies ◽  
Erigeron Canadensis ◽  
Intact Leaves

The Ser264ÆGly substitution on the D1 protein is accompanied by a higher photosensitivity of the mutant plant. This may be due to an increased D1 protein turnover and/or to a lower xanthophyll cycle activity in vivo. The relative importance of these two photoprotective mechanisms in wild and D1 protein mutant biotypes of Erigeron canadensis L. was established by using dithiothreitol and streptomycin. Moreover, the interconversion of violaxan-thin to zeaxanthin via antheraxanthin was studied in isolated thylakoids and in intact leaves treated with paraquat. Streptomycin caused a more severe decrease in the optimal quantum yield (Fv/Fm) of PS II and a large increase in the initial fluorescence yield (Fo) in the mutant compared to the wild biotype. In the fluorescence-quenching parameters of the wild-type leaves, dithiothreitol caused alterations similar to those observed in the mutant plant without dithiothreitol. A lowered activity of the xanthophyll cycle was detected in the mutant biotype compared to the wild-type in vivo. However, under in vitro, conditions which were optimal for violaxanthin de-epoxidation, or when paraquat was used on intact leaves to accelerate the electron transport, violaxanthin could readily be converted to zeaxanthin even in the mutant plants. This demonstrates that neither the decrease in the enzymatic activity of violaxanthin de-epoxidase nor the low availability of violaxanthin is responsible for the low zeaxanthin formation under in vivo conditions. It is presumed that, in vivo, the D1 protein mutation results in slower electron transport, a smaller DpH and lower zeaxanthin formation, and thereby in alterations in the defensive strategies against high light illumination.

Xanthophyll cycle, light energy dissipation and electron transport in transgenic tobacco with reduced carbon assimilation capacity

2000 ◽  
Vol 27 (4) ◽  
pp. 289 ◽  
Author(s):  
Sari A. Ruuska ◽  
Susanne von Caemmerer ◽  
Murray R. Badger ◽  
T. John Andrews ◽  
G. Dean Price ◽  
...  
Keyword(s):  
Electron Transport ◽  
Transgenic Tobacco ◽  
Xanthophyll Cycle ◽  
Co2 Assimilation ◽  
Light Energy ◽  
Pigment Composition ◽  
Wild Type ◽  
Xanthophyll Cycle Pigments ◽  
Leaf Pigment ◽  
Assimilation Capacity

The effects of reduced CO2 assimilation capacity on the leaf pigment composition and the dissipation of light energy were studied using transgenic tobacco (Nicotiana tabacum L. cv. W38). Two plant types were used: anti-SSu plants with reduced amounts of Rubisco and anti-GAPDH plants with reduced activity of chloroplast glycer-aldehyde 3-phosphate dehydrogenase. A moderate reduction in the photosynthetic capacity increased the de-epoxidation state of the xanthophyll-cycle pigments. In contrast, there was no large effect on the leaf pigment composition and the ratio of the xanthophyll cycle pigments to chlorophyll, and total carotenoids increased only in the most severe transgenic plants. The light induction of photosynthesis, fluorescence quenching and de-epoxida ion of the xanthophyll cycle pigments were also followed in wild-type and anti-SSu plants. Anti-SSu plants maintained high nonphotochemical quenching and increased xanthophyll de-epoxidation in the light but the reduction state of QA remained high. For both wild-type and anti-SSu plants, the electron transport rate estimated from chlorophyll a fluorescence appeared to be much higher than that required to support the observed rate of CO2 assimilation and photorespiration during the early phase of photosynthetic induction. However, the two estimates converged with the onset of steady-state photosynthesis.

scholarly journals Involvement of Lhcb6 and Lhcb5 in Photosynthesis Regulation in Physcomitrella patens Response to Abiotic Stress

2019 ◽  
Vol 20 (15) ◽  
pp. 3665 ◽  
Author(s):  
Xingji Peng ◽  
Xingguang Deng ◽  
Xiaoya Tang ◽  
Tinghong Tan ◽  
Dawei Zhang ◽  
...  
Keyword(s):  
Abiotic Stress ◽  
Physcomitrella Patens ◽  
Light Harvesting ◽  
Light Stress ◽  
High Light ◽  
Photochemical Quenching ◽  
Wild Type ◽  
Knock Out ◽  
Non Photochemical Quenching ◽  
Photosynthesis Regulation

There are a number of highly conserved photosystem II light-harvesting antenna proteins in moss whose functions are unclear. Here, we investigated the involvement of chlorophyll-binding proteins, Lhcb6 and Lhcb5, in light-harvesting and photosynthesis regulation in Physcomitrella patens. Lhcb6 or Lhcb5 knock-out resulted in a disordered thylakoid arrangement, a decrease in the number of grana membranes, and an increase in the number of starch granule. The absence of Lhcb6 or Lhcb5 did not noticeably alter the electron transport rates. However, the non-photochemical quenching activity in the lhcb5 mutant was dramatically reduced when compared to wild-type or lhcb6 plants under abiotic stress. Lhcb5 plants were more sensitive to photo-inhibition, while lhcb6 plants showed little difference compared to the wild-type plants under high-light stress. Moreover, both mutants showed a growth malformation phenotype with reduced chlorophyll content in the gametophyte. These results suggested that Lhcb6 or Lhcb5 played a unique role in plant development, thylakoid organization, and photoprotection of PSII in Physcomitrella, especially when exposed to high light or osmotic environments.

scholarly journals Role of an ancient light-harvesting protein of PSI in light absorption and photoprotection

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yandu Lu ◽  
Qinhua Gan ◽  
Masakazu Iwai ◽  
Alessandro Alboresi ◽  
Adrien Burlacot ◽  
...  
Keyword(s):  
Light Absorption ◽  
Red Algae ◽  
Light Harvesting ◽  
High Light ◽  
Secondary Endosymbiosis ◽  
Ros Production ◽  
Nannochloropsis Oceanica ◽  
Wild Type ◽  
Dynamic Balancing

AbstractDiverse algae of the red lineage possess chlorophyll a-binding proteins termed LHCR, comprising the PSI light-harvesting system, which represent an ancient antenna form that evolved in red algae and was acquired through secondary endosymbiosis. However, the function and regulation of LHCR complexes remain obscure. Here we describe isolation of a Nannochloropsis oceanica LHCR mutant, named hlr1, which exhibits a greater tolerance to high-light (HL) stress compared to the wild type. We show that increased tolerance to HL of the mutant can be attributed to alterations in PSI, making it less prone to ROS production, thereby limiting oxidative damage and favoring growth in HL. HLR1 deficiency attenuates PSI light-harvesting capacity and growth of the mutant under light-limiting conditions. We conclude that HLR1, a member of a conserved and broadly distributed clade of LHCR proteins, plays a pivotal role in a dynamic balancing act between photoprotection and efficient light harvesting for photosynthesis.

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