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  • 1.
    Brelsford, Craig C.
    et al.
    Organismal and Evolutionary Biology Research Programme, Viikki Plant Science Center (ViPS), Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
    Morales, Luis Orlando
    Organismal and Evolutionary Biology Research Programme, Viikki Plant Science Center (ViPS), Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
    Nezval, Jakub
    Faculty of Science, University of Ostrava, Ostrava, Czech Republic.
    Kotilainen, Titta K.
    Organismal and Evolutionary Biology Research Programme, Viikki Plant Science Center (ViPS), Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
    Hartikainen, Saara M.
    Organismal and Evolutionary Biology Research Programme, Viikki Plant Science Center (ViPS), Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
    Aphalo, Pedro J.
    Organismal and Evolutionary Biology Research Programme, Viikki Plant Science Center (ViPS), Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
    Robson, Matthew
    Organismal and Evolutionary Biology Research Programme, Viikki Plant Science Center (ViPS), Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
    Do UV‐A radiation and blue light during growth prime leaves to cope with acute high light in photoreceptor mutants of Arabidopsis thaliana?2019In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 165, no 3, p. 537-554Article in journal (Refereed)
    Abstract [en]

    We studied how plants acclimated to growing conditions that included combinations of blue light (BL) and ultraviolet (UV)‐A radiation, and whether their growing environment affected their photosynthetic capacity during and after a brief period of acute high light (as might happen during an under‐canopy sunfleck). Arabidopsis thaliana Landsberg erecta wild‐type were compared with mutants lacking functional blue light and UV photoreceptors: phototropin 1, cryptochromes (CRY1 and CRY2) and UV RESISTANT LOCUS 8 (uvr8). This was achieved using light‐emitting‐diode (LED) lamps in a controlled environment to create treatments with or without BL, in a split‐plot design with or without UV‐A radiation. We compared the accumulation of phenolic compounds under growth conditions and after exposure to 30 min of high light at the end of the experiment (46 days), and likewise measured the operational efficiency of photosystem II (ϕPSII, a proxy for photosynthetic performance) and dark‐adapted maximum quantum yield (Fv/Fm to assess PSII damage). Our results indicate that cryptochromes are the main photoreceptors regulating phenolic compound accumulation in response to BL and UV‐A radiation, and a lack of functional cryptochromes impairs photosynthetic performance under high light. Our findings also reveal a role for UVR8 in accumulating flavonoids in response to a low UV‐A dose. Interestingly, phototropin 1 partially mediated constitutive accumulation of phenolic compounds in the absence of BL. Low‐irradiance BL and UV‐A did not improve ϕPSII and Fv/Fm upon our acute high‐light treatment; however, CRYs played an important role in ameliorating high‐light stress.

  • 2.
    Comont, David
    et al.
    Aberystwyth University, Aberystwyth, UK.
    Albert, Andreas
    Helmholtz Zentrum, München, Germany.
    Aphalo, Pedro
    Helsingfors universitet, Helsingfors, Finland.
    Gabersick, Alenka
    University of Ljubljana, Ljubljana, Slovenia.
    Hauser, Marie Teres
    University of Natural Resources and Life Sciences, Vienna, Austria.
    Jansen, Marcel
    University College of Cork, Cork, Ireland.
    Robson, Matthew
    Helsingfors universitet, Helsingfors, Finland.
    Schreiner, Monika
    Leibniz-Institute of Vegetable and Ornamental Plants, Großbeeren, Germany.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Gwynn-Jones, Dylan
    Aberystwyth University, Aberystwyth, UK.
    Exploring latitudinal variation in UV radiation and climate: impacts on a model grass system2011In: Abstracts of the 1st Annual Meeting of COST Action FA0906 UV4growth, Szeged: Biological Research Center of the Hungarian Academy of Sciences , 2011, p. 14-14Conference paper (Refereed)
    Abstract [en]

    Perennial ryegrass (Lolium perenne) seedlings were grown at 14 European locations across a latitudinal gradient spanning 37 to 68°N. Seedlings planted in nutrient enriched vermiculite were grown outdoors over five weeks between the 29th June and the 3rd August 2010. At each location there were three treatments – open, filtered with cellulose acetate (UV transparent) and filtered with Mylar (UV opaque). Plants were regularly watered and outdoor climatic conditions were monitored at nearby meteorological stations. The aim of the experiment was to assess the significance of ambient UV radiation to L.perenne, both at each location and across the gradient in terms of aboveground biomass, tiller number, and the level of UV protective plant pigments. Material was further screened using metabolite fingerprinting (FT-IR spectroscopy) to assess local, regional and latitudinal variation in total plant chemistry. Data presented will explore and interpret the complex variations in growth and chemistry looking at local responses and the latitudinal gradient explored.

  • 3.
    Czégény, Gyula
    et al.
    Department of Plant Biology, University of Pécs, Pécs, Hungary.
    Körösi, Laszlo
    Research institute for Viticulture and Oenology, University of Pécs, Pécs, Hungary.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Hideg, Éva
    Department of Plant Biology, University of Pécs, Pécs, Hungary.
    Multiple roles for Vitamin B6in plant acclimation to UV-B2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, no 1, article id 1259Article in journal (Refereed)
    Abstract [en]

    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.

  • 4.
    Ekblad, Alf
    et al.
    Umeå universitet, Umeå, Sweden.
    Huss-Danell, K.
    Sjöström, M.
    Variation in nitrogenase activity explained by abiotic and biotic factors: a multivariate study1990In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 79, no 2, p. A77-A77Article in journal (Other academic)
  • 5.
    Ekblad, Alf
    et al.
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Huss-Danell, Kerstin
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Nitrogen fixation by Alnus incana and nitrogen transfer from A-incana to Pinus sylvestris influenced by macronutrients and ectomycorrhiza1995In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 131, no 4, p. 453-459Article in journal (Refereed)
    Abstract [en]

    The aims of this study were to evaluate the effect of macronutrients on nitrogen fixation in mycorrhizal and non-mycorrhizal grey alder (Alnus incana (L.) Moench), and to evaluate the effect of ectomycorrhizal mycelium on the transfer of symbolically fixed nitrogen from grey alder to Scots pine (Pinus sylvestris L). One alder and one pine were grown together in pots with root systems separated by a 20μm mesh nylon filter which allowed hyphae but not roots to penetrate. Half the plants of both species were inoculated with Paxillus involutus (Ft.) Ft. and all alders were inoculated with Frankia. Nutrient solutions were added with macronutrient (N, K, P, Ca, Mg and S) concentrations varied according to a two-level fractional factorial design. The plants were harvested after two growing periods in a growth chamber. Nitrogen fixation by alder and transfer of symbiotically fixed N from alder to pine was measured by 15N-dilution. Fixed N (mg) correlated with nodule biomass in both mycorrhizal and non-mycorrhizal alders. On average, specific nodule activity over the two periods was 510 mg N fixed R' nodule d. wt. This was not affected by mycorrhizal infection or by the different nutrient treatments. By contrast there was a strong nutrient effect on the proportion of N derived from fixation. These results indicate that the regulation of nitrogen fixation was via nodule growth rather than via nodule specific activity. Nitrogen had a strong negative effect and P a positive effect on the percentage of N derived from fixation (%Ndfa). However, the effect of N depended on the level of P. This N × P interaction resulted in a %Ndfa when N was high, of 5-10%, at low P and 45–48%, at high P. The highest value of 90% Ndfa was found at the combination of low N and high P. Potassium had a small but statistically significant effect on the %Ndfa but Ca, Mg and S had no significant effects. No mycorrhizal effect was found on the %Ndfa in alder. By contrast, the %Ndfa and biomass were lower in mycorrhizal than in non-mycorrhizal alders. The proportion of fixed N in pine, transferred from alder, was greatest (9%) when the pine was nitrogen starved and mycorrhizal and the alder was fixing maximally (low N and high P). However, the amount of fixed N transferred to pine was not statistically different from zero.

  • 6.
    Ekblad, Alf
    et al.
    Umeå University, Umeå, Sweden.
    Lundquist, Per-Olof
    Sjöström, M
    Umeå University, Umeå, Sweden.
    Huss-Danell, Kerstin
    Umeå University, Umeå, Sweden.
    Day-to-day variation in nitrogenase activity of alnus-incana explained by weather variables: a multivariate time-series analysis1994In: Plant, Cell and Environment, ISSN 0140-7791, E-ISSN 1365-3040, Vol. 17, no 3, p. 319-325Article in journal (Refereed)
    Abstract [en]

    A modelling system is described that indicates the extent to which day-to-day variations in nitrogenase activity in young Alnus incana (L.) Moench, grown in defined conditions in the field, may be affected by weather conditions both during and prior to the day of measurement. Nitrogenase activity (acetylene reduction activity, ARA) was measured weekly on intact field-grown grey alder (A. incana) plants, 0.15–0.42 m tall at planting, nodulated with Frankia. The measurements were done at noon on two groups of plants in 1987 and on two other groups in 1988. Each group was made up of five or six plants. Seven weather variables: daily sunshine hours, daily mean, maximum and minimum air temperature, daily mean and 1300 h relative humidity, and daily rainfall were used. The relation between log(ARA/leaf area) and the weather variables were analysed using a PLS model (partial least squares projection to latent structures). The advantage of PLS is that it can handle x-variables that are correlated. Data from 1987 were chosen as a training set. Multivariate PLS time series analysis was made by adding, in a stepwise manner, the weather data up to 5 d before the day of measurement. This procedure gave six models with n * 7 x-variables (n= 1–6). With the models from the time series analysis of 1987 data, true predictions of ARA per leaf area were made from weather data 1988 (test set 1) and from ‘early-season’ weather data from 1987 and 1988 (test set 2). The variation in ARA/leaf area could be predicted from the weather conditions. The predictions of the two test sets improved when the weather conditions one and two days before the day of measurements were added to the model. The further addition of weather data from 3 to 5 d before the day of measurement did not improve the model. The good predictions of ARA/leaf area show that the alders responded to the variable weather conditions in the same way in 1988 as in 1987, despite the ten-fold difference in size (leaf area) at the end of the growing season. Among the weather variables, air temperature and the daily sunshine hours were positively correlated to ARA, while relative air humidity and rainfall were negatively correlated to ARA. The daily minimum temperature and rainfall appeared to have least impact on ARA. By use of PLS, we could extract information out of a data set containing highly correlated x-variables, information that is non-accessible with conventional statistical tools such as multiple regression. When making measurements of nitrogenase activities under field conditions, we propose that attention should be paid to the weather conditions on the days preceding the day of measurement. The day-to-day variation in nitrogenase activity is discussed with reference to known effects of stress factors under controlled conditions.

  • 7.
    Ekblad, Alf
    et al.
    University of Umeå, Umeå, Sweden.
    Näsholm, Torgny
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Determination of chitin in fungi and mycorrhizal roots by an improved HPLC analysis of glucosamine1996In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 178, no 1, p. 29-35Article in journal (Refereed)
    Abstract [en]

    A method to measure chitin content in fungi and ectomycorrhizal roots with high-performance liquid chromatography (HPLC) was developed. Measurements of fluorescence of 9-fluorenylmethylchloroformate (FMOC-CI) derivatives of glucosamine were made on acid hydrolysates of pure chitin, chitin-root mixtures and fungal-root mixtures. The method was applied on 5 isolates of ectomycorrhizal fungi, and ectomycorrhizal and non-mycorrhizal Pinus sylvestris roots. Interference from amino acids was removed by pre-treatment of samples with 0.2 N NaOH. This pre-treatment did not reduce the recovery of chitin, nor did plant material affect the recovery of chitin. The HPLC method was compared with a colorimetric chitin-method by measurements on root-fungal mixtures, with known fungal content. The HPLC method gave estimates of fungal biomass which were equal to the expected while the colorimetric method showed values significantly (p<0.001) lower than the expected. The present chitin method offers a sensitive and specific tool for the quantification of chitin in fungi and in ectomycorrhizal roots.

  • 8.
    Ekblad, Alf
    et al.
    Umeå University, Umeå, Sweden.
    Wallander, Håkan
    Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Carlsson, Rolf
    Umeå University, Umeå, Sweden.
    Huss-Danell, Kerstin
    Umeå University, Umeå, Sweden.
    Fungal biomass in roots and extramatrical mycelium in relation to macronutrients and plant biomass of ectomycorrhizal Pinus sylvestris and Alnus incana1995In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 131, no 4, p. 443-451Article in journal (Refereed)
    Abstract [en]

    Summary

    We studied the effects of macronutrients on the production and distribution of fungal biomass and plant biomass in ectomycorrhizal (Paxillus involutus (Fr.) Fr.) or non-mycorrhiza] Pinus sylvestris L, and Alnus incana (L.) Moench. Fungal biomass was measured as ergosterol content in roots and extramatrical mycelium, Alnus infants was nodulated with Frankia. All six macronutrients were varied according to a two-level fractional factorial design, The plants were grown in pots during two growing periods in a growth chamber. Levels of N, P and sometimes K and interactions between them, had highly significant effects, whereas Ca. Mg and S had no significant effects. The production of extramatrical mycelial biomass peaked when P was low and other nutrients were high. This investment in extramatrical mycelium resulted in a 660%, higher biomass in mycorrhizal compared with non-mycorrhizal P. sylvestris at this nutrient regime. The proportion of fungal biomass in roots was stable in P. sylvestris hut more variable in A. incana. Alnus incana grew less when mycorrhizal then when non-mycorrhizal. The growth responses to mycorrhiza and to the different nutrient treatments were evident at the end of the first growing period. Non-mycorrhizal P. sylvestris did not respond to P limitation by a production of proportionally more roots. This might be a reflection of an obligate dependency on mycorrhiza for effective P uptake. By contrast, the root/shoot ratio in both mycorrhizal and non-mycorrhiza] P. sylvestris decreased strongly in response to increased N. The opposite root/shoot response was found in Alnus incana, and the ratio decreased strongly in response to increased P and increased in response to increased N.

  • 9.
    Ekblad, Alf
    et al.
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Wallander, Håkan
    Lund University, Lund, Sweden.
    Näsholm, Torgny
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Chitin and ergosterol combined to measure total and living fungal biomass in ectomycorrhizas1998In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 138, no 1, p. 143-149Article in journal (Refereed)
    Abstract [en]

    We have studied the chitin and ergosterol contents of ectomycorrhizal roots in three sets of experiments to evaluate them as indicators of fungal biomass. The first set of experiments showed that ageing had a marked effect on ergosterol concentrations. The ergosterol content of 7-month-old, brown, shrunken Pinus sylvestris L.–Paxillus involutus (Fr.) Fr. mycorrhizas was found to be only 10% of that found in white, turgid, 1- or 4-month-old specimens. This supports the hypothesis that the compound is a good indicator of living fungal biomass. Ageing had a lesser effect on chitin concentrations since the chitin levels found in 7-month-old mycorrhizas were still 60% of the levels found in 1- and 4-month-old specimens.

    Consequently, the chitin∶ergosterol ratio increased from about 14 to 19 in 1- and 4-month-old mycorrhizas respectively to about 110 in 7-month-old mycorrhizas. In the second set of experiments, we found that variation in plant growth had no effect on the chitin∶ergosterol ratio in whole root systems of either Alnus incana (L.) Moench or Pinus sylvestris mycorrhizal with Paxillus involutus. In the third set of experiments, we found a constant relationship between the two marker concentrations in 10-month-old root systems of Pinus sylvestris, regardless of fungal species involved, using Paxillus involutus, Piloderma croceum Erikss. & Hjorts and Suillus variegatus (Fr.) O. Kuntze as test organisms. Taken together, the results of this study suggest that both chitin and ergosterol give reliable, but different, relative measures of fungal biomass in mycorrhizal roots. Furthermore, we demonstrate that, in combination, the two chemical markers can be used to estimate both total and living fungal biomass (derived from the chitin∶ergosterol ratio).

  • 10.
    Eriksson, Leif A.
    et al.
    Gothrnburgs University, Gothenburg, Sweden.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Chemistry of vitamin B6 under oxidative stress2012In: UV4growth COST-Action FA0906: Plant responses to ultraviolet radiation – roles of antioxidants and pro-oxidants / [ed] Petra Majer, Köpenhamn: University of Copenhagen , 2012, p. 28-28Conference paper (Refereed)
    Abstract [en]

    Vitamin B6, or pyridoxine, is the precursor of the biologically active derivatives pyridoxal-5’-phosphate and pyridoxamine-5’-phosphate (Fig.1), with functional roles in a number of different enzymes. Pyridoxine itself is a cofactor of several enzymes that catalyze decarboxylations, transaminations, and racemations of amino acids. Bacteria, fungi, and plants produce their own vitamin B6, whereas parasitic organisms and higher animals have to acquire vitamin B6 through nutrient intake.

    Lately, pyridoxine biosynthesis-deficient mutants of fungi and yeast have been shown to be sensitive to reactive oxygen species (ROS) such as singlet oxygen and hydrogen peroxide. This suggests that vitamin B6 and its derivatives are also involved in stress tolerance in living organisms, especially in alleviating oxidative stress. In eukaryotes, stress resistance has been implied to involve pyridoxine-dependent singlet oxygen quenching, whereby the pyridoxine itself would react with and quench the singlet oxygen. The oxidative stress-protective effect of pyridoxine has also been described both in red blood cells and in lens cells in animals. Pyridoxine itself was found to be the most effective of the vitamin B6 species, twice as effective as pyridoxal-5’-phosphate, and as effective as vitamin E.

     Knowledge about this novel mechanism of reaction between pyridoxine or its derivatives (cf. Figure 1) and singlet oxygen and other ROS is however very limited. However, since both the aldehyde (pyridoxal) and the amino (pyridoxamine) derivatives only to a small extent influence the rate of reaction, these moieties are probably not involved. Also, since the heteroaromatic absorbance peak at 323 nm disappears during the reaction, at least one of the targets for singlet oxygen is most likely the core of the aromatic ring, leading to ring opening.

    In order to shed more light on the possible role of pyridoxine in stress tolerance / protection we herein report on computational studies of possible reaction mechanisms between pyridoxine and different ROS (singlet oxygen, superoxide and hydrogen peroxide) by means of density functional theory (DFT) based methods. It is concluded that the compound has an extremely high quenching power towards hydroxyl radicals. We furthermore explore the explicit UV-induced photolysis pathways of the compound, as well as enzymatic degradation (ring-opening) by bacterial flavoprotein monooxygenases.

  • 11.
    Hideg, Éva
    et al.
    Pécs University, Pécs, Hungary.
    Jansen, Marcel A. K.
    University College of Cork, Cork, Ireland.
    Strid, Åke
    Örebro University, School of Science and Technology.
    UV-B exposure, ROS, and stress: inseparable companions or loosely linked associates?2013In: Trends in Plant Science, ISSN 1360-1385, E-ISSN 1878-4372, Vol. 18, no 2, p. 107-115Article in journal (Refereed)
    Abstract [en]

    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.

  • 12.
    Hideg, Éva
    et al.
    University of Pécs, Pécs, Hungary.
    Strid, Åke
    Örebro University, School of Science and Technology.
    The effects of UV-B on the biochemistry and metabolism of plants2017In: UV-B radiation and plant life: molecular biology to ecology / [ed] Brian R. Jordan, Wallingford, UK: CABI Publishing, 2017, p. 90-110Chapter in book (Refereed)
    Abstract [en]

    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.

  • 13.
    Huss-Danell, Kerstin
    et al.
    Department of Plant Physiology, University of Umeå, S-901 87, Umeå, Sweden .
    Lundquist, Per-Olof
    Department of Plant Physiology, University of Umeå, S-901 87, Umeå, Sweden .
    Ekblad, Alf
    Department of Plant Physiology, University of Umeå, S-901 87, Umeå, Sweden .
    Growth and acetylene reduction activity by intact plants of Alnus incana under field conditions1989In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 118, no 1-2, p. 61-73Article in journal (Refereed)
  • 14.
    Jansen, Marcel A. K.
    et al.
    School of Biological Earth and Environmental Sciences, University College Cork, Cork, Ireland; Global Change Research Institute CAS, Brno, Czech Republic.
    Bilger, Wolfgang
    Botanisches Institut, Christian-Albrechts-Universität zu Kiel, Kiel, Germany.
    Hideg, Éva
    Institute of Biology, University of Pécs, Pécs, Hungary.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Urban, Otmar
    Global Change Research Institute CAS, Brno, Czech Republic.
    Interactive effects of UV-B radiation in a complex environment2019In: Plant physiology and biochemistry (Paris), ISSN 0981-9428, E-ISSN 1873-2690, Vol. 134, p. 1-8Article in journal (Refereed)
  • 15.
    Jordan, Brian R
    et al.
    Lincoln University, Lincoln, New Zeeland.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Wargent, Jason J
    Massey University, Palmerston North, New Zealand.
    What role does UVB play in determining photosynthesis?2016In: Handbook of Photosynthesis / [ed] Mohammad Pessarakli, Boca Raton: CRC Press, 2016, 3, p. 275-286Chapter in book (Refereed)
  • 16.
    Järvinen, Pia
    et al.
    Department of Biology, University of Joensuu, Joensuu, Finland.
    Palmé, Anna
    Department of Conservation Biology and Genetics, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.
    Morales, Luis Orlando
    Department of Biology, University of Joensuu, Joensuu, Finland.
    Lännenpää, Mika
    Department of Biology, University of Joensuu, Joensuu, Finland.
    Keinänen, Markku
    Department of Biology, University of Joensuu, Joensuu, Finland.
    Sopanen, Tuomas
    Department of Biology, University of Joensuu, Joensuu, Finland.
    Lascoux, Martin
    Department of Conservation Biology and Genetics, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.
    Phylogenetic relationships of Betula species (Betulaceae) based on nuclear Adh and chloroplast matK sequences2004In: American Journal of Botany, ISSN 0002-9122, E-ISSN 1537-2197, Vol. 91, no 11, p. 1834-1845Article in journal (Refereed)
    Abstract [en]

    The phylogenetic relationships within the genus Betula (Betulaceae) were investigated using a part of the nuclear ADH gene and DNA sequences of the chloroplast matK gene with parts of its flanking regions. Two well‐supported phylogenetic groups could be identified in the chloroplast DNA sequence: one containing the three American species B. lenta, B. alleghaniensis, and B. papyrifera and the other including all the other species studied. The ADH gene displayed more variation, and three main groups could be identified. In disagreement with the classical division of the genus Betula, B. schmidtii and B. nana grouped with the species in subgenus Betula, and B. ermanii grouped with species in subgenus Chamaebetula, including B. humilis and B. fruticosa. The ADH phylogeny suggests that several independent polyploidizations within the genus Betula could have taken place. The ADH and chloroplast phylogenies were in part incongruent due to the placement of B. papyrifera. The most likely reason for this seems to be cytoplasmic introgression.

  • 17. Morales, Luis Orlando
    Accumulation of epidermal flavonoids in Betula pendula leaves of different ages under altered solar UV radiation2011Conference paper (Other academic)
  • 18. Morales, Luis Orlando
    ROS regulation of gene expression and cell death in Arabidopsis: From natural variation to miRNAs2018Conference paper (Other academic)
  • 19.
    Morales, Luis Orlando
    et al.
    Division of Plant Biology, Department of Biosciences, University of Helsinki, Helsinki, Finland; School of Chemical Technology, Department of Forest Products Technology, Aalto University, Espo, Finland .
    Brosché, Mikael
    Division of Plant Biology, Department of Biosciences, University of Helsinki, Helsinki, Finland; Institute of Technology, University of Tartu, Tartu, Estonia .
    Vainonen, Julia P
    Division of Plant Biology, Department of Biosciences, University of Helsinki, Helsinki, Finland .
    Sipari, Nina
    Metabolomics Unit, Department of Biosciences, University of Helsinki, Helsinki, Finland .
    Lindfors, Anders
    Kuopio Unit, Finnish Meteorological Institute, Kuopio, Finland .
    Strid, Åke
    Örebro University, School of Science and Technology.
    Aphalo, Pedro J
    Division of Plant Biology, Department of Biosciences, University of Helsinki, Helsinki, Finland .
    Are solar UV-B- and UV-A-dependent gene expression and metabolite accumulation in Arabidopsis mediated by the stress response regulator RADICAL-INDUCED CELL DEATH1?2015In: Plant, Cell and Environment, ISSN 0140-7791, E-ISSN 1365-3040, Vol. 38, no 5, p. 878-891Article in journal (Refereed)
    Abstract [en]

    Wavelengths in the ultraviolet (UV) region of the solar spectrum, UV-B (280-315nm) and UV-A (315-400nm), are key environmental signals modifying several aspects of plant physiology. Despite significant advances in the understanding of plant responses to UV-B and the identification of signalling components involved, there is limited information on the molecular mechanisms that control UV-B signalling in plants under natural sunlight. Here, we aimed to corroborate the previous suggested role for RADICAL-INDUCED CELL DEATH1 (RCD1) in UV-B signalling under full spectrum sunlight. Wild-type Arabidopsis thaliana and the rcd1-1 mutant were used in an experimental design outdoors where UV-B and UV-A irradiances were manipulated using plastic films, and gene expression, PYRIDOXINE BIOSYNTHESIS1 (PDX1) accumulation and metabolite profiles were analysed in the leaves. At the level of transcription, RCD1 was not directly involved in the solar UV-B regulation of genes with functions in UV acclimation, hormone signalling and stress-related markers. Furthermore, RCD1 had no role on PDX1 accumulation but modulated the UV-B induction of flavonoid accumulation in leaves of Arabidopsis exposed to solar UV. We conclude that RCD1 does not play an active role in UV-B signalling but rather modulates UV-B responses under full spectrum sunlight.

  • 20.
    Morales, Luis Orlando
    et al.
    Department of Biosciences, Division of Plant Biology, University of Helsinki, Helsinki, Finland.
    Tegelberg, Riita
    Department of Biosciences, Division of Plant Biology, University of Helsinki, Helsinki, Finland.
    Brosché, Mikael
    Department of Biosciences, Division of Plant Biology, University of Helsinki, Helsinki, Finland.
    Keinänen, Markku
    Faculty of Biosciences, University of Eastern Finland, Joensuu, Finland.
    Lindfors, Anders
    School of Geosciences, University of Edinburgh, Edinburgh, UK.
    Aphalo, Pedro J.
    Department of Biosciences, Division of Plant Biology, University of Helsinki, Helsinki, Finland.
    Effects of solar UV-A and UV-B radiation on gene expression and phenolic accumulation in Betula pendula leaves2010In: Tree Physiology, ISSN 0829-318X, E-ISSN 1758-4469, Vol. 30, no 7, p. 923-934Article in journal (Refereed)
    Abstract [en]

    Ultraviolet (UV) radiation is an important environmental factor for plant communities; however, plant responses to solar UV are not fully understood. Here, we report differential effects of solar UV-A and UV-B radiation on the expression of flavonoid pathway genes and phenolic accumulation in leaves of Betula pendula Roth (silver birch) seedlings grown outdoors. Plants were exposed for 30 days to six UV treatments created using three types of plastic film. Epidermal flavonoids measured in vivo decreased when UV-B was excluded. In addition, the concentrations of six flavonoids determined by high-performance liquid chromatography-mass spectrometry declined linearly with UV-B exclusion, and transcripts of PAL and HYH measured by quantitative real-time polymerase chain reaction were expressed at lower levels. UV-A linearly regulated the accumulation of quercetin-3-galactoside and quercetin-3-arabinopyranoside and had a quadratic effect on HYH expression. Furthermore, there were strong positive correlations between PAL expression and accumulation of four flavonols under the UV treatments. Our findings in silver birch contribute to a more detailed understanding of plant responses to solar UV radiation at both molecular and metabolite levels.

  • 21.
    Morales, Luis Orlando
    et al.
    Department of Biosciences, Plant Biology, University of Helsinki, Helsinki, Finland.
    Tegelberg, Riitta
    Department of Biosciences, Plant Biology, University of Helsinki, Helsinki, Finland.
    Brosché, Mikael
    Department of Biosciences, Plant Biology, University of Helsinki, Helsinki, Finland; Institute of Technology, University of Tartu, Tartu, Estonia.
    Lindfors, Anders
    School of Geosciences, University of Edinburg, Edinburgh, UK, Climate Change Research, Finnish Meteorological Institute, Helsinki, Finland.
    Siipola, Sari
    Department of Biosciences, Plant Biology, University of Helsinki, Helsinki, Finland.
    Aphalo, Pedro J.
    Department of Biosciences, Plant Biology, University of Helsinki, Helsinki, Finland.
    Temporal variation in epidermal flavonoids due to altered solar UV radiation is moderated by the leaf position in Betula pendula2011In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 143, no 3, p. 261-270Article in journal (Refereed)
    Abstract [en]

    The physiological mechanisms controlling plant responses to dynamic changes in ambient solar ultraviolet (UV) radiation are not fully understood: this information is important to further comprehend plant adaptation to their natural habitats. We used the fluorimeter Dualex to estimate in vivo the epidermal flavonoid contents by measuring epidermal UV absorbance (A375) in Betula pendula Roth (silver birch) leaves of different ages under altered UV. Seedlings were grown in a greenhouse for 15 days without UV and transferred outdoors under three UV treatments (UV‐0, UV‐A and UV‐A+B) created by three types of plastic film. After 7 and 13 days, Dualex measurements were taken at adaxial and abaxial epidermis of the first three leaves (L1, L2 and L3) of the seedlings. After 14 days, some of the seedlings were reciprocally swapped amongst the treatments to study the accumulation of epidermal flavonoids in the youngest unfolded leaves (L3) during leaf expansion under changing solar UV environments. A375 of the leaves responded differently to the UV treatment depending on their position. UV‐B increased the A375 in the leaves independently of leaf position. L3 quickly adjusted A375 in their epidermis according to the UV they received and these adjustments were affected by previous UV exposure. The initial absence of UV‐A+B or UV‐A, followed by exposure to UV‐A+B, particularly enhanced leaf A375. Silver birch leaves modulate their protective pigments in response to changes in the UV environment during their expansion, and their previous UV exposure history affects the epidermal‐absorbance achieved during later UV exposure.

  • 22.
    Nahar, Noor
    et al.
    Systems Biology Research Center, School of Bioscience, University of Skövde, Skövde, Sweden.
    Rahman, Aminur
    Systems Biology Research Center, School of Bioscience, University of Skövde, Skövde, Sweden.
    Nawani, Neelu N.
    Microbial Diversity Research Centre, Dr. D. Y. Patil Biotechnology and Bioinformatics Institute, Dr. D. Y. Patil Vidyapeeth, Tathawade, Pune, India.
    Ghosh, Sibdas
    School of Arts and Science, Iona College, New Rochelle, NY, USA.
    Mandal, Abul
    Systems Biology Research Center, School of Bioscience, University of Skövde, Skövde, Sweden.
    Phytoremediation of arsenic from the contaminated soil using transgenic tobacco plants expressing ACR2 gene of Arabidopsis thaliana2017In: Journal of plant physiology (Print), ISSN 0176-1617, E-ISSN 1618-1328, Vol. 218, p. 121-126Article in journal (Refereed)
    Abstract [en]

    We have cloned, characterized and transformed the AtACR2 gene (arsenic reductase 2) of Arabidopsis thaliana into the genome of tobacco (Nicotiana tabacum, var Sumsun). Our results revealed that the transgenic tobacco plants are more tolerant to arsenic than the wild type ones. These plants can grow on culture medium containing 200μM arsenate, whereas the wild type can barely survive under this condition. Furthermore, when exposed to 100μM arsenate for 35days the amount of arsenic accumulated in the shoots of transgenic plants was significantly lower (28μg/g d wt.) than that found in the shoots of non-transgenic controls (40μg/g d wt.). However, the arsenic content in the roots of transgenic plants was significantly higher (2400μg/g d. wt.) than that (2100μg/g d. wt.) observed in roots of wild type plants. We have demonstrated that Arabidopsis thaliana AtACR2 gene is a potential candidate for genetic engineering of plants to develop new crop cultivars that can be grown on arsenic contaminated fields to reduce arsenic content of the soil and can become a source of food containing no arsenic or exhibiting substantially reduced amount of this metalloid.

  • 23.
    Nahar, Nour
    et al.
    Systems Biology Research Center, School of Bioscience, University of Skövde, Skövde, Sweden.
    Rahman, Aminur
    Örebro University, School of Science and Technology. Systems Biology Research Center, School of Bioscience, University of Skövde, Skövde, Sweden.
    Ghosh, Sibdas
    School of Arts and Science, Iona College, New Rochelle, NY, USA.
    Nawani, Neelu
    Microbial Diversity Research Centre, Dr. D. Y. Patil Biotechnology and Bioinformatics Institute, Dr. D. Y. Patil Vidyapeeth, Tathawade, Pune, India.
    Mandal, Abul
    Systems Biology Research Center, School of Bioscience, University of Skövde, Skövde, Sweden.
    Functional studies of AtACR2 gene putatively involved in accumulation, reduction and/or sequestration of arsenic species in plants2017In: Biologia (Bratislava), ISSN 0006-3088, E-ISSN 1336-9563, Vol. 72, no 5, p. 520-526Article in journal (Refereed)
    Abstract [en]

    Food-based exposure to arsenic is a human carcinogen and can severely impact human health resulting in many cancerous diseases and various neurological and vascular disorders. This project is a part of our attempts to develop new varieties of crops for avoiding arsenic contaminated foods. For this purpose, we have previously identified four key genes, and molecular functions of two of these, AtACR2 and AtPCSl, have been studied based on both in silico and in vivo experiments. In the present study, a T-DNA tagged mutant, (SALK-143282C with mutation in AtACR2 gene) of Arabidopsis thaliana was studied for further verification of the function of AtACR2 gene. Semi-quantitative RT-PCR analyses revealed that this mutant exhibits a significantly reduced expression of the AtACR2 gene. When exposed to 100 μM of arsenate (AsV) for three weeks, the mutant plants accumulated arsenic approximately three times higher (778 μg/g d. wt.) than that observed in the control plants (235 μg/g d. wt.). In contrast, when the plants were exposed to 100 μM of arsenite (AsIII), no significant difference in arsenic accumulation was observed between the control and the mutant plants (535 μg/g d. wt. and 498 μg/g d. wt., respectively). Also, when arsenate and arsenite was measured separately either in shoots or roots, significant differences in accumulation of these substances were observed between the mutant and the control plants. These results suggest that AtACR2 gene is involved not only in accumulation of arsenic in plants, but also in conversion of arsenate to arsenite inside the plant cells. © 2017 Institute of Molecular Biology, Slovak Academy of Sciences.

  • 24.
    Pettersson, Olga Vinnere
    et al.
    Department of Microbiology, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Leong, Su-lin L.
    Department of Microbiology, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Lantz, Henrik
    Department of Microbiology, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Rice, Therese
    Department of Microbiology, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Dijksterhuis, Jan
    CBS-KNAW Fungal Biodiversity Centre (Centraalbureau voor Schimmelcultures), Utrecht, The Netherlands.
    Houbraken, Jos
    CBS-KNAW Fungal Biodiversity Centre (Centraalbureau voor Schimmelcultures), Utrecht, The Netherlands.
    Samson, Robert A.
    CBS-KNAW Fungal Biodiversity Centre (Centraalbureau voor Schimmelcultures), Utrecht, The Netherlands.
    Schnürer, Johan
    Department of Microbiology, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Phylogeny and intraspecific variation of the extreme xerophile, Xeromyces bisporus2011In: Fungal Biology, ISSN 1878-6146, E-ISSN 1878-6162, Vol. 115, no 11, p. 1100-1111Article in journal (Refereed)
    Abstract [en]

    The filamentous ascomycete Xeromyces bisporus is an extreme xerophile able to grow down to a water activity of 0.62. We have inferred the phylogenetic position of Xeromyces in relation to other xerophilic and xerotolerant fungi in the order Eurotiales. Using nrDNA and betatubulin sequences, we show that it is more closely related to the xerophilic food-borne species of the genus Chrysosporium, than to the genus Monascus. The taxonomy of X. bisporus and Monascus is discussed. Based on physiological, morphological, and phylogenetic distinctiveness, we suggest that Xeromyces should be retained as a separate genus.

  • 25.
    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.

  • 26.
    Rai, Neha
    et al.
    Organismal and Evolutionary Biology Research Programme, Viikki Plant Science Centre (ViPS), University of Helsinki, Helsinki, Finland.
    Neugart, Susanne
    Research Area of Plant Quality and Food Security, Leibniz Institute of Vegetable and Ornamental Crops e. V., Grossbeeren, Germany.
    Yan, Yan
    Organismal and Evolutionary Biology Research Programme, Viikki Plant Science Centre (ViPS), University of Helsinki, Helsinki, Finland.
    Wang, Fang
    Organismal and Evolutionary Biology Research Programme, Viikki Plant Science Centre (ViPS), University of Helsinki, Helsinki, Finland.
    Siipola, Sari M.
    Organismal and Evolutionary Biology Research Programme, Viikki Plant Science Centre (ViPS), University of Helsinki, Helsinki, Finland.
    Lindfors, Anders V.
    Finnish Meteorological Institute, Helsinki, Finland.
    Winkler, Jana Barbro
    Research Unit Environmental Simulation, Helmholtz Zentrum München, Neuherberg, Germany.
    Albert, Andreas
    Research Unit Environmental Simulation, Helmholtz Zentrum München, Neuherberg, Germany.
    Brosché, Mikael
    Organismal and Evolutionary Biology Research Programme, Viikki Plant Science Centre (ViPS), University of Helsinki, Helsinki, Finland.
    Lehto, Tarja
    School of Forest Sciences, University of Eastern Finland, Joensuu, Finland.
    Morales, Luis Orlando
    Organismal and Evolutionary Biology Research Programme, Viikki Plant Science Centre (ViPS), University of Helsinki, Helsinki, Finland.
    Aphalo, Pedro J.
    Organismal and Evolutionary Biology Research Programme, Viikki Plant Science Centre (ViPS), University of Helsinki, Helsinki, Finland.
    How do cryptochromes and UVR8 interact in natural and simulated sunlight?2019In: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431Article in journal (Refereed)
    Abstract [en]

    Cryptochromes (CRYs) and UV RESISTANCE LOCUS 8 (UVR8) photoreceptors perceive UV-A/blue (315–500 nm) and UV-B (280–315 nm) radiation in plants, respectively. While the roles of CRYs and UVR8 have been studied in separate controlled environment experiments, little is known about the interaction between these photoreceptors. Here, Arabidopsis thaliana wild-type Ler, CRYs and UVR8 photoreceptor mutants (uvr82, cry1cry2 and cry1cry2uvr82), and a flavonoid biosynthesis defective mutant (tt4) were grown in a sun simulator. Plants were exposed to filtered radiation for 17 d or for 6 h, to study the effects of blue, UV-A and UV-B radiation. Both CRYs and UVR8 independently enabled growth and survival of plants under solar levels of UV, while their joint absence was lethal under UV-B. CRYs mediated gene expression under blue light. UVR8 mediated gene expression under UV-B radiation, and in the absence of CRYs, also under UV-A. This negative regulation of UVR8-mediated gene expression by CRYs was also observed for UV-B. The accumulation of flavonoids was also consistent with this interaction between CRYs and UVR8. In conclusion, we provide evidence for an antagonistic interaction between CRYs and UVR8 and a role of UVR8 in UV-A perception.

  • 27.
    Rodriguez-Calzada, Tania
    et al.
    Biosystems Engineering Group, School of Engineering, Autonomous University of Queretaro-Campus Amazcala, Querétaro, Mexico.
    Qian, Minjie
    Örebro University, School of Science and Technology.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Neugart, Susanne
    Department of Quality, Leibniz Institute for Ornamental and Horticultural Crops, Großbeeren, Germany.
    Schreiner, Monika
    Department of Quality, Leibniz Institute for Ornamental and Horticultural Crops, Großbeeren, Germany.
    Torres-Pacheco, Ireno
    Biosystems Engineering Group, School of Engineering, Autonomous University of Queretaro-Campus Amazcala, Querétaro, Mexico.
    Guevara-Gonzales, Ramon
    Biosystems Engineering Group, School of Engineering, Autonomous University of Queretaro-Campus Amazcala, Querétaro, Mexico.
    Effect of UV-B radiation on morphology, phenolic compound production, gene expression, and subsequent drought stress responses in chili pepper (Capsicum annuum L.)2019In: Plant physiology and biochemistry (Paris), ISSN 0981-9428, E-ISSN 1873-2690, Vol. 134, p. 94-102Article in journal (Refereed)
    Abstract [en]

    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.

  • 28.
    Rozpadek, Piotr
    et al.
    Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland; Institute of Plant Physiology, Polish Academy of Sciences, Kraków, Poland.
    Rapala-Kozik, Maria
    Department of Comparative Biochemistry and Bioanalytics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
    Wezowicz, Katarzyna
    Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland.
    Grandin, Anna
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Wazny, Rafal
    Malopolska Centre of Biotechnology, Jagiellonian University, Kraków, Poland.
    Anielska, Teresa
    Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland.
    Turnau, Katarzyna
    Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland; Malopolska Centre of Biotechnology, Jagiellonian University, Kraków, Poland.
    Arbuscular mycorrhiza improves yield and nutritional properties of onion (Allium cepa)2016In: Plant physiology and biochemistry (Paris), ISSN 0981-9428, E-ISSN 1873-2690, Vol. 107, p. 264-272Article in journal (Refereed)
    Abstract [en]

    Improving the nutritional value of commonly cultivated crops is one of the most pending problems for modern agriculture. In natural environments plants associate with a multitude of fungal microorganisms that improve plant fitness. The best described group are arbuscular mycorrhizal fungi (AMF). These fungi have been previously shown to improve the quality and yield of several common crops. In this study we tested the potential utilization of Rhizophagus irregularis in accelerating growth and increasing the content of important dietary phytochemicals in onion (Allium cepa). Our results clearly indicate that biomass production, the abundance of vitamin B1 and its analogs and organic acid concentration can be improved by inoculating the plant with AM fungi. We have shown that improved growth is accompanied with up-regulated electron transport in PSII and antioxidant enzyme activity.

  • 29.
    Siipola, Sari M.
    et al.
    Plant Biology Division, Department of Biosciences, University of Helsinki, , Helsinki, Finland.
    Kotilainen, Titta
    Valoya Ltd, , Helsinki, Finland.
    Sipari, Nina
    Viikki Metabolomics Unit, Department of Biosciences, University of Helsinki, , Helsinki, Finland.
    Morales, Luis Orlando
    Plant Biology Division, Department of Biosciences, University of Helsinki, , Helsinki, Finland.
    Lindfors, Anders V.
    Kuopio Unit, Finnish Meteorological Institute, , Kuopio, Finland.
    Robson, Matthew
    Plant Biology Division, Department of Biosciences, University of Helsinki, , Helsinki, Finland.
    Aphalo, Pedro J.
    Plant Biology Division, Department of Biosciences, University of Helsinki, , Helsinki, Finland.
    Epidermal UV-A absorbance and whole leaf flavonoid composition in pea respond more to solar blue light than solar UV radiation2015In: Plant, Cell and Environment, ISSN 0140-7791, E-ISSN 1365-3040, Vol. 38, no 5, p. 941-952Article in journal (Refereed)
    Abstract [en]

    Plants synthesize phenolic compounds in response to certain environmental signals or stresses. One large group of phenolics, flavonoids, is considered particularly responsive to ultraviolet (UV) radiation. However, here we demonstrate that solar blue light stimulates flavonoid biosynthesis in the absence of UV‐A and UV‐B radiation. We grew pea plants (Pisum sativum cv. Meteor) outdoors, in Finland during the summer, under five types of filters differing in their spectral transmittance. These filters were used to (1) attenuate UV‐B; (2) attenuate UV‐B and UV‐A < 370 nm; (3) attenuate UV‐B and UV‐A; (4) attenuate UV‐B, UV‐A and blue light; and (5) as a control not attenuating these wavebands. Attenuation of blue light significantly reduced the flavonoid content in leaf adaxial epidermis and reduced the whole‐leaf concentrations of quercetin derivatives relative to kaempferol derivatives. In contrast, UV‐B responses were not significant. These results show that pea plants regulate epidermal UV‐A absorbance and accumulation of individual flavonoids by perceiving complex radiation signals that extend into the visible region of the solar spectrum. Furthermore, solar blue light instead of solar UV‐B radiation can be the main regulator of phenolic compound accumulation in plants that germinate and develop outdoors.

  • 30.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Knowledge for knowledge’s sake: Personal thoughts on Professor Lars Olof Björn’s impact on plant UV photobiology and on Swedish popular science over the last three decades (at least)2017In: UV4Plants Bulletin, ISSN 2343-323X, Vol. 2016, no 2, p. 29-31Article in journal (Refereed)
  • 31.
    Verdaguer, Dolors
    et al.
    Environmental Sciences Department, Faculty of Sciences, University of Girona, Campus de Montilivi, Girona, Spain.
    Jansen, Marcel A.K.
    School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland.
    Llorens, Laura
    Environmental Sciences Department, Faculty of Sciences, University of Girona, Campus de Montilivi, Girona, Spain.
    Morales, Luis Orlando
    Division of Plant Biology, Department of Biosciences, Viikki Plant Science Center, University of Helsinki, Helsinki, Finland.
    Neugart, Susanne
    Leibniz-Institute of Vegetable and Ornamental Crops Grossbeeren/Erfurt e.V., Grossbeeren, Germany.
    UV-A radiation effects on higher plants: Exploring the known unknown2017In: Plant Science, ISSN 0168-9452, E-ISSN 1873-2259, Vol. 255, p. 72-81Article in journal (Refereed)
    Abstract [en]

    Ultraviolet-A radiation (UV-A: 315–400 nm) is a component of solar radiation that exerts a wide range of physiological responses in plants. Currently, field attenuation experiments are the most reliable source of information on the effects of UV-A. Common plant responses to UV-A include both inhibitory and stimulatory effects on biomass accumulation and morphology. UV-A effects on biomass accumulation can differ from those on root: shoot ratio, and distinct responses are described for different leaf tissues. Inhibitory and enhancing effects of UV-A on photosynthesis are also analysed, as well as activation of photoprotective responses, including UV-absorbing pigments. UV-A-induced leaf flavonoids are highly compound-specific and species-dependent. Many of the effects on growth and development exerted by UV-A are distinct to those triggered by UV-B and vary considerably in terms of the direction the response takes. Such differences may reflect diverse UV-perception mechanisms with multiple photoreceptors operating in the UV-A range and/or variations in the experimental approaches used. This review highlights a role that various photoreceptors (UVR8, phototropins, phytochromes and cryptochromes) may play in plant responses to UV-A when dose, wavelength and other conditions are taken into account.

  • 32.
    Wingsle, G
    et al.
    Swedish University of Agricultural Sciences, Umeå.
    Mattson, A
    University of Umeå, Umeå, Sweden.
    Ekblad, Alf
    University of Umeå, Umeå, Sweden.
    Hällgren, J-E
    Swedish University of Agricultural Sciences, Umeå.
    Selstam, E
    University of Umeå, Umeå, Sweden.
    Activities of glutathione reductase and superoxide dismutase in relation to changes of lipids and pigments due to ozone in seedlings of Pinus sylvestris (L.)1992In: Plant Science, ISSN 0168-9452, E-ISSN 1873-2259, Vol. 82, no 2, p. 167-178Article in journal (Refereed)
  • 33.
    Wu, Min
    et al.
    Chalmers University of Technology, Gothenburg, Sweden.
    Farkas, Daniel
    Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden; School of Science and Technology, Örebro University, Örebro, Sweden.
    Eriksson, Leif A.
    University of Gothenburg, Gothenburg, Sweden.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Proline 411 biases the conformation of the intrinsically disordered plant UVR8 photoreceptor C27 domain altering the functional properties of the peptide2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 818Article in journal (Refereed)
    Abstract [en]

    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 vivoexperiments have shown that the UVR8 C-terminal region (aa 397-423; UVR8C27) alone is sufficient to regulate the activity of COP1. In this work, CD spectroscopy and NMR experiments showed that the UVR8C27domain 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 UVR8C27. 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. UVR8C27is 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.
    Wu, Min
    et al.
    National University of Ireland, Galway, Ireland.
    Grahn, Elin M.
    Örebro University, School of Science and Technology.
    Eriksson, Leif
    National University of Ireland, Galway, Ireland.
    Strid, Åke
    Örebro University, School of Science and Technology.
    Theoretical study of the UVR8 protein structure, its tryptophan amino acid array and its role as a UV-B photoreceptor2011In: UV4growth, COST-Action FA0906, 1st Annual network Meeting, Abstracts / [ed] Éva Hideg, Szeged: Biological Research Center of the Hungarian Academy of Sciences , 2011, p. 16-16Conference paper (Refereed)
    Abstract [en]

    The protein UV resistance locus 8 (UVR8) is known to be involved in the specific UV-B response resulting in regulation of a large number of genes in plants. However, the precise mechanism for the function of the protein is not yet known. We have built a homology model of the protein UVR8 from Arabidopsis thaliana, and subjected the model to energy minimization. As predicted from sequence alignments, the model has a seven-bladed β-propeller fold. The final model shows that a large amount of the highly conserved tryptophans in UVR8 are clustered on one face of the globular protein structure. After obtaining the model, a quantum chemical calculation of the excitation spectra was performed based on the structure and relative orientation of the tryptophan residues. The calculated spectrum shows two peaks, corresponding to absorption maxima around 280 and 300 nm, a result in accordance with the previous experimental studies on regulation of gene expression. In summary, the distribution of the conserved tryptophan residues in the UVR8 model, together with the involvement of these residues in the UV absorption as calculated using quantum chemical methods, suggest that UVR8 itself could act as the UV-B receptor molecule in plants absorbing at both 280 and 300 nm.

  • 35.
    Zeiner, Michaela
    et al.
    Örebro University, School of Science and Technology. Division of Analytical Chemistry, Department of Chemistry, BOKU ⁻ University of Natural Resources and Life Sciences, Vienna, Austria.
    Kuhar, Ana
    Department of Chemistry, Faculty of Science, University of Zagreb, Zagreb, Croatia.
    Juranović Cindrić, Iva
    Department of Chemistry, Faculty of Science, University of Zagreb, Zagreb, Croatia.
    Geographic Differences in Element Accumulation in Needles of Aleppo Pines (Pinus halepensis Mill.) Grown in Mediterranean Region2019In: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 24, no 10, article id E1877Article in journal (Refereed)
    Abstract [en]

    Miller is a pine species native to the Mediterranean region, which has been used for restoration activities in arid and semiarid areas leading to vast spatial expansion. Needles from pine trees collected in the southeastern to northwestern extension of Croatia's coastal area at twelve sampling sites were analysed for twenty-one metals and metalloids. Statistical evaluation of the obtained data revealed significant differences for Al, As, B, Ba, Ca, Cr, Fe, K, Mg, Mn, Na, Se, and Sr between the different regions. Needles from trees growing on islands did not show elevated levels of Mg and/or Na as a result of the sea spray influence. The differences in metal accumulation are supposed to be linked to the environmental conditions at the respective sampling site, since the species was the same everywhere. By comparing the elemental contents of the soil those of with needles, it can be clearly seen, that the root as well as the foliar uptake contribute to the final amount.

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