umu.sePublikationer
Ändra sökning
Avgränsa sökresultatet
2345678 201 - 250 av 1096
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 201. DELUCIA, EH
    et al.
    DAY, TA
    Oquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    THE POTENTIAL FOR PHOTOINHIBITION OF PINUS-SYLVESTRIS L SEEDLINGS EXPOSED TO HIGH LIGHT AND LOW SOIL-TEMPERATURE1991Ingår i: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431, Vol. 42, nr 238, s. 611-617Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of high light and root chilling on gas exchange, chlorophyll fluorescence, and bulk shoot water potential (PSI-shoot) was examined for Pinus sylvestris seedlings. Transferring plants from low light (200-mu-mol m-2 s-1, PAR) and a soil temperature of 15-degrees-C to high light (850-mu-mol m-2 S-1) and 1-degrees-C caused > 90% decrease in net photosynthesis and leaf conductance measured at 350 mm3 dm-3 CO2, and a decrease in the ratio of variable to maximum fluorescence (F(v)/F(m)) from 0.83 to 0.63. The decrease in F(v)/F(m) was, however, only marginally greater than when seedlings were transferred from low to high light but kept at a soil temperature of 15-degrees-C. Thus, photoinhibition was a minor component of the substantial decrease observed for net photosynthesis at 1-degrees-C soil temperature. The decrease in net photosynthesis and PSI-shoot at 1-degrees-C was associated with an increased in calculated intracellular CO2 concentration, suggesting that non-stomatal factors related to water stress were involved in inhibiting carbon assimilation. Measurements at saturating external CO2 concentration, however, indicate that stomatal closure was the dominant factor limiting net photosynthesis at low soil temperature. This interpretation was confirmed with additional experiments using Pinus taeda and Picea engelmannii seedlings. Decreases in gas-exchange variables at 5-degrees-C soil temperature were not associated with changes in PSI-shoot. Thus, hormonal factors, localized decreases in PSI-needle, or changes in xylem flux may mediate the response to moderate root chilling.

  • 202. Demmig-Adams, Barbara
    et al.
    Ebbert, Volker
    Mellman, David L
    Mueh, Kristine E
    Schaffer, Lisa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Funk, Christiane
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Zarter, C Ryan
    Adamska, Iwona
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Adams III, William W
    Modulation of PsbS and flexible vs sustained energy dissipation by light environment in different species2006Ingår i: Physiologia Plantarum, Vol. 127, s. 670-80Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Contrasting acclimation strategies of photosynthesis and photoprotection were identified for annual mesophytes (spinach, pumpkin, and Arabidopsis) vs the tropical evergreen Monstera deliciosa. The annual species utilized full sunlight for photosynthesis to a much greater extent than the evergreen species. Conversely, the evergreen species exhibited a greater capacity for photoprotective thermal energy dissipation as well as a greater expression of the PsbS protein in full sun than the annual species. In all species, the majority of thermal energy dissipation [assessed as non-photochemical fluorescence quenching (NPQ)] was the flexible, ΔpH-dependent form of NPQ over the entire range of growth light environments. However, in response to a transfer of shade-grown plants to high light, the evergreen species exhibited a high level of sustained thermal dissipation (qI), but the annual species did not. This sustained energy dissipation in the evergreen species was not ΔpH-dependent nor did the low level of PsbS in shade leaves increase upon transfer to high light for several days. Sustained ΔpH-independent NPQ was correlated (a) initially, with sustained D1 protein phosphorylation and xanthophyll cycle arrest and (b) subsequently, with an accumulation over several days of PsbS-related one-helix proteins and newly synthesized zeaxanthin and lutein.

  • 203. Deng, Xiaodong
    et al.
    Eriksson, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Two iron-responsive promoter elements control expression of FOX1 in Chlamydomonas reinhardtii.2007Ingår i: Eukaryotic Cell, ISSN 1535-9778, Vol. 6, nr 11, s. 2163-7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    FOX1 encodes an iron deficiency-induced ferroxidase involved in a high-affinity iron uptake system. Mutagenesis analysis of the FOX1 promoter identified two separate iron-responsive elements, FeRE1 (CACACG) and FeRE2 (CACGCG), between positions –87 and –82 and between positions –65 and –60, respectively, and both are needed for induced FOX1 expression under conditions of iron deficiency.

  • 204. Derbyshire, Paul
    et al.
    Menard, Delphine
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Green, Porntip
    Saalbach, Gerhard
    Buschmann, Henrik
    Lloyd, Clive W.
    Pesquet, Edouard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, 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 Arabidopsis2015Ingår i: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 27, nr 10, s. 2709-2726Artikel i tidskrift (Refereegranskat)
    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.

  • 205.
    Devadas, Arun
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Characterization of fungual strains for bioethanol production and sugar utilization2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Bioethanol production from cellulose based sources is currently in focus in several research projects and the need of the hour is a versatile fermenting organism that can utilize both 5C and 6C sugars effectively. Several naturally occurring fungi have the property of fermenting both types of sugars more efficiently than the traditionally used Saccharomyces cerevisiae which only can ferment hexose sugars. In this study, six different fungi were grown on a media with sugar concentrations similar to the spent sulphite liquor (SSL) from the paper pulp industry. Known fungi such as S. cerevisiae and T. versicolor as well as 4 unidentified wood rot species were grown in sealed bottles with media containing mixture of 6C and 5C. Comparison was made between ethanol fermentation, sugar consumption and enzyme activities (ALDH and PDC). The fermentation experiment was run for 21 days and ethanol concentrations up to 18g/L were achieved. We conclude that two of the fungi produce sufficient amount of ethanol and could be used in large-scale fermentation processes.

  • 206.
    Dimotakis, Charilaos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Understanding of the role of CAD4, CAD5 and CAD6 gene redundancy during the lignification of Arabidopsis xylem.2015Självständigt arbete på avancerad nivå (masterexamen), 40 poäng / 60 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Abstract

     

    Lignin is a cell wall polyphenolic polymer constituting the second most abundant bio-polymer on earth. This polymer is mostly accumulated in wood or xylem where it covers the other cell wall polysaccharides. Thus the removal of lignin allows accessing the polysaccharidic cell wall polymers which can then be converted into bio-fuels, textile or paper. Understanding lignin biosynthesis is therefore important to improve the industrial processing of the woody biomass. Lignin derives from the oxidative polymerization of different types of monomers called monolignols including 4-hydroxyphenylpropene alcohols as the most common monomers. Monolignols derive from the amino acid phenylalanine which is converted by a biosynthetic pathway known as the phenylpropanoid pathway. The last step of the multiple enzymatic process use the enzyme cinnamyl alcohol dehydrogenase (CAD) to convert 4-hydroxyphenylpropene aldehydes into 4-hydroxyphenylpropene alcohols. CAD is encoded by a small multigenic family in Arabidopsis thaliana comprising 17 genes.

    The aim of this master thesis is to understand the role of cinnamyl alcohol dehydrogenase gene redundancy during xylem lignification. CAD4, CAD5 and CAD6 have been associated in previous studies with xylem lignification and the main aim is to decipher if these genes are redundant or if they exhibit specificity in their expression (level, time and/or localization) and/or protein activity and structure. To do so, a genetic analysis of the single and double T-DNA insertional loss-of-function mutants in each of these genes were studied to compare their morphological characteristics, their biochemical structure (for both lignin quantification and composition) as well as their gene expression levels.

    Although minor changes in the lignin quantity and composition were observed for all of the single mutants, double mutants exhibited significant reductions and changes. Gene expression analysis moreover showed that the loss-of-function in any one of the three CADs caused a reduction ranging from 48% to 95% of the expression of the other CADs independently of the gene mutated. CAD4 and CAD5 both catalyzed the reduction of classical 4-hydroxyphenylpropene aldehydes into their corresponding alcohols: CAD5 catalytic activity is more specific to doubly methoxylated 4-hydroxyphenylpropene aldehydes than CAD4. In contrast, CAD6 did not affect the classical monolignols incorporation into lignin, but instead appeared to assist the function of CAD4 and CAD5. A clear synergetic effect of the double mutants suggested that a potential interaction could occur between these CAD proteins. Overall, our analysis showed that these three CAD genes were not redundant, but instead exhibited distinct function during xylem lignin biosynthesis.

  • 207. Dinant, S.
    et al.
    Wolff, N.
    De Marco, F.
    Vilaine, F.
    Gissot, L.
    Aubry, E.
    Sandt, C.
    Bellini, C.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France.
    Le Hir, R.
    Synchrotron FTIR and Raman spectroscopy provide unique spectral fingerprints for Arabidopsis floral stem vascular tissues2019Ingår i: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431, Vol. 70, nr 3, s. 871-883Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cell walls are highly complex structures that are modified during plant growth and development. For example, the development of phloem and xylem vascular cells, which participate in the transport of sugars and water as well as providing support, can be influenced by cell-specific wall composition. Here, we used synchrotron radiation-based Fourier-transform infrared (SR-FTIR) and Raman spectroscopy to analyse the cell wall composition of floral stem vascular tissues of wild-type Arabidopsis and the double-mutant sweet11-1 sweet12-1, which has impaired sugar transport. The SR-FTIR spectra showed that in addition to modified xylem cell wall composition, phloem cell walls in the double-mutant line were characterized by modified hemicellulose composition. Combining Raman spectroscopy with a classification and regression tree (CART) method identified combinations of Raman shifts that could distinguish xylem vessels and fibers. In addition, the disruption of the SWEET11 and SWEET12 genes impacted on xylem wall composition in a cell-specific manner, with changes in hemicelluloses and cellulose observed at the xylem vessel interface. These results suggest that the facilitated transport of sugars by transporters that exist between vascular parenchyma cells and conducting cells is important in ensuring correct phloem and xylem cell wall composition.

  • 208. Ding, Jihua
    et al.
    Böhlenius, Henrik
    Rühl, Mark Georg
    Chen, Peng
    Sane, Shashank
    Zambrano, Jose A.
    Zheng, Bo
    Nilsson, Ove
    Eriksson, Maria E.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    GIGANTEA-like genes control seasonal growth cessation in Populus2018Ingår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 218, nr 4, s. 1491-1503Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Survival of trees growing in temperate zones requires cycling between active growth and dormancy. This involves growth cessation in the autumn triggered by a photoperiod shorter than the critical day length. Variations in GIGANTEA (GI)-like genes have been associated with phenology in a range of different tree species, but characterization of the functions of these genes in the process is still lacking. We describe the identification of the Populus orthologs of GI and their critical role in short-day-induced growth cessation. Using ectopic expression and silencing, gene expression analysis, protein interaction and chromatin immunoprecipitation experiments, we show that PttGIs are likely to act in a complex with PttFKF1s (FLAVIN-BINDING, KELCH REPEAT, F-BOX 1) and PttCDFs (CYCLING DOF FACTOR) to control the expression of PttFT2, the key gene regulating short-day-induced growth cessation in Populus. In contrast to Arabidopsis, in which the GI-CONSTANS (CO)-FLOWERING LOCUS T (FT) regulon is a crucial day-length sensor for flowering time, our study suggests that, in Populus, PttCO-independent regulation of PttFT2 by PttGI is more important in the photoperiodic control of growth cessation and bud set.

  • 209.
    Dobrenel, Thomas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Institut Jean-Pierre Bourgin, UMR 1318 INRA AgroParisTech, ERL CNRS 3559, Saclay Plant Sciences, Versailles 78026, France.
    Caldana, Camila
    Hanson, Johannes
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Robaglia, Christophe
    Vincentz, Michel
    Veit, Bruce
    Meyer, Christian
    TOR Signaling and Nutrient Sensing2016Ingår i: Annual Review of Plant Biology, ISSN 1543-5008, E-ISSN 1545-2123, Vol. 67, s. 261-285Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    All living organisms rely on nutrients to sustain cell metabolism and energy production, which in turn need to be adjusted based on available resources. The evolutionarily conserved target of rapamycin (TOR) protein kinase is a central regulatory hub that connects environmental information about the quantity and quality of nutrients to developmental and metabolic processes in order to maintain cellular homeostasis. TOR is activated by both nitrogen and carbon metabolites and promotes energy-consuming processes such as cell division, mRNA translation, and anabolism in times of abundance while repressing nutrient remobilization through autophagy. In animals and yeasts, TOR acts antagonistically to the starvation-induced AMP-activated kinase (AMPK)/sucrose nonfermenting 1 (Snf1) kinase, called Snf1-related kinase 1 (SnRK1) in plants. This review summarizes the immense knowledge on the relationship betweenTORsignaling and nutrients in nonphotosynthetic organisms and presents recent findings in plants that illuminate the crucial role of this pathway in conveying nutrient-derived signals and regulating many aspects of metabolism and growth.

  • 210.
    Dobrenel, Thomas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Institut Jean-Pierre Bourgin, Institut National de la Recherche Agronomique, AgroParisTech, Centre National de la Recherche Scientifique, Université Paris-Saclay, Versailles, France; Université Paris-Sud–Université Paris-Saclay, Orsay, France.
    Mancera-Martinez, Eder
    Forzani, Celine
    Azzopardi, Marianne
    Davanture, Marlene
    Moreau, Manon
    Schepetilnikov, Mikhail
    Chicher, Johana
    Langella, Olivier
    Zivy, Michel
    Robaglia, Christophe
    Ryabova, Lyubov A.
    Hanson, Johannes
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Meyer, Christian
    The Arabidopsis TOR Kinase Specifically Regulates the Expression of Nuclear Genes Coding for Plastidic Ribosomal Proteins and the Phosphorylation of the Cytosolic Ribosomal Protein S62016Ingår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 7, artikel-id 1611Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Protein translation is an energy consuming process that has to be fine-tuned at both the cell and organism levels to match the availability of resources. The target of rapamycin kinase (TOR) is a key regulator of a large range of biological processes in response to environmental cues. In this study, we have investigated the effects of TOR inactivation on the expression and regulation of Arabidopsis ribosomal proteins at different levels of analysis, namely from transcriptomic to phosphoproteomic. TOR inactivation resulted in a coordinated down-regulation of the transcription and translation of nuclear-encoded mRNAs coding for plastidic ribosomal proteins, which could explain the chlorotic phenotype of the TOR silenced plants. We have identified in the 5' untranslated regions (UTRs) of this set of genes a conserved sequence related to the 5' terminal oligopyrimidine motif, which is known to confer translational regulation by the TOR kinase in other eukaryotes. Furthermore, the phosphoproteomic analysis of the ribosomal fraction following TOR inactivation revealed a lower phosphorylation of the conserved Ser240 residue in the C-terminal region of the 40S ribosomal protein S6 (RPS6). These results were confirmed by Western blot analysis using an antibody that specifically recognizes phosphorylated Ser240 in RPS6. Finally, this antibody was used to follow TOR activity in plants. Our results thus uncover a multi-level regulation of plant ribosomal genes and proteins by the TOR kinase.

  • 211. Doyle, Siamsa M.
    et al.
    Haeger, Ash
    Vain, Thomas
    Rigal, Adeline
    Viotti, Corrado
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Langowska, Malgorzata
    Ma, Qian
    Friml, Jiri
    Raikhel, Natasha V.
    Hicks, Glenn R.
    Robert, Stephanie
    An early secretory pathway mediated by GNOM-LIKE 1 and GNOM is essential for basal polarity establishment in Arabidopsis thaliana2015Ingår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 112, nr 7, s. E806-E815Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Spatial regulation of the plant hormone indole-3-acetic acid (IAA, or auxin) is essential for plant development. Auxin gradient establishment is mediated by polarly localized auxin transporters, including PIN-FORMED (PIN) proteins. Their localization and abundance at the plasma membrane are tightly regulated by endo-membrane machinery, especially the endocytic and recycling pathways mediated by the ADP ribosylation factor guanine nucleotide exchange factor (ARF-GEF) GNOM. We assessed the role of the early secretory pathway in establishing PIN1 polarity in Arabidopsis thaliana by pharmacological and genetic approaches. We identified the compound endosidin 8 (ES8), which selectively interferes with PIN1 basal polarity without altering the polarity of apical proteins. ES8 alters the auxin distribution pattern in the root and induces a strong developmental phenotype, including reduced root length. The ARF-GEF-defective mutants gnom-like 1 (gnl1-1) and gnom (van7) are significantly resistant to ES8. The compound does not affect recycling or vacuolar trafficking of PIN1 but leads to its intracellular accumulation, resulting in loss of PIN1 basal polarity at the plasma membrane. Our data confirm a role for GNOM in endoplasmic reticulum (ER)-Golgi trafficking and reveal that a GNL1/GNOM-mediated early secretory pathway selectively regulates PIN1 basal polarity establishment in a manner essential for normal plant development.

  • 212.
    Druart, Nathalie
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Johansson, Annika
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Baba, Kyoko
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Schrader, Jarmo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Sjödin, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Bhalerao, Rupali R
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Resman, Lars
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Trygg, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Moritz, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Bhalerao, Rishikesh P
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Environmental and hormonal regulation of the activity–dormancy cycle in the cambial meristem involves stage-specific modulation of transcriptional and metabolic networks2007Ingår i: The Plant Journal, Vol. 50, s. 557-73Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have performed transcript and metabolite profiling of isolated cambial meristem cells of the model tree aspen during the course of their activity–dormancy cycle to better understand the environmental and hormonal regulation of this process in perennial plants. Considerable modulation of cambial transcriptome and metabolome occurs throughout the activity–dormancy cycle. However, in addition to transcription, post-transcriptional control is also an important regulatory mechanism as exemplified by the regulation of cell-cycle genes during the reactivation of cambial cell division in the spring. Genes related to cold hardiness display temporally distinct induction patterns in the autumn which could explain the step-wise development of cold hardiness. Factors other than low temperature regulate the induction of early cold hardiness-related genes whereas abscisic acid (ABA) could potentially regulate the induction of late cold hardiness-related genes in the autumn. Starch breakdown in the autumn appears to be regulated by the ‘short day’ signal and plays a key role in providing substrates for the production of energy, fatty acids and cryoprotectants. Catabolism of sucrose and fats provides energy during the early stages of reactivation in the spring, whereas the reducing equivalents are generated through activation of the pentose phosphate shunt. Modulation of gibberellin (GA) signaling and biosynthesis could play a key role in the regulation of cambial activity during the activity–dormancy cycle as suggested by the induction of PttRGA which encodes a negative regulator of growth in the autumn and that of a GA-20 oxidase, a key gibberellin biosynthesis gene during reactivation in spring. In summary, our data reveal the dynamics of transcriptional and metabolic networks and identify potential targets of environmental and hormonal signals in the regulation of the activity–dormancy cycle in cambial meristem.

  • 213. Druart, Nathalie
    et al.
    Rodriguez-Buey, Marisa
    Barron-Gafford, Greg
    Sjödin, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Bhalerao, Rishikesh
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Molecular targets of elevated [CO2] in leaves and stems of Populus deltoides: implications for future tree growth and carbon sequestration2006Ingår i: Functional Plant Biology, Vol. 33, s. 121-131Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report the first comprehensive analysis of the effects of elevated [CO2] on gene expression in source leaf and stem sink tissues in woody plants. We have taken advantage of coppiced Populus deltoides (Bartr.) stands grown for 3 years under three different and constant elevated [CO2] in the agriforest mesocosms of Biosphere 2. Leaf area per tree was doubled by elevated [CO2] but although growth at 800 v. 400 µmol mol–1 CO2 resulted in a significant increase in stem biomass, growth was not stimulated at 1200 µmol mol–1 CO2. Growth under elevated [CO2] also resulted in significant increases in stem wood density. Analysis of expression data for the 13 490 clones present on POP1 microarrays revealed 95 and 277 [CO2]-responsive clones in leaves and stems respectively, with the response being stronger at 1200 µmol mol–1. When these [CO2]-responsive genes were assigned to functional categories, metabolism-related genes were the most responsive to elevated [CO2]. However within this category, expression of genes relating to bioenergetic processes was unchanged in leaves whereas the expression of genes for storage proteins and of those involved in control of wall expansion was enhanced. In contrast to leaves, the genes up-regulated in stems under elevated [CO2] were primarily enzymes responsible for lignin formation and polymerisation or ethylene response factors, also known to induce lignin biosynthesis. Concomitant with this enhancement of lignin biosynthesis in stems, there was a pronounced repression of genes related to cell wall formation and cell growth. These changes in gene expression have clear consequences for long-term carbon sequestration, reducing the carbon-fertilisation effect, and the potential for increased lignification may negatively impact on future wood quality for timber and paper production.

  • 214. Du, Qingzhang
    et al.
    Tian, Jiaxing
    Yang, Xiaohui
    Pan, Wei
    Xu, Baohua
    Li, Bailian
    Ingvarsson, Pär K
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Zhang, Deqiang
    Identification of additive, dominant, and epistatic variation conferred by key genes in cellulose biosynthesis pathway in Populus tomentosa2015Ingår i: DNA research, ISSN 1340-2838, E-ISSN 1756-1663, Vol. 22, nr 1, s. 53-67Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Economically important traits in many species generally show polygenic, quantitative inheritance. The components of genetic variation (additive, dominant and epistatic effects) of these traits conferred by multiple genes in shared biological pathways remain to be defined. Here, we investigated 11 full-length genes in cellulose biosynthesis, on 10 growth and wood-property traits, within a population of 460 unrelated Populus tomentosa individuals, via multi-gene association. To validate positive associations, we conducted single-marker analysis in a linkage population of 1,200 individuals. We identified 118, 121, and 43 associations (P < 0.01) corresponding to additive, dominant, and epistatic effects, respectively, with low to moderate proportions of phenotypic variance (R-2). Epistatic interaction models uncovered a combination of three non-synonymous sites from three unique genes, representing a significant epistasis for diameter at breast height and stem volume. Single-marker analysis validated 61 associations (false discovery rate, Q <= 0.10), representing 38 SNPs from nine genes, and its average effect (R-2 = 3.8%) nearly 2-fold higher than that identified with multi-gene association, suggesting that multi-gene association can capture smaller individual variants. Moreover, a structural gene-gene network based on tissue-specific transcript abundances provides a better understanding of the multi-gene pathway affecting tree growth and lignocellulose biosynthesis. Our study highlights the importance of pathway-based multiple gene associations to uncover the nature of genetic variance for quantitative traits and may drive novel progress in molecular breeding.

  • 215. Du, Shuhui
    et al.
    Wang, Zhaoshan
    Ingvarsson, Pär K
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Wang, Dongsheng
    Wang, Junhui
    Wu, Zhiqiang
    Tembrock, Luke R.
    Zhang, Jianguo
    Multilocus analysis of nucleotide variation and speciation in three closely related Populus (Salicaceae) species2015Ingår i: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 24, nr 19, s. 4994-5005Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Historical tectonism and climate oscillations can isolate and contract the geographical distributions of many plant species, and they are even known to trigger species divergence and ultimately speciation. Here, we estimated the nucleotide variation and speciation in three closely related Populus species, Populus tremuloides, P.tremula and P.davidiana, distributed in North America and Eurasia. We analysed the sequence variation in six single-copy nuclear loci and three chloroplast (cpDNA) fragments in 497 individuals sampled from 33 populations of these three species across their geographic distributions. These three Populus species harboured relatively high levels of nucleotide diversity and showed high levels of nucleotide differentiation. Phylogenetic analysis revealed that P.tremuloides diverged earlier than the other two species. The cpDNA haplotype network result clearly illustrated the dispersal route from North America to eastern Asia and then into Europe. Molecular dating results confirmed that the divergence of these three species coincided with the sundering of the Bering land bridge in the late Miocene and a rapid uplift of the Qinghai-Tibetan Plateau around the Miocene/Pliocene boundary. Vicariance-driven successful allopatric speciation resulting from historical tectonism and climate oscillations most likely played roles inthe formation of the disjunct distributions and divergence of these three Populus species.

  • 216.
    Dubreuil, Carole
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Ji, Yan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Strand, Åsa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Grönlund, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    A quantitative model of the phytochrome-PIF light signalling initiating chloroplast development2017Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikel-id 13884Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The components required for photosynthesis are encoded in two separate genomes, the nuclear and the plastid. To address how synchronization of the two genomes involved can be attained in early light-signalling during chloroplast development we have formulated and experimentally tested a mathematical model simulating light sensing and the following signalling response. The model includes phytochrome B (PhyB), the phytochrome interacting factor 3 (PIF3) and putative regulatory targets of PIF3. Closed expressions of the phyB and PIF3 concentrations after light exposure are derived, which capture the relevant timescales in the response of genes regulated by PIF3. Sequence analysis demonstrated that the promoters of the nuclear genes encoding sigma factors (SIGs) and polymerase-associated proteins (PAPs) required for expression of plastid encoded genes, contain the cis-elements for binding of PIF3. The model suggests a direct link between light inputs via PhyB-PIF3 to the plastid transcription machinery and control over the expression of photosynthesis components both in the nucleus and in the plastids. Using a pluripotent Arabidopsis cell culture in which chloroplasts develop from undifferentiated proplastids following exposure to light, we could experimentally verify that the expression of SIGs and PAPs in response to light follow the calculated expression of a PhyB-PIF3 regulated gene.

  • 217.
    Dubreuil, Carole
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Jin, Xu
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Barajas-López, Juan de Dios
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Hewitt, Timothy C.
    Tanz, Sandra K.
    Dobrenel, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Schröder, Wolfgang P.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Hanson, Johannes
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Pesquet, Edouard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Arrhenius Laboratory, Department of Ecology, Environment, and Plant Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
    Grönlund, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Small, Ian
    Strand, Åsa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Establishment of Photosynthesis through Chloroplast Development Is Controlled by Two Distinct Regulatory Phases2018Ingår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 176, nr 2, s. 1199-1214Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Chloroplasts develop from undifferentiated proplastids present in meristematic tissue. Thus, chloroplast biogenesis is closely connected to leaf development, which restricts our ability to study the process of chloroplast biogenesis per se. As a consequence, we know relatively little about the regulatory mechanisms behind the establishment of the photosynthetic reactions and how the activities of the two genomes involved are coordinated during chloroplast development. We developed a single cell-based experimental system from Arabidopsis (Arabidopsis thaliana) with high temporal resolution allowing for investigations of the transition from proplastids to functional chloroplasts. Using this unique cell line, we could show that the establishment of photosynthesis is dependent on a regulatory mechanism involving two distinct phases. The first phase is triggered by rapid light-induced changes in gene expression and the metabolome. The second phase is dependent on the activation of the chloroplast and generates massive changes in the nuclear gene expression required for the transition to photosynthetically functional chloroplasts. The second phase also is associated with a spatial transition of the chloroplasts from clusters around the nucleus to the final position at the cell cortex. Thus, the establishment of photosynthesis is a two-phase process with a clear checkpoint associated with the second regulatory phase allowing coordination of the activities of the nuclear and plastid genomes.

  • 218.
    Dubreuil, Carole
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå 901 83, Sweden.
    Jin, Xu
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå 901 83, Sweden.
    Grönlund, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Fischer, Urs
    A local auxin gradient regulates root cap self-renewal and size homeostasis2018Ingår i: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 28, nr 16, s. 2581-+Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Organ size homeostasis, compensatory growth to replace lost tissue, requires constant measurement of size and adjustment of growth rates. Morphogen gradients control organ and tissue sizes by regulating stem cell activity, cell differentiation, and removal in animals [1-3]. In plants, control of tissue size is of specific importance in root caps to protect the growing root tip from mechanical damage [4]. New root cap tissue is formed by the columella and lateral root-cap-epidermal stem cells, whose activity is regulated through non-dividing niche-like cells, the quiescent center (QC) [4, 5]. Columella daughter cells in contact with the QC retain the potency to divide, while derivatives oriented toward the mature cap undergo differentiation. The outermost columella layers are sequentially separated from the root body, involving remodeling of cell walls [6]. Factors regulating the balance between cell division, elongation, and separation to keep root cap size constant are currently unknown [4]. Here, we report that stem cell proliferation induced cell separation at the periphery of the root cap, resulting in tissue size homeostasis. An auxin response gradient with a maximum in the QC and a minimum in the detaching layer was established prior to the onset of cell separation. In agreement with a mathematical model, tissue size was positively regulated by the amount of auxin released from the source. Auxin transporters localized non-polarly to plasma membranes of the inner cap, partly isolating separating layers from the auxin source. Together, these results are in support of an auxin gradient measuring and regulating tissue size.

  • 219.
    Edlund, Erik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Novak, Ondrej
    Karady, Michael
    Ljung, Karin
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Contrasting patterns of cytokinins between years in senescing aspen leaves2017Ingår i: Plant, Cell and Environment, ISSN 0140-7791, E-ISSN 1365-3040, Vol. 40, s. 622-634Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cytokinins are plant hormones that typically block or delay leaf senescence. We profiled 34 different cytokinins/cytokinin metabolites (including precursors, conjugates and degradation products) in leaves of a free-growing mature aspen (Populus tremula) before and after the initiation of autumnal senescence over three consecutive years. The levels and profiles of individual cytokinin species, or classes/groups, varied greatly between years, despite the fact that the onset of autumn senescence was at the same time each year, and senescence was not associated with depletion of either active or total cytokinin levels. Levels of aromatic cytokinins (topolins) were low and changed little over the autumn period. Diurnal variations and weather-dependent variations in cytokinin content were relatively limited. We also followed the expression patterns of all aspen genes implicated as having roles in cytokinin metabolism or signaling, but neither the pattern of regulation of any group of genes nor the expression of any particular gene supported the notion that decreased cytokinin signaling could explain the onset of senescence. Based on the results from this tree, we therefore suggest that cytokinin depletion is unlikely to explain the onset of autumn leaf senescence in aspen.

  • 220. Edvardsson, Anna
    et al.
    Shapiguzov, Alexey
    Petersson, Ulrika A
    Schröder, Wolfgang
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi. Umeå Plant Science Centre.
    Vener, Alexander V
    Immunophilin AtFKBP13 Sustains All Peptidyl-Prolyl Isomerase Activity in the Thylakoid Lumen from Arabidopsis thaliana Deficient in AtCYP20-22007Ingår i: Biochemistry, Vol. 46, nr 33, s. 9432-42Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The physiological roles of immunophilins are unclear, but many possess peptidyl-prolyl isomerase (PPIase) activity, and they have been found in all organisms examined to date, implying that they are involved in fundamental, protein-folding processes. The chloroplast thylakoid lumen of the higher plant Arabidopsis thaliana contains up to 16 immunophilins (five cyclophilins and 11 FKBPs), but only two of them, AtCYP20-2 and AtFKBP13, have been found to be active PPIases, indicating that the other immunophilins in this cellular compartment may have lost their putative PPIase activities. To assess this possibility, we characterized two independent Arabidopsis knockout lines lacking AtCYP20-2 in enzymological and quantitative proteomic analyses. The PPIase activity in thylakoid lumen preparations of both mutants was equal to that of corresponding wild-type preparations, and comparative two-dimensional difference gel electrophoresis analyses of the lumenal proteins of the mutants and wild type showed that none of the potential PPIases was more abundant in the AtCYP20-2 deficient plants. Enzymatic analyses established that all PPIase activity in the mutant thylakoid lumen was attributable to AtFKBP13, and oxidative activation of this enzyme compensated for the lack of AtCYP20-2. Accordingly, sequence analyses of the potential catalytic domains of lumenal cyclophilins and FKBPs demonstrated that only AtCYP20-2 and AtFKBP13 possess all of the amino acid residues found to be essential for PPIase activity in earlier studies of human cyclophilin A and FKBP12. Thus, none of the immunophilins in the chloroplast thylakoid lumen of Arabidopsis except AtCYP20-2 and AtFKBP13 appear to possess prolyl isomerase activity toward peptide substrates.

  • 221. EDWARDS, GE
    et al.
    Gardeström, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    ISOLATION OF MITOCHONDRIA FROM LEAVES OF C-3, C-4, AND CRASSULACEAN ACID METABOLISM PLANTS1987Ingår i: Methods in Enzymology, ISSN 0076-6879, E-ISSN 1557-7988, Vol. 148, s. 421-433Artikel i tidskrift (Refereegranskat)
  • 222. Edwards, Kieron D.
    et al.
    Takata, Naoki
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Johansson, Mikael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). RNA Biology and Molecular Physiology, Bielefeld University, Bielefeld, Germany.
    Jurca, Manuela
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Novak, Ondrej
    Henykova, Eva
    Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Liverani, Silvia
    Kozarewa, Iwanka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Strnad, Miroslav
    Millar, Andrew J.
    Ljung, Karin
    Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Eriksson, Maria E.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Circadian clock components control daily growth activities by modulating cytokinin levels and cell division-associated gene expression in Populus trees2018Ingår i: Plant, Cell and Environment, ISSN 0140-7791, E-ISSN 1365-3040, Vol. 41, nr 6, s. 1468-1482Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Trees are carbon dioxide sinks and major producers of terrestrial biomass with distinct seasonal growth patterns. Circadian clocks enable the coordination of physiological and biochemical temporal activities, optimally regulating multiple traits including growth. To dissect the clock's role in growth, we analysed Populus tremula x P. tremuloides trees with impaired clock function due to down-regulation of central clock components. late elongated hypocotyl (lhy-10) trees, in which expression of LHY1 and LHY2 is reduced by RNAi, have a short free-running period and show disrupted temporal regulation of gene expression and reduced growth, producing 30-40% less biomass than wild-type trees. Genes important in growth regulation were expressed with an earlier phase in lhy-10, and CYCLIN D3 expression was misaligned and arrhythmic. Levels of cytokinins were lower in lhy-10 trees, which also showed a change in the time of peak expression of genes associated with cell division and growth. However, auxin levels were not altered in lhy-10 trees, and the size of the lignification zone in the stem showed a relative increase. The reduced growth rate and anatomical features of lhy-10 trees were mainly caused by misregulation of cell division, which may have resulted from impaired clock function.

  • 223.
    Egertsdotter, Ulrika
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Plant physiological and genetical aspects of the somatic embryogenesis process in conifers2019Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 34, nr 5, s. 360-369Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The processes for producing conifer planting stock by somatic embryogenesis (SE) in conifers are described. Implementation of SE presents opportunities and limitations at various stages of the in vitro process. The topic of genetic stability, or somaclonal variation, is a particular concern and reviewed. Following the in vitro processes, several factors affect the successful acclimation, early growth and field performance of SE planting stock. Experiences with other conifer species in the context of commercial production are reviewed. While SE production has historically been a very labor-intensive process, recent advances have been made to automate the various steps. Developments to enable SE for Norway spruce in Sweden are described.

  • 224. Eimert, K
    et al.
    Luo, C
    Dejardin, A
    Villand, P
    Thorbjornsen, T
    Kleczkowski, Leszek A
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Molecular cloning and expression of the large subunit of ADP-glucose pyrophosphorylase from barley (Hordeum vulgare) leaves1997Ingår i: Gene, ISSN 0378-1119, E-ISSN 1879-0038, Vol. 189, nr 1, s. 79-82Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A cDNA clone, blpl14, corresponding to the large subunit of ADP-glucose pyrophosphorylase (AGPase), has been isolated from a cDNA library prepared from leaves of barley (Hordeum vulgare L.). An open reading frame encodes a protein of 503 aa, with a calculated molecular weight of 54 815. The derived aa sequence contains a putative transit peptide sequence, required for targeting to plastids, and has a highly conserved positioning of critical Lys residues that are believed to be involved in effector binding. The derived aa sequence shows 97% identity with the corresponding protein from wheat, but only 36% identity with AGPase from E. coli. The blpl14 gene is expressed predominantly in leaves and to a lesser degree in seed endosperm, but not roots, of barley.

  • 225. Eimert, K
    et al.
    Villand, P
    Kilian, A
    Kleczkowski, Leszek A
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Cloning and characterization of several cDNAs for UDP-glucose pyrophosphorylase from barley (Hordeum vulgare) tissues1996Ingår i: Gene, ISSN 0378-1119, E-ISSN 1879-0038, Vol. 170, nr 2, s. 227-232Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Eleven cDNA clones encoding UDP-glucose pyrophosphorylase (UGPase) have been isolated from cDNA libraries prepared from seed embryo, seed endosperm and leaves of barley (Hordeum vulgare L.). The sequences were identical, with the exception of positioning of the poly(A) tail; at least five clones with different polyadenylation sites were found. For a putative full-length cDNA [1775 nucleotides (nt) plus polyadenylation tail], isolated from an embryo cDNA library, an open reading frame of 1419 nt encodes a protein of 473 amino acids (aa) of 51.6 kDa. An alignment of the derived aa sequence with other UGPases has revealed high identity to UGPases from eukaryotic tissues, but not from bacteria. Within the aa sequence, no homology was found to a UDP-glucose-binding motif that has been postulated for a family of glucosyl transferases. The derived aa sequence of UGPase contains three putative N-glycosylation sites and has a highly conserved positioning of five Lys residues, previously shown to be critical for catalysis and substrate binding of potato tuber UGPase. A possible role for N-glycosylation in the intracellular targeting of UGPase is discussed.

  • 226.
    Ekström, Jens-Ola
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Habayeb, Mazen S
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Srivastava, Vaibhav
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Kieselbach, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wingsle, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hultmark, Dan
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Drosophila Nora virus capsid proteins differ from those of other picorna-like viruses2011Ingår i: Virus Research, ISSN 0168-1702, E-ISSN 1872-7492, Vol. 160, nr 1-2, s. 51-58Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The recently discovered Nora virus from Drosophila melanogaster is a single-stranded RNA virus. Its published genomic sequence encodes a typical picorna-like cassette of replicative enzymes, but no capsid proteins similar to those in other picorna-like viruses. We have now done additional sequencing at the termini of the viral genome, extending it by 455 nucleotides at the 5' end, but no more coding sequence was found. The completeness of the final 12,333-nucleotide sequence was verified by the production of infectious virus from the cloned genome. To identify the capsid proteins, we purified Nora virus particles and analyzed their proteins by mass spectrometry. Our results show that the capsid is built from three major proteins, VP4A, B and C, encoded in the fourth open reading frame of the viral genome. The viral particles also contain traces of a protein from the third open reading frame, VP3. VP4A and B are not closely related to other picorna-like virus capsid proteins in sequence, but may form similar jelly roll folds. VP4C differs from the others and is predicted to have an essentially α-helical conformation. In a related virus, identified from EST database sequences from Nasonia parasitoid wasps, VP4C is encoded in a separate open reading frame, separated from VP4A and B by a frame-shift. This opens a possibility that VP4C is produced in non-equimolar quantities. Altogether, our results suggest that the Nora virus capsid has a different protein organization compared to the order Picornavirales.

  • 227.
    Eliasson, Mattias
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Rännar, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Madsen, Rasmus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Donten, Magdalena A
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Marsden-Edwards, Emma
    Waters Corp, Milford, MA 01757 USA .
    Moritz, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Shockcor, John P
    Waters Corp, Milford, MA 01757 USA .
    Johansson, Erik
    Umetr AB, Umeå, Sweden.
    Trygg, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Strategy for optimizing LC-MS data processing in Metabolomics: A design of experiments approach2012Ingår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 84, nr 15, s. 6869-6876Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A strategy for optimizing LC-MS metabolomics data processing is proposed. We applied this strategy on the XCMS open source package written in R on both human and plant biology data. The strategy is a sequential design of experiments (DoE) based on a dilution series from a pooled sample and a measure of correlation between diluted concentrations and integrated peak areas. The reliability index metric, used to define peak quality, simultaneously favors reliable peaks and disfavors unreliable peaks using a weighted ratio between peaks with high and low response linearity. DoE optimization resulted in the case studies in more than 57% improvement in the reliability index compared to the use of the default settings. The proposed strategy can be applied to any other data processing software involving parameters to be tuned, e.g., MZmine 2. It can also be fully automated and used as a module in a complete metabolomics data processing pipeline.

  • 228. Endo, Satoshi
    et al.
    Pesquet, Edouard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Tashiro, Gen
    Kuriyama, Hideo
    Goffner, Deborah
    Fukuda, Hiroo
    Demura, Taku
    Transient transformation and RNA silencing in Zinnia tracheary element differentiating cell cultures.2008Ingår i: The Plant journal : for cell and molecular biology, ISSN 1365-313X, Vol. 53, nr 5, s. 864-75Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Zinnia elegans cell culture system is a robust and physiologically relevant in vitro system for the study of xylem formation. Freshly isolated mesophyll cells of Zinnia can be hormonally induced to semisynchronously transdifferentiate into tracheary elements (TEs). Although the system has proven to be valuable, its utility is diminished by the lack of an efficient transformation protocol. We herein present a novel method to introduce DNA/RNA efficiently into Zinnia cells by electroporation-based transient transformation. Using reporter gene plasmids, we optimized the system for efficiency of transformation and ability for the transformed cells to transdifferentiate into TEs. Optimal conditions included a partial digestion of the cell walls by pectolyase, a low voltage and high capacitance electrical pulse and an optimal medium to maintain cell viability during transformation. Beyond the simple expression of a reporter protein in Zinnia cells, we extended our protocol to subcellular protein targeting, simultaneous co-expression of several reporter proteins and promoter-activity monitoring during TE differentiation. Most importantly, we tested the system for double-stranded RNA (dsRNA)-induced RNA silencing. By introducing in vitro-synthesized dsRNAs, we were able to phenocopy the Arabidopsis cellulose synthase (CesA) mutants that had defects in secondary cell-wall synthesis. Suppressing the expression ofZinnia CesA homologues resulted in an increase of abnormal TEs with aberrant secondary walls. Our electroporation-based transient transformation protocol provides the suite of tools long required for functional analysis and developmental studies at single cell levels.

  • 229. Engelhorn, Julia
    et al.
    Blanvillain, Robert
    Kroner, Christian
    Parrinello, Hugues
    Rohmer, Marine
    Pose, David
    Ott, Felix
    Schmid, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Department of Molecular Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany.
    Carles, Cristel C.
    Dynamics of H3K4me3 Chromatin Marks Prevails over H3K27me3 for Gene Regulation during Flower Morphogenesis in Arabidopsis thaliana2017Ingår i: Epigenomes, ISSN 2075-4655, Vol. 1, nr 2, artikel-id 8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plant life-long organogenesis involves sequential, time and tissue specific expression of developmental genes. This requires activities of Polycomb Group (PcG) and trithorax Group complexes (trxG), respectively responsible for repressive Histone 3 trimethylation at lysine 27 (H3K27me3) and activation-related Histone 3 trimethylation at lysine 4 (H3K4me3). However, the genome-wide dynamics in histone modifications that occur during developmental processes have remained elusive. Here, we report the distributions of H3K27me3 and H3K4me3 along with expression changes, in a developmental series including Arabidopsis thaliana leaf and three stages of flower development. We found that chromatin mark levels are highly dynamic over the time series on nearly half of all Arabidopsis genes. Moreover, during early flower morphogenesis, changes in H3K4me3 prevail over changes in H3K27me3 and quantitatively correlate with expression changes, while H3K27me3 changes occur later. Notably, we found that H3K4me3 increase during the early activation of PcG target genes while H3K27me3 level remain relatively constant at the locus. Our results reveal that H3K4me3 predicts changes in gene expression better than H3K27me3, unveil unexpected chromatin mechanisms at gene activation and underline the relevance of tissue-specific temporal epigenomics.

  • 230.
    Engelken, Johannes
    et al.
    Department of Biology, University of Konstanz, Constance, Germany .
    Funk, Christiane
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Adamska, Iwona
    Department of Biology, University of Konstanz, Constance, Germany.
    The extended light-harvesting complex (LHC) protein superfamily: Classification and evolutionary dynamics2012Ingår i: Functinal genomics and evolution of photosynthetic systems / [ed] Robert Burnap, Wim Vermaas, Dordrecht, Netherlands: Springer Netherlands, 2012, s. 265-284Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    The evolution of algae and land plants and their photosynthetic machineries is closely connected to the development of the extended light-harvesting complex (LHC) protein superfamily. Therefore, it is not surprising that the molecular organization, function and origin of the LHC proteins have been a central topic in plant biology and photosynthesis research during the last few years. The extended LHC protein superfamily in cyanobacteria and photosynthetic eukaryotes comprises different families, such as the LHC proteins and three groups of light stress-induced proteins, consisting of the LHC-like proteins, the red lineage CAB-like proteins and the photosystem II subunit S. This chapter provides a description of the different extended LHC superfamily members and shows their taxonomic distribution. Furthermore, an overview of scenarios suggested for the evolution of the extended LHC protein superfamily is provided and arised implications for light harvesting, stress responses and photoprotection are discussed.

  • 231. Ensminger, Ingo
    et al.
    Sveshnikov, Dmitry
    Campbell, Douglas A.
    Funk, Christiane
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Lloyd, Jon
    Shibistova, Olga
    Öquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Intermittent low temperatures constrain spring recovery of photosynthesis in boreal Scots pine forests2004Ingår i: Global Change Biology, ISSN 1354-1013, Vol. 10, nr 6, s. 995-1008Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    During winter and early spring, evergreen boreal conifers are severely stressed because light energy cannot be used when photosynthesis is pre-empted by low ambient temperatures. To study photosynthetic performance dynamics in a severe boreal climate, seasonal changes in photosynthetic pigments, chloroplast proteins and photochemical efficiency were studied in a Scots pine forest near Zotino, Central Siberia. In winter, downregulation of photosynthesis involved loss of chlorophylls, a twofold increase in xanthophyll cycle pigments and sustained high levels of the light stress-induced zeaxanthin pigment. The highest levels of xanthophylls and zeaxanthin did not occur during the coldest winter period, but rather in April when light was increasing, indicating an increased capacity for thermal dissipation of excitation energy at that time. Concomitantly, in early spring the D1 protein of the photosystem II (PSII) reaction centre and the light-harvesting complex of PSII dropped to their lowest annual levels. In April and May, recovery of PSII activity, chloroplast protein synthesis and rearrangements of pigments were observed as air temperatures increased above 0°C. Nevertheless, severe intermittent low-temperature episodes during this period not only halted but actually reversed the physiological recovery. During these spring low-temperature episodes, protective processes involved a complementary function of the PsbS and early light-induced protein thylakoid proteins. Full recovery of photosynthesis did not occur until the end of May. Our results show that even after winter cold hardening, photosynthetic activity in evergreens responds opportunistically to environmental change throughout the cold season. Therefore, climate change effects potentially improve the sink capacity of boreal forests for atmospheric carbon. However, earlier photosynthesis in spring in response to warmer temperatures is strongly constrained by environmental variation, counteracting the positive effects of an early recovery process.

  • 232. Eriksson, M
    et al.
    Villand, P
    Gardeström, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Induction and regulation of expression of a low-CO2-induced mitochondrial carbonic anhydrase in Chlamydomonas reinhardtii1998Ingår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 116, nr 2, s. 637-641Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The time course of and the influence of light intensity and light quality on the induction of a mitochondrial carbonic anhydrase (CA) in the unicellular green alga Chlamydomonas reinhardtii was characterized using western and northern blots. This CA was expressed only under low-CO2 conditions (ambient air). In asynchronously grown cells, the mRNA was detected 15 min after transfer from air containing 5% CO2 to ambient air, and the 21-kD polypeptide was detected on western blots after 1 h. When transferred back to air containing 5% CO2, the mRNA disappeared within 1 h and the polypeptide was degraded within 3 d. Photosynthesis was required for the induction in asynchronous cultures. The induction increased with light up to 500 mu mol m(-2) s(-1), where saturation occurred. In cells grown synchronously, however, expression of the mitochondrial CA was also detected in darkness. Under such conditions the expression followed a circadian rhythm, with mRNA appearing in the dark 30 min before the light was turned on. Algae left in darkness continued this rhythm for several days.

  • 233.
    Eriksson, Maria E.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hoffman, Daniel
    Kaduk, Mateusz
    Mauriat, Melanie
    Moritz, Thomas
    Transgenic hybrid aspen trees with increased gibberellin (GA) concentrations suggest that GA acts in parallel with FLOWERING LOCUS T2 to control shoot elongation2015Ingår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 205, nr 3, s. 1288-1295Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bioactive gibberellins (GAs) have been implicated in short day (SD)-induced growth cessation in Populus, because exogenous applications of bioactive GAs to hybrid aspens (Populus tremulaxtremuloides) under SD conditions delay growth cessation. However, this effect diminishes with time, suggesting that plants may cease growth following exposure to SDs due to a reduction in sensitivity to GAs.

    In order to validate and further explore the role of GAs in growth cessation, we perturbed GA biosynthesis or signalling in hybrid aspen plants by overexpressing AtGA20ox1, AtGA2ox2 and PttGID1.3 (encoding GA biosynthesis enzymes and a GA receptor).

    We found trees with elevated concentrations of bioactive GA, due to overexpression of AtGA20ox1, continued to grow in SD conditions and were insensitive to the level of FLOWERING LOCUS T2 (FT2) expression. As transgenic plants overexpressing the PttGID1.3 GA receptor responded in a wild-type (WT) manner to SD conditions, this insensitivity did not result from limited receptor availability.

    As high concentrations of bioactive GA during SD conditions were sufficient to sustain shoot elongation growth in hybrid aspen trees, independent of FT2 expression levels, we conclude elongation growth in trees is regulated by both GA- and long day-responsive pathways, similar to the regulation of flowering in Arabidopsis thaliana.

  • 234.
    Eriksson, Maria E.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Webb, Alex A. R.
    Plant cell responses to cold are all about timing2011Ingår i: Current opinion in plant biology, ISSN 1369-5266, E-ISSN 1879-0356, Vol. 14, nr 6, s. 731-737Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Changes in temperature present the cells of plants with particular challenges. Fortunately, many changes in temperature can be anticipated due to the rhythms of day/night and the seasons. To anticipate changes in the environment most organisms have a circadian clock to optimize daily and seasonal timing of gene expression, metabolism, physiology and cell biology. Circadian clocks comprised positive and negative feedback loops which ensure an internal period of approximately 24 hours. We describe the role of the circadian clock in modulating cellular cold signalling networks to prepare the cell for the onset of winter.

  • 235. Eriksson, Mats
    et al.
    Gardeström, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    ISOLATION, PURIFICATION, AND CHARACTERIZATION OF MITOCHONDRIA FROM CHLAMYDOMONAS-REINHARDTII1995Ingår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 107, nr 2, s. 479-483Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mitochondria were isolated from autotrophically grown Chlamydomonas reinhardtii cell-wall-less mutant CW 92. The cells were broken by vortexing with glass beads, and the mitochondria were collected by differential centrifugation and purified on a Percoll gradient. The isolated mitochondria oxidized malate, pyruvate, succinate, NADH, and a-ketoglutarate. Respiratory control was obtained with malate (2.0) and pyruvate (2.2) but not with the other substrates. From experiments with KCN and salicylhydroxamic acid, it was estimated that the capacity of the cytochrome pathway was at least 100 nmol O-2 mg(-1) protein min(-1) and the capacity of the alternative oxidase was at least 50 nmol O-2 mg(-1) protein min(-1). A low sensitivity to oligomycin indicates some difference in the properties of the mitochondrial ATPase from Chlamydomonas as compared to higher plants.

  • 236.
    Eriksson, Mats
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Moseley, Jeffrey L
    Tottey, Stephen
    Del Campo, Jose A
    Quinn, Jeanette
    Kim, Youngbae
    Merchant, Sabeeha
    Genetic dissection of nutritional copper signaling in chlamydomonas distinguishes regulatory and target genes2004Ingår i: Genetics, ISSN 0016-6731, E-ISSN 1943-2631, Vol. 168, nr 2, s. 795-807Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A genetic screen for Chlamydomonas reinhardtii mutants with copper-dependent growth or nonphotosynthetic phenotypes revealed three loci, COPPER RESPONSE REGULATOR 1 (CRR1), COPPER RESPONSE DEFECT 1 (CRD1), and COPPER RESPONSE DEFECT 2 (CRD2), distinguished as regulatory or target genes on the basis of phenotype. CRR1 was shown previously to be required for transcriptional activation of target genes like CYC6, CPX1, and CRD1, encoding, respectively, cytochrome c(6) (which is a heme-containing substitute for copper-containing plastocyanin), coproporphyrinogen III oxidase, and Mg-protoporphyrin IX monomethylester cyclase. We show here that CRR1 is required also for normal accumulation of copper proteins like plastocyanin and ferroxidase in copper-replete medium and for apoplastocyanin degradation in copper-deficient medium, indicating that a single pathway controls nutritional copper homeostasis at multiple levels. CRR1 is linked to the SUPPRESSOR OF PCY1-AC208 13 (SOP13) locus, which corresponds to a gain-of-function mutation resulting in copper-independent expression of CYC6. CRR1 is required also for hypoxic growth, pointing to a physiologically meaningful regulatory connection between copper deficiency and hypoxia. The growth phenotype of crr1 strains results primarily from secondary iron deficiency owing to reduced ferroxidase abundance, suggesting a role for CRR1 in copper distribution to a multicopper ferroxidase involved in iron assimilation. Mutations at the CRD2 locus also result in copper-conditional iron deficiency, which is consistent with a function for CRD2 in a pathway for copper delivery to the ferroxidase. Taken together, the observations argue for a specialized copper-deficiency adaptation for iron uptake in Chlamydomonas.

  • 237.
    Eriksson, Sylvia K
    et al.
    Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, 106 91 Stockholm, Sweden.
    Kutzer, Michael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Procek, Jan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Gröbner, Gerhard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    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 protein2011Ingår i: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 23, nr 6, s. 2391-2404Artikel i tidskrift (Refereegranskat)
    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.

  • 238.
    Escamez, Sacha
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Xylem cells cooperate in the control of lignification and cell death during plant vascular development2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The evolutionary success of land plants was fostered by the acquisition of the xylem vascular tissue which conducts water and minerals upwards from the roots. The xylem tissue of flowering plants is composed of three main types of cells: the sap-conducting tracheary elements (TE), the fibres which provide mechanical support and the parenchyma cells which provide metabolic support to the tissue. Both the TEs and the fibres deposit thick polysaccharidic secondary cell walls (SCWs), reinforced by a rigid phenolic polymer called lignin. The cell walls of TEs form efficient water conducting hollow tubes after the TEs have undergone programmed cell death (PCD) and complete protoplast degradation as a part of their differentiation. The work presented in this thesis studied the regulation of TE PCD by characterizing the function of the candidate PCD regulator METACASPASE 9 (MC9) in Arabidopsis thaliana xylogenic cell suspensions. These cell suspensions can be externally induced to differentiate into a mix of TEs and parenchymatic non-TE cells, thus representing an ideal system to study the cellular processes of TE PCD. In this system, TEs with reduced expression of MC9 were shown to have increased levels of autophagy and to trigger the ectopic death of the non-TE cells. The viability of the non-TE cells could be restored by down-regulating autophagy specifically in the TEs with reduced MC9 expression. Therefore, this work showed that MC9 must tightly regulate the level of autophagy during TE PCD in order to prevent the TEs from becoming harmful to the non-TEs. Hence, this work demonstrated the existence of a cellular cooperation between the TEs and the surrounding parenchymatic cells during TE PCD. The potential cooperation between the TEs and the neighbouring parenchyma during the biosynthesis of lignin was also investigated. The cupin domain containing protein PIRIN2 was found to regulate TE lignification in a non-cell autonomous manner in Arabidopsis thaliana. More precisely, PIRIN2 was shown to function as an antagonist of positive transcriptional regulators of lignin biosynthetic genes in xylem parenchyma cells. Part of the transcriptional regulation by PIRIN2 involves chromatin modifications, which represent a new type of regulation of lignin biosynthesis. Because xylem constitutes the wood in tree species, this newly discovered regulation of non-cell autonomous lignification represents a potential target to modify lignin biosynthesis in order to overcome the recalcitrance of the woody biomass for the production of biofuels.

  • 239.
    Escamez, Sacha
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    André, Domenique
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Sztojka, Bernadette
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Bollhöner, Benjamin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hall, Hardy
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Berthet, Béatrice
    Voss, Ute
    Lers, Amnon
    Maizel, Alexis
    Andersson, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Bennett, Malcolm
    Tuominen, Hannele
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Cell Death in Cells Overlying Lateral Root Primordia Facilitates Organ Growth in Arabidopsis2020Ingår i: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 30, nr 3, s. 455-464Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plant organ growth is widely accepted to be determined by cell division and cell expansion, but, unlike that in animals, the contribution of cell elimination has rarely been recognized. We investigated this paradigm during Arabidopsis lateral root formation, when the lateral root primordia (LRP) must traverse three overlying cell layers within the parent root. A subset of LRP-overlying cells displayed the induction of marker genes for cell types undergoing developmental cell death, and their cell death was detected by electron, confocal, and light sheet microscopy techniques. LRP growth was delayed in cell-deathdeficient mutants lacking the positive cell death regulator ORESARA1/ANAC092 (ORE1). LRP growth was restored in ore1-2 knockout plants by genetically inducing cell elimination in cells overlying the LRP or by physically killing LRP-overlying cells by ablation with optical tweezers. Our results support that, in addition to previously discovered mechanisms, cell elimination contributes to regulating lateral root emergence.

  • 240.
    Escamez, Sacha
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Latha Gandla, Madhavi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Derba-Maceluch, Marta
    Lundqvist, Sven-Olof
    Mellerowicz, Ewa J.
    Jönsson, Leif J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Tuominen, Hannele
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    A collection of genetically engineered Populus trees reveals wood biomass traits that predict glucose yield from enzymatic hydrolysis2017Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikel-id 15798Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wood represents a promising source of sugars to produce bio-based renewables, including biofuels. However, breaking down lignocellulose requires costly pretreatments because lignocellulose is recalcitrant to enzymatic saccharification. Increasing saccharification potential would greatly contribute to make wood a competitive alternative to petroleum, but this requires improving wood properties. To identify wood biomass traits associated with saccharification, we analyzed a total of 65 traits related to wood chemistry, anatomy and structure, biomass production and saccharification in 40 genetically engineered Populus tree lines. These lines exhibited broad variation in quantitative traits, allowing for multivariate analyses and mathematical modeling. Modeling revealed that seven wood biomass traits associated in a predictive manner with saccharification of glucose after pretreatment. Four of these seven traits were also negatively associated with biomass production, suggesting a trade-off between saccharification potential and total biomass, which has previously been observed to offset the overall sugar yield from whole trees. We therefore estimated the "total-wood glucose yield" (TWG) from whole trees and found 22 biomass traits predictive of TWG after pretreatment. Both saccharification and TWG were associated with low abundant, often overlooked matrix polysaccharides such as arabinose and rhamnose which possibly represent new markers for improved Populus feedstocks.

  • 241.
    Escamez, Sacha
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Stael, Simon
    Vainonen, Julia P.
    Willems, Patrick
    Jin, Huiting
    Kimura, Sachie
    Van Breusegem, Frank
    Gevaert, Kris
    Wrzaczek, Michael
    Tuominen, Hannele
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Extracellular peptide Kratos restricts cell death during vascular development and stress in Arabidopsis2019Ingår i: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431, Vol. 70, nr 7, s. 2199-2210Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    During plant vascular development, xylem tracheary elements (TEs) form water-conducting, empty pipes by genetically regulated cell death. Cell death is prevented from spreading to non-TEs by unidentified intercellular mechanisms, downstream of METACASPASE9 (MC9)-mediated regulation of autophagy in TEs. Here, we identified differentially abundant extracellular peptides in vascular-differentiating wild-type and MC9-down-regulated Arabidopsis cell suspensions. A peptide named Kratos rescued the abnormally high ectopic non-TE death resulting from either MC9 knockout or TE-specific overexpression of the ATG5 autophagy protein during experimentally induced vascular differentiation in Arabidopsis cotyledons. Kratos also reduced cell death following mechanical damage and extracellular ROS production in Arabidopsis leaves. Stress-induced but not vascular non-TE cell death was enhanced by another identified peptide, named Bia. Bia is therefore reminiscent of several known plant cell death-inducing peptides acting as damage-associated molecular patterns. In contrast, Kratos plays a novel extracellular cell survival role in the context of development and during stress response.

  • 242.
    Escamez, Sacha
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Tuominen, Hannele
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Contribution of cellular autolysis to tissular functions during plant development2017Ingår i: Current opinion in plant biology, ISSN 1369-5266, E-ISSN 1879-0356, Vol. 35, s. 124-130Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Plant development requires specific cells to be eliminated in a predictable and genetically regulated manner referred to as programmed cell death (PCD). However, the target cells do not merely die but they also undergo autolysis to degrade their cellular corpses. Recent progress in understanding developmental cell elimination suggests that distinct proteins execute PCD sensu stricto and autolysis. In addition, cell death alone and cell dismantlement can fulfill different functions. Hence, it appears biologically meaningful to distinguish between the modules of PCD and autolysis during plant development.

  • 243.
    Fahlén, Jessica
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Statistiska institutionen.
    Landfors, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Freyhult, Eva
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Klinisk bakteriologi. Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS).
    Bylesjö, Max
    Trygg, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Hvidsten, Torgeir
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Rydén, Patrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Bioinformatics strategies for cDNA-microarray data processing2009Ingår i: Batch effects and noise in microarray experiments: sources and solutions / [ed] Scherer, Andreas, Wiley and Sons , 2009, 1, , s. 272s. 61-74Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    

    Pre-processing plays a vital role in cDNA-microarray data analysis. Without proper pre-processing it is likely that the biological conclusions will be misleading. However, there are many alternatives and in order to choose a proper pre-processing procedure it is necessary to understand the effect of different methods. This chapter discusses several pre-processing steps, including image analysis, background correction, normalization, and filtering. Spike-in data are used to illustrate how different procedures affect the analytical ability to detect differentially expressed genes and estimate their regulation. The result shows that pre-processing has a major impact on both the experiment’s sensitivity andits bias. However, general recommendations are hard to give, since pre-processing consists of several actions that are highly dependent on each other. Furthermore, it is likely that pre-processing have a major impact on downstream analysis, such as clustering and classification, and pre-processing methods should be developed and evaluated with this in mind.

  • 244. FALK, S
    et al.
    LEVERENZ, JW
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Oquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    CHANGES IN PHOTOSYSTEM-II FLUORESCENCE IN CHLAMYDOMONAS-REINHARDTII EXPOSED TO INCREASING LEVELS OF IRRADIANCE IN RELATIONSHIP TO THE PHOTOSYNTHETIC RESPONSE TO LIGHT1992Ingår i: Photosynthesis Research, ISSN 0166-8595, E-ISSN 1573-5079, Vol. 31, nr 1, s. 31-40Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of a 60 min exposure to photosynthetic photon flux densities ranging from 300 to 2200-mu-mol m-2 s-1 on the photosynthetic light response curve and on PS II heterogeneity as reflected in chlorophyll a fluorescence were investigated using the unicellular green alga Chlamydomonas reinhardtii. It was established that exposure to high light acts at three different regulatory or inhibitory levels; 1) regulation occurs from 300 to 780-mu-mol m-2 s-1 where total amount of PS II centers and the shape of the light response curve is not significantly changed, 2) a first photoinhibitory range above 780 up to 1600-mu-mol m-2 s-1 where a progressive inhibition of the quantum yield and the rate of bending (convexity) of the light response curve can be related to the loss of Q(B)-reducing centers and 3) a second photoinhibitory range above 1600-mu-mol m-2 s-1 where the rate of light saturated photosynthesis also decreases and convexity reaches zero. This was related to a particularly large decrease in PS II(alpha) centers and a large increase in spill-over in energy to PS I.

  • 245. FALK, S
    et al.
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    RECOVERY OF PHOTOSYNTHESIS AND PHOTOSYSTEM-II FLUORESCENCE IN CHLAMYDOMONAS-REINHARDTII AFTER EXPOSURE TO 3 LEVELS OF HIGH LIGHT1992Ingår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 85, nr 1, s. 61-68Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recovery from 60 min of photoinhibitory treatment at photosynthetic photon flux densities of 500, 1400 and 2200-mu-mol m-2 s-1 was followed in cells of the green alga Chlamydomonas reinhardtii grown at 125-mu-mol m-2 s-1. These light treatments re resent photoregulation, moderate photoinhibition and strong photoinhibition, respectively. Treatment in photoregulatory light resulted in an increased maximal rate of oxygen evolution (P(max)) and an increased quantum yield (PHI), but a 15% decrease in F(V)/F(M). Treatment at moderately photoinhibitory light resulted in a 30% decrease in F(V)/F(M) and an approximately equal decrease in PHI. Recovery in dim light restored F(V)/F(M) within 15 and 45 min after high light treatment at 500 and 1 400-mu-mol m-2 s-1 respectively. Convexity (THETA), a measure of the extent of co-limitation between PS II turnover and whole-chain electron transport, and PHI approached, but did not reach the control level during recovery after exposure to 1 400-mu-mol m 2 s-1, whereas P(max) increased above the control. Treatment at 2200-mu-mol m-2 s-1 resulted in a strong reduction of the modeled parameters PHI, THETA and P(max). Subsequent recovery was initially rapid but the rate decreased, and a complete recovery was not reached within 120 min. Based on the results, it is hypothesized that exposure to high light results in two phenomena. The first, expressed at all three light intensities, involves redistribution within the different aspects of PS II heterogeneity rather than a photoinhibitory destruction of PS II reaction centers. The second, most strongly expressed at 2200-mu-mol m-2 s-1, is a physical damage to PS II shown as an almost total loss of PS II(alpha) and PS II Q(B)-reducing centers. Thus recovery displayed two phases, the first was rapid and the only visible phase in algae exposed to 500 and 1 400-mu-mol m-2 s-1. The second phase was slow and visible only in the later part of recovery in cells exposed to 2 200-mu-mol m-2 s-1.

  • 246. FALK, S
    et al.
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Oquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    TEMPERATURE-DEPENDENT PHOTOINHIBITION AND RECOVERY OF PHOTOSYNTHESIS IN THE GREEN-ALGA CHLAMYDOMONAS-REINHARDTII ACCLIMATED TO 12 AND 27-DEGREES-C1990Ingår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 78, nr 2, s. 173-180Artikel i tidskrift (Refereegranskat)
  • 247. Fallath, Thorya
    et al.
    Kidd, Brendan N.
    Stiller, Jiri
    Davoine, Celine
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Björklund, Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Manners, John M.
    Kazan, Kemal
    Schenk, Peer M.
    MEDIATOR18 and MEDIATOR20 confer susceptibility to Fusarium oxysporum in Arabidopsis thaliana2017Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, nr 4, artikel-id e0176022Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The conserved protein complex known as Mediator conveys transcriptional signals by acting as an intermediary between transcription factors and RNA polymerase II. As a result, Mediator subunits play multiple roles in regulating developmental as well as abiotic and biotic stress pathways. In this report we identify the head domain subunits MEDIATOR18 and MEDIATOR20 as important susceptibility factors for Fusarium oxysporum infection in Arabidopsis thaliana. Mutants of MED18 and MED20 display down-regulation of genes associated with jasmonate signaling and biosynthesis while up-regulation of salicylic acid associated pathogenesis related genes and reactive oxygen producing and scavenging genes. We propose that MED18 and MED20 form a sub-domain within Mediator that controls the balance of salicylic acid and jasmonate associated defense pathways.

  • 248. Fei, Xiaowen
    et al.
    Eriksson, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Li, Yajun
    Deng, Xiaodong
    A novel negative Fe-deficiency-responsive element and a TGGCA-type-like FeRE control the expression of FTR1 in Chlamydomonas reinhardtii.2010Ingår i: Journal of Biomedicine and Biotechnology, ISSN 1110-7243, E-ISSN 1110-7251, Vol. 2010, s. 790247-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have reported three Fe-deficiency-responsive elements (FEREs), FOX1, ATX1, and FEA1, all of which are positive regulatory elements in response to iron deficiency in Chlamydomonas reinhardtii. Here we describe FTR1, another iron regulated gene and mutational analysis of its promoter. Our results reveal that the FeREs of FTR1 distinguish itself from other iron response elements by containing both negative and positive regulatory regions. In FTR1, the -291/-236 region from the transcriptional start site is necessary and sufficient for Fe-deficiency-inducible expression. This region contains two positive FeREs with a TGGCA-like core sequence: the FtrFeRE1 (ATGCAGGCT) at -287/-279 and the FtrFeRE2 (AAGCGATTGCCAGAGCGC) at -253/-236. Furthermore, we identified a novel FERE, FtrFeRE3 (AGTAACTGTTAAGCC) localized at -319/-292, which negatively influences the expression of FTR1.

  • 249.
    Fei, Xiaowen
    et al.
    Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, Haikou 571101, China.
    Eriksson, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Yang, Jinghao
    Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, Haikou 571101, China.
    Deng, Xiaodong
    Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, Haikou 571101, China.
    An Fe deficiency responsive element with a core sequence of TGGCA regulates the expression of FEA1 in Chlamydomonas reinharditii2009Ingår i: Journal of biochemistry, ISSN 1756-2651, Vol. 146, nr 2, s. 157-166Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Iron is essential to the unicellular green alga Chlamydomonas, but the molecular mechanism for response to iron deficiency remains largely unknown. In previous studies, we have identified FOX1 and ATX1 FEREs (Fe deficiency-responsive elements) as important regulation components of iron response in this organism. Here we present another iron regulated gene FEA1, which promoter was analysed by using a 5'-and 3'-end deletion and a scanning mutagenesis assay. The results reveal that the co-existence of -273/-188 and -118/-49 regions from transcriptional start site of FEA1 were sufficient and necessary for Fe deficiency-induced expression. Further deletion analysis indicates both -273/-253 and -103/-85 regions are essential for inducible expression. The scanning mutagenesis analysis of these regions identifies two cis-acting elements: the FeaFeRE1 at -273/-259 (CTGCGGTGGCAAAGT) and FeaFeRE2 at -106/-85 (CCGCCGCNNNTGGCACCAGCCT). Sequence comparison of FeaFeRE1 and FeaFeRE2 reveals a core sequence of TGGCA, which had been found in our previously reported Fe-deficiency-inducible gene ATX1. Moreover, we show that the promoter region of several genes, including FRE1, IRT1, ISCA, ZRT1, ZRT5, NRAMP2 and COPT1, also contains this core sequence, suggesting that at least two classes FeRE elements exist in Clamydomonas, one in FEA1 and ATX1 and others the second in FOX1, FEA2, MTP4, NRAMP3 and RBOL1.

  • 250. Felten, Judith
    et al.
    Vahala, Jorma
    Love, Jonathan
    Gorzsás, András
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ruggeberg, Markus
    Delhomme, Nicolas
    Lesniewska, Joanna
    Kangasjarvi, Jaakko
    Hvidsten, Torgeir R.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences,Ås, Norway.
    Mellerowicz, Ewa J.
    Sundberg, Bjorn
    Ethylene signaling induces gelatinous layers with typical features of tension wood in hybrid aspen2018Ingår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 218, nr 3, s. 999-1014Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The phytohormone ethylene impacts secondary stem growth in plants by stimulating cambial activity, xylem development and fiber over vessel formation. We report the effect of ethylene on secondary cell wall formation and the molecular connection between ethylene signaling and wood formation. We applied exogenous ethylene or its precursor 1-aminocyclopropane-1-carboxylic acid (ACC) to wild-type and ethylene-insensitive hybrid aspen trees (Populus tremulaxtremuloides) and studied secondary cell wall anatomy, chemistry and ultrastructure. We furthermore analyzed the transcriptome (RNA Seq) after ACC application to wild-type and ethylene-insensitive trees. We demonstrate that ACC and ethylene induce gelatinous layers (G-layers) and alter the fiber cell wall cellulose microfibril angle. G-layers are tertiary wall layers rich in cellulose, typically found in tension wood of aspen trees. A vast majority of transcripts affected by ACC are downstream of ethylene perception and include a large number of transcription factors (TFs). Motif-analyses reveal potential connections between ethylene TFs (Ethylene Response Factors (ERFs), ETHYLENE INSENSITIVE 3/ETHYLENE INSENSITIVE3-LIKE1 (EIN3/EIL1)) and wood formation. G-layer formation upon ethylene application suggests that the increase in ethylene biosynthesis observed during tension wood formation is important for its formation. Ethylene-regulated TFs of the ERF and EIN3/EIL1 type could transmit the ethylene signal.

2345678 201 - 250 av 1096
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf