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  • 1.
    Andersson, Jenny
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Walters, Robin G
    Horton, Peter
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Antisense inhibition of the photosynthetic antenna proteins CP29 and CP26: implications for the mechanism of protective energy dissipation2001In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 13, no 5, p. 1193-1204Article in journal (Refereed)
    Abstract [en]

    The specific roles of the chlorophyll a/b binding proteins CP29 and CP26 in light harvesting and energy dissipation within the photosynthetic apparatus have been investigated. Arabidopsis was transformed with antisense constructs against the genes encoding the CP29 or CP26 apoprotein, which gave rise to several transgenic lines with remarkably low amounts of the antisense target proteins. The decrease in the level of CP24 protein in the CP29 antisense lines indicates a physical interaction between these complexes. Analysis of chlorophyll fluorescence showed that removal of the proteins affected photosystem II function, probably as a result of changes in the organization of the light-harvesting antenna. However, whole plant measurements showed that overall photosynthetic rates were similar to those in the wild type. Both antisense lines were capable of the qE type of nonphotochemical fluorescence quenching, although there were minor changes in the capacity for quenching and in its induction kinetics. High-light-induced violaxanthin deepoxidation to zeaxanthin was not affected, although the pool size of these pigments was decreased slightly. We conclude that CP29 and CP26 are unlikely to be sites for nonphotochemical quenching.

  • 2. Boerjan, W.
    et al.
    Cervera, M. T.
    Delarue, M.
    Beeckman, T.
    Dewitte, W.
    Bellini, C.
    Caboche, M.
    Vanonckelen, H.
    Vanmontagu, M.
    Inze, D.
    Superroot, a recessive mutation in Arabidopsis, confers auxin overproduction1995In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 7, no 9, p. 1405-1419Article in journal (Refereed)
    Abstract [en]

    We have isolated seven allelic recessive Arabidopsis mutants, designated superroot (sur1-1 to sur1-7), displaying several abnormalities reminiscent of auxin effects. These characteristics include small and epinastic cotyledons, an elongated hypocotyl in which the connection between the stele and cortical and epidermal cells disintegrates, the development of excess adventitious and lateral roots, a reduced number of leaves, and the absence of an inflorescence. When germinated in the dark, sur1 mutants did not develop the apical hook characteristic of etiolated seedlings, We were able to phenocopy the Sur1(-) phenotype by supplying auxin to wild-type seedlings, to propagate sur7 explants on phytohormone-deficient medium, and to regenerate shoots from these explants by the addition of cytokinins alone to the culture medium. Analysis by gas chromatography coupled to mass spectrometry indicated increased levels of both free and conjugated indole-3-acetic acid. sur1 was crossed to the mutant axr2 and the altered-auxin response mutant ctr1. The phenotype of both double mutants was additive. The sur1 gene was mapped on chromosome 2 at 0.5 centimorgans from the gene encoding phytochrome B.

  • 3. Camilleri, Christine
    et al.
    Azimzadeh, Juliette
    Pastuglia, Martine
    Bellini, Catherine
    Grandjean, Olivier
    Bouchez, David
    The Arabidopsis TONNEAU2 gene encodes a putative novel protein phosphatase 2A regulatory subunit essential for the control of the cortical cytoskeleton.2002In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 14, no 4Article in journal (Refereed)
    Abstract [en]

    In Arabidopsis ton2 mutants, abnormalities of the cortical microtubular cytoskeleton, such as disorganization of the interphase microtubule array and lack of the preprophase band before mitosis, markedly affect cell shape and arrangement as well as overall plant morphology. We present the molecular isolation of the TON2 gene, which is highly conserved in higher plants and has a vertebrate homolog of unknown function. It encodes a protein similar in its C-terminal part to B" regulatory subunits of type 2A protein phosphatases (PP2As). We show that the TON2 protein interacts with an Arabidopsis type A subunit of PP2A in the yeast two-hybrid system and thus likely defines a novel subclass of PP2A subunits that are possibly involved in the control of cytoskeletal structures in plants.

  • 4.
    Damkjær, Jakob T
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Kereïche, Sami
    Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands.
    Johnson, Matthew P
    School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, United Kingdom.
    Kovacs, Laszlo
    Institute of Plant Biology, Biological Research Center, Hungarian Academy of Sciences, H-6726 Szeged, Hungary.
    Kiss, Anett Z
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Boekema, Egbert J
    Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands.
    Ruban, Alexander V
    School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, United Kingdom.
    Horton, Peter
    Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield, S10 2TN, United Kingdom.
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    The photosystem II light-harvesting protein Lhcb3 affects the macrostructure of photosystem II and the rate of state transitions in Arabidopsis2009In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 21, p. 3245-3256Article in journal (Refereed)
    Abstract [en]

    The main trimeric light-harvesting complex of higher plants (LHCII) consists of three different Lhcb proteins (Lhcb1-3). We show that Arabidopsis thaliana T-DNA knockout plants lacking Lhcb3 (koLhcb3) compensate for the lack of Lhcb3 by producing increased amounts of Lhcb1 and Lhcb2. As in wild-type plants, LHCII-photosystem II (PSII) supercomplexes were present in Lhcb3 knockout plants (koLhcb3), and preservation of the LHCII trimers (M trimers) indicates that the Lhcb3 in M trimers has been replaced by Lhcb1 and/or Lhcb2. However, the rotational position of the M LHCII trimer was altered, suggesting that the Lhcb3 subunit affects the macrostructural arrangement of the LHCII antenna. The absence of Lhcb3 did not result in any significant alteration in PSII efficiency or qE type of nonphotochemical quenching, but the rate of transition from State 1 to State 2 was increased in koLhcb3, although the final extent of state transition was unchanged. The level of phosphorylation of LHCII was increased in the koLhcb3 plants compared with wild-type plants in both State 1 and State 2. The relative increase in phosphorylation upon transition from State 1 to State 2 was also significantly higher in koLhcb3. It is suggested that the main function of Lhcb3 is to modulate the rate of state transitions.

  • 5. Derbyshire, Paul
    et al.
    Menard, Delphine
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Green, Porntip
    Saalbach, Gerhard
    Buschmann, Henrik
    Lloyd, Clive W.
    Pesquet, Edouard
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). John Innes Ctr, Norwich NR4 7UH, Norfolk, England.
    Proteomic Analysis of Microtubule Interacting Proteins over the Course of Xylem Tracheary Element Formation in Arabidopsis2015In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 27, no 10, p. 2709-2726Article in journal (Refereed)
    Abstract [en]

    Plant vascular cells, or tracheary elements (TEs), rely on circumferential secondary cell wall thickenings to maintain sap flow. The patterns in which TE thickenings are organized vary according to the underlying microtubule bundles that guide wall deposition. To identify microtubule interacting proteins present at defined stages of TE differentiation, we exploited the synchronous differentiation of TEs in Arabidopsis thaliana suspension cultures. Quantitative proteomic analysis of microtubule pull-downs, using ratiometric N-14/N-15 labeling, revealed 605 proteins exhibiting differential accumulation during TE differentiation. Microtubule interacting proteins associated with membrane trafficking, protein synthesis, DNA/RNA binding, and signal transduction peaked during secondary cell wall formation, while proteins associated with stress peaked when approaching TE cell death. In particular, CELLULOSE SYNTHASE-INTERACTING PROTEIN1, already associated with primary wall synthesis, was enriched during secondary cell wall formation. RNAi knockdown of genes encoding several of the identified proteins showed that secondary wall formation depends on the coordinated presence of microtubule interacting proteins with nonoverlapping functions: cell wall thickness, cell wall homogeneity, and the pattern and cortical location of the wall are dependent on different proteins. Altogether, proteins linking microtubules to a range of metabolic compartments vary specifically during TE differentiation and regulate different aspects of wall patterning.

  • 6.
    Eriksson, Sylvia K
    et al.
    Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, 106 91 Stockholm, Sweden.
    Kutzer, Michael
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Procek, Jan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gröbner, Gerhard
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Harryson, Pia
    Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, 106 91 Stockholm, Sweden.
    Tunable membrane binding of the intrinsically disordered dehydrin Lti30, a cold-induced plant stress protein2011In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 23, no 6, p. 2391-2404Article in journal (Refereed)
    Abstract [en]

    Dehydrins are intrinsically disordered plant proteins whose expression is upregulated under conditions of desiccation and cold stress. Their molecular function in ensuring plant survival is not yet known, but several studies suggest their involvement in membrane stabilization. The dehydrins are characterized by a broad repertoire of conserved and repetitive sequences, out of which the archetypical K-segment has been implicated in membrane binding. To elucidate the molecular mechanism of these K-segments, we examined the interaction between lipid membranes and a dehydrin with a basic functional sequence composition: Lti30, comprising only K-segments. Our results show that Lti30 interacts electrostatically with vesicles of both zwitterionic (phosphatidyl choline) and negatively charged phospholipids (phosphatidyl glycerol, phosphatidyl serine, and phosphatidic acid) with a stronger binding to membranes with high negative surface potential. The membrane interaction lowers the temperature of the main lipid phase transition, consistent with Lti30's proposed role in cold tolerance. Moreover, the membrane binding promotes the assembly of lipid vesicles into large and easily distinguishable aggregates. Using these aggregates as binding markers, we identify three factors that regulate the lipid interaction of Lti30 in vitro: (1) a pH dependent His on/off switch, (2) phosphorylation by protein kinase C, and (3) reversal of membrane binding by proteolytic digest.

  • 7.
    Gutierrez, Laurent
    et al.
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden.
    Bussell, John D
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden.
    Pacurar, Daniel I
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden.
    Schwambach, Josèli
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden.
    Pacurar, Monica
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden.
    Bellini, Catherine
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden.
    Phenotypic plasticity of adventitious rooting in Arabidopsis is controlled by complex regulation of Auxin response factor transcripts and microRNA abundance2009In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 21, no 10, p. 3119-3132Article in journal (Refereed)
    Abstract [en]

    The development of shoot-borne roots, or adventitious roots, is indispensable for mass propagation of elite genotypes. It is a complex genetic trait with a high phenotypic plasticity due to multiple endogenous and environmental regulatory factors. We demonstrate here that a subtle balance of activator and repressor AUXIN RESPONSE FACTOR (ARF) transcripts controls adventitious root initiation. Moreover, microRNA activity appears to be required for fine-tuning of this process. Thus, ARF17, a target of miR160, is a negative regulator, and ARF6 and ARF8, targets of miR167, are positive regulators of adventitious rooting. The three ARFs display overlapping expression domains, interact genetically, and regulate each other's expression at both transcriptional and posttranscriptional levels by modulating miR160 and miR167 availability. This complex regulatory network includes an unexpected feedback regulation of microRNA homeostasis by direct and nondirect target transcription factors. These results provide evidence of microRNA control of phenotypic variability and are a significant step forward in understanding the molecular mechanisms regulating adventitious rooting.

  • 8. Gutierrez, Laurent
    et al.
    Mauriat, Melanie
    Pelloux, Jerome
    Bellini, Catherine
    van Wuytswinkel, Olivier
    Towards a systematic validation of references in real-time RT-PCR2008In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 20, no 7, p. 1734-1735Article in journal (Refereed)
  • 9. Gutierrez, Laurent
    et al.
    Mongelard, Gaelle
    Flokova, Kristyna
    Pacurar, Daniel I.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Novak, Ondrej
    Staswick, Paul
    Kowalczyk, Mariusz
    Pacurar, Monica
    Demailly, Herve
    Geiss, Gaia
    Bellini, Catherine
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Auxin Controls Arabidopsis Adventitious Root Initiation by Regulating Jasmonic Acid Homeostasis2012In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 24, no 6, p. 2515-2527Article in journal (Refereed)
    Abstract [en]

    Vegetative shoot-based propagation of plants, including mass propagation of elite genotypes, is dependent on the development of shoot-borne roots, which are also called adventitious roots. Multiple endogenous and environmental factors control the complex process of adventitious rooting. In the past few years, we have shown that the auxin response factors ARF6 and ARF8, targets of the microRNA miR167, are positive regulators of adventitious rooting, whereas ARF17, a target of miR160, is a negative regulator. We showed that these genes have overlapping expression profiles during adventitious rooting and that they regulate each other's expression at the transcriptional and posttranscriptional levels by modulating the homeostasis of miR160 and miR167. We demonstrate here that this complex network of transcription factors regulates the expression of three auxin-inducible Gretchen Hagen3 (GH3) genes, GH3.3, GH3.5, and GH3.6, encoding acyl-acid-amido synthetases. We show that these three GH3 genes are required for fine-tuning adventitious root initiation in the Arabidopsis thaliana hypocotyl, and we demonstrate that they act by modulating jasmonic acid homeostasis. We propose a model in which adventitious rooting is an adaptive developmental response involving crosstalk between the auxin and jasmonate regulatory pathways.

  • 10. Hartmann, Laura
    et al.
    Pedrotti, Lorenzo
    Weiste, Christoph
    Fekete, Agnes
    Schierstaedt, Jasper
    Göttler, Jasmin
    Kempa, Stefan
    Krischke, Markus
    Dietrich, Katrin
    Mueller, Martin J
    Vicente-Carbajosa, Jesus
    Hanson, Johannes
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Department of Molecular Plant Physiology, Utrecht University, The Netherlands .
    Dröge-Laser, Wolfgang
    Crosstalk between Two bZIP Signaling Pathways Orchestrates Salt-Induced Metabolic Reprogramming in Arabidopsis Roots2015In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 27, no 8, p. 2244-2260Article in journal (Refereed)
    Abstract [en]

    Soil salinity increasingly causes crop losses worldwide. Although roots are the primary targets of salt stress, the signaling networks that facilitate metabolic reprogramming to induce stress tolerance are less understood than those in leaves. Here, a combination of transcriptomic and metabolic approaches was performed in salt-treated Arabidopsis thaliana roots, which revealed that the group S1 basic leucine zipper transcription factors bZIP1 and bZIP53 reprogram primary C- and N-metabolism. In particular, gluconeogenesis and amino acid catabolism are affected by these transcription factors. Importantly, bZIP1 expression reflects cellular stress and energy status in roots. In addition to the well-described abiotic stress response pathway initiated by the hormone abscisic acid (ABA) and executed by SnRK2 (Snf1-RELATED-PROTEIN-KINASE2) and AREB-like bZIP factors, we identify a structurally related ABA-independent signaling module consisting of SnRK1s and S1 bZIPs. Crosstalk between these signaling pathways recruits particular bZIP factor combinations to establish at least four distinct gene expression patterns. Understanding this signaling network provides a framework for securing future crop productivity.

  • 11.
    Jones, Brian
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Gunnerås, Sara Andersson
    Petersson, Sara V
    Tarkowski, Petr
    Graham, Neil
    May, Sean
    Dolezal, Karel
    Sandberg, Göran
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Ljung, Karin
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Cytokinin regulation of auxin synthesis in Arabidopsis involves a homeostatic feedback loop regulated via auxin and cytokinin signal transduction.2010In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 22, no 9, p. 2956-2969Article in journal (Refereed)
    Abstract [en]

    Together, auxin and cytokinin regulate many of the processes that are critical to plant growth, development, and environmental responsiveness. We have previously shown that exogenous auxin regulates cytokinin biosynthesis in Arabidopsis thaliana. In this work, we show that, conversely, the application or induced ectopic biosynthesis of cytokinin leads to a rapid increase in auxin biosynthesis in young, developing root and shoot tissues. We also show that reducing endogenous cytokinin levels, either through the induction of CYTOKININ OXIDASE expression or the mutation of one or more of the cytokinin biosynthetic ISOPENTENYLTRANSFERASE genes leads to a reduction in auxin biosynthesis. Cytokinin modifies the abundance of transcripts for several putative auxin biosynthetic genes, suggesting a direct induction of auxin biosynthesis by cytokinin. Our data indicate that cytokinin is essential, not only to maintain basal levels of auxin biosynthesis in developing root and shoot tissues but also for the dynamic regulation of auxin biosynthesis in response to changing developmental or environmental conditions. In combination with our previous work, the data suggest that a homeostatic feedback regulatory loop involving both auxin and cytokinin signaling acts to maintain appropriate auxin and cytokinin concentrations in developing root and shoot tissues.

  • 12.
    Kloth, Karen J.
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Laboratory of Entomology, Wageningen University, 6700 AA Wageningen, The Netherlands; Laboratory of Plant Physiology, Wageningen University, 6700 AA Wageningen, The Netherlands; Bioscience, Wageningen University & Research, 6708 PB Wageningen, The Netherlands.
    Busscher-Lange, Jacqueline
    Wiegers, Gerrie L.
    Kruijer, Willem
    Buijs, Gonda
    Meyer, Rhonda C.
    Albrectsen, Benedicte R.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Bouwmeester, Harro J.
    Dicke, Marcel
    Jongsma, Maarten A.
    SIEVE ELEMENT-LINING CHAPERONE1 Restricts Aphid Feeding on Arabidopsis during Heat Stress2017In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 29, no 10, p. 2450-2464Article in journal (Refereed)
    Abstract [en]

    The role of phloem proteins in plant resistance to aphids is still largely elusive. By genome-wide association mapping of aphid behavior on 350 natural Arabidopsis thaliana accessions, we identified the small heat shock-like SIEVE ELEMENT-LINING CHAPERONE1 (SLI1). Detailed behavioral studies on near-isogenic and knockout lines showed that SLI1 impairs phloem feeding. Depending on the haplotype, aphids displayed a different duration of salivation in the phloem. On sli1 mutants, aphids prolonged their feeding sessions and ingested phloem at a higher rate than on wild-type plants. The largest phenotypic effects were observed at 26 degrees C, when SLI1 expression is upregulated. At this moderately high temperature, sli1 mutants suffered from retarded elongation of the inflorescence and impaired silique development. Fluorescent reporter fusions showed that SLI1 is confined to the margins of sieve elements where it lines the parietal layer and colocalizes in spherical bodies around mitochondria. This localization pattern is reminiscent of the clamp-like structures observed in previous ultrastructural studies of the phloem and shows that the parietal phloem layer plays an important role in plant resistance to aphids and heat stress.

  • 13.
    Kovács, Laszlo
    et al.
    Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom.
    Damkjaer, Jakob
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Kereïche, Sami
    Department of Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands.
    Ilioaia, Cristian
    Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom.
    Ruban, Alexander V
    Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom.
    Boekema, Egbert J
    Department of Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands.
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Horton, Peter
    Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom.
    Lack of the light-harvesting complex CP24 affects the structure and function of the grana membranes of higher plant chloroplasts.2006In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 18, no 11, p. 3106-20Article in journal (Refereed)
    Abstract [en]

    The photosystem II (PSII) light-harvesting antenna in higher plants contains a number of highly conserved gene products whose function is unknown. Arabidopsis thaliana plants depleted of one of these, the CP24 light-harvesting complex, have been analyzed. CP24-deficient plants showed a decrease in light-limited photosynthetic rate and growth, but the pigment and protein content of the thylakoid membranes were otherwise almost unchanged. However, there was a major change in the macroorganization of PSII within these membranes; electron microscopy and image analysis revealed the complete absence of the C2S2M2 light-harvesting complex II (LHCII)/PSII supercomplex predominant in wild-type plants. Instead, only C2S2 supercomplexes, which are deficient in the LHCIIb M-trimers, were found. Spectroscopic analysis confirmed the disruption of the wild-type macroorganization of PSII. It was found that the functions of the PSII antenna were disturbed: connectivity between PSII centers was reduced, and maximum photochemical yield was lowered; rapidly reversible nonphotochemical quenching was inhibited; and the state transitions were altered kinetically. CP24 is therefore an important factor in determining the structure and function of the PSII light-harvesting antenna, providing the linker for association of the M-trimer into the PSII complex, allowing a specific macroorganization that is necessary both for maximum quantum efficiency and for photoprotective dissipation of excess excitation energy.

  • 14. Lan, Ting
    et al.
    Yang, Zhi-Ling
    Yang, Xue
    Liu, Yan-Jing
    Wang, Xiao-Ru
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Zeng, Qing-Yin
    Extensive functional diversification of the Populus glutathione S-transferase supergene family2009In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 21, no 12, p. 3749-3766Article in journal (Refereed)
    Abstract [en]

    Identifying how genes and their functions evolve after duplication is central to understanding gene family radiation. In this study, we systematically examined the functional diversification of the glutathione S-transferase (GST) gene family in Populus trichocarpa by integrating phylogeny, expression, substrate specificity, and enzyme kinetic data. GSTs are ubiquitous proteins in plants that play important roles in stress tolerance and detoxification metabolism. Genome annotation identified 81 GST genes in Populus that were divided into eight classes with distinct divergence in their evolutionary rate, gene structure, expression responses to abiotic stressors, and enzymatic properties of encoded proteins. In addition, when all the functional parameters were examined, clear divergence was observed within tandem clusters and between paralogous gene pairs, suggesting that subfunctionalization has taken place among duplicate genes. The two domains of GST proteins appear to have evolved under differential selective pressures. The C-terminal domain seems to have been subject to more relaxed functional constraints or divergent directional selection, which may have allowed rapid changes in substrate specificity, affinity, and activity, while maintaining the primary function of the enzyme. Our findings shed light on mechanisms that facilitate the retention of duplicate genes, which can result in a large gene family with a broad substrate spectrum and a wide range of reactivity toward different substrates.

  • 15. Marchant, Alan
    et al.
    Bhalerao, Rishikesh
    Casimiro, Ilda
    Eklöf, Jan
    Department of Forest Genetics and Plant Physiology, The Swedish University of Agricultural Sciences, S-901 83, Umeå, Sweden.
    Casero, Pedro J
    Bennett, Malcolm
    Sandberg, Goran
    AUX1 promotes lateral root formation by facilitating indole-3-acetic acid distribution between sink and source tissues in the Arabidopsis seedling2002In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 14, no 3, p. 589-597Article in journal (Refereed)
    Abstract [en]

    Arabidopsis root architecture is regulated by shoot-derived signals such as nitrate and auxin. We report that mutations in the putative auxin influx carrier AUX1 modify root architecture as a result of the disruption in hormone transport between indole-3-acetic acid (IAA) source and sink tissues. Gas chromatography-selected reaction monitoring-mass spectrometry measurements revealed that the aux1 mutant exhibited altered IAA distribution in young leaf and root tissues, the major IAA source and sink organs, respectively, in the developing seedling. Expression studies using the auxin-inducible reporter IAA2::uidA revealed that AUX1 facilitates IAA loading into the leaf vascular transport system. AUX1 also facilitates IAA unloading in the primary root apex and developing lateral root primordium. Exogenous application of the synthetic auxin 1-naphthylacetic acid is able to rescue the aux1 lateral root phenotype, implying that root auxin levels are suboptimal for lateral root primordium initiation in the mutant.

  • 16. Moyroud, Edwige
    et al.
    Minguet, Eugenio Gomez
    Ott, Felix
    Yant, Levi
    Pose, David
    Monniaux, Marie
    Blanchet, Sandrine
    Bastien, Olivier
    Thevenon, Emmanuel
    Weigel, Detlef
    Schmid, Markus
    Max Planck Institute for Developmental Biology, Department of Molecular Biology, 72076 Tuebingen, Germany .
    Parcy, Francois
    Prediction of Regulatory Interactions from Genome Sequences Using a Biophysical Model for the Arabidopsis LEAFY Transcription Factor2011In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 23, no 4, p. 1293-1306Article in journal (Refereed)
  • 17. Pencik, Ales
    et al.
    Simonovik, Biljana
    Petersson, Sara V.
    Henykova, Eva
    Simon, Sibu
    Greenham, Kathleen
    Zhang, Yi
    Kowalczyk, Mariusz
    Estelle, Mark
    Zazimalova, Eva
    Novak, Ondrej
    Sandberg, Göran
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Ljung, Karin
    Regulation of Auxin Homeostasis and Gradients in Arabidopsis Roots through the Formation of the Indole-3-Acetic Acid Catabolite 2-Oxindole-3-Acetic Acid2013In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 25, no 10, p. 3858-3870Article in journal (Refereed)
    Abstract [en]

    The native auxin, indole-3-acetic acid (IAA), is a major regulator of plant growth and development. Its nonuniform distribution between cells and tissues underlies the spatiotemporal coordination of many developmental events and responses to environmental stimuli. The regulation of auxin gradients and the formation of auxin maxima/minima most likely involve the regulation of both metabolic and transport processes. In this article, we have demonstrated that 2-oxindole-3-acetic acid (oxIAA) is a major primary IAA catabolite formed in Arabidopsis thaliana root tissues. OxIAA had little biological activity and was formed rapidly and irreversibly in response to increases in auxin levels. We further showed that there is cell type-specific regulation of oxIAA levels in the Arabidopsis root apex. We propose that oxIAA is an important element in the regulation of output from auxin gradients and, therefore, in the regulation of auxin homeostasis and response mechanisms.

  • 18.
    Pesquet, Edouard
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Zhang, Bo
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Gorzsas, Andras
    Puhakainen, Tuula
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Serk, Henrik
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Escamez, Sacha
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Barbier, Odile
    Gerber, Lorenz
    Courtois-Moreau, Charleen
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Alatalo, Edward
    Paulin, Lars
    Kangasjärvi, Jaakko
    Sundberg, Björn
    Goffner, Deborah
    Tuominen, Hannele
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Non-Cell-Autonomous Postmortem Lignification of Tracheary Elements in Zinnia elegans2013In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 25, no 4, p. 1314-1328Article in journal (Refereed)
    Abstract [en]

    Postmortem lignification of xylem tracheary elements (TEs) has been debated for decades. Here, we provide evidence in Zinnia elegans TE cell cultures, using pharmacological inhibitors and in intact Z. elegans plants using Fourier transform infrared microspectroscopy, that TE lignification occurs postmortem (i.e., after TE programmed cell death). In situ RT-PCR verified expression of the lignin monomer biosynthetic cinnamoyl CoA reductase and cinnamyl alcohol dehydrogenase in not only the lignifying TEs but also in the unlignified non-TE cells of Z. elegans TE cell cultures and in living, parenchymatic xylem cells that surround TEs in stems. These cells were also shown to have the capacity to synthesize and transport lignin monomers and reactive oxygen species to the cell walls of dead TEs. Differential gene expression analysis in Z. elegans TE cell cultures and concomitant functional analysis in Arabidopsis thaliana resulted in identification of several genes that were expressed in the non-TE cells and that affected lignin chemistry on the basis of pyrolysis-gas chromatography/mass spectrometry analysis. These data suggest that living, parenchymatic xylem cells contribute to TE lignification in a non-cellautonomous manner, thus enabling the postmortem lignification of TEs.

  • 19.
    Petersson, Sara V
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Johansson, Annika I
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Kowalczyk, Mariusz
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Makoveychuk, Alexander
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Wang, Jean Y
    Department of Biology and Institute for Genome Sciences & Policy, Center for Systems Biology, Duke University, Durham, North Carolina 27708, USA.
    Moritz, Thomas
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Grebe, Markus
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Benfey, Philip N
    Department of Biology and Institute for Genome Sciences & Policy, Center for Systems Biology, Duke University, Durham, North Carolina 27708, USA.
    Sandberg, Göran
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Ljung, Karin
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    An auxin gradient and maximum in the arabidopsis root apex shown by high-resolution cell-specific analysis of IAA distribution and synthesis2009In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 21, no 6, p. 1659-1668Article in journal (Refereed)
    Abstract [en]

    Local concentration gradients of the plant growth regulator auxin (indole-3-acetic acid [IAA]) are thought to instruct the positioning of organ primordia and stem cell niches and to direct cell division, expansion, and differentiation. High-resolution measurements of endogenous IAA concentrations in support of the gradient hypothesis are required to substantiate this hypothesis. Here, we introduce fluorescence-activated cell sorting of green fluorescent protein-marked cell types combined with highly sensitive mass spectrometry methods as a novel means for analyses of IAA distribution and metabolism at cellular resolution. Our results reveal the presence of IAA concentration gradients within the Arabidopsis thaliana root tip with a distinct maximum in the organizing quiescent center of the root apex. We also demonstrate that the root apex provides an important source of IAA and that cells of all types display a high synthesis capacity, suggesting a substantial contribution of local biosynthesis to auxin homeostasis in the root tip. Our results indicate that local biosynthesis and polar transport combine to produce auxin gradients and maxima in the root tip.

  • 20.
    Pietrzykowska, Malgorzata
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Suorsa, Marjaana
    Molecular Plant Biology, Department of Biochemistry, University of Turku, 20520 Turku, Finland.
    Semchonok, Dmitry A.
    Electron Microscopy Group, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747AG.
    Tikkanen, Mikko
    Molecular Plant Biology, Department of Biochemistry, University of Turku, 20520 Turku, Finland.
    Boekema, Egbert J.
    Electron Microscopy Group, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747AG.
    Aro, Eva-Mari
    Molecular Plant Biology, Department of Biochemistry, University of Turku, 20520 Turku, Finland.
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    The light-harvesting chlorophyll a/b binding proteins Lhcb1 and Lhcb2 play complementary roles during state transitions in Arabidopsis2014In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 26, no 9, p. 3646-3660Article in journal (Refereed)
    Abstract [en]

    Photosynthetic light harvesting in plants is regulated by phosphorylation-driven state transitions: functional redistributions of the major trimeric light-harvesting complex II (LHCII) to balance the relative excitation of photosystem I and photosystem II. State transitions are driven by reversible LHCII phosphorylation by the STN7 kinase and PPH1/TAP38 phosphatase. LHCII trimers are composed of Lhcb1, Lhcb2, and Lhcb3 proteins in various trimeric configurations. Here, we show that despite their nearly identical amino acid composition, the functional roles of Lhcb1 and Lhcb2 are different but complementary. Arabidopsis thaliana plants lacking only Lhcb2 contain thylakoid protein complexes similar to wild-type plants, where Lhcb2 has been replaced by Lhcb1. However, these do not perform state transitions, so phosphorylation of Lhcb2 seems to be a critical step. In contrast, plants lacking Lhcb1 had a more profound antenna remodeling due to a decrease in the amount of LHCII trimers influencing thylakoid membrane structure and, more indirectly, state transitions. Although state transitions are also found in green algae, the detailed architecture of the extant seed plant light-harvesting antenna can now be dated back to a time after the divergence of the bryophyte and spermatophyte lineages, but before the split of the angiosperm and gymnosperm lineages more than 300 million years ago.

  • 21. Ren, Lin-Ling
    et al.
    Liu, Yan-Jing
    Liu, Hai-Jing
    Qian, Ting-Ting
    Qi, Li-Wang
    Wang, Xiao-Ru
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Zeng, Qing-Yin
    Subcellular relocalization and positive selection play key Roles in the retention of duplicate genes of populus class III peroxidase family2014In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 26, no 6, p. 2404-2419Article in journal (Refereed)
    Abstract [en]

    Gene duplication is the primary source of new genes and novel functions. Over the course of evolution, many duplicate genes lose their function and are eventually removed by deletion. However, some duplicates have persisted and evolved diverse functions. A particular challenge is to understand how this diversity arises and whether positive selection plays a role. In this study, we reconstructed the evolutionary history of the class III peroxidase (PRX) genes from the Populus trichocarpa genome. PRXs are plant-specific enzymes that play important roles in cell wall metabolism and in response to biotic and abiotic stresses. We found that two large tandem-arrayed clusters of PRXs evolved from an ancestral cell wall type PRX to vacuole type, followed by tandem duplications and subsequent functional specification. Substitution models identified seven positively selected sites in the vacuole PRXs. These positively selected sites showed significant effects on the biochemical functions of the enzymes. We also found that positive selection acts more frequently on residues adjacent to, rather than directly at, a critical active site of the enzyme, and on flexible regions rather than on rigid structural elements of the protein. Our study provides new insights into the adaptive molecular evolution of plant enzyme families.

  • 22. Sairanen, Ilkka
    et al.
    Novak, Ondrej
    Pencik, Ales
    Ikeda, Yoshihisa
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Jones, Brian
    Sandberg, Göran
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Ljung, Karin
    Soluble Carbohydrates Regulate Auxin Biosynthesis via PIF Proteins in Arabidopsis2012In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 24, no 12, p. 4907-4916Article in journal (Refereed)
    Abstract [en]

    Plants are necessarily highly competitive and have finely tuned mechanisms to adjust growth and development in accordance with opportunities and limitations in their environment. Sugars from photosynthesis form an integral part of this growth control process, acting as both an energy source and as signaling molecules in areas targeted for growth. The plant hormone auxin similarly functions as a signaling molecule and a driver of growth and developmental processes. Here, we show that not only do the two act in concert but that auxin metabolism is itself regulated by the availability of free sugars. The regulation of the biosynthesis and degradation of the main auxin, indole-3-acetic acid (IAA), by sugars requires changes in the expression of multiple genes and metabolites linked to several IAA biosynthetic pathways. The induction also involves members of the recently described central regulator PHYTOCHROME-INTERACTING FACTOR transcription factor family. Linking these three known regulators of growth provides a model for the dynamic coordination of responses to a changing environment.

  • 23.
    Shaikhali, Jehad
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Barajas-Lopez, Juan de Dios
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Ötvös, Krisztina
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Kremnev, Dmitry
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Garcia, Ana Sanchez
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Srivastava, Vaibhav
    Swedish Univ Agr Sci, Dept Forest Genet & Plant Physiol, Umea Plant Sci Ctr, S-90187 Umea, Sweden.
    Wingsle, Gunnar
    Swedish Univ Agr Sci, Dept Forest Genet & Plant Physiol, Umea Plant Sci Ctr, S-90187 Umea, Sweden.
    Bako, Laszlo
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Strand, Åsa
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    The CRYPTOCHROME1-Dependent Response to Excess Light Is Mediated through the Transcriptional Activators ZINC FINGER PROTEIN EXPRESSED IN INFLORESCENCE MERISTEM LIKE1 and ZML2 in Arabidopsis2012In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 24, no 7, p. 3009-3025Article in journal (Refereed)
    Abstract [en]

    Exposure of plants to light intensities that exceed the electron utilization capacity of the chloroplast has a dramatic impact on nuclear gene expression. The photoreceptor Cryptochrome 1 (cry1) is essential to the induction of genes encoding photoprotective components in Arabidopsis thaliana. Bioinformatic analysis of the cry1 regulon revealed the putative ciselement CryR1 (GnTCKAG), and here we demonstrate an interaction between CryR1 and the zinc finger GATA-type transcription factors ZINC FINGER PROTEIN EXPRESSED IN INFLORESCENCE MERISTEM LIKE1 (ZML1) and ZML2. The ZML proteins specifically bind to the CryR1 cis-element as demonstrated in vitro and in vivo, and TCTAG was shown to constitute the core sequence required for ZML2 binding. In addition, ZML2 activated transcription of the yellow fluorescent protein reporter gene driven by the CryR1 cis-element in Arabidopsis leaf protoplasts. T-DNA insertion lines for ZML2 and its homolog ZML1 demonstrated misregulation of several cry1-dependent genes in response to excess light. Furthermore, the zml1 and zml2 T-DNA insertion lines displayed a high irradiance-sensitive phenotype with significant photoinactivation of photosystem II (PSII), indicated by reduced maximum quantum efficiency of PSII, and severe photobleaching. Thus, we identified the ZML2 and ZML1 GATA transcription factors as two essential components of the cry1-mediated photoprotective response.

  • 24.
    Sorin, Céline
    et al.
    Versailles Cedex, France; Swedish University of Agricultural Sciences, 90183 Umeå, Swed.
    Bussell, John D
    Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
    Camus, Isabelle
    Versailles Cedex, France.
    Ljung, Karin
    Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
    Kowalczyk, Mariusz
    Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
    Geiss, Gaia
    Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
    McKhann, Heather
    Versailles Cedex, France.
    Garcion, Christophe
    Versailles Cedex, France.
    Vaucheret, Hervé
    Versailles Cedex, France.
    Sandberg, Göran
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
    Bellini, Catherine
    Versailles Cedex, France; Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
    Auxin and light control of adventitious rooting in Arabidopsis require ARGONAUTE12005In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 17, no 5, p. 1343-1359Article in journal (Refereed)
    Abstract [en]

    Adventitious rooting is a quantitative genetic trait regulated by both environmental and endogenous factors. To better understand the physiological and molecular basis of adventitious rooting, we took advantage of two classes of Arabidopsis thaliana mutants altered in adventitious root formation: the superroot mutants, which spontaneously make adventitious roots, and the argonaute1 (ago1) mutants, which unlike superroot are barely able to form adventitious roots. The defect in adventitious rooting observed in ago1 correlated with light hypersensitivity and the deregulation of auxin homeostasis specifically in the apical part of the seedlings. In particular, a clear reduction in endogenous levels of free indoleacetic acid (IAA) and IAA conjugates was shown. This was correlated with a downregulation of the expression of several auxin-inducible GH3 genes in the hypocotyl of the ago1-3 mutant. We also found that the Auxin Response Factor17 (ARF17) gene, a potential repressor of auxin-inducible genes, was overexpressed in ago1-3 hypocotyls. The characterization of an ARF17-overexpressing line showed that it produced fewer adventitious roots than the wild type and retained a lower expression of GH3 genes. Thus, we suggest that ARF17 negatively regulates adventitious root formation in ago1 mutants by repressing GH3 genes and therefore perturbing auxin homeostasis in a light-dependent manner. These results suggest that ARF17 could be a major regulator of adventitious rooting in Arabidopsis.

  • 25.
    Sundell, David
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Street, Nathaniel R.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Kumar, Manoj
    Mellerowicz, Ewa J.
    Kucukoglu, Melis
    Johnsson, Christoffer
    Kumar, Vikash
    Mannapperuma, Chanaka
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Delhomme, Nicolas
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Nilsson, Ove
    Tuominen, Hannele
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Pesquet, Edouard
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91 Stockholm, Sweden.
    Fischer, Urs
    Niittyla, Totte
    Sundberg, Bjorn
    Hvidsten, Torgeir R.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Department of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, 1433 Ås, Norway.
    AspWood: High-Spatial-Resolution Transcriptome Profiles Reveal Uncharacterized Modularity of Wood Formation in Populus tremula2017In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 29, no 7, p. 1585-1604Article in journal (Refereed)
    Abstract [en]

    Trees represent the largest terrestrial carbon sink and a renewable source of ligno-cellulose. There is significant scope for yield and quality improvement in these largely undomesticated species, and efforts to engineer elite varieties will benefit from improved understanding of the transcriptional network underlying cambial growth and wood formation. We generated high-spatial-resolution RNA sequencing data spanning the secondary phloem, vascular cambium, and wood-forming tissues of Populus tremula. The transcriptome comprised 28,294 expressed, annotated genes, 78 novel protein-coding genes, and 567 putative long intergenic noncoding RNAs. Most paralogs originating from the Salicaceae whole-genome duplication had diverged expression, with the exception of those highly expressed during secondary cell wall deposition. Coexpression network analyses revealed that regulation of the transcriptome underlying cambial growth and wood formation comprises numerous modules forming a continuum of active processes across the tissues. A comparative analysis revealed that a majority of these modules are conserved in Picea abies. The high spatial resolution of our data enabled identification of novel roles for characterized genes involved in xylan and cellulose biosynthesis, regulators of xylem vessel and fiber differentiation and lignification. An associated web resource (AspWood, http://aspwood.popgenie.org) provides interactive tools for exploring the expression profiles and coexpression network.

  • 26. Suorsa, Marjaana
    et al.
    Jarvi, Sari
    Grieco, Michele
    Nurmi, Markus
    Pietrzykowska, Malgorzata
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Rantala, Marjaana
    Kangasjarvi, Saijaliisa
    Paakkarinen, Virpi
    Tikkanen, Mikko
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Aro, Eva-Mari
    PROTON GRADIENT REGULATION5 Is Essential for Proper Acclimation of Arabidopsis Photosystem I to Naturally and Artificially Fluctuating Light Conditions2012In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 24, no 7, p. 2934-2948Article in journal (Refereed)
    Abstract [en]

    In nature, plants are challenged by constantly changing light conditions. To reveal the molecular mechanisms behind acclimation to sometimes drastic and frequent changes in light intensity, we grew Arabidopsis thaliana under fluctuating light conditions, in which the low light periods were repeatedly interrupted with high light peaks. Such conditions had only marginal effect on photosystem II but induced damage to photosystem I (PSI), the damage being most severe during the early developmental stages. We showed that PROTON GRADIENT REGULATION5 (PGR5)-dependent regulation of electron transfer and proton motive force is crucial for protection of PSI against photodamage, which occurred particularly during the high light phases of fluctuating light cycles. Contrary to PGR5, the NAD(P)H dehydrogenase complex, which mediates cyclic electron flow around PSI, did not contribute to acclimation of the photosynthetic apparatus, particularly PSI, to rapidly changing light intensities. Likewise, the Arabidopsis pgr5 mutant exhibited a significantly higher mortality rate compared with the wild type under outdoor field conditions. This shows not only that regulation of PSI under natural growth conditions is crucial but also the importance of PGR5 in PSI protection.

  • 27. Swarup, Ranjan
    et al.
    Perry, Paula
    Hagenbeek, Dik
    Van Der Straeten, Dominique
    Beemster, Gerrit T S
    Sandberg, Göran
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Bhalerao, Rishikesh
    Ljung, Karin
    Bennett, Malcolm J
    Ethylene upregulates auxin biosynthesis in Arabidopsis seedlings to enhance inhibition of root cell elongation.2007In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 19, no 7, p. 2186-96Article in journal (Refereed)
    Abstract [en]

    Ethylene represents an important regulatory signal for root development. Genetic studies in Arabidopsis thaliana have demonstrated that ethylene inhibition of root growth involves another hormone signal, auxin. This study investigated why auxin was required by ethylene to regulate root growth. We initially observed that ethylene positively controls auxin biosynthesis in the root apex. We subsequently demonstrated that ethylene-regulated root growth is dependent on (1) the transport of auxin from the root apex via the lateral root cap and (2) auxin responses occurring in multiple elongation zone tissues. Detailed growth studies revealed that the ability of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid to inhibit root cell elongation was significantly enhanced in the presence of auxin. We conclude that by upregulating auxin biosynthesis, ethylene facilitates its ability to inhibit root cell expansion.

  • 28.
    Torabi, Salar
    et al.
    Biozentrum der Ludwig-Maximilians-Universität München, Department Biologie I, Planegg-Martinsried, Germany .
    Umate, Pavan
    Biozentrum der Ludwig-Maximilians-Universität München, Department Biologie I, Planegg-Martinsried, Germany .
    Manavski, Nikolay
    Biozentrum der Ludwig-Maximilians-Universität München, Department Biologie I, Planegg-Martinsried, Germany .
    Ploechinger, Magdalena
    Biozentrum der Ludwig-Maximilians-Universität München, Department Biologie I, Planegg-Martinsried, Germany .
    Kleinknecht, Laura
    Biozentrum der Ludwig-Maximilians-Universität München, Department Biologie I, Planegg-Martinsried, Germany .
    Bogireddi, Hanumakumar
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Herrmann, Reinhold G.
    Biozentrum der Ludwig-Maximilians-Universität München, Department Biologie I, Planegg-Martinsried, Germany .
    Wanner, Gerhard
    Biozentrum der Ludwig-Maximilians-Universität München, Department Biologie I, Planegg-Martinsried, Germany .
    Schröder, Wolfgang P.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Meurer, Joerg
    Biozentrum der Ludwig-Maximilians-Universität München, Department Biologie I, Planegg-Martinsried, Germany .
    PsbN is required for assembly of the photosystem II reaction center in Nicotiana tabacum2014In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 26, no 3, p. 1183-1199Article in journal (Refereed)
    Abstract [en]

    The chloroplast-encoded low molecular weight protein PsbN is annotated as a photosystem II (PSII) subunit. To elucidate the localization and function of PsbN, encoded on the opposite strand to the psbB gene cluster, we raised antibodies and inserted a resistance cassette into PsbN in both directions. Both homoplastomic tobacco (Nicotiana tabacum) mutants Delta psbN-F and Delta psbN-R show essentially the same PSII deficiencies. The mutants are extremely light sensitive and failed to recover from photoinhibition. Although synthesis of PSII proteins was not altered significantly, both mutants accumulated only similar to 25% of PSII proteins compared with the wild type. Assembly of PSII precomplexes occurred at normal rates, but heterodimeric PSII reaction centers (RCs) and higher order PSII assemblies were not formed efficiently in the mutants. The Delta psbN-R mutant was complemented by allotopic expression of the PsbN gene fused to the sequence of a chloroplast transit peptide in the nuclear genome. PsbN represents a bitopic trans-membrane peptide localized in stroma lamellae with its highly conserved C terminus exposed to the stroma. Significant amounts of PsbN were already present in dark-grown seedling. Our data prove that PsbN is not a constituent subunit of PSII but is required for repair from photoinhibition and efficient assembly of the PSII RC.

  • 29.
    Viotti, Corrado
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). University of Heidelberg, Germany.
    Krüger, Falco
    Neubert, Christoph
    Fink, Fabian
    Lupanga, Upendo
    Krebs, Melanie
    Scheuring, David
    Hemsley, Piers A.
    Boutté, Yohann
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Frescatada-Rosa, Márcia
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Wolfenstetter, Susanne
    Sauer, Norbert
    Hillmer, Stefan
    Grebe, Marcus
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Schumacher, Karin
    The Endoplasmic Reticulum Is the Main Membrane Source for Biogenesis of the Lytic Vacuole in Arabidopsis2013In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 25, no 9, p. 3434-3449Article in journal (Refereed)
    Abstract [en]

    Vacuoles are multifunctional organelles essential for the sessile lifestyle of plants. Despite their central functions in cell growth, storage, and detoxification, knowledge about mechanisms underlying their biogenesis and associated protein trafficking pathways remains limited. Here, we show that in meristematic cells of the Arabidopsis thaliana root, biogenesis of vacuoles as well as the trafficking of sterols and of two major tonoplast proteins, the vacuolar H+-pyrophosphatase and the vacuolar H+-adenosinetriphosphatase, occurs independently of endoplasmic reticulum (ER)-Golgi and post-Golgi trafficking. Instead, both pumps are found in provacuoles that structurally resemble autophagosomes but are not formed by the core autophagy machinery. Taken together, our results suggest that vacuole biogenesis and trafficking of tonoplast proteins and lipids can occur directly from the ER independent of Golgi function.

  • 30. Wullschleger, S D
    et al.
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Taylor, G
    Genomics and forest biology: Populus emerges as the perennial favorite2002In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 14, no 11, p. 2651-2655Article in journal (Refereed)
  • 31. Yant, Levi
    et al.
    Mathieu, Johannes
    Dinh, Thanh Theresa
    Ott, Felix
    Lanz, Christa
    Wollmann, Heike
    Chen, Xuemei
    Schmid, Markus
    Max Planck Institute for Developmental Biology, D-72076 Tübingen, Germany.
    Orchestration of the Floral Transition and Floral Development in Arabidopsis by the Bifunctional Transcription Factor APETALA22010In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 22, no 7, p. 2156-2170Article in journal (Refereed)
  • 32. Yin, Xiao-Jun
    et al.
    Volk, Sara
    Ljung, Karin
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Mehlmer, Norbert
    Dolezal, Karel
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Laboratory of Growth Regulators, Palacky University and Institute of Experimental Botany, Academy of Sciences of the Czech Republic, CZ-78371 Olomouc, Czech Republic.
    Ditengou, Franck
    Hanano, Shigeru
    Davis, Seth J
    Schmelzer, Elmon
    Sandberg, Göran
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Teige, Markus
    Palme, Klaus
    Pickart, Cecile
    Bachmair, Andreas
    Ubiquitin lysine 63 chain forming ligases regulate apical dominance in Arabidopsis2007In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 19, no 6, p. 1898-1911Article in journal (Refereed)
    Abstract [en]

    Lys-63-linked multiubiquitin chains play important roles in signal transduction in yeast and in mammals, but the functions for this type of chain in plants remain to be defined. The RING domain protein RGLG2 (for RING domain Ligase2) from Arabidopsis thaliana can be N-terminally myristoylated and localizes to the plasma membrane. It can form Lys-63-linked multiubiquitin chains in an in vitro reaction. RGLG2 has overlapping functions with its closest sequelog, RGLG1, and single mutants in either gene are inconspicuous. rglg1 rglg2 double mutant plants exhibit loss of apical dominance and altered phyllotaxy, two traits critically influenced by the plant hormone auxin. Auxin and cytokinin levels are changed, and the plants show a decreased response to exogenously added auxin. Changes in the abundance of PIN family auxin transport proteins and synthetic lethality with a mutation in the auxin transport regulator BIG suggest that the directional flow of auxin is modulated by RGLG activity. Modification of proteins by Lys-63-linked multiubiquitin chains is thus important for hormone-regulated, basic plant architecture.

  • 33. Yu, Sha
    et al.
    Galvao, Vinicius C.
    Zhang, Yan-Chun
    Horrer, Daniel
    Zhang, Tian-Qi
    Hao, Yan-Hong
    Feng, Yu-Qi
    Wang, Shui
    Schmid, Markus
    Max Planck Institute for Developmental Biology, Department of Molecular Biology, Tuebingen, Germany.
    Wang, Jia-Wei
    Gibberellin Regulates the Arabidopsis Floral Transition through miR156-Targeted SQUAMOSA PROMOTER BINDING-LIKE Transcription Factors2012In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 24, no 8, p. 3320-3332Article in journal (Refereed)
1 - 33 of 33
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