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1.	Ristilä, Mikael (författare) Vitamin B6 as a potential antioxidant : a study emanating from UV-B-stressed plants 2006 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Increased influx of solar UV-B radiation (280-320 nm), due to a decreasing stratospheric ozone layer, impacts severely on plants. Some of the UV-B effects on plants are related to stress induced by produced reactive oxygen species (ROS). Pyridoxine (vitamin B6) has been reported to be a potential quencher of ROS.Previous studies have shown that the PDX1.3 gene (encoding a key enzyme in vitamin B6 biosynthesis) is up-regulated by UV-B. We showed that this up-regulation also occurs at the protein level in UV-B exposed Col-0 wild-type plants. Studies performed using pdx1 knock-out mutants of Arabidopsis thaliana showed elevated transcripts levels for LHCB1*3 and PR-5 compared with the Col-0 wild-type. The pdx1 knock-out mutants showed an increased sensitivity towards H2O2-stress, but no increased sensitivity towards low dose UV-B-stress.To study the postulated role of pyridoxine as quencher of ROS in more detail, both theoretical and experimental studies were performed. Theoretical and experimental UV absorption spectra obtained at different protonation/deprotonation states of pyridoxine showed a very close resemblance at low and high pH. However, for the computational studies at physiological pH addition of counterions were required to accurately describe the experimental spectra.When theoretically studying the reactivity of pyridoxine towards three different ROS, .OH, .OOH and .O2-, the hydroxyl radical (.OH) was shown to be the most reactive species, while the superoxide radical (.O2-) showed no reactivity towards pyridoxine.In order to study the role of G-proteins in UV-B signal transduction pathways, UV-B irradiated G-protein mutants of Arabidopsis thaliana were studied. The regulation of the PDX1.3 gene was not affected in the G-protein mutants, regardless of the developmental stage of the plant. However, the expression of CHS was affected in the Ga subunit mutants.
2.	Lindh, Ingrid, 1982- (författare) Plant-produced STI vaccine antigens with special emphasis on HIV-1 p24 2011 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Objective: To establish stable transgenic non-toxic plants as a platform for plant-based vaccine production as well as potential oral delivery system of vaccine antigens for sexually transmitted infections (STIs). The concept is to immunize the mucosal immune system present in the gut-associated lymphoid tissues (GALT). HIV-1 p24 subtype C protein has been used as the main antigen model, in parallel with an engineered unique chimeric MOMP antigen from Chlamydia trachomatis serovar E.Methods: Chimeric MOMP and p24 vaccine antigens were successfully inserted into the nuclear genomes of Arabidopsis thaliana and Daucus carota via Agrobacterium-mediated gene transfer. The characteristics of the genetic inserts and corresponding mRNAs and recombinant proteins in planta were described using several methods, including northern, Southern, and western blotting, ELISA, and a commercial HIV Ag/Ab combination assay. Immunogenicity of the antigens was studied in mice models.Results: Transgenes of both plant species expressing p24 or chimeric MOMP were successfully generated. Additional HIV-1 vaccine antigen candidates were introduced and the genetic inserts have been confirmed in Arabidopsis thaliana. The Arabidopsis thaliana expressing p24 and chimeric MOMP were demonstrated to be stable over generations and antigenicity analyses showed that plant-derived HIV-1 p24 and chimeric MOMP retained immunological epitopes when they were expressed in planta. Oral administration of transgenic plant material generated a priming effect of the immune competent cells present in the GALT, shown by the presence of antigen-specific-IgG in mice sera after boosting. Mice immunized with plant-derived HIV-1 p24 antigen were also analyzed for antigen-specific faecal IgA as well as cellular immune responses. However, detectable levels of the two latter immune responses were not observed. The Chlamydia trachomatis chimeric MOMP antigen was further evaluated for its potential as a vaccine antigen candidate, with positive results indicating a more rapid clearance of the Chlamydia trachomatis infection post immunization.Conclusion: Stable non-toxic transgenic plants expressing either HIV-1 p24 or a novel Chlamydia trachomatis chimeric MOMP antigens have successfully been developed. The two plant-produced STI vaccine antigens have in initial mice feeding studies provided important proof-of-concept for the oral vaccination approach. Now, immunization studies to expand, en-hance, and improve knowledge of the immune responses generated by the orally delivered transgenic plants are of high priority.
3.	Strid, Anna, 1978- (författare) Organohalogen contaminants in Greenland shark (Somniosus microcephalus) 2010 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract The remote sub-Arctic/Arctic environment has due to human activities become a sink for organohalogen contaminants (OHCs). These OHC include traditional contaminants such as polychlorinated biphenyls (PCBs), DDTs and technical mixtures of polybrominated diphenyl ethers (PBDEs), all included in the Stockholm Convention list of persistent organic pollutants (POPs). Other OHCs, currently under evaluation to be included among the POPs i.e. short chain chlorinated paraffins (SCCPs) and hexabromocyclododecane (HBCDD) are also found in these environments as well as a whole range of other OHCs. The main objective of this thesis is to increase the knowledge about the presence of OHCs in a high trophic Arctic shark species, the Greenland shark (Somniosus microcephalus). The Greenland shark is an opportunistic feeder, occasionally feeding at the top of the Arctic marine food chain. Furthermore may this species have a life span in excess of 100 years and is probably among the oldest of any fish species. These traits make the shark prone to accumulate elevated concentrations of OHCs. This has shown to be true for the Greenland sharks studied and most of the targeted OHCs were determined in the species. The highest concentrations were observed for the DDTs, ranging up to 26 μg/g fat. Other OHCs reported that are of special interest are SCCPs and brominated flame retardants used as replacement products to PBDEs; pentabromoethylbenzene (PBEB) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE). Also a range of OHCs whose origin is assumed to be natural, were shown to be present in Greenland sharks. This thesis is stressing the fact that even though the use of certain OHCs has been banned for decades they are still present at high concentrations in the deep waters of the Arctic. Therefore it is of major importance to continue to monitor the fate of traditional and emerging OHCs in the environment, and for this purpose the Greenland shark is an excellent species.
4.	Andersson, Sören, 1957-, et al. (författare) CHIMERIC MOMP ANTIGEN 2015 Patent (populärvet., debatt m.m.)
5.	Andersson, Sören, 1957-, et al. (författare) Chimeric MOMP antigen 2014 Patent (populärvet., debatt m.m.)abstract The present invention regards polypeptides capable of eliciting an immunological response that is protective against Chlamydia trachomatis. The polypeptide comprises a first amino acid sequence which has at least 90% homology with the amino acid sequence according to SEQ ID NO: 1 and a second amino acid sequence which has at least 90% homology with the amino acid sequence according to SEQ ID NO: 2. Furthermore, production of these polypeptides and pharmaceutical compositions comprising them are also provided.
6.	Asghar, Naveed, 1983-, et al. (författare) Transient Expression of Flavivirus Structural Proteins in Nicotiana benthamiana 2022 Ingår i: Vaccines. - : MDPI. - 2076-393X. ; 10:10 Tidskriftsartikel (refereegranskat)abstract Flaviviruses are a threat to public health and can cause major disease outbreaks. Tick-borne encephalitis (TBE) is caused by a flavivirus, and it is one of the most important causes of viral encephalitis in Europe and is on the rise in Sweden. As there is no antiviral treatment availa-ble, vaccination remains the best protective measure against TBE. Currently available TBE vaccines are based on formalin-inactivated virus produced in cell culture. These vaccines must be delivered by intramuscular injection, have a burdensome immunization schedule, and may exhibit vaccine failure in certain populations. This project aimed to develop an edible TBE vaccine to trigger a stronger immune response through oral delivery of viral antigens to mucosal surfaces. We demonstrated successful expression and post-translational processing of flavivirus structural pro-teins which then self-assembled to form virus-like particles in Nicotiana benthamiana. We performed oral toxicity tests in mice using various plant species as potential bioreactors and evaluated the immunogenicity of the resulting edible vaccine candidate. Mice immunized with the edible vaccine candidate did not survive challenge with TBE virus. Interestingly, immunization of female mice with a commercial TBE vaccine can protect their offspring against TBE virus infection.
7.	Castro Alves, Victor, 1986-, et al. (författare) Integration of non-target metabolomics and sensory analysis unravels vegetable plant metabolite signatures associated with sensory quality : A case study using dill (Anethum graveolens) 2021 Ingår i: Food Chemistry. - : Elsevier. - 0308-8146 .- 1873-7072. ; 344 Tidskriftsartikel (refereegranskat)abstract Using dill (Anethum graveolens L.) as a model herb, we revealnovel associations between metabolite profile and sensory quality, by integrating non-target metabolomics with sensory data. Low night temperatures and exposure to UV-enriched light was used to modulate plant metabolism, thereby improving sensory quality. Plant age is a crucial factor associated with accumulation of dill ether and α-phellandrene, volatile compounds associated with dill flavour. However, sensory analysis showed that neither of these compounds has any strong association with dill taste. Rather, amino acids alanine, phenylalanine, glutamic acid, valine, and leucine increased in samples exposed to eustress and were positively associated with dill and sour taste. Increases in amino acids and organic acids changed the taste from lemon/grass to a more bitter/pungent dill-related taste. Our approach reveals a novel approach to establish links between effects of eustressors on sensory quality, and may be applicable to a broad range of crops.
8.	Castro Alves, Victor, 1986-, et al. (författare) The taste of UV light : Using sensomics to improve horticultural quality 2020 Ingår i: UV4Plants Bulletin. - Helsingfors : University of Helsinki. - 2343-323X. ; :1, s. 39-43 Tidskriftsartikel (refereegranskat)abstract Greenhouse horticulture is in its broad definition the production of plant products within, under or sheltered by structures that provide protection against biotic and/or abiotic stress. In greenhouses, horticultural crops can grow protected from infectious agents and adverse weather conditions, allowing off-season, year-round production. However, greenhouse production often comes with a trade-off, which is a skewed light environment with a lack of UV light. In some instances, the blockage of UV by greenhouse glass and plastic covers is beneficial from a commercial perspective, especially on tropical latitudes where plants can often encounter higher UV levels, which may impair plant growth and nutrient absorption (Krause et al. 1999; Verdaguer et al. 2017). On the other hand, reduced UV inside greenhouses may reduce the synthesis of metabolites associated with crop protection against biotic and abiotic stress, such as flavonoids, terpenoids and alkaloids (Yang et al. 2018). This reduction in the amount of protective compounds may not be seen as an important limitation in a protected environment, but these metabolic changes caused by reduced UV exposure may in fact negatively impact on product quality. For example, it is possible to improve of the aroma and taste of greenhouse tomato by exposing plants to low levels of supplementary UV light (Dzakovich et al. 2016).
9.	Chow, Wah Soon, et al. (författare) A tribute to Robert John Porra (august 7, 1931–may 16, 2019) 2021 Ingår i: Photosynthesis Research. - : Springer Nature. - 0166-8595 .- 1573-5079. ; 147:2, s. 125-130 Tidskriftsartikel (refereegranskat)abstract Robert John Porra (7.8.1931–16.5.2019) is probably best known for his substantial practical contributions to plant physiology and photosynthesis by addressing the problems of both the accurate spectroscopic estimation and the extractability of chlorophylls in many organisms. Physiological data and global productivity estimates, in particular of marine primary productivity, are often quoted on a chlorophyll basis. He also made his impact by work on all stages of tetrapyrrole biosynthesis: he proved the C5 pathway to chlorophylls, detected an alternative route to protoporphyrin in anaerobes and the different origin of the oxygen atoms in anaerobes and aerobes. A brief review of his work is supplemented by personal memories of the authors.
10.	Czégény, Gyula, et al. (författare) Multiple roles for Vitamin B6in plant acclimation to UV-B 2019 Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 9:1 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.
11.	Díaz-Ramos, L. Aranzazú, et al. (författare) Difference in the action spectra for UVR8 monomerisation and HY5 transcript accumulation in Arabidopsis 2018 Ingår i: Photochemical and Photobiological Sciences. - : Royal Society of Chemistry. - 1474-905X .- 1474-9092. ; 17:8, s. 1108-1117 Tidskriftsartikel (refereegranskat)abstract The photoreceptor UV RESISTANCE LOCUS 8 (UVR8) activates photomorphogenic responses when plants are exposed to ultraviolet-B (UVB) light. However, whereas the absorption spectrum of UVR8 peaks at 280 nm, action spectra for several photomorphogenic UV-B responses show maximal photon effectiveness at 290-300 nm. To investigate this apparent discrepancy we measured the effectiveness of UV wavelengths in initiating two responses in Arabidopsis: photoconversion of homodimeric UVR8 into the monomeric form, which is active in signaling, and accumulation of transcripts of the ELONGATED HYPOCOTYL 5 (HY5) transcription factor, which has a key role in UVR8-mediated responses. When purified UVR8 or Arabidopsis leaf extracts were exposed to UV light monomerisation was maximal at approximately 280 nm, which correlates with the UVR8 absorption spectrum. When intact plants were exposed to UV, monomerisation was most strongly initiated at approximately 290 nm, and this shift in maximal effectiveness could be explained by strong absorption or reflectance at 280 nm by leaf tissue. Notably, the action spectrum for accumulation of HY5 transcripts in the same leaf tissue samples used to assay UVR8 dimer/monomer status peaked at approximately 300 nm. Possible reasons for the difference in maximal photon effectiveness of UVR8 monomerisation and HY5 transcript accumulation in leaf tissue are discussed.
12.	Eriksson, Leif A., 1964-, et al. (författare) Tetrazole derivatives as cytochrome p450 inhibitors 2019 Patent (populärvet., debatt m.m.)abstract According to the invention there is provided a compound of formula I, wherein R1 and R2 have meanings given in the description, which compounds are useful in the treatment of skin disorders and other diseases.
13.	Jansen, Marcel A. K., et al. (författare) Interactive effects of UV-B radiation in a complex environment 2019 Ingår i: Plant physiology and biochemistry (Paris). - : Elsevier Masson. - 0981-9428 .- 1873-2690. ; 134, s. 1-8 Tidskriftsartikel (refereegranskat)
14.	Kalbina, Irina, 1961- (författare) The molecular mechanisms behind perception and signal transduction of UV-B irradiation in Arabidopsis thaliana 2005 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Elevation of UV-B radiation (280-315 nm), occurring as a result of depletion of the stratospheric ozone, causes a number of physiological and biochemical changes in plants. Damage to the photosynthetic apparatus (including the bleaching of the pigments which trap the sun's energy), to the processes of cell division and growth regulation, and to the composition and replication of genetic material are just some of these changes. The consequences include reduction in growth yield, changes in levels and effects of plant hormones and secondary metabolites, and alteration of interactions between plants and other organisms.This thesis deals with several mechanistic questions related to regulation of responses during UV-B stress in plants. Our results show significant ecotype-specific variability in UV-B response in the model plant Arabidopsis thaliana. Differences at the molecular level (expression of PR-5 and steady-state concentration of H2O2) resulted in statistically significant differences in biomass, rosette size and leaf area. Therefore, it is of great importance to pay attention to the responses of the background ecotypes when for instance studying mechanisms of responses toward ultraviolet-B radiation in mutants.Using a DNA microarray approach, we found a number of novel genes to be differentially expressed under UV-B radiation. Two of the genes (PYROA and MEB5.2) were later used as molecular markers for monitoring of UV-B stress. Promoters of PYROA and MEB5.2 were compared with promoters of genes for the phenylpropanoid pathway. The comparisons indicated only few common elements with the UV-B-regulated promoters of CHS, PAL and CHI. In contrast, the genes identified as being UV-B regulated in this study (MEB5.2, PYROA and UBQ3), completely lacked elements required for the UV-B induction of CHS, indicating that these genes are regulated by different transcription factors. In addition, novel unidentified cis-elements are probably also present upstream of the transcription start.Reverse and forward genetics were used for searching novel genes responsive to UV-B and for examination of proposed candidates of the UV-B signal transduction chain. Screening of more than 2000 T-DNA mutants for differential response to UV-B resulted in the identification of a mutant displaying insensitivity to UV-B induced inhibition of hypocotyl growth. By using the corresponding knock-out mutants, the involvement of NADPH oxidase and MAPK phosphatase 1 in UV-B signalling was demonstrated.For the plant to be able to respond appropriately to UV-B irradiation, UV-B quanta have to be absorbed. There are indirect evidences for the existence of specific UV-B receptor(s), whereas the receptor itself still remains unknown. By the classical approach of action spectroscopy, we undertook an attempt to identify the absorption spectra of the chromophore(s) sensing UV-B radiation in plants. The investigated molecular markers revealed the presence of two potential chromophores absorbing in the UV-B region and peaking at 280-290 and 300 nm, respectively.
15.	Neugart, Susanne, et al. (författare) A synchronized, large-scale field experiment using Arabidopsis thaliana reveals the significance of the UV-B photoreceptor UVR8 under natural conditions 2024 Ingår i: Plant, Cell and Environment. - : Blackwell Publishing. - 0140-7791 .- 1365-3040. 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.
16.	Neugart, Susanne, et al. (författare) 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 Ingår i: Photochemical and Photobiological Sciences. - : Royal Society of Chemistry. - 1474-905X .- 1474-9092. ; 19:2, s. 217-228 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.
17.	Ni, Junbei, et al. (författare) Ethylene mediates the branching of the jasmonate-induced flavonoid biosynthesis pathway by suppressing anthocyanin biosynthesis in red Chinese pear fruits 2020 Ingår i: Plant Biotechnology Journal. - : Wiley-Blackwell. - 1467-7644 .- 1467-7652. ; 18:5, s. 1223-1240 Tidskriftsartikel (refereegranskat)abstract Flavonoid accumulation in most fruitsis enhanced by ethylene and jasmonate. However, little is known about the hormone functions related to red pear fruit coloration or their combined effects and potential underlying mechanisms. Various treatments were used to investigate the flavonoid metabolite profile and pear transcriptome to verify the effects of ethylene and jasmonate on flavonoid biosynthesis in red pear fruits as well as the mechanism behind this. Ethylene inhibits anthocyanin biosynthesis in red Chinese pear fruits, whereas jasmonate increases anthocyanin and flavone/isoflavone biosyntheses. The branching of the jasmonate-induced flavonoid biosynthesis pathway is determined by ethylene. Co-expression network and Mfuzz analyses revealed 4,368 candidate transcripts. Additionally, ethylene suppresses PpMYB10 and PpMYB114 expression via TF repressors, ultimately decreasing anthocyanin biosynthesis. Jasmonate induces anthocyanin accumulation through transcriptional or post-translational regulation of TFs like MYB and bHLH in the absence of ethylene. However, jasmonate induces ethylene biosynthesis and the associated signaling pathway in pear, thereby decreasing anthocyanin production, increasing the availability of the precursors for flavone/isoflavone biosynthesis, and enhancing deep yellow fruit coloration. We herein present new phenotypes and fruit coloration regulatory patterns controlled by jasmonate and ethylene, and confirm that the regulation of fruit coloration is complex.
18.	O'Hara, Andrew, 1983-, et al. (författare) Regulation of Arabidopsis gene expression by low fluence rate UV-B independently of UVR8 and stress signaling 2019 Ingår i: Photochemical and Photobiological Sciences. - : RSC Publishing. - 1474-905X .- 1474-9092. ; 18:7, s. 1675-1684 Tidskriftsartikel (refereegranskat)abstract UV-B exposure of plants regulates expression of numerous genes concerned with various responses. Sudden exposure of non-acclimated plants to high fluence rate, short wavelength UV-B induces expression via stress-related signaling pathways that are not specific to the UV-B stimulus, whereas low fluence rates of UV-B can regulate expression via the UV-B photoreceptor UV RESISTANCE LOCUS 8 (UVR8). However, there is little information about whether non-stressful, low fluence rate UV-B treatments can activate gene expression independently of UVR8. Here, transcriptomic analysis of wild-type and uvr8 mutant Arabidopsis exposed to low fluence rate UV-B showed that numerous genes were regulated independently of UVR8. Moreover, nearly all of these genes were distinct to those induced by stress treatments. A small number of genes were expressed at all UV-B fluence rates employed and may be concerned with activation of eustress responses that facilitate acclimation to changing conditions. Expression of the gene encoding the transcription factor ARABIDOPSIS NAC DOMAIN CONTAINING PROTEIN 13 (ANAC13) was studied to characterise a low fluence rate, UVR8-independent response. ANAC13 is induced by as little as 0.1 μmol m−2 s−1 UV-B and its regulation is independent of components of the canonical UVR8 signaling pathway COP1 and HY5/HYH. Furthermore, UV-B induced expression of ANAC13 is independent of the photoreceptors CRY1, CRY2, PHOT1 and PHOT2 and phytochromes A, B, D and E. ANAC13 expression is induced over a range of UV-B wavelengths at low doses, with maximum response at 310 nm. This study provides a basis for further investigation of UVR8 and stress independent, low fluence rate UV-B signaling pathway(s).
19.	Palma, Carolina Falcato Fialho, et al. (författare) Effects of UV radiation on transcript and metabolite accumulation are dependent on monochromatic light background in cucumber 2021 Ingår i: Physiologia Plantarum. - : John Wiley & Sons. - 0031-9317 .- 1399-3054. ; 173:3, s. 750-761 Tidskriftsartikel (refereegranskat)abstract During recent years we have advanced our understanding of plant molecular responses to ultraviolet radiation (UV, 280-400 nm); however, how plants respond to UV radiation under different spectral light qualities is poorly understood. In this study, cucumber plants (Cucumis sativus ‘Lausanna RZ F1’) were grown under monochromatic blue, green, red and broadband white light in combination with UV radiation. The effects of light quality and UV radiation on acclimatory responses were assessed by measuring transcript accumulation of ELONGATED HYPOCOTYL 5 (HY5), CHALCONE SYNTHASE 2 (CHS2) and LIGHT HARVESTING COMPLEX II (LHCII), and the accumulation of flavonoids and hydroxycinnamic acids in the leaves. The growth light backgrounds differentially regulated gene expression and metabolite accumulation. While HY5 and CHS2 transcripts were induced by blue and white light, LHCII was induced by white and red light. Furthermore, UV radiation antagonized the effects of blue, red, green, and white light on transcript accumulation in a gene dependent manner. Plants grown under blue light with supplementary UV radiation increased phenylalanine, flavonol disaccharide I and caffeic acid contents compared to those exposed only to blue light. UV radiation also induced the accumulation of flavonol disaccharide I and II, ferulic acid hexose and coumaric acid hexose in plants grown under green light. Our findings provide further understanding of plant responses to UV radiation in combination with different light spectra and contribute to the design of light recipes for horticultural practices that aim to modify plant metabolism and ultimately improve crop quality.
20.	Palma, Carolina Falcato Fialho, et al. (författare) Metabolic changes in cucumber leaves are enhanced by blue light and differentially affected by UV interactions with light signalling pathways in the visible spectrum 2022 Ingår i: Plant Science. - : Elsevier. - 0168-9452 .- 1873-2259. ; 321 Tidskriftsartikel (refereegranskat)abstract Ultraviolet radiation (UV, 280-400 nm) as an environmental signal triggers metabolic acclimatory responses. However, how different light qualities affect UV acclimation during growth is poorly understood. Here, cucumber plants (Cucumis sativus) were grown under blue, green, red, or white light in combination with UV. Their effects on leaf metabolites were determined using untargeted metabolomics. Blue and white growth light triggered the accumulation of compounds related to primary and secondary metabolism, including amino acids, phenolics, hormones, and compounds related to sugar metabolism and the TCA cycle. In contrast, supplementary UV in a blue or white light background decreased leaf content of amino acids, phenolics, sugars, and TCA-related compounds, without affecting abscisic acid, auxin, zeatin, or jasmonic acid levels. However, in plants grown under green light, UV-induced accumulation of phenolics, hormones (auxin, zeatin, dihydrozeatin-7-N-dihydrozeatin, jasmonic acid), amino acids, sugars, and TCA cycle-related compounds. Plants grown under red light with UV mainly showed decreased sugar content. These findings highlight the importance of the blue light component for metabolite accumulation. Also, data on interactions of UV with green light on the one hand, and blue or white light on the other, further contributes to our understanding of light quality regulation of plant metabolism.
21.	Qian, Minjie, 1987-, et al. (författare) Downsizing in plants—UV light induces pronounced morphological changes in the absence of stress 2021 Ingår i: Plant Physiology. - : Oxford University Press. - 0032-0889 .- 1532-2548. ; 187:1, s. 378-395 Tidskriftsartikel (refereegranskat)abstract Ultraviolet (UV) light induces a stocky phenotype in many plant species. In this study, we investigate this effect with regard to specific UV wavebands (UV-A or UV-B) and the cause for this dwarfing. UV-A- or UV-B-enrichment of growth light both resulted in a smaller cucumber (Cucumis sativus L.) phenotype, exhibiting decreased stem and petiole lengths and leaf area (LA). Effects were larger in plants grown in UV-B- than in UV-A-enriched light. In plants grown in UV-A-enriched light, decreases in stem and petiole lengths were similar independent of tissue age. In the presence of UV-B radiation, stems and petioles were progressively shorter the younger the tissue. Also, plants grown under UV-A-enriched light significantly reallocated photosynthates from shoot to root and also had thicker leaves with decreased specific LA. Our data therefore imply different morphological plant regulatory mechanisms under UV-A and UV-B radiation. There was no evidence of stress in the UV-exposed plants, neither in photosynthetic parameters, total chlorophyll content, or in accumulation of damaged DNA (cyclobutane pyrimidine dimers). The abscisic acid content of the plants also was consistent with non-stress conditions. Parameters such as total leaf antioxidant activity, leaf adaxial epidermal flavonol content and foliar total UV-absorbing pigment levels revealed successful UV acclimation of the plants. Thus, the UV-induced dwarfing, which displayed different phenotypes depending on UV wavelengths, occurred in healthy cucumber plants, implying a regulatory adjustment as part of the UV acclimation processes involving UV-A and/or UV-B photoreceptors.
22.	Qian, Minjie, et al. (författare) Supplementary UV-A and UV-B radiation differentially regulate morphology in Ocimum basilicum 2023 Ingår i: Photochemical and Photobiological Sciences. - : Springer. - 1474-905X .- 1474-9092. ; 22:9, s. 2219-2230 Tidskriftsartikel (refereegranskat)abstract UV-A- or UV-B-enriched growth light were given to basil plants at non-stress-inducing intensities. UV-A-enriched growth light gave rise to a sharp rise in expression of PAL and CHS genes in leaves, an effect that rapidly declined after 1-2 days of exposure. On the other hand, leaves of plants grown in UV-B-enriched light had a more stable and long-lasting increase in expression of these genes and also showed a stronger increase in leaf epidermal flavonol content. UV supplementation of growth light also led to shorter more compact plants with a stronger UV effect the younger the tissue. The effect was more prominent in plants grown under UV-B-enriched light than in those grown under UV-A. Parameters particularly affected were internode lengths, petiole lengths and stem stiffness. In fact, the bending angle of the 2nd internode was found to increase as much as 67% and 162% for plants grown in the UV-A- and UV-B-enriched treatments, respectively. The decreased stem stiffness was probably caused by both an observed smaller internode diameter and a lower specific stem weight, as well as a possible decline in lignin biosynthesis due to competition for precursor by the increased flavonoid biosynthesis. Overall, at the intensities used, UV-B wavelengths are stronger regulators of morphology, gene expression and flavonoid biosynthesis than UV-A wavelengths.
23.	Qian, Minjie, et al. (författare) UV-A light induces a robust and dwarfed phenotype in cucumber plants (Cucumis sativus L.) without affecting fruit yield 2020 Ingår i: Scientia Horticulturae. - : Elsevier. - 0304-4238 .- 1879-1018. ; 263 Tidskriftsartikel (refereegranskat)abstract Solar ultraviolet (UV) light influences plant growth and metabolism. Whereas high doses of UV can be deleterious for plants, natural UV doses are important for morphogenesis in many plants species, including those used in horticulture. Greenhouses are widely used for horticultural production and common cladding materials strongly absorb UV. Thus, low amounts of UV may be limiting the optimal development in some plant species. Light supplementation using UV tubes can overcome UV deficiency. Here we study cucumber seedling production in the absence or presence of different UV wavelengths. UV-A- (315-400 nm) and UV-B- (280-315 nm) enriched light was used for exposure and parameters such as the maximum quantum yield of photosystem II, stem development (internode length and diameter, stem dry weight, stem weight per unit of stem length, and stem bending), root biomass, leaf biomass and specific leaf mass were measured. We found that UV-A supplementation resulted in shorter more compact and sturdy plants, properties that are positive from a horticultural perspective. In contrast, UV-B-enriched light led to even smaller plants that lacked the sturdy phenotype. There were no signs of decreased Fv/Fmunder any of the treatments, nor statistically significant differences in fruit yield between the control plants and the UV-treated plants when grown to harvest. In particular, the differences in fruit yield between the controls and the UV-A-treated plants were negligible in all cases. Thus, supplementary UV-A light can be an interesting alternative to chemical growth regulators for production of sturdy horticultural plants.
24.	Qian, Minjie, 1987-, et al. (författare) UV regulates expression of phenylpropanoid biosynthesis genes in cucumber (Cucumis sativus L.) in an organ and spectrum dependent manner 2019 Ingår i: Photochemical and Photobiological Sciences. - London, UK : Royal Society of Chemistry. - 1474-905X .- 1474-9092. ; 18:2, s. 424-433 Tidskriftsartikel (refereegranskat)abstract Expression of cucumber (Cucumis sativus) genes encoding the phenylpropanoid and flavonoid biosynthetic enzymes phenylalanine ammonia lyase (PAL), cinnamic acid 4-hydroxylase (C4H), and chalcone synthase (CHS), was studied under control light conditions (photosynthetically active radiation, PAR) in root, stem, and leaf. Furthermore, expression was quantified in leaves illuminated with PAR and supplemental ultraviolet-A (315-400nm) or ultraviolet-B (280-315 nm) radiation. The expression pattern of all twelve CsPAL, threeCsC4H, and three CsCHS genes was established. Among the genes regulated by UV two general expression patterns emerge. One pattern applies to genes primarily regulated by enriched UV-A illumination (pattern 1). Another (pattern 2) was found for the genes regulated by enriched UV-B. Three of the pattern 2 genes (CsPAL4, CsPAL10, CsCHS2) displayed a particular sub-pattern (pattern 2b) with transcription enriched by at least 30 fold. In contrast to the other genes studied, the promoters of the genes regulated according to pattern 2b contained a combination of a number of cis-acting regulatory elements (MREs, ACEs, and G-boxes) that may be of importance for the particularly high enhancement of expression under UV-B- containing light. The regulation of phenylpropanoid and flavonoid biosynthesis genes in cucumber resembles that of a number of other plants. However, cucumber, due to its greater size, is an attractive species for more detailed studies of the fine regulation of spatial and temporal expression of key genes. This in turn, can facilitate the quantitative investigation of the relationships between different promotor motifs, the expression levels of each of these three genes, and metabolite accumulation profiles.
25.	Rai, Neha, et al. (författare) The photoreceptor UVR8 mediates the perception of both UV-B and UV-A wavelengths up to 350 nm of sunlight with responsivity moderated by cryptochromes 2020 Ingår i: Plant, Cell and Environment. - : John Wiley & Sons. - 0140-7791 .- 1365-3040. ; 43:6, s. 1513-1527 Tidskriftsartikel (refereegranskat)abstract The photoreceptors UV RESISTANCE LOCUS 8 (UVR8) and CRYPTOCHROMES 1 and 2 (CRYs) play major roles in the perception of UV-B (280–315 nm) and UV-A/blue radiation (315–500 nm), respectively. However, it is poorly understood how they function in sunlight. The roles of UVR8 and CRYs were assessed in a factorial experiment with Arabidopsis thaliana wild-type and photoreceptor mutants exposed to sunlight for 6 h or 12 h under five types of filters with cut-offs in UV and blue-light regions. Transcriptome-wide responses triggered by UV-B and UV-A wavelengths shorter than 350 nm (UV-Asw) required UVR8 whereas those induced by blue and UV-A wavelengths longer than 350 nm (UV-Alw) required CRYs. UVR8 modulated gene expression in response to blue light while lack of CRYs drastically enhanced gene expression in response to UV-B and UV-Asw. These results agree with our estimates of photons absorbed by these photoreceptors in sunlight and with in vitro monomerization of UVR8 by wavelengths up to 335 nm. Motif enrichment analysis predicted complex signaling downstream of UVR8 and CRYs. Our results highlight that it is important to use UV waveband definitions specific to plants’ photomorphogenesis as is routinely done in the visible region.
26.	Rodriguez-Calzada, Tania, et al. (författare) Effect of UV-B radiation on morphology, phenolic compound production, gene expression, and subsequent drought stress responses in chili pepper (Capsicum annuum L.) 2019 Ingår i: Plant physiology and biochemistry (Paris). - Paris, France : Elsevier. - 0981-9428 .- 1873-2690. ; 134, s. 94-102 Tidskriftsartikel (refereegranskat)abstract It has been suggested that accumulation of flavonoids could be a key step in development of plant tolerance to different environmental stresses. Moreover, it has been recognized that abiotic stresses such as drought and UV-B radiation (280-315 nm) induce phenolic compound accumulation, suggesting a role for these compounds in drought tolerance. The aim of the present study was to evaluate the effect of UV-B exposure on chili pepper (Capsicum annuum, cv. ‘Coronel’) plant performance, phenolic compound production, and gene expression associated with response to subsequent drought stress. Additionally, the phenotypic response to drought stress of these plants was studied. UV-B induced a reduction both in stem length, stem dry weight and number of floral primordia. The largest reduction in these variables was observed when combining UV-B and drought. UV-B-treated well-watered plants displayed fructification approximately 1 week earlier than non-UV-B-treated controls. Flavonoids measured epidermally in leaves significantly increased during UV-B treatment. Specifically, UV-B radiation significantly increased chlorogenic acid and apigenin 8-C-hexoside levels in leaves and a synergistic increase of luteolin 6-C-pentoside-8-C-hexoside was obtained by UV-B and subsequent drought stress. Gene expression of phenylalanine ammonia lyase (PAL) and chalcone synthase (CHS) genes also increased during UV-B treatments. On the other hand, expression of genes related to an oxidative response, such as mitochondrial Mn-superoxide dismutase (Mn-SOD) and peroxidase (POD) was not induced by UV-B. Drought stress in UV-B-treated plants induced mitochondrial Mn-SOD gene expression. Taken together, the UV-B treatment did not induce significant tolerance in plants towards drought stress under the conditions used.
27.	Saénz-de la O, Diana, et al. (författare) Antioxidant and drought‑acclimation responses in UV‑B‑exposed transgenic Nicotiana tabacum displaying constitutive overproduction of H2O2 2023 Ingår i: Photochemical and Photobiological Sciences. - : Springer. - 1474-905X .- 1474-9092. ; 22:10, s. 2373-2387 Tidskriftsartikel (refereegranskat)abstract Hydrogen peroxide (H2O2) is an important molecule that regulates antioxidant responses that are crucial for plant stress resistance. Exposure to low levels of ultraviolet-B radiation (UV-B, 280–315 nm) can also activate antioxidant defenses and acclimation responses. However, how H2O2 and UV-B interact to promote stress acclimation remains poorly understood. In this work, a transgenic model of Nicotiana tabacum cv Xanthi nc, with elevated Mn-superoxide dismutase (Mn-SOD)activity, was used to study the interaction between the constitutive overproduction of H2O2 and a 14-day UV-B treatment (1.75 kJ m−2 d−1 biologically effective UV-B). Subsequently, these plants were subjected to a 7-day moderate drought treatment to evaluate the impact on drought resistance of H2O2- and UV-dependent stimulation of the plants' antioxidant system. The UV-B treatment enhanced H2O2 levels and altered the antioxidant status by increasing the epidermal flavonol index, Trolox Equivalent Antioxidant Capacity, and catalase, peroxidase and phenylalanine ammonia lyase activities in the leaves. UV-B also retarded growth and suppressed acclimation responses in highly H2O2-overproducing transgenic plants. Plants not exposed to UV-B had a higher drought resistance in the form of higher relative water content of leaves. Our data associate the interaction between Mn-SOD transgene overexpression and the UV-B treatment with a stress response. Finally, we propose a hormetic biphasic drought resistance response curve as a function of leaf H2O2 content in N. tabacum cv Xanthi.
28.	Sáenz-de la, O. Diana, et al. (författare) Ultraviolet-B exposure and exogenous hydrogen peroxide application lead to cross-tolerance toward drought in Nicotiana tabacum L. 2021 Ingår i: Physiologia Plantarum. - : Blackwell Publishing. - 0031-9317 .- 1399-3054. ; 173:3, s. 666-679 Tidskriftsartikel (refereegranskat)abstract Acclimation of plants to water deficit involves biochemical and physiological adjustments. Here, we studied how UV‐B exposure and exogenously applied hydrogen peroxide (H2O2) potentiates drought tolerance in tobacco (Nicotiana tabacum L. cv. xanthi nc). Separate and combined applications for 14 days of 1.75 kJ m−2 day−1 UV‐B radiation and 0.2 mM H2O2 were assessed. Both factors, individually and combined, resulted in inhibition of growth. Furthermore, the combined treatment led to the most compacted plants. UV‐B‐ and UV‐B+H2O2‐treated plants increased total antioxidant capacity and foliar epidermal flavonol index. H2O2‐ and UV‐B+H2O2‐pre‐treated plants showed cross‐tolerance to a subsequent 7‐day moderate drought treatment, which was assessed as the absence of negative impact on growth, leaf wilting, and leaf relative water content (RWC). Plant responses to the pre‐treatment were notably different: (1) H2O2 increased the activity of catalase (CAT, EC 1.11.1.6), phenylalanine ammonia lyase (PAL; EC 4.3.1.5) and peroxidase activities (POD, EC 1.11.1.7), and (2) the combined treatment induced epidermal flavonols which were key to drought tolerance. We report synergistic effects of UV‐B and H2O2 on transcription accumulation of UV RESISTANCE LOCUS 8, NAC DOMAIN PROTEIN 13 (NAC13), and BRI1‐EMS‐SUPPRESSOR 1 (BES1). Our data demonstrate a pre‐treatment‐dependent response to drought for NAC13, BES1 and CHALCONE SYNTHASE transcript accumulation. This study highlights the potential of combining UV‐B and H2O2 to improve drought tolerance which could become a useful tool to reduce water use.
29.	Santin, Marco, et al. (författare) The outer influences the inner : postharvest UV-B radiation modulates peach flesh metabolome although shielded by the skin 2020 Ingår i: Food Chemistry. - : Elsevier. - 0308-8146 .- 1873-7072. Tidskriftsartikel (refereegranskat)abstract UV-B-driven modulation of secondary metabolism in peach fruit by enhancing the biosynthesis of specific phenolic subclasses, is attracting interest among consumers. However, current literature explored the UV-B-induced metabolic changes only in peach skin subjected to direct UV-B irradiation. Accordingly, this study aimed to understand whether UV-B radiation penetrates the fruit skin and is able to induce metabolic changes also within the inner flesh. Peaches were UV-B irradiated either 10 or 60 min, and the flesh was sampled after 24 and 36 h. Non-targeted metabolomics revealed that UV-B has a strong impact on peach flesh metabolome, determining an initial decrease after 24 h, followed by an overall increase after 36 h, particularly for terpenoids, phenylpropanoids, phytoalexins and fatty acids in the 60 min UV-B-treated samples (+150.02, +99.14, +43.79 and +25.44 log2FC, respectively). Transmittance analysis indicated that UV-B radiation does not penetrate below the skin, suggesting a possible signalling pathway between tissues.
30.	Scherbak, Nikolai, 1967- (författare) Characterization of stress-inducible short-chain dehydrogenases/reductases (SDR) in plants : study of a novel small protein family from Pisum sativum (pea) 2005 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract In pea (Pisum sativum), the short-chain alcohol dehydrogenase-like protein (SAD) gene family consists of at least three members (SAD-A, -B, and -C). The SAD genes are transiently expressed in plants after short exposures to ultraviolet-B radiation, which in turn leads to formation of SAD protein in leaf and stem tissue upon prolonged irradiation. SAD gene expression is also seen as a result of wounding stress.The recombinant SAD-C protein (which was the most highly over-expressed isoform in Escherichia coli of the isoforms) was shown to be a tetramer that probably consists of a dimer of dimers and which possesses quinone-reducing capability. The enzyme shows approximately the same NADH- and NADPH-dependent activity with 2,5- and 2,6-dimethylbenzoquinone and menadione as substrates.Western blotting and immunohistochemistry (IHC) shows that the SAD protein is present to a smaller or larger extent in all the different pea tissues examined. Environmental stress such as UV-B radiation clearly increases the content of SAD in leaf and stem tissue but not in roots. This indicates that increased expression of the SAD genes, as a result of UV-B exposure, is limited to the exposed tissue. This is substantiated by the heterologous GUS expression from the pea SAD-C promoter in Arabidopsis during wounding. Only the wound site and the vicinal tissue show transcription from this promoter. In non-stressed tissue (as well as in UV-B-stressed leaves and stem), SAD predominantly occurred in epidermal or sub-epidermal cells as judged by IHC. The protoderm of the pea seed cotyledonary axis contains the most heavily stained cells. This indicates a possible role for the SAD protein in development as well as in protection against environmental stress. Also, discrete staining was obtained in particular cell types of the ovary.To be able to understand the biochemical and physiological role of the SAD enzyme, an in silico modeling study of the SAD protein structure was performed. The simulations of our SAD protein, as well as of related proteins with known crystal structure (3alfa,20beta-hydroxysteroid dehydrogenase and secoisolariciresinol dehydrogenase), allowed us to obtain an energy-minimized structure for the monomeric SAD as well as important data on the cofactor interaction in the active site.Crystallization of recombinant SAD-C has been performed. The needle-like crystals, which diffract to 3.5Å, contain probably eight monomers in the asymmetric unit, presumably containing a pair of tetramers.SAD enhances the reduction rates of quinones with NADH. However, NADH can also accomplish reduction of certain quinones non-enzymatically. Both theoretical calculations and experimental techniques were used to elucidate the structural and electronic pre-requisites for this non-enzymatic quinone reduction.
31.	Seeburger, P., et al. (författare) From farm to fork… and beyond! UV enhances Aryl hydrocarbon receptor-mediated activity of cruciferous vegetables in human intestinal cells upon colonic fermentation 2023 Ingår i: Food Chemistry. - : Elsevier. - 0308-8146 .- 1873-7072. ; 426 Tidskriftsartikel (refereegranskat)abstract While the "farm to fork" strategy ticks many boxes in the sustainability agenda, it does not go far enough in addressing how we can improve crop nutraceutical quality. Here, we explored whether supplementary ultraviolet (UV) radiation exposure during growth of broccoli and Chinese cabbage can induce bioactive tryptophan- and glucosinolate-specific metabolite accumulation thereby enhancing Aryl hydrocarbon receptor (AhR) activation in human intestinal cells. By combining metabolomics analysis of both plant extracts and in vitro human colonic fermentation extracts with AhR reporter cell assay, we reveal that human colonic fermentation of UVB-exposed Chinese cabbage led to enhanced AhR activation in human intestinal cells by 23% compared to plants grown without supplementary UV. Thus, by exploring aspects beyond "from farm to fork", our study highlights a new strategy to enhance nutraceutical quality of Brassicaceae, while also providing new insights into the effects of cruciferous vegetables on human intestinal health.
32.	Sommer, Søren Gjedde, et al. (författare) The light spectrum differentially influences morphology, physiology and metabolism of Chrysanthemum × morifolium without affecting biomass accumulation 2023 Ingår i: Physiologia Plantarum. - : John Wiley & Sons. - 0031-9317 .- 1399-3054. ; 175:6 Tidskriftsartikel (refereegranskat)abstract The development of light emitting diodes (LED) gives new possibilities to use the light spectrum to manipulate plant morphology and physiology in plant production and research. Here, vegetative Chrysanthemum × morifolium were grown at a photosynthetic photon flux density of 230 μmol m−2 s−1 under monochromatic blue, cyan, green, and red, and polychromatic red:blue or white light with the objective to investigate the effect on plant morphology, gas exchange and metabolic profile. After 33 days of growth, branching and leaf number increased from blue to red light, while area per leaf, leaf weight fraction, flavonol index, and stomatal density and conductance decreased, while dry matter production was mostly unaffected. Plants grown under red light had decreased photosynthesis performance compared with blue or white light-grown plants. The primary and secondary metabolites, such as organic acids, amino acids and phenylpropanoids (measured by non-targeted metabolomics of polar metabolites), were regulated differently under the different light qualities. Specifically, the levels of reduced ascorbic acid and its oxidation products, and the total ascorbate pool, were significantly different between blue light-grown plants and plants grown under white or red:blue light, which imply photosynthesis-driven alterations in oxidative pressure under different light regimens. The overall differences in plant phenotype, inflicted by blue, red:blue or red light, are probably due to a shift in balance between regulatory pathways controlled by blue light receptors and/or phytochrome. Although morphology, physiology, and metabolism differed substantially between plants grown under different qualities of light, these changes had limited effects on biomass accumulation.
33.	Wu, Min, 1986, et al. (författare) Proline 411 biases the conformation of the intrinsically disordered plant UVR8 photoreceptor C27 domain altering the functional properties of the peptide 2019 Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9 Tidskriftsartikel (refereegranskat)abstract UVR8 (UV RESISTANCE LOCUS 8) is a UV-B photoreceptor responsible for initiating UV-B signalling in plants. UVR8 is a homodimer in its signalling inactive form. Upon absorption of UV radiation, the protein monomerizes into its photoactivated state. In the monomeric form, UVR8 binds the E3 ubiquitin ligase COP1 (CONSTITUTIVELY PHOTOMORPHOGENIC 1), triggering subsequent UV-B-dependent photomorphogenic development in plants. Recent in vivo experiments have shown that the UVR8 C-terminal region (aa 397-423; UVR8(C27)) alone is sufficient to regulate the activity of COP1. In this work, CD spectroscopy and NMR experiments showed that the UVR8(C27) domain was non-structured but gained secondary structure at higher temperatures leading to increased order. Bias-exchange metadynamics simulations were also performed to evaluate the free energy landscape of UVR8(C27). An inverted free energy landscape was revealed, with a disordered structure in the global energy minimum. Flanking the global energy minimum, more structured states were found at higher energies. Furthermore, stabilization of the low energy disordered state was attributed to a proline residue, P411, as evident from P411A mutant data. P411 is also a key residue in UVR8 binding to COP1. UVR8(C27) is therefore structurally competent to function as a molecular switch for interaction of UVR8 with different binding partners since at higher free energies different structural conformations are being induced in this peptide. P411 has a key role for this function.
34.	Yang, Chengkun, et al. (författare) Postharvest white light combined with different UV-B doses differently promotes anthocyanin accumulation and antioxidant capacity in mango peel 2024 Ingår i: Lebensmittel-Wissenschaft + Technologie. - : Academic Press. - 0023-6438 .- 1096-1127. ; 203 Tidskriftsartikel (refereegranskat)abstract Fruit peel color is an important index of mango fruit quality. Therefore, increasing the anthocyanin accumulation and improving coloration in red mango are crucial for mango industry. The anthocyanin accumulation in mango is light-regulated. However, the effect of white light combined with different doses of UV-B on anthocyanin biosynthesis has not been clarified. Also lacking is a comprehensive analysis of responses of mango fruit peel to UV-B/white light treatments. In this study, green mature ‘Guifei’ mango fruits were subjected to white light combined with low (WL+UV-BL) or high dose UV-B (WL+UV-BH). Anthocyanin concentration, anthocyanin-related gene expression, reactive oxygen species (ROS), antioxidant, and plant hormone concentrations, and antioxidant enzyme activity were measured. The results showed that especially a WL+UV-BH regimen promoted anthocyanin formation in mango peel. Anthocyaninand light signal-related gene expression, ROS content, antioxidant enzyme activity, antioxidant concentrations, and total antioxidant capacity were also increased by UVB/ white light. Such treatments led to higher concentrations of jasmonic acid and cytokines, but decreased content of 1-aminocyclopropane-1-carboxylic acid and salicylic acids. Commercially, our findings may contribute to improving the commercial quality of mango. Scientifically, the present data sheds light on the mango fruit peelspecific molecular and physiological response network under UV-B/white light treatments.

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