| 1. |
- Czégény, Gyula, et al.
(författare)
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Multiple roles for Vitamin B6in plant acclimation to UV-B
- 2019
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Direct and indirect roles of vitamin B6in leaf acclimation to supplementary UV-B radiation are shown in vitamin B6deficient Arabidopsis thalianamutant rsr4-1 and C24 wild type. Responses to 4 days of 3.9 kJ m-2d-1 biologically effective UV-B dose were compared in terms of leaf photochemistry, vitamer content, and antioxidant enzyme activities; complemented with a comprehensive study of vitamer ROS scavenging capacities. Under UV-B, rsr4-1 leaves lost more (34%) photochemical yield than C24 plants (24%). In the absence of UV-B, rsr4-1 leaves contained markedly less pyridoxal-5’-phosphate (PLP) than C24 ones, but levels increased up to the C24 contents in response to UV-B. Activities of class-III ascorbate and glutathione peroxidases increased in C24 leaves upon the UV-B treatment but not in the rsr4-1 mutant. SOD activities remained the same in C24 but decreased by more than 50% in rsr4-1 under UV-B. Although PLP was shown to be an excellent antioxidant in vitro, our results suggest that the UV-B protective role of B6 vitamers is realized indirectly, via supporting peroxidase defence rather than by direct ROS scavenging. We hypothesize that the two defence pathways are linked through the PLP-dependent biosynthesis of cystein and heme, affecting peroxidases.
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| 2. |
- Hideg, Éva, 1960-, et al.
(författare)
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The effects of UV-B on the biochemistry and metabolism of plants
- 2017
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Ingår i: UV-B radiation and plant life. - Wallingford, UK : CABI Publishing. - 9781780648590 - 9781780648606 ; , s. 90-110
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Bokkapitel (refereegranskat)abstract
- This chapter focuses on the effects of UV-B radiation on the biochemistry and metabolism of plants and their underlying mechanisms. Information on the UV-inducible metabolites and protection responses of plants against UV-B radiation are also discussed.
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| 3. |
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| 4. |
- Neugart, Susanne, et al.
(författare)
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A synchronized, large-scale field experiment using Arabidopsis thaliana reveals the significance of the UV-B photoreceptor UVR8 under natural conditions
- 2024
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Ingår i: Plant, Cell and Environment. - : Blackwell Publishing. - 0140-7791 .- 1365-3040.
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Tidskriftsartikel (refereegranskat)abstract
- This study determines the functional role of the plant ultraviolet-B radiation (UV-B) photoreceptor, UV RESISTANCE LOCUS 8 (UVR8) under natural conditions using a large-scale 'synchronized-genetic-perturbation-field-experiment'. Laboratory experiments have demonstrated a role for UVR8 in UV-B responses but do not reflect the complexity of outdoor conditions where 'genotype × environment' interactions can mask laboratory-observed responses. Arabidopsis thaliana knockout mutant, uvr8-7, and the corresponding Wassilewskija wild type, were sown outdoors on the same date at 21 locations across Europe, ranging from 39°N to 67°N latitude. Growth and climatic data were monitored until bolting. At the onset of bolting, rosette size, dry weight, and phenolics and glucosinolates were quantified. The uvr8-7 mutant developed a larger rosette and contained less kaempferol glycosides, quercetin glycosides and hydroxycinnamic acid derivatives than the wild type across all locations, demonstrating a role for UVR8 under field conditions. UV effects on rosette size and kaempferol glycoside content were UVR8 dependent, but independent of latitude. In contrast, differences between wild type and uvr8-7 in total quercetin glycosides, and the quercetin-to-kaempferol ratio decreased with increasing latitude, that is, a more variable UV response. Thus, the large-scale synchronized approach applied demonstrates a location-dependent functional role of UVR8 under natural conditions.
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| 5. |
- Neugart, Susanne, et al.
(författare)
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Ultraviolet-B radiation exposure lowers the antioxidant capacity in the Arabidopsis thaliana pdx1.3-1 mutant and leads to glucosinolate biosynthesis alteration in both wild type and mutant
- 2020
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Ingår i: Photochemical and Photobiological Sciences. - : Royal Society of Chemistry. - 1474-905X .- 1474-9092. ; 19:2, s. 217-228
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Tidskriftsartikel (refereegranskat)abstract
- Pyridoxine (vitamin B6) and its vitamers are used by living organisms both as enzymatic cofactors and as antioxidants. We used Arabidopsis pyridoxine biosynthesis mutant pdx1.3-1to study involvement of the PLP-synthase main polypeptide PDX1 in plant responses to ultraviolet radiation of two different qualities, one containing primarily UV-A (315-400 nm), the other containing both UV-A and UV-B (280-315 nm). The antioxidant capacity and the flavonoid and glucosinolate (GS) profiles were examined. As indicator of stress, Fv/Fmof photosystem II reaction centers was used. In pdx1.3-1, UV-A+B exposure led to a significant 5% decrease in Fv/Fmon the last day (day 15), indicating mild stress at this time point. Antioxidant capacity of Col-0 wildtype increased significantly (50-73%) after 1 and 3 days of UV-A+B. Instead, in pdx1.3-1, the antioxidant capacity significantly decreased by 44-52% over the same time period, proving the importance of a full complement of functional PDX1genes for detoxification of reactive oxygen species. There were no significant changes in flavonoid glycoside profile under any light condition. However, the GS profile was significantly altered, both with respect to Arabidopsis accession and exposure to UV. The difference in flavonoid and GS profiles reflect that the GS biosynthesis pathway contains at least one pyridoxine-dependent enzyme, whereas no such enzyme is used in flavonoid biosynthesis. Also, there was strong correlation between the antioxidant capacity and the content of some GS compounds. Our results show that vitamin B6vitamers, functioning both as antioxidants and co-factors, are of importance for physiological fitness of plants.
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| 6. |
- Petra, Majer, et al.
(författare)
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Evaluation of procedures for assessing anti- and pro-oxidants in plant samples
- 2016
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Ingår i: Analytical Methods. - Cambridge, United Kingdom : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 8:28, s. 5569-5580
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Forskningsöversikt (refereegranskat)abstract
- Plants as well as other aerobic organisms constantly produce reactive oxygen species (ROS). At regulatedlow concentrations ROS may serve as signal molecules, while in excessive amounts these may causeoxidative damage to biomolecules. Actual cellular concentrations are controlled by a network of variousantioxidants, and acclimation to stress conditions is achieved by a dynamic balance of ROS productionand neutralization. Accordingly, plant stress physiology studies generally include an array of methodstesting the occurrence of ROS as well as evaluating antioxidant capacities. The aim of the present workis to provide an overview of these methods, with special emphasis on avoiding errors that can possiblylead to either inaccurate data or misinterpretations of otherwise correct measurements.
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| 7. |
- Hideg, Éva, et al.
(författare)
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UV-B exposure, ROS, and stress : inseparable companions or loosely linked associates?
- 2013
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Ingår i: Trends in Plant Science. - : Cell Press. - 1360-1385 .- 1878-4372. ; 18:2, s. 107-115
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Tidskriftsartikel (refereegranskat)abstract
- Ultraviolet-B (UV-B) radiation has long been perceived as a stressor. However, a conceptual U-turn has taken place, and UV-B damage is now considered rare. We question whether UV-stress and UV-B-induced reactive oxygen species (ROS) are still relevant concepts, and if ROS-mediated signaling contributes to UV-B acclimation. Measurements of antioxidants and of antioxidant genes show that both low and high UV-B doses alter ROS metabolism. Yet, there is no evidence that ROS control gene expression under low UV-B. Instead, expression of antioxidant genes is linked to the UV RESISTANCE LOCUS 8 pathway. We hypothesize that low UVB doses cause ‘eustress’ (good stress) and that stimulispecific signaling pathways pre-dispose plants to a state of low alert that includes activation of antioxidant defenses.
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