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  • 1. Brosché, Mikael
    et al.
    Schuler, Mary A.
    Kalbina, Irina
    Örebro University, Department of Natural Sciences.
    Connor, Lynn
    Strid, Åke
    Örebro University, Department of Natural Sciences.
    Gene regulation by low level UV-B radiation: identification by DNA array analysis2002In: Photochemical and Photobiological Sciences, ISSN 1474-905X, E-ISSN 1474-9092, Vol. 1, no 9, p. 656-664Article in journal (Refereed)
    Abstract [en]

    UV-B radiation alters transcript levels of various defence genes and photosynthetic genes in plants. Utilising a DNA array with 5000 ESTs and cDNAs from Arabidopsis thaliana, 70 genes were found to show a greater than two-fold induction or repression of transcript levels. Six genes (MEB5.2, PyroA, Ubq3, Lhcb6, F5D21.10 and the gene for an RNA polymerase II subunit) were tested for stress specific gene regulation on northern blots with RNA from plants exposed to low dose UV-B radiation, ozone or wounding. Transcript levels for PyroA, Uhq3 and the gene for a RNA polymerase II subunit were all specifically increased by UV-B. MEB5.2 mRNA levels also rose, whereas Lhcb6 and FSD21.10 transcript levels decreased under all stresses. The PyroA gene product in fungi is needed for biosynthesis of pyridoxine, and might have a role in protection against singlet oxygen. The Ubq3 gene encodes the ubiquitin protein that is attached to proteins destined for degradation. MEB5.2 and F5D21.10 represent novel gene products whose function have not yet been identified. Pairwise comparisons between the UV-B inducible promoters have identified a series of elements present in the MEB5.2 and PyroA promoters, absent from promoters of genes for early phenylpropanoid metabolism and that may be responsible for modulating their UV-B responses.

  • 2.
    Díaz-Ramos, L. Aranzazú
    et al.
    Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, Bower Building, University of Glasgow, Glasgow, UK.
    O'Hara, Andrew
    Örebro University, School of Science and Technology. Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, Bower Building, University of Glasgow, Glasgow, UK.
    Kanagarajan, Selvaraju
    Department of Plant Breeding, Swedish University of Agricultural Sciences, Alnarp, Sweden; School of Science & Technology, Örebro Life Science Center, Örebro University, Örebro, Sweden.
    Farkas, Daniel
    Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Jenkins, Gareth I
    Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, Bower Building, University of Glasgow, Glasgow, UK.
    Difference in the action spectra for UVR8 monomerisation and HY5 transcript accumulation in Arabidopsis2018In: Photochemical and Photobiological Sciences, ISSN 1474-905X, E-ISSN 1474-9092, Vol. 17, no 8, p. 1108-1117Article in journal (Refereed)
    Abstract [en]

    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.

  • 3. Guedes, Rita Cardoso
    et al.
    Eriksson, Leif A.
    Örebro University, Department of Natural Sciences.
    Photophysics, photochemistry, and reactivity: Molecular aspects of perylenequinone reactions2007In: Photochemical and Photobiological Sciences, ISSN 1474-905X, E-ISSN 1474-9092, Vol. 6, no 10, p. 1089-1096Article in journal (Refereed)
    Abstract [en]

    Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were used to elucidate the photochemistry and photophysics of eight different perylenequinones (PQ). The objective of this work has been to quantitatively investigate the photodynamic therapeutic potential of this family of compounds and give an overview of their photoreactivity. The effects of solvation were evaluated through single-point calculations using the integral equation formalism of the polarised continuum model. It is concluded that the eight studied perylenequinones can generate singlet oxygen (in aqueous solution) and superoxide radical anions, and that the autoionisation of two nearby PQ molecules is possible.

  • 4.
    Neugart, Susanne
    et al.
    Division of Quality and Sensory of Plant Products, University of Göttingen, Göttingen, Germany.
    Hideg, Éva
    bDepartment of Plant Biology, University of Pécs, Pécs, Hungary.
    Czégény, Gyula
    Department of Plant Biology, University of Pécs, Pécs, Hungary.
    Schreiner, Monika
    Department of Plant Quality and Food Security, Leibniz Institute of Vegetable and Ornamental Crops, Großbeeren, Germany.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Ultraviolet-B radiation exposure lowers the antioxidant capacity in the Arabidopsis thaliana pdx1.3-1mutant and leads to glucosinolate biosynthesis alteration in both wild type and mutant2020In: Photochemical and Photobiological Sciences, ISSN 1474-905X, E-ISSN 1474-9092, Vol. 19, p. 217-228Article in journal (Refereed)
    Abstract [en]

    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.

  • 5.
    O'Hara, Andrew
    et al.
    Örebro University, School of Science and Technology. Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
    Headland, Lauren R.
    Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
    Díaz-Ramos, L. Aranzazú
    Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
    Morales, Luis Orlando
    Örebro University, School of Science and Technology.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Jenkins, Gareth I.
    Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
    Regulation of Arabidopsis gene expression by low fluence rate UV-B independently of UVR8 and stress signaling2019In: Photochemical and Photobiological Sciences, ISSN 1474-905X, E-ISSN 1474-9092, Vol. 18, no 7, p. 1675-1684Article in journal (Refereed)
    Abstract [en]

    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).

  • 6.
    Omar, Salama
    et al.
    Örebro University, School of Science and Technology.
    Eriksson, Leif A.
    Örebro University, School of Science and Technology.
    Computational study of khellin excited states and photobinding to DNA2009In: Photochemical and Photobiological Sciences, ISSN 1474-905X, E-ISSN 1474-9092, Vol. 8, no 8, p. 1179-1186Article in journal (Refereed)
    Abstract [en]

    A theoretical investigation of the formation and spectroscopic properties of the furan and pyrone monoadducts between the photosensitizer khellin and DNA base thymine is reported. The thermal reaction pathways involve very high barriers, whereas the excited state surfaces display low barriers in regions leading to the ground state TS structures and potential wells at the ground state TS geometries. Computed UV absorption spectra are interpreted with the support of molecular orbital calculations, and the role of solvent effects on the spectra is discussed. The red-shift in the khellin spectra upon intercalation in DNA is excellently reproduced by the computational methodology, as is the solvent induced spectral shift. The data also provides an explanation to why khellin predominantly forms furan monoadducts in DNA, as opposed to the closely related psoralen compounds.

  • 7.
    Qian, Minjie
    et al.
    Örebro University, School of Science and Technology. Department of Horticulture, The State Agricultural Ministry Key Laboratory of Horticultural Plant Growth, Development & Quality Improvement, Zhejiang University, Hangzhou, Zhejiang Province, China.
    Kalbina, Irina
    Örebro University, School of Science and Technology.
    Rosenqvist, Eva
    Section of Crop Sciences, Department of Plant and Environmental Sciences, Copenhagen University, University of Copenhagen, Copenhagen, Denmark.
    Jansen, Marcel A. K.
    School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland.
    Teng, Yuanwen
    Department of Horticulture, The State Agricultural Ministry Key Laboratory of Horticultural Plant Growth, Development & Quality Improvement, Zhejiang University, Hangzhou, Zhejiang Province, China.
    Strid, Åke
    Örebro University, School of Science and Technology.
    UV regulates expression of phenylpropanoid biosynthesis genes in cucumber (Cucumis sativus L.) in an organ and spectrum dependent manner2019In: Photochemical and Photobiological Sciences, ISSN 1474-905X, E-ISSN 1474-9092, Vol. 18, no 2, p. 424-433Article in journal (Refereed)
    Abstract [en]

    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.

  • 8.
    Robson, T. Matthew
    et al.
    Organismal and Evolutionary Biology, Viikki Plant Science Centre (ViPS), University of Helsinki, Helsinki, Finland.
    Aphalo, Pedro J.
    Organismal and Evolutionary Biology, Viikki Plant Science Centre (ViPS), University of Helsinki, Helsinki, Finland.
    Banas, Agnieszka Katyrzyna
    Department of Plant Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland.
    Barnes, Paul W.
    Department of Biological Sciences and Environment Program, Loyola University New Orleans New Orleans, USA.
    Brelsford, Craig C.
    Organismal and Evolutionary Biology, Viikki Plant Science Centre (ViPS), University of Helsinki, Helsinki, Finland.
    Jenkins, Gareth I.
    Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow, UK.
    Kotilainen, Titta K.
    Organismal and Evolutionary Biology, Viikki Plant Science Centre (ViPS), University of Helsinki, Helsinki, Finland; Natural Resources Institute Finland (Luke), Turku, Finland.
    Labuz, Justyna
    Laboratory of Photobiology, Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland.
    Martínez-Abaigar, Javier
    Faculty of Science and Technology, University of La Rioja, La Rioja, Spain.
    Morales, Luis Orlando
    Örebro University, School of Science and Technology. Organismal and Evolutionary Biology, Viikki Plant Science Centre (ViPS), University of Helsinki, Helsinki, Finland.
    Neugart, Susanne
    Leibniz-Institute of Vegetable and Ornamental Crops, Grossbeeren, Germany.
    Pieristè, Marta
    Organismal and Evolutionary Biology, Viikki Plant Science Centre (ViPS), University of Helsinki, Helsinki, Finland; Normandie Université, UNIROUEN, Ecodiv URA/EA1293, IRSTEA, Rouen, France.
    Rai, Neha
    Organismal and Evolutionary Biology, Viikki Plant Science Centre (ViPS), University of Helsinki, Helsinki, Finland.
    Vandenbussche, Filip
    Laboratory of Functional Plant Biology, Department of Biology, Faculty of Sciences, Ghent University, Ghent, Belgium.
    Jansen, Marchel A. K.
    School of Biological Earth, and Environmental Sciences, University College Cork, Cork, Ireland.
    A perspective on ecologically relevant plant-UV research and its practical application2019In: Photochemical and Photobiological Sciences, ISSN 1474-905X, E-ISSN 1474-9092, Vol. 18, no 5, p. 970-988Article in journal (Refereed)
    Abstract [en]

    Plants perceive ultraviolet-B (UV-B) radiation through the UV-B photoreceptor UV RESISTANCE LOCUS 8 (UVR8), and initiate regulatory responses via associated signalling networks, gene expression and metabolic pathways. Various regulatory adaptations to UV-B radiation enable plants to harvest information about fluctuations in UV-B irradiance and spectral composition in natural environments, and to defend themselves against UV-B exposure. Given that UVR8 is present across plant organs and tissues, knowledge of the systemic signalling involved in its activation and function throughout the plant is important for understanding the context of specific responses. Fine-scale understanding of both UV-B irradiance and perception within tissues and cells requires improved application of knowledge about UV-attenuation in leaves and canopies, warranting greater consideration when designing experiments. In this context, reciprocal crosstalk among photoreceptor-induced pathways also needs to be considered, as this appears to produce particularly complex patterns of physiological and morphological response. Through crosstalk, plant responses to UV-B radiation go beyond simply UV-protection or amelioration of damage, but may give cross-protection over a suite of environmental stressors. Overall, there is emerging knowledge showing how information captured by UVR8 is used to regulate molecular and physiological processes, although understanding of upscaling to higher levels of organisation, i.e. organisms, canopies and communities remains poor. Achieving this will require further studies using model plant species beyond Arabidopsis, and that represent a broad range of functional types. More attention should also be given to plants in natural environments in all their complexity, as such studies are needed to acquire an improved understanding of the impact of climate change in the context of plant-UV responses. Furthermore, broadening the scope of experiments into the regulation of plant-UV responses will facilitate the application of UV radiation in commercial plant production. By considering the progress made in plant-UV research, this perspective highlights prescient topics in plant-UV photobiology where future research efforts can profitably be focussed. This perspective also emphasises burgeoning interdisciplinary links that will assist in understanding of UV-B effects across organisational scales and gaps in knowledge that need to be filled so as to achieve an integrated vision of plant responses to UV-radiation.

  • 9.
    Yan, Yan
    et al.
    Viikki Plant Science Centre (ViPS), Department of Biosciences, University of Helsinki, Uusimaa, Finland.
    Stoddard, Frederick L.
    Viikki Plant Science Centre (ViPS), Department of Agricultural Sciences, University of Helsinki, Uusimaa, Finland.
    Neugart, Susanne
    Leibniz-Institute of Vegetable and Ornamental Crops, Grossbeeren, Germany.
    Sadras, Victor O.
    South Australian Research and Development Institute, Australia.
    Lindfors, Anders
    Finnish Meteorological institute, Helsinki, Finland.
    Morales, Luis Orlando
    Örebro University, School of Science and Technology. Örebro Life Science Centre.
    Aphalo, Pedro J.
    Viikki Plant Science Centre (ViPS), Department of Biosciences, University of Helsinki, Uusimaa, Finland.
    Responses of flavonoid profile and associated gene expression to solar blue and UV radiation in two accessions of Vicia faba L. from contrasting UV environments2019In: Photochemical and Photobiological Sciences, ISSN 1474-905X, E-ISSN 1474-9092, Vol. 18, no 2, p. 434-447Article in journal (Refereed)
    Abstract [en]

    Blue light and UV radiation shape a plant's morphology and development, but accession-dependent responses under natural conditions are unclear. Here we tested the hypothesis that two faba bean (Vicia faba L.) accessions adapted to different latitudes and altitudes vary in their responses to solar blue and UV light. We measured growth, physiological traits, phenolic profiles and expression of associated genes in a factorial experiment combining two accessions (Aurora, a Swedish cultivar adapted to high latitude and low altitude; ILB938, from the Andean region of Colombia and Ecuador, adapted to low latitude and high altitude) and four filter treatments created with plastic sheets: 1. transparent as control; 2. attenuated short UV (290-350 nm); 3. attenuated UV (290-400 nm); 4. attenuated blue and UV light. In both accessions, the exclusion of blue and UV light increased plant height and leaf area, and decreased transcript abundance of ELONGATED HYPOCOTYL 5 (HY5) and TYROSINE AMINOTRANSFERASE 3 (TAT3). Blue light and short UV induced the accumulation of epidermal and whole-leaf flavonoids, mainly quercetins, and the responses in the two accessions were through different glycosides. Filter treatments did not affect kaempferol concentration, but there were more tri-glycosides in Aurora and di-glycosides in ILB938. Furthermore, fewer quercetin glycosides were identified in ILB938. The transcript abundance was consistently higher in Aurora than in ILB938 for all seven investigated genes: HY5, TAT3, CHALCONE SYNTHASE (CHS), CHALCONE ISOMERASE (CHI), DON-GLUCOSYLTRANSFERASE 1 (DOGT1), ABA INSENSITIVE 2 (ABI2), AUXIN-INDUCIBLE 2-27 (IAA5). The two largest differences in transcript abundance between the two accessions across treatments were 132-fold in CHS and 30-fold in DOGT1 which may explain the accession-dependent glycosylation patterns. Our findings suggest that agronomic selection for adaptation to high altitude may favour phenotypes with particular adaptations to the light environment, including solar UV and blue light.

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