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  • 301.
    Grebe, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Cell polarity: lateral perspectives2010Ingår i: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 20, nr 10, s. R446-R448Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The outer and inner (lateral) plasma membranes of the outermost cell layer in plants provide selective barriers to the environment. Recent studies provide perspectives on how asymmetric protein localization is established at lateral membranes.

  • 302.
    Grebe, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Out of the shade and into the light2011Ingår i: Nature Cell Biology, ISSN 1465-7392, E-ISSN 1476-4679, Vol. 13, nr 4, s. 347-349Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plants reach for the sun by avoiding the shade and by directly growing towards the light. Two studies now suggest that the polar relocation of PIN3, a transporter directing the flow of the plant hormone auxin, drives both growth processes. PIN3 repolarization occurs downstream of shade perception through phytochrome photoreceptors, whereas blue light perceived by phototropin initiates polar recycling of PIN3 and growth towards the light.

  • 303.
    Grebe, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Plant biology: Unveiling the Casparian strip.2011Ingår i: Nature, ISSN 1476-4687, Vol. 473, nr 7347, s. 294-5Artikel i tidskrift (Refereegranskat)
  • 304. Grebe, Steffen
    et al.
    Trotta, Andrea
    Bajwa, Azfar A.
    Suorsa, Marjaana
    Gollan, Peter J.
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Tikkanen, Mikko
    Aro, Eva-Mari
    The unique photosynthetic apparatus of Pinaceae: analysis of photosynthetic complexes in Picea abies2019Ingår i: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431, Vol. 70, nr 12, s. 3211-3225Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pinaceae are the predominant photosynthetic species in boreal forests, but so far no detailed description of the protein components of the photosynthetic apparatus of these gymnosperms has been available. In this study we report a detailed characterization of the thylakoid photosynthetic machinery of Norway spruce (Picea abies (L.) Karst). We first customized a spruce thylakoid protein database from translated transcript sequences combined with existing protein sequences derived from gene models, which enabled reliable tandem mass spectrometry identification of P. abies thylakoid proteins from two-dimensional large pore blue-native/SDS-PAGE. This allowed a direct comparison of the two-dimensional protein map of thylakoid protein complexes from P. abies with the model angiosperm Arabidopsis thaliana. Although the subunit composition of P. abies core PSI and PSII complexes is largely similar to that of Arabidopsis, there was a high abundance of a smaller PSI subcomplex, closely resembling the assembly intermediate PSI* complex. In addition, the evolutionary distribution of light-harvesting complex (LHC) family members of Pinaceae was compared in silico with other land plants, revealing that P. abies and other Pinaceae (also Gnetaceae and Welwitschiaceae) have lost LHCB4, but retained LHCB8 (formerly called LHCB4.3). The findings reported here show the composition of the photosynthetic apparatus of P. abies and other Pinaceae members to be unique among land plants.

  • 305. Greer, DH
    et al.
    Ottander, Christina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
    Öquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Photoinhibition and recovery of photosynthesis in intact barley leaves at 5 and 20°C1991Ingår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 81, nr 2, s. 203-210Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Photoinhibition of photosynthesis and its recovery were studied in intact barley (Hordeum vulgare L. cv. Gunilla) leaves grown in a controlled environment by exposing them to two temperatures, 5 and 20-degrees-C, and a range of photon flux densities in excess of that during growth. Additionally, photoinhibition was examined in the presence of chloramphenicol (CAP, an inhibitor of chloroplast protein synthesis) and of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). Susceptibility to photoinhibition was much higher at 5 than at 20-degrees-C. Furthermore, at 20-degrees-C CAP exacerbated photoinhibition strongly, whereas CAP had little additional effect (10%) at 5-degrees-C. These results support the model that net photoinhibition is the difference between the inactivation and repair of photosystem II (PSII); i.e. the degradation and synthesis of the reaction centre protein, D1. Furthermore, the steady-state extent of photoinhibition was strongly dependent on temperature and the results indicated this was manifested through the effects of temperature on the repair process of PSII. We propose that the continuous repair of PSII at 20-degrees-C conferred at least some protection from photoinhibition. At 5-degrees-C the repair process was largely inhibited, with increased photoinhibition as a consequence. However, we suggest where repair is inhibited by low temperature, some protection is alternatively conferred by the photoinhibited reaction centres. Providing they are not degraded, such centres could still dissipate excitation energy non-radiatively, thereby conferring protection of remaining photochemically active centres under steady-state conditions. A fraction of PS II centres were capable of resisting photoinhibition when the repair process was inhibited by CAP. This is discussed in relation to PS II heterogeneity. Furthermore, the repair process was not apparently activated within 3 h when barley leaves were transferred to photoinhibitory light conditions at 20-degrees-C.

  • 306. Grimberg, Åsa
    et al.
    Lager, Ida
    Street, Nathaniel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Robinson, Kathryn M
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Marttila, Salla
    Mähler, Niklas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Ingvarsson, Pär K.
    Bhalerao, Rishikesh P.
    Storage lipid accumulation is controlled by photoperiodic signal acting via regulators of growth cessation and dormancy in hybrid aspen2018Ingår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 219, nr 2, s. 619-630Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The signalling pathways that control seasonal modulation of carbon metabolism in perennial plants are poorly understood. Using genetic, metabolic and natural variation approaches, we identify factors mediating photoperiodic control of storage lipid accumulation in the model tree hybrid aspen (Populus tremula x tremuloides). We characterized lipid accumulation in transgenic hybrid aspen with impaired photoperiodic and hormonal responses. Genome-wide association mapping was performed in Swedish aspen (P.tremula) genotypes to determine genetic loci associated with genotype variation in lipid content. Our data show that the storage lipid triacylglycerol (TAG) accumulates in cambial meristem and pith rays of aspen in response to photoperiodic signal controlling growth cessation and dormancy induction. We show that photoperiodic control of TAG accumulation is mediated by the FLOWERING LOCUS T/CONSTANS module, which also controls the induction of growth cessation. Hormonal and chromatin remodelling pathways also contribute to TAG accumulation by photoperiodic signal. Natural variation exists in lipid accumulation that is controlled by input from multiple loci. Our data shed light on how the control of storage metabolism is temporally coordinated with growth cessation and dormancy by photoperiodic signal, and reveals that storage lipid accumulation between seeds and perennating organs of trees may involve distinct regulatory circuits.

  • 307.
    Grönlund, Andreas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Bhalerao, Rishikesh P
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Karlsson, Jan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Modular gene expression in Poplar: a multilayer network approach2009Ingår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 181, nr 2, s. 315-322Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    * By applying a multilayer network approach to an extensive set of Poplar microarray data, a genome-wide coexpression network has been detected and explored.

    * Multilayer networks were generated from minimum spanning trees (MSTs) using Kruskal's algorithm from random jack-knife resamplings of half of the full data set. The final network is obtained from the union of all the generated MSTs.

    * The gene expression correlations display a highly clustered topology, which is more pronounced when introducing links appearing in relatively few of the generated MSTs. The network also reveals a modular architecture, reflecting functional groups with relatively frequent gene-to-gene communication. Furthermore, the observed modular structure overlaps with different gene activities in different tissues, and closely related tissues show similar over- and/or under-expression patterns at the modular scale.

    * It is shown that including links that appear in a few of the generated MSTs increases the information quality of the network. In other words, a link may be 'weak' because it reflects rare signaling events rather than merely a signal weakened by noise. The method allows, from comparisons of random 'null networks', tuning to maximize the information obtainable.

  • 308.
    Grönlund, Andreas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Holme, Petter
    Minnhagen, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Dynamic scaling regimes of collective decision making2008Ingår i: EPL - Europhysics Letters, Vol. 81, nr 2, s. 28003-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigate a social system of agents faced with a binary choice. We assume there is a correct, or beneficial, outcome of this choice. Furthermore, we assume agents are influenced by others in making their decision, and that the agents can obtain information that may guide them towards making a correct decision. The dynamic model we propose is of nonequilibrium type, converging to a final decision. We run it on random graphs and scale-free networks. On random graphs, we find two distinct regions in terms of the finalizing time —the time until all agents have finalized their decisions. On scale-free networks, on the other hand, there do not seem to be such distinct scaling regions.

  • 309.
    Grönlund, Andreas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Lötstedt, Per
    Elf, Johan
    Transcription factor binding kinetics constrain noise suppression via negative feedback2013Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 4, s. 1864-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Negative autoregulation, where a transcription factor regulates its own expression by preventing transcription, is commonly used to suppress fluctuations in gene expression. Recent single molecule in vivo imaging has shown that it takes significant time for a transcription factor molecule to bind its chromosomal binding site. Given the slow association kinetics, transcription factor mediated feedback cannot at the same time be fast and strong. Here we show that with a limited association rate follows an optimal transcription factor binding strength where noise is maximally suppressed. At the optimal binding strength the binding site is free a fixed fraction of the time independent of the transcription factor concentration. One consequence is that high-copy number transcription factors should bind weakly to their operators, which is observed for transcription factors in Escherichia coli. The results demonstrate that a binding site's strength may be uncorrelated to its functional importance.

  • 310.
    Guinea Diaz, Manuel
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hernandez-Verdeja, Tamara
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Kremnev, Dmitry
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Crawford, Tim
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Dubreuil, Carole
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Strand, Åsa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Redox regulation of PEP activity during seedling establishment in Arabidopsis thaliana2018Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 9, artikel-id 50Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Activation of the plastid-encoded RNA polymerase is tightly controlled and involves a network of phosphorylation and, as yet unidentified, thiol-mediated events. Here, we characterize PLASTID REDOX INSENSITIVE2, a redox-regulated protein required for full PEP-driven transcription. PRIN2 dimers can be reduced into the active monomeric form by thioredoxins through reduction of a disulfide bond. Exposure to light increases the ratio between the monomeric and dimeric forms of PRIN2. Complementation of prin2-2 with different PRIN2 protein variants demonstrates that the monomer is required for light-activated PEP-dependent transcription and that expression of the nuclear-encoded photosynthesis genes is linked to the activity of PEP. Activation of PEP during chloroplast development likely is the source of a retrograde signal that promotes nuclear LHCB expression. Thus, regulation of PRIN2 is the thiol-mediated mechanism required for full PEP activity, with PRIN2 monomerization via reduction by TRXs providing a mechanistic link between photosynthetic electron transport and activation of photosynthetic gene expression.

  • 311.
    Gullberg, Jonas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Jonsson, Pär
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Nordström, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Sjöström, Michael
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Moritz, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Design of experiments: an efficient strategy to identify factors influencing extraction and derivatization of Arabidopsis thaliana samples in metabolomic studies with gas chromatography/mass spectrometry2004Ingår i: Analytical Biochemistry, ISSN 0003-2697, E-ISSN 1096-0309, Vol. 331, nr 2, s. 283-295Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The usual aim in metabolomic studies is to quantify the entire metabolome of each of a series of biological samples. To do this for complex biological matrices, e.g., plant tissues, efficient and reproducible extraction protocols must be developed. However, derivatization protocols must also be developed if GC/MS (one of the mostly widely used analytical methods for metabolomics) is involved. The aim of this study was to investigate how different chemical and physical factors (extraction solvent, derivatization reagents, and temperature) affect the extraction and derivatization of the metabolome from leaves of the plant Arabidopsis thaliana. Using design of experiment procedures, variation was systematically introduced, and the effects of this variation were analyzed using regression models. The results show that this approach allows a reliable protocol for metabolomic analysis of Arabidopsis to be determined with a relatively limited number of experiments. Following two different investigations an extraction and derivatization protocol was chosen. Further, the reproducibility of the analysis of 66 endogenous compounds was investigated, and it was shown that both hydrophilic and lipophilic compounds were detected with high reproducibility.

  • 312. Gundale, Michael J.
    et al.
    Sverker, Jennie
    Albrectsen, Benedicte R.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Nilsson, Marie-Charlotte
    Wardle, David A.
    Variation in protein complexation capacity among and within six plant species across a boreal forest chronosequence2010Ingår i: Plant Ecology, ISSN 1385-0237, E-ISSN 1573-5052, Vol. 211, nr 2, s. 253-266Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigated among and within species variation in several litter chemical properties, including protein complexation capacity (PCC), for six plant species across a boreal forest chronosequence in northern Sweden across which stand fertility declines sharply with stand age. We hypothesized (1) that evergreen species which dominate in late-successional stands would exhibit higher PCCs than deciduous species that dominate in young stands, (2) that individual species would increase their PCCs in response to nutrient limitation as succession proceeds, and (3) that differences in PCC among litter types would determine their interactive effects with proteins on soil N and C mineralization. The data demonstrated a high PCC, but a low PCC per unit of soluble phenol, for two deciduous species that dominate in early-successional high fertility stands, providing mixed support for our first hypothesis. No species demonstrated a significant correlation between their PCC and stand age, which did not support our second hypothesis. Finally, a soil incubation assay revealed that litter extracts for three of the six species had negative interactive effects with added proteins on N mineralization rates, and that all six species demonstrated positive interactive effects with protein on C mineralization. This pattern did not provide strong support for our third hypothesis, and suggests that N immobilization was likely a more important factor regulating N mineralization than stabilization of proteins into tannin complexes. These data suggest that multiple interactive mechanisms between litter extracts and proteins likely occur simultaneously to influence the availability of N in soils.

  • 313. GUSTAFSSON, L
    et al.
    Gustafsson, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    LOW GENETIC-VARIATION IN SWEDISH POPULATIONS OF THE RARE SPECIES VICIA-PISIFORMIS (FABACEAE) REVEALED WITH RFLP (RDNA) AND RAPD1994Ingår i: Plant Systematics and Evolution, ISSN 0378-2697, E-ISSN 1615-6110, Vol. 189, nr 3-4, s. 133-148Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nine Swedish populations, 1-5 individuals/population, and one cultivated individual of the rare species Vicia pisiformis were investigated for genetic variation. In hybridizations with two rDNA probes using 8 restriction enzymes, only two individuals belonging to one population were polymorphic. A map of the rDNA gene cluster was constructed for four of the restriction enzymes used. Two of the polymorphic sites were mapped and were found to be located outside regions coding for rRNA, presumably caused by single point mutations or small deletions. The repeat length of the rDNA region was c. 10,000 bp, which corresponds well with the size found for other species belonging to Fabaceae. No length polymorphism was found in the intergenic spacer, contrary to the situation found for most other plant species investigated for rDNA variation. The haplotype diversity for the species (Hsp Shannon) was very low (0.055). Within-population values (Hpop) was 0 for all populations except the variable one, which had 0.301. PCR amplification with 6 random primers also revealed very low levels of genetic diversity. A polymorphism was observed in a limited number of individuals for four populations. Hsp was 0.065 and HpopBAR was 0.050. The average D value (Wetton) for the PCR haplotypes was 0.99.

  • 314.
    Gustafsson, Petter
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. 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).
    LIDHOLM, J
    LUNDBERG, AK
    STRUCTURE AND REGULATION OF PHOTOSYNTHESIS GENES IN PINUS-SYLVESTRIS (SCOTS PINE) AND PINUS-CONTORTA (LODGEPOLE PINE)1991Ingår i: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 43, nr 3-4, s. 287-300Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The structure and regulation of one nuclear and one chloroplast gene was studied in Pinus sylvestris (Scots pine) and Pinus contorta (lodgepole pine). cDNA copies of the nuclear located cab genes of Pinus sylvestris, coding for the light-harvesting chlorophyll a/b-binding proteins of photosystem II (LHC-II), were cloned. cab-II genes coding for both types of LHC-II polypeptides, Types 1 and 2, were found. An analysis of the DNA sequences of several different cab-II cDNAs shows that they have a high bias for the nucleotides G and C at the third base positions of the codons, making them more similar to monocot than to dicot genes. Two of the three genes were found to be located within CpG islands. The cab-II genes were found to be expressed in dark-grown seedlings in contrast to what has been found for most angiosperms. The chloroplast genomes of conifers were shown to lack the inverted repeat organization normally found in higher plants, mosses and green algae. The psbA gene, located in the chloroplast genome and coding for the D1 polypeptide in the reaction center of photosystem II, was found to be tandemly duplicated in P. contorta. Cloning and sequence analysis of the two psbA genes and the surrounding regions showed that the duplicated segment is 1.97 kb long and that it ends 19 bp downstream from the psbA stop codon. The corresponding locus of P. sylvestris, which lacks the duplication, was cloned and characterized. A comparison with P. contorta indicates how the duplication/insertion event has occurred. A comparison of third codon position between P. contorta psbA and that of other plants indicated an almost equidistant evolutionary relationship between P. contorta, spinach (or barley) and Marchantia polymorpha.

  • 315. Gutierrez, Laurent
    et al.
    Mongelard, Gaelle
    Flokova, Kristyna
    Pacurar, Daniel I.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Novak, Ondrej
    Staswick, Paul
    Kowalczyk, Mariusz
    Pacurar, Monica
    Demailly, Herve
    Geiss, Gaia
    Bellini, Catherine
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Auxin Controls Arabidopsis Adventitious Root Initiation by Regulating Jasmonic Acid Homeostasis2012Ingår i: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 24, nr 6, s. 2515-2527Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 316. Guy, Charles
    et al.
    Porat, Ron
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Plant cold and abiotic stress gets hot2006Ingår i: Physiologia Plantarum, Vol. 126, s. 1-4Artikel i tidskrift (Refereegranskat)
  • 317.
    Haas, Julia Christa
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Street, Nathaniel R.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Sjödin, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Division of CBRN Security and Defence, FOI–Swedish Defence Research Agency, Umeå, Sweden.
    Lee, Natuschka M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Högberg, Mona N.
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Umeå, Sweden.
    Näsholm, Torgny
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Umeå, Sweden; Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, SLU, Umeå, Sweden.
    Hurry, Vaughan
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, SLU, Umeå, Sweden.
    Microbial community response to growing season and plant nutrient optimisation in a boreal Norway spruce forest2018Ingår i: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 125, s. 197-209Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Interactions between Norway spruce trees and bacteria and fungi in nutrient limited boreal forests can be beneficial for tree growth and fitness. Tree-level effects of anthropogenic nutrient addition have been well studied, however understanding of the long-term effects on the associated microbiota is limited. Here, we report on the sensitivity of microbial community composition to the growing season and nutrient additions. Highthroughput sequencing of the bacterial 16S rRNA gene and fungal ITS1 region was used to characterise changes in the microbial community after application of a complete mineral nutrient mixture for five and 25 years. The experiment was conducted using the Flakaliden forest research site in northern boreal Sweden and included naturally low nutrient control plots. Needle and fine root samples of Norway spruce were sampled in addition to bulk soil during one growing season to provide comprehensive insight into phyllosphere and belowground microbiota community changes. The phyllosphere microbiota was compositionally distinct from the belowground communities and phyllosphere diversity increased significantly over the growing season but was not influenced by the improved nutrient status of the trees. In both root and soil samples, alpha diversity of fungal, in particular ectomycorrhizal fungi (EMF), and bacterial communities increased after long-term nutrient optimisation, and with increasing years of treatment the composition of the fungal and bacterial communities changed toward a community with a higher relative abundance of nitrophilic EMF and bacterial species but did not cause complete loss of nitrophobic species from the ecosystem. From this, we conclude that 25 years of continuous nutrient addition to a boreal spruce stand increased phylotype richness and diversity of the microbiota in the soil, and at the root-soil interface, suggesting that long-term anthropogenic nutrient inputs can have positive effects on belowground biodiversity that may enhance ecosystem robustness. Future studies are needed to assess the impact of these changes to the microbiota on ecosystem carbon storage and nitrogen cycling in boreal forests.

  • 318.
    Hall, David
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Luquez, Virginia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Garcia, Maribel Victoria
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    St Onge, Kate R
    Department of Evolutionary Functional Genomics, Evolutionary Biology Centre, Uppsala University, Sweden.
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Ingvarsson, Pär
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Adaptive population differentiation in phenology across a latitudinal gradient in European aspen (Populus tremula, L.): a comparison of neutral markers, candidate genes and phenotypic traits2007Ingår i: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 61, s. 2849-2860Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A correct timing of growth cessation and dormancy induction represents a critical ecological and evolutionary trade-off between survival and growth in most forest trees (Rehfeldt et al. 1999; Horvath et al. 2003; Howe et al. 2003). We have studied the deciduous tree European Aspen (Populus tremula) across a latitudinal gradient and compared genetic differentiation in phenology traits with molecular markers. Trees from 12 different areas covering 10 latitudinal degrees were cloned and planted in two common gardens. Several phenology traits showed strong genetic differentiation and clinal variation across the latitudinal gradient, with QST values generally exceeding 0.5. This is in stark contrast to genetic differentiation at several classes of genetic markers (18 neutral SSRs, 7 SSRs located close to phenology candidate genes and 50 SNPs from five phenology candidate genes) that all showed FST values around 0.015. We thus find strong evidence for adaptive divergence in phenology traits across the latitudinal gradient. However, the strong population structure seen at the quantitative traits is not reflected in underlying candidate genes. This result fit theoretical expectations that suggest that genetic differentiation at candidate loci is better described by FST at neutral loci rather than by QST at the quantitative traits themselves.

  • 319.
    Hall, David
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Ma, Xiao-Fei
    Program in Evolutionary Functional Genomics, Evolutionary Biology Center, Uppsala University.
    Ingvarsson, Pär K
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Adaptive evolution of the Populus tremula photoperiod pathway2011Ingår i: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 20, nr 7, s. 1463-1474Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Environmental cues entrain the circadian clock, a core component of the photoperiod pathway in plants, to daily and seasonal changes. The circadian clock mediates input signals from light and temperature receptors to downstream target genes through feedback loops. Several studies have shown that a correct timing of the circadian system is a fitness advantage and genes in photoperiod network have been implied to evolve in response to the diversifying selection in heterogeneous environment. In an attempt to quantify the extent of the historical patterns of selection on genes in the photoperiod pathway in the widely distributed tree species European aspen (Populus tremula) we obtained sequences for twenty-five of the genes in the network and these genes were compared to patterns of nucleotide diversity in 77 randomly chosen genes from across the genome of P. tremula. We found a significant reduction in synonymous diversity in photoperiod genes while non-synonymous diversity was in line with data from control genes. A substantial fraction of the genes show signs of selection, with eight genes showing signs of rapid protein evolution. In contrast to our expectations, genes closely associated with the core circadian clock show rapid protein evolution despite their central position in the pathway. Furthermore, selection on non-synonymous mutations is negatively correlated with synonymous diversity across all genes, indicating the action of recurrent selective sweeps.

  • 320.
    Hall, Michael
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    von Sydow, Lotta
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Storm, Patrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sauer, Uwe
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kieselbach, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Schröder, Wolfgang
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    The lumenal pentapeptide repeat proteins TL15 and TL20.3 are novel chaperone-like proteins in the chloroplast lumen of higher plantsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    In the thylakoid lumen of Arabidopsis thaliana, three pentapeptide repeat family proteins of unknown function are localized. Pentapeptide repeat proteins (PRP) are comprised of at least eight tandem repeats of five amino acids of the consensus sequence A(D/N)LXX, which fold into a quadrilateral beta helix structure. Here we have solved the crystal structure of the mature form of the lumenal PRP protein TL15 to 1.3 Å resolution. TL15 is comprised of a main pentapeptide domain, consisting of a total of 19 pentapeptide repeats which form five turns of a beta helix, and a C-terminal alpha helix domain consisting of two alpha helices. The alpha helices form a ‘cap’ at the C-terminal end of the beta helix and are connected by a disulphide bond between the conserved cysteine residues C122 and C142. Furthermore we show that the lumenal PRPs TL15 and TL20.3 can assist in refolding of a chemically denatured substrate in vitro, indicating foldase chaperone activity. The three lumenal PRPs have been previously identified as targets of thioredoxin, and interestingly we observed a greatly increased chaperone activity of TL15 and TL20.3 after reduction of their disulphide bonds. Our results provide the high resolution crystal structure of the TL15 protein and our analysis of chaperone activity suggests that TL15 and TL20.3 may constitute a novel type of redox-regulated molecular chaperones in the chloroplast lumen of higher plants.

  • 321. Halperin, Tami
    et al.
    Zheng, Bo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Itzhaki, Hanan
    Clarke, Adrian
    Adam, Zach
    Plant mitochondria contain proteolytic and regulatory subunits of the ATP-dependent Clp protease2001Ingår i: Plant Molecular Biology, Vol. 45, nr 4, s. 461-468Artikel i tidskrift (Refereegranskat)
  • 322. Hankamer, B
    et al.
    Nield, J
    Zheleva, D
    Boekema, E
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Barber, J
    Isolation and biochemical characterisation of monomeric and dimeric photosystem II complexes from spinach and their relevance to the organisation of photosystem II in vivo1997Ingår i: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 243, nr 1-2, s. 422-429Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Membranes enriched in photosystem II were isolated from spinach and further solubilised using n-octyl beta-D-glucopyranoside (OctGlc) and n-dodecyl beta-D-maltoside (DodGlc(2)). The OctGlc preparation had high rates of oxygen evolution and when subjected to size-exclusion HPLC and sucrose density gradient centrifugation, in the presence of DodGlc(2), separated into dimeric (430 kDa), monomeric (236 kDa) photosystem II cores and a fraction containing photosystem II light-harvesting complex (Lhcb) proteins. The dimeric core fraction was more stable, contained higher levels of chlorophyll, beta-carotene and plastoquinone per photosystem II reaction centre and had a higher oxygen-evolving activity than the monomeric cores. Their subunit composition was similar (CP43, CP47, D1, D2, cytochrome b 559 and several lower-molecular-mass components) except that the level of 33-kDa extrinsic protein was lower in the monomeric fraction. Direct solubilisation of photosystem-II-enriched membranes with DodGlc(2), followed by sucrose density gradient centrifugation, yielded a super complex (700 kDa) containing the dimeric form of the photosystem II core and Lhcb proteins: Lhcb1, Lhcb2, Lhcb4 (CP29), and Lhcb5 (CP26). Like the dimeric and monomeric photosystem II core complexes, the photosystem II-LHCII complex had lost the 23-kDa and 17-kDa extrinsic proteins, but maintained the 33-kDa protein and the ability to evolve oxygen. It is suggested, with a proposed model, that the isolated photosystem II-LHCII super complex represents an in vivo organisation that can sometimes form a lattice in granal membranes of the type detected by freeze-etch electron microscopy [Seibert, M., DeWit, M. & Staehelin, L. A. (1987) J. Cell Biol. 105, 2257-2265].

  • 323. Hanson, D T
    et al.
    Franklin, L A
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Badger, M R
    The Chlamydomonas reinhardtii cia3 mutant lacking a thylakoid lumen-localized carbonic anhydrase is limited by CO2 supply to rubisco and not photosystem II function in vivo2003Ingår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 132, nr 4, s. 2267-2275Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Chlamydomonas reinhardtii cia3 mutant has a phenotype indicating that it requires high-CO2 levels for effective photosynthesis and growth. It was initially proposed that this mutant was defective in a carbonic anhydrase (CA) that was a key component of the photosynthetic CO2-concentrating mechanism (CCM). However, more recent identification of the genetic lesion as a defect in a lumenal CA associated with photosystem II (PSII) has raised questions about the role of this CA in either the CCM or PSII function. To resolve the role of this lumenal CA, we re-examined the physiology of the cia3 mutant. We confirmed and extended previous gas exchange analyses by using membrane-inlet mass spectrometry to monitor O-16(2), O-18(2), and CO2 fluxes in vivo. The results demonstrate that PSII electron transport is not limited in the cia3 mutant at low inorganic carbon (Ci). We also measured metabolite pools sizes and showed that the RuBP pool does not fall to abnormally low levels at low Ci as might be expected by a photosynthetic electron transport or ATP generation limitation. Overall, the results demonstrate that under low Ci conditions, the mutant lacks the ability to supply Rubisco with adequate CO2 for effective CO2 fixation and is not limited directly by any aspect of PSII function. We conclude that the thylakoid CA is primarily required for the proper functioning of the CCM at low Ci by providing an ample supply of CO2 for Rubisco.

  • 324.
    Hansson, Andreas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Jensen, Poul E
    Chlorophyll limitation in plants remodels and balances the photosynthetic apparatus by changing the accumulation of photosystems I and II through two different approaches.2009Ingår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 135, nr 2, s. 214-228Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Arabidopsis plants with a reduced expression of CHL27 (chl27), an enzyme (EC 1.14.13.81) required for the synthesis of Pchlide, are chlorotic and have a Chl a/b ratio two times higher than wild-type (WT). Knockdown plants transformed with a construct constitutively expressing CHL27 recovered regarding Chl level, a/b ratio and 77K fluorescence. A negative correlation was found between total Chl and Chl a/b ratio in the examined plants. The chl27 plants fail to assemble WT amounts of complete PSI and PSII, leading to an elevated PSII/PSI ratio. The PSI remaining in chl27 is fully functional with a quantum yield higher than for WT. Despite a severe reduction of photosystem II antennae protein (LHCII) and an increased proportion of stroma lammella, the chl27 plants are able to perform state transitions. No major differences were found regarding PSII quantum yield, qN and 1 - qp whereas non-photochemical quenching was decreased by a factor two in chl27 plants. The PSII quantum yield for dark-adapted plants and plants given 10 min recovery after high light treatment were similar for both WT and chl27 showing that chl27 plants are not more susceptible to photoinhibition than WT. Taken together the plant manage to acclimate and to balance the two photosystems well even when it is severely limited in Chl. The way to achieve this differs for the two photosystems: regarding PSI a general reduction of core and antenna subunits occurs with no apparent change in the antenna composition; whereas for PSII there is a preferential loss of antenna proteins.

  • 325.
    Harinikumar, K. M.
    et al.
    Department of Plant Biotechnology, University of Agricultural Sciences, G.K.V.K Campus. Bengaluru, India.
    Kudahettige-Nilsson, Rasika Lasanthi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Devadas, A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Holmgren, Marie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Sellstedt, Anita
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Bioethanol production from four abundant Indian agricultural wastes2017Ingår i: Biofuels, ISSN 1759-7269, E-ISSN 1759-7277Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lignocellulose feedstocks are promising second-generation sources of ethanol biofuel. They include massive amounts of agricultural waste generated in India, much of which is currently burnt (exacerbating major pollution problems), but could potentially be fermented. To assist efforts to realize this potential, four abundant kinds of Indian agricultural residues (sugarcane bagasse and straw from rice, sweet sorghum and millet) were hydrolyzed via a dilute-acid method and fermented at 27 °C, using the white-rot fungus Trametes versicolor as a biocatalyst. The total carbohydrate contents of the agriculture wastes were analyzed, as well as soluble sugar contents of the hydrolysates at the start and end of the fermentations; their ethanol yields and activities of the key enzymes aldehyde dehydrogenase and pyruvate decarboxylase were also measured. Results show that ca. 85–90% of the fermentable sugars were used for ethanol production, and the enzyme activities are consistent with the observed yields. The findings indicate a great potential for ethanol production from Indian agricultural waste.

  • 326. HARR, R
    et al.
    FALLMAN, P
    HAGGSTROM, M
    WAHLSTROM, L
    Gustafsson, Petter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    GENEUS, A COMPUTER-SYSTEM FOR DNA AND PROTEIN-SEQUENCE ANALYSIS CONTAINING AN INFORMATION-RETRIEVAL SYSTEM FOR THE EMBL DATA LIBRARY1986Ingår i: Nucleic Acids Research, ISSN 0305-1048, E-ISSN 1362-4962, Vol. 14, nr 1, s. 273-284Artikel i tidskrift (Refereegranskat)
  • 327. Hartmann, Laura
    et al.
    Pedrotti, Lorenzo
    Weiste, Christoph
    Fekete, Agnes
    Schierstaedt, Jasper
    Göttler, Jasmin
    Kempa, Stefan
    Krischke, Markus
    Dietrich, Katrin
    Mueller, Martin J
    Vicente-Carbajosa, Jesus
    Hanson, Johannes
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Department of Molecular Plant Physiology, Utrecht University, The Netherlands .
    Dröge-Laser, Wolfgang
    Crosstalk between Two bZIP Signaling Pathways Orchestrates Salt-Induced Metabolic Reprogramming in Arabidopsis Roots2015Ingår i: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 27, nr 8, s. 2244-2260Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 328. Hasselquist, Niles J.
    et al.
    Metcalfe, Daniel B.
    Inselsbacher, Erich
    Stangl, Zsofia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Oren, Ram
    Näsholm, Torgny
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden.
    Högberg, Peter
    Greater carbon allocation to mycorrhizal fungi reduces tree nitrogen uptake in a boreal forest2016Ingår i: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 97, nr 4, s. 1012-1022Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The central role that ectomycorrhizal (EM) symbioses play in the structure and function of boreal forests pivots around the common assumption that carbon (C) and nitrogen (N) are exchanged at rates favorable for plant growth. However, this may not always be the case. It has been hypothesized that the benefits mycorrhizal fungi convey to their host plants strongly depends upon the availability of C and N, both of which are rapidly changing as a result of intensified human land use and climate change. Using large-scale shading and N addition treatments, we assessed the independent and interactive effects of changes in C and N supply on the transfer of N in intact EM associations with similar to 15 yr. old Scots pine trees. To assess the dynamics of N transfer in EM symbioses, we added trace amounts of highly enriched (NO3-)-N-15 label to the EM-dominated mor-layer and followed the fate of the N-15 label in tree foliage, fungal chitin on EM root tips, and EM sporocarps. Despite no change in leaf biomass, shading resulted in reduced tree C uptake, ca. 40% lower fungal biomass on EM root tips, and greater N-15 label in tree foliage compared to unshaded control plots, where more N-15 label was found in fungal biomass on EM colonized root tips. Short-term addition of N shifted the incorporation of N-15 label from EM fungi to tree foliage, despite no significant changes in below-ground tree C allocation to EM fungi. Contrary to the common assumption that C and N are exchanged at rates favorable for plant growth, our results show for the first time that under N-limited conditions greater C allocation to EM fungi in the field results in reduced, not increased, N transfer to host trees. Moreover, given the ubiquitous nature of mycorrhizal symbioses, our results stress the need to incorporate mycorrhizal dynamics into process-based ecosystem models to better predict forest C and N cycles in light of global climate change.

  • 329. He, Hanzi
    et al.
    Willems, Leo
    Batushansky, Albert
    Fait, Aaron
    Hanson, Johannes
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Department of Molecular Plant Physiology, Utrecht University, NL-3584 CH Utrecht, The Netherlands.
    Nijveen, Harm
    Hilhorst, Henk W M
    Bentsink, Leónie
    Effects of Parental Temperature and Nitrate on Seed Performance are Reflected by Partly Overlapping Genetic and Metabolic Pathways2016Ingår i: Plant and Cell Physiology, ISSN 0032-0781, E-ISSN 1471-9053, Vol. 57, nr 3, s. 473-487Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Seed performance is affected by the seed maturation environment and previously, we have shown that temperature, nitrate and light intensity were the most influential environmental factors affecting seed performance. Seeds developed in these environments were selected to assess the underlying metabolic pathways, using a combination of transcriptomics and metabolomics. These analyses revealed that the effects of the temperature and nitrate parental environments were reflected by partly overlapping genetic and metabolic networks, as indicated by similar changes in metabolites and transcripts expression levels. Nitrogen-metabolism related metabolites (asparagine, GABA and allantoin) were significantly decreased in both low temperature (15°C) and low nitrate (N0) maturation environments. Correspondingly, nitrogen-metabolism genes (ALLANTOINASE, NITRATE REDUCTASE 1, NITRITE REDUCTASE 1 and NITRILASE 4) were differentially regulated in the low temperature and nitrate maturation environments, as compared with control conditions. High light intensity during seed maturation increased galactinol content, and displayed a high correlation with seed longevity. Low light had a genotype-specific effect on cell surface encoding genes in the DELAY OF GERMINATION 6-Near Isogenic Line (NILDOG6). Overall, the integration of phenotypes, metabolites and transcripts led to new insights in the regulation of seed performance.

  • 330. Hedwall, P-O
    et al.
    Strengbom, J
    Nordin, A
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Can thinning alleviate negative effects of fertilization on boreal forest floor vegetation?2013Ingår i: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 310, s. 382-392Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Society's increased interest in renewable energy and materials put pressure on forest biomass production. Intensive fertilization of young Norway spruce (Picea abies) forest has a considerable potential to increase the production of tree biomass, but there are concerns about negative side-effects on forest ecosystem structure and function. Fertilization of young forest has a strong negative impact on light availability below the tree canopy and reduces the abundance of the forest floor vegetation. The silvicultural practice of thinning has been shown to affect composition and diversity of forest floor vegetation, and it has been proposed, but rarely tested, that the effects of fertilization are interdependent on the type of thinning performed. Here we present responses on the forest floor vegetation following 25 years of fertilization and eighth years after thinning (removing 30% or 60% of the tree basal area) in a Norway spruce forest in northern Sweden. Fertilization without thinning led to a considerable reduction in abundance of most forest floor plants. It did not affect species richness but resulted in an increased evenness. Thinning reduced the fertilization effects so that the total abundance of the vegetation was comparable to the unfertilized control plots. A considerable change in species composition had, however, taken place. Thinning favored early-successional species and pteridophytes on the account of dwarf-shrubs. Thinning also increased species richness and functional richness, while none, or negative effects were seen on evenness and functional evenness, respectively. A comparison with data from the National Forest Inventory revealed that the type of vegetation generated by fertilization, without or in combination with thinning, is a type of vegetation very uncommon in Swedish boreal forests. First, we conclude that the effects of fertilization on forest floor vegetation in young stands of Norway spruce are largely dependent on thinning regime. Secondly, fertilization will, independently of thinning, lead to considerable changes in the vegetation, including a functional shift from dwarf-shrubs with ericoid mycorrhiza to ferns and grasses with arbuscular mycorrhiza, resulting in a functional type of vegetation that is rare in this part of the boreal forest biome. Finally, in contrast to what previously has been suggested for unfertilized forests, thinning of fertilized forests may not promote late-successional species.

    (C) 2013 Elsevier B.V. All rights reserved.

  • 331. Heineke, D
    et al.
    Bykova, N
    Gardeström, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Bauwe, H
    Metabolic response of potato plants to an antisense reduction of the P-protein of glycine decarboxylase2001Ingår i: Planta, ISSN 0032-0935, E-ISSN 1432-2048, Vol. 212, nr 5-6, s. 880-887Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Potato (Solanum tuberosum L. cv. Desire) plants with reduced amounts of P-protein, one of the subunits of glycine decarboxylase (GDC), have been generated by introduction of an antisense transgene. Two transgenic lines, containing about 60-70% less P-protein in the leaves compared to wild-type potato, were analysed in more detail. The reduction in P-protein amount led to a decrease in the ability of leaf mitochondria to decarboxylate glycine. Photosynthetic and growth rates were reduced but the plants were viable under ambient air and produced tubers. Glycine concentrations within the leaves were elevated up to about 100-fold during illumination. Effects: on other amino acids and on sucrose and hexoses were minor. Nearly all of the glycine accumulated during the day was metabolised during the following night. The data suggest that the GDC operates far below substrate saturation under normal conditions thus allowing a flexible and fast response to changes in the environment.

  • 332. Hendrickson, Luke
    et al.
    Vlcková, Alexandra
    Selstam, Eva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Huner, Norman
    Öquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. 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).
    Cold acclimation of the Arabidopsis dgd1 mutant results in recovery from photosystem I-limited photosynthesis.2006Ingår i: FEBS Letters, ISSN 0014-5793, Vol. 580, nr 20, s. 4959-68Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We compared the thylakoid membrane composition and photosynthetic properties of non- and cold-acclimated leaves from the dgd1 mutant (lacking >90% of digalactosyl–diacylglycerol; DGDG) and wild type (WT) Arabidopsis thaliana. In contrast to warm grown plants, cold-acclimated dgd1 leaves recovered pigment-protein pools and photosynthetic function equivalent to WT. Surprisingly, this recovery was not correlated with an increase in DGDG. When returned to warm temperatures the severe dgd1 mutant phenotype reappeared. We conclude that the relative recovery of photosynthetic activity at 5 °C resulted from a temperature/lipid interaction enabling the stable assembly of PSI complexes in the thylakoid.

  • 333. Hermansen, Russell A.
    et al.
    Hvidsten, Torgeir R.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1432 Ås, Norway.
    Sandve, Simen Rod
    Liberles, David A.
    Extracting functional trends from whole genome duplication events using comparative genomics2016Ingår i: Biological Procedures Online, ISSN 1480-9222, E-ISSN 1480-9222, Vol. 18, artikel-id 11Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Background: The number of species with completed genomes, including those with evidence for recent whole genome duplication events has exploded. The recently sequenced Atlantic salmon genome has been through two rounds of whole genome duplication since the divergence of teleost fish from the lineage that led to amniotes. This quadrupoling of the number of potential genes has led to complex patterns of retention and loss among gene families. Results: Methods have been developed to characterize the interplay of duplicate gene retention processes across both whole genome duplication events and additional smaller scale duplication events. Further, gene expression divergence data has become available as well for Atlantic salmon and the closely related, pre-whole genome duplication pike and methods to describe expression divergence are also presented. These methods for the characterization of duplicate gene retention and gene expression divergence that have been applied to salmon are described. Conclusions: With the growth in available genomic and functional data, the opportunities to extract functional inference from large scale duplicates using comparative methods have expanded dramatically. Recently developed methods that further this inference for duplicated genes have been described.

  • 334.
    Hernandez-Verdeja, Tamara
    et al.
    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).
    Retrograde Signals Navigate the Path to Chloroplast Development2018Ingår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 176, nr 2, s. 967-976Artikel i tidskrift (Refereegranskat)
  • 335. Heskel, Mary A.
    et al.
    Atkin, Owen K.
    O'Sullivan, Odhran S.
    Reich, Peter
    Tjoelker, Mark G.
    Weerasinghe, Lasantha K.
    Penillard, Aurore
    Egerton, John J. G.
    Creek, Danielle
    Bloomfield, Keith J.
    Xiang, Jen
    Sinca, Felipe
    Stangl, Zsofia R.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Martinez-de la Torre, Alberto
    Griffin, Kevin L.
    Huntingford, Chris
    Hurry, Vaughan
    Meir, Patrick
    Turnbull, Matthew H.
    Reply to Adams et al.: Empirical versus process-based approaches to modeling temperature responses of leaf respiration2016Ingår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 113, nr 41, s. E5996-E5997Artikel i tidskrift (Refereegranskat)
  • 336. Heskel, Mary A.
    et al.
    O'Sullivan, Odhran S.
    Reich, Peter B.
    Tjoelker, Mark G.
    Weerasinghe, Lasantha K.
    Penillard, Aurore
    Egerton, John J. G.
    Creek, Danielle
    Bloomfield, Keith J.
    Xiang, Jen
    Sinca, Felipe
    Stangl, Zsofia R.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Martinez-de la Torre, Alberto
    Griffin, Kevin L.
    Huntingford, Chris
    Hurry, Vaughan
    Meir, Patrick
    Turnbull, Matthew H.
    Atkin, Owen K.
    Convergence in the temperature response of leaf respiration across biomes and plant functional types2016Ingår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 113, nr 14, s. 3832-3837Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plant respiration constitutes a massive carbon flux to the atmosphere, and a major control on the evolution of the global carbon cycle. It therefore has the potential to modulate levels of climate change due to the human burning of fossil fuels. Neither current physiological nor terrestrial biosphere models adequately describe its short-term temperature response, and even minor differences in the shape of the response curve can significantly impact estimates of ecosystem carbon release and/or storage. Given this, it is critical to establish whether there are predictable patterns in the shape of the respiration-temperature response curve, and thus in the intrinsic temperature sensitivity of respiration across the globe. Analyzing measurements in a comprehensive database for 231 species spanning 7 biomes, we demonstrate that temperature-dependent increases in leaf respiration do not follow a commonly used exponential function. Instead, we find a decelerating function as leaves warm, reflecting a declining sensitivity to higher temperatures that is remarkably uniform across all biomes and plant functional types. Such convergence in the temperature sensitivity of leaf respiration suggests that there are universally applicable controls on the temperature response of plant energy metabolism, such that a single new function can predict the temperature dependence of leaf respiration for global vegetation. This simple function enables straightforward description of plant respiration in the land-surface components of coupled earth system models. Our cross-biome analyses shows significant implications for such fluxes in cold climates, generally projecting lower values compared with previous estimates.

  • 337. HETHERINGTON, SE
    et al.
    Oquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    MONITORING CHILLING INJURY - A COMPARISON OF CHLOROPHYLL FLUORESCENCE MEASUREMENTS, POST-CHILLING GROWTH AND VISIBLE SYMPTOMS OF INJURY IN ZEA-MAYS1988Ingår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 72, nr 2, s. 241-247Artikel i tidskrift (Refereegranskat)
  • 338.
    Hiltonen, Thomas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Bjorkbacka, H
    Forsman, C
    Clarke, A K
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Intracellular beta-carbonic anhydrase of the unicellular green alga Coccomyxa1998Ingår i: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 117, nr 4, s. 1341-1349Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Carbonic anhydrase (CA) (EC 4.2.1.1) enzymes catalyze the reversible hydration of CO,, a reaction that is important in many physiological processes. We have cloned and sequenced a full length cDNA encoding an intracellular P-CA from the unicellular green alga Coccomyxa. Nucleotide sequence data show that the isolated cDNA contains an open reading frame encoding a polypeptide of 227 amino acids. The predicted polypeptide is similar to beta-type CAs from Escherichia coli and higher plants, with an identity of 26% to 30%. The Coccomyxa cDNA was overexpressed in E. coli, and the enzyme was purified and biochemically characterized. The mature protein is a homotetramer with an estimated molecular mass of 100 kD. The CO2-hydration activity of the Coccomyxa enzyme is comparable with that of the pea homolog. However, the activity of Coccomyxa CA is largely insensitive to oxidative conditions, in contrast to similar enzymes from most higher plants. Fractionation studies further showed that Coccomyxa CA is extrachloroplastic.

  • 339.
    Hiltonen, Thomas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Karlsson, Jan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    PALMQVIST, K
    CLARKE, AK
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    PURIFICATION AND CHARACTERIZATION OF AN INTRACELLULAR CARBONIC-ANHYDRASE FROM THE UNICELLULAR GREEN-ALGA COCCOMYXA1995Ingår i: Planta, ISSN 0032-0935, E-ISSN 1432-2048, Vol. 195, nr 3, s. 345-351Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An intracellular carbonic anhydrase (CA; EC 4.2.1.1) was purified and characterised from the unicellular green alga Coccomyxa sp. Initial studies showed that cultured Coccomyxa cells contain an intracellular CA activity around 100 times higher than that measured in high-CO2-grown cells of Chlamydomonas reinhardtii CW 92. Purification of a protein extract containing the CA activity was carried out using ammonium-sulphate precipitation followed by anion-exchange chromatography. Proteins were then separated by native (non-dissociating) polyacrylamide gel electrophoresis, with each individual protein band excised and assayed for CA activity. Measurements revealed CA activity associated with two discrete protein bands with similar molecular masses of 80 +/- 5 kDa. Dissociation by denaturing polyacrylamide gel electrophoresis showed that both proteins contained a single polypeptide of 26 kDa, suggesting that each 80-kDa native protein was a homogeneous trimer. Isoelectric focusing of the 80-kDa proteins also produced a single protein band at a pH of 6.5. Inhibition studies on the purified CA extract showed that 50% inhibition of CA activity was obtained using 1 mu M azetazolamide. Polyclonal antibodies against the 26-kDa CA were produced and shown to have a high specific binding to a single polypeptide in soluble protein extracts from Coccomyxa. cells. The same antiserum, however, failed to cross-react with soluble proteins isolated from two different species of green algae, Chlamydomonas reinhardtii and Chlorella vulgaris. Correspondingly, antisera directed against pea chloroplastic CA, extracellular CA from C. reinhardtii and human CAII, showed no cross-hybridisation to the 26-kDa polypeptide in Coccomyxa. The 26-kDa protein was confirmed as being a CA by N-terminal sequencing of two internal polypeptide fragments and alignment of these sequences with that of previously identified CA proteins from several different species.

  • 340. Hjelm, Ulrika
    et al.
    Ögren, Erling
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Umeå Plant Science Centre.
    Photosynthetic responses to short-term and long-term light variation in Pinus sylvestris and Salix dasyclados2004Ingår i: Trees, ISSN 0931-1890, E-ISSN 1432-2285, Vol. 18, s. 622-629Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Trees-Structure and Function: 2004 18:622-629 Pinus sylvestris and Salix dasyclados, which differ in leaf longevity, were compared with respect to four aspects of photosynthetic light use and response: high light acclimation, photoinhibition resistance and recovery, lightfleck exposure and use and chloroplast acclimation across leaves. The first two aspects were examined using seedlings under controlled conditions and the other two were tested using trees in the field. When exposed to high light, shade leaves of Pinus acclimated completely, achieving the same photosynthetic capacities as sun leaves, whereas shade leaves of Salix did not reach sun leaf capacities although the absolute magnitude of their acclimation was larger. Shade leaves of Pinus were also more resistant to photoinhibition than those of Salix. Much of the direct light supplied within the canopy was in the form of rapid fluctuations, lightflecks, for Pinus and Salix alike. They exploited short lightflecks with similar efficiency. The greater proportion of diffuse light in the canopy for Pinus than Salix seems to lead to a lesser degree of differential intra-leaf acclimation of chloroplasts, in turn leading to lower efficiency of photosynthesis under unilateral light as reflected by a lower convexity, rate of bending, of the light-response curve. The differences in light use and responses are discussed in relation to possible differences in characteristics of the long and short-lived leaf.

  • 341. Hjältén, Joakim
    et al.
    Lindau, Anna
    Wennström, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Blomberg, Patrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Witzell, Johanna
    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).
    Ericson, Lars
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Unintentional changes of defence traits in GM trees can influence plant-herbivore interactions2007Ingår i: Basic and Applied Ecology, Vol. 8, nr 3, s. 434-443Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    GM trees hold promises of increased quality and yield and reduced use of herbicides and pesticides but could also have ecological consequences. We investigated whether modification of a non-defensive trait unintentionally influenced plant traits important for plant-herbivore interactions. We found that over-expression of sucrose phosphate synthase (SPS), which is known to increase mesophyll sucrose content and biomass production in GM aspens, also unintentionally induced changes in the concentration of plant phenolics and nitrogen. One of the GM lines, SPS33A, had higher concentrations of salicin, tremuloidin, condensed tannins and nitrogen and lower concentrations of coumaric acid and four flavonoids compared with the isogenic wild type. Line SPS33A was also utilized less by the leaf-beetle Phratora vitellinae than the isogenic wild type. Ecological consequences such as this are not specific to GM trees or GM plants but can occur as a result of the introduction of all introduced new varieties of crops or trees. Nevertheless, the results underline the need to consider these unexpected effects when evaluating both the potential benefits and the potential risks with GM plants, and highlight the need to establish and implement comprehensive product-by-product evaluation protocols for GM plants.

  • 342. Hodges, Michael
    et al.
    Dellero, Younes
    Keech, Olivier
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Betti, Marco
    Raghavendra, Agepati S.
    Sage, Rowan
    Zhu, Xin-Guang
    Allen, Doug K.
    Weber, Andreas P. M.
    Perspectives for a better understanding of the metabolic integration of photorespiration within a complex plant primary metabolism network2016Ingår i: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431, Vol. 67, nr 10, s. 3015-3026Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Recent advances in photorespiration research are described and future priorities to better understand the metabolic integration of the photorespiratory cycle within the complex network of plant primary metabolism are discussed.Photorespiration is an essential high flux metabolic pathway that is found in all oxygen-producing photosynthetic organisms. It is often viewed as a closed metabolic repair pathway that serves to detoxify 2-phosphoglycolic acid and to recycle carbon to fuel the Calvin-Benson cycle. However, this view is too simplistic since the photorespiratory cycle is known to interact with several primary metabolic pathways, including photosynthesis, nitrate assimilation, amino acid metabolism, C-1 metabolism and the Krebs (TCA) cycle. Here we will review recent advances in photorespiration research and discuss future priorities to better understand (i) the metabolic integration of the photorespiratory cycle within the complex network of plant primary metabolism and (ii) the importance of photorespiration in response to abiotic and biotic stresses.

  • 343. HODGINS, RRW
    et al.
    Oquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    PORPHYRIN METABOLISM IN CHILL-STRESSED SEEDLINGS OF SCOTS PINE (PINUS-SYLVESTRIS)1989Ingår i: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 77, nr 4, s. 620-624Artikel i tidskrift (Refereegranskat)
  • 344.
    Hoengenaert, Lennart
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    The role of microtubule binding proteins and post-translational modifications of tubulin during plant vessel formation in Arabidopsis2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In vascular plants, xylem tracheary elements (TEs) form the conducting tubes responsible for the hydro-mineral sap distribution between roots and leaves. Besides their role in sap transport, they also strengthen plant stems allowing upward growth of plants on land. TEs enable plants to resist mechanical constrains by laying down a thick lateral patterned secondary cell wall. The deposition of secondary cell wall material in TEs is strictly controlled by the underlying network of cortical microtubules. Such a microtubular network is a highly dynamic structure that organizes the content of the cell by anchoring or moving cellular components. The dynamic instability of the microtubules is controlled by three main factors. First, the amount of tubulin; the basic building blocks of microtubules, which are necessary for the microtubular assembly or disassembly. Second, microtubule associated proteins (MAPs), proteins capable of binding microtubules, which control microtubule stability and organization. Third, the cytoplasmic energy in GTP levels which regulate the energy dependent assembly of microtubules.

    In this research project we try to decipher if secondary cell wall patterning in TEs is achieved to a process of local microtubule stabilization or destabilization. To accomplish this, we investigated variations in tubulin quantities during TE differentiation in Arabidopsis cell cultures. Our data shows that fluctuation in tubulin levels during TE differentiation are not correlated to the process of secondary cell wall formation. In addition, we investigated how the microtubular state changes between undifferentiating and differentiating cell cultures. Using a new protocol we were able to show that differentiating TEs are enriched with stable microtubules. Since the increase in stability is not correlated to increasing tubulin amounts, other factors such as TE-specific MAPs and post-translational modifications (PTMs) of tubulin, have been investigated.

    Because such PTMs could act as molecular beacons, modifying the properties and behaviour of microtubules or its interacting MAPs, we investigated changes in tubulin-tyrosination during TE differentiation. Our experiments show a positive correlation between tubulin-tyrosination, secondary cell wall formation and the amount of available tubulin. This suggest that the tyrosination of tubulin might act as a signal for microtubular stabilization.

    Furthermore we evaluated the effect of xylem-specific MAPs on TE patterning in planta. Using tDNA mutants of MAP70-5 and MIDD1, respectively stabilizing and destabilizing MAPs, we were able to show that TE secondary cell wall patterning is mainly determined by microtubular stabilization rather than destabilization.

  • 345. Hoffman, Daniel E.
    et al.
    Jonsson, Pär
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. SweTree Technologies AB, Umeå, Sweden.
    Bylesjö, Max
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Almac Diagnostics Ltd, Craigavon, UK.
    Trygg, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Antti, Henrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Eriksson, Maria E.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Moritz, Thomas
    Changes in diurnal patterns within the Populus transcriptome and metabolome in response to photoperiod variation2010Ingår i: Plant, Cell and Environment, ISSN 0140-7791, E-ISSN 1365-3040, Vol. 33, nr 8, s. 1298-1313Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Changes in seasonal photoperiod provides an important environmental signal that affects the timing of winter dormancy in perennial, deciduous, temperate tree species, such as hybrid aspen (Populus tremula x Populus tremuloides). In this species, growth cessation, cold acclimation and dormancy are induced in the autumn by the detection of day-length shortening that occurs at a given critical day length. Important components in the detection of such day-length changes are photoreceptors and the circadian clock, and many plant responses at both the gene regulation and metabolite levels are expected to be diurnal. To directly examine this expectation and study components in these events, here we report transcriptomic and metabolomic responses to a change in photoperiod from long to short days in hybrid aspen. We found about 16% of genes represented on the arrays to be diurnally regulated, as assessed by our pre-defined criteria. Furthermore, several of these genes were involved in circadian-associated processes, including photosynthesis and primary and secondary metabolism. Metabolites affected by the change in photoperiod were mostly involved in carbon metabolism. Taken together, we have thus established a molecular catalog of events that precede a response to winter.

  • 346. HOFSLAGARE, O
    et al.
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    HALLGREN, JE
    PEJRYD, C
    SJOBERG, S
    A COMPARISON BETWEEN 3 METHODS OF MEASURING PHOTOSYNTHETIC UPTAKE OF INORGANIC CARBON IN ALGAE1985Ingår i: Photosynthetica (Praha), ISSN 0300-3604, E-ISSN 1573-9058, Vol. 19, nr 4, s. 578-585Artikel i tidskrift (Refereegranskat)
  • 347. HOFSLAGARE, O
    et al.
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    SJOBERG, S
    CADMIUM EFFECTS ON PHOTOSYNTHESIS AND NITRATE ASSIMILATION IN SCENEDESMUS-OBLIQUUS - A POTENTIOMETRIC STUDY IN AN OPEN CO2-SYSTEM1985Ingår i: Environmental and Experimental Botany, ISSN 0098-8472, E-ISSN 1873-7307, Vol. 25, nr 1, s. 75-82Artikel i tidskrift (Refereegranskat)
  • 348. HOFSLAGARE, O
    et al.
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    SJOBERG, S
    INGRI, N
    A PRECISE POTENTIOMETRIC METHOD FOR DETERMINATION OF ALGAL ACTIVITY IN AN OPEN CO2 SYSTEM1983Ingår i: Plant, Cell and Environment, ISSN 0140-7791, E-ISSN 1365-3040, Vol. 6, nr 3, s. 195-201Artikel i tidskrift (Refereegranskat)
  • 349. HOFSLAGARE, O
    et al.
    SJOBERG, S
    Samuelsson, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    THE EFFECT OF ARSENATE AND ARSENITE ON PHOTOSYNTHESIS IN SCENEDESMUS-OBLIQUUS - A POTENTIOMETRIC STUDY IN A CLOSED CO2-SYSTEM1994Ingår i: Chemical speciation and bioavailability, ISSN 0954-2299, E-ISSN 2047-6523, Vol. 6, nr 4, s. 95-102Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A potentiometric titration method was used to study the adverse effect of arsenate (As(V) and arsenite (As(III) on inorganic carbon uptake in suspensions of the green alga Scenedesmus obliquus. The measurements were performed in a closed CO2-system with diluted synthetic seawater (1 parts per thousand salinity) as ionic medium. Usually, the algal chlorophyll concentration was 0.4 mg dm-3, while the arsenate- and arsenite-concentrations were varied within the limits 0.1 to 200 mumol dm-3. In some experiments arsenate toxicity was studied in the presence of 1 to 100 mumol dm-3 of phosphate (P(V)). With concentrations of arsenate or arsenite less than 0.1 mumol dm-3 no toxic effects were observed. However, at As-concentrations of 200 mumol dm-3, the algal carbon uptake was reduced by 41% with arsenate and 29% with arsenite, i.e., arsenate is more toxic to Scenedesmus obliquus than arsenite. The toxicity of arsenate was negligible in the presence of a ten fold excess of phosphate. This is probably due to chemical similarities between arsenate and phosphate causing competition between the ions for the binding sites. The importance of taking the speciation as well as the buffer capacity of the algal system into account, when calculating the carbon uptake, is also discussed.

  • 350. Hogberg, Mona N.
    et al.
    Briones, Maria J. I.
    Keel, Sonja G.
    Metcalfe, Daniel B.
    Campbell, Catherine
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Midwood, Andrew J.
    Thornton, Barry
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Linder, Sune
    Nasholm, Torgny
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hogberg, Peter
    Quantification of effects of season and nitrogen supply on tree below-ground carbon transfer to ectomycorrhizal fungi and other soil organisms in a boreal pine forest2010Ingår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 187, nr 2, s. 485-493Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    P>The flux of carbon from tree photosynthesis through roots to ectomycorrhizal (ECM) fungi and other soil organisms is assumed to vary with season and with edaphic factors such as nitrogen availability, but these effects have not been quantified directly in the field. To address this deficiency, we conducted high temporal-resolution tracing of 13C from canopy photosynthesis to different groups of soil organisms in a young boreal Pinus sylvestris forest. There was a 500% higher below-ground allocation of plant C in the late (August) season compared with the early season (June). Labelled C was primarily found in fungal fatty acid biomarkers (and rarely in bacterial biomarkers), and in Collembola, but not in Acari and Enchytraeidae. The production of sporocarps of ECM fungi was totally dependent on allocation of recent photosynthate in the late season. There was no short-term (2 wk) effect of additions of N to the soil, but after 1 yr, there was a 60% reduction of below-ground C allocation to soil biota. Thus, organisms in forest soils, and their roles in ecosystem functions, appear highly sensitive to plant physiological responses to two major aspects of global change: changes in seasonal weather patterns and N eutrophication.

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