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  • 1.
    Bylesjö, Max
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Segura, Vincent
    Soolanayakanahally, Raju Y
    Rae, Anne M
    Trygg, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gustafsson, Petter
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Street, Nathaniel R
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    LAMINA: a tool for rapid quantification of leaf size and shape parameters2008In: BMC Plant Biology, ISSN 1471-2229, Vol. 8, no 82, p. 1-9Article in journal (Refereed)
    Abstract [en]

    Background

    An increased understanding of leaf area development is important in a number of fields: in food and non-food crops, for example short rotation forestry as a biofuels feedstock, leaf area is intricately linked to biomass productivity; in paleontology leaf shape characteristics are used to reconstruct paleoclimate history. Such fields require measurement of large collections of leaves, with resulting conclusions being highly influenced by the accuracy of the phenotypic measurement process.

    Results

    We have developed LAMINA (Leaf shApe deterMINAtion), a new tool for the automated analysis of images of leaves. LAMINA has been designed to provide classical indicators of leaf shape (blade dimensions) and size (area), which are typically required for correlation analysis to biomass productivity, as well as measures that indicate asymmetry in leaf shape, leaf serration traits, and measures of herbivory damage (missing leaf area). In order to allow Principal Component Analysis (PCA) to be performed, the location of a chosen number of equally spaced boundary coordinates can optionally be returned.

    Conclusion

    We demonstrate the use of the software on a set of 500 scanned images, each containing multiple leaves, collected from a common garden experiment containing 116 clones of Populus tremula (European trembling aspen) that are being used for association mapping, as well as examples of leaves from other species. We show that the software provides an efficient and accurate means of analysing leaf area in large datasets in an automated or semi-automated work flow.

  • 2.
    de La Torre, Amanda R
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Birol, Inanc
    Bousquet, Jean
    Ingvarsson, Pär K
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Jones, Steven J. M
    Keeling, Christopher I
    MacKay, John
    Nilsson, Ove
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Ritland, Kermit
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Yanchuk, Alvin
    Zerbe, Philipp
    Bohlmann, Jörg
    Insights into conifer giga-genomes2014In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 166, no 4, p. 1724-1732Article in journal (Refereed)
    Abstract [en]

    Insights from sequenced genomes of major land plant lineages have advanced research in almost every aspect of plant biology. Until recently, however, assembled genome sequences of gymnosperms have been missing from this picture. Conifers of the pine family (Pinaceae) are a group of gymnosperms that dominate large parts of the world's forests. Despite their ecological and economic importance, conifers seemed long out of reach for complete genome sequencing, due in part to their enormous genome size (20-30 Gb) and the highly repetitive nature of their genomes. Technological advances in genome sequencing and assembly enabled the recent publication of three conifer genomes: white spruce (Picea glauca), Norway spruce (Picea abies), and loblolly pine (Pinus taeda). These genome sequences revealed distinctive features compared with other plant genomes and may represent a window into the past of seed plant genomes. This Update highlights recent advances, remaining challenges, and opportunities in light of the publication of the first conifer and gymnosperm genomes.

  • 3.
    Delhomme, Nicolas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Sundström, Görel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Uppsala Univ, Dept Med Biochem & Microbiol, Sci Life Lab, Uppsala, Sweden.
    Zamani, Neda
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Uppsala Univ, Dept Med Biochem & Microbiol, Sci Life Lab, Uppsala, Sweden.
    Lantz, Henrik
    Lin, Yao-Cheng
    Hvidsten, Torgeir R.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Norwegian Univ Life Sci, Dept Chem Biotechnol & Food Sci, As, Norway.
    Hoppner, Marc P.
    Jern, Patric
    Van de Peer, Yves
    Lundeberg, Joakim
    Grabherr, Manfred G.
    Street, Nathaniel R.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Serendipitous Meta-Transcriptomics: The Fungal Community of Norway Spruce (Picea abies)2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 9, article id e0139080Article in journal (Refereed)
    Abstract [en]

    After performing de novo transcript assembly of >1 billion RNA-Sequencing reads obtained from 22 samples of different Norway spruce (Picea abies) tissues that were not surface sterilized, we found that assembled sequences captured a mix of plant, lichen, and fungal transcripts. The latter were likely expressed by endophytic and epiphytic symbionts, indicating that these organisms were present, alive, and metabolically active. Here, we show that these serendipitously sequenced transcripts need not be considered merely as contamination, as is common, but that they provide insight into the plant's phyllosphere. Notably, we could classify these transcripts as originating predominantly from Dothideomycetes and Leotiomycetes species, with functional annotation of gene families indicating active growth and metabolism, with particular regards to glucose intake and processing, as well as gene regulation.

  • 4. Grimberg, Åsa
    et al.
    Lager, Ida
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Robinson, Kathryn M
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Marttila, Salla
    Mähler, Niklas
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Ingvarsson, Pär K.
    Bhalerao, Rishikesh P.
    Storage lipid accumulation is controlled by photoperiodic signal acting via regulators of growth cessation and dormancy in hybrid aspen2018In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 219, no 2, p. 619-630Article in journal (Refereed)
    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.

  • 5.
    Haas, Julia Christa
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Sjödin, Andreas
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Division of CBRN Security and Defence, FOI–Swedish Defence Research Agency, SE-906 21, Umeå, Sweden.
    Lee, Natuschka
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Högberg, Mona N
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), SE-901 83, Umeå, Sweden.
    Näsholm, Torgny
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), SE-901 83, Umeå, Sweden;Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, SLU, SE-901 85, Umeå, Sweden.
    Hurry, Vaughan
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, SLU, SE-901 85, Umeå, Sweden.
    Microbial community response to growing season and plant nutrient optimisation in a boreal Norway spruce forest2018In: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 125, p. 197-209Article in journal (Refereed)
    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.

  • 6.
    Ingvarsson, Pär K.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Hvidsten, Torgeir R.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1432,As, Norway.
    Street, Nathaniel R.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Towards integration of population and comparative genomics in forest trees2016In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 212, no 2, p. 338-344Article, review/survey (Refereed)
    Abstract [en]

    The past decade saw the initiation of an ongoing revolution in sequencing technologies that is transforming all fields of biology. This has been driven by the advent and widespread availability of high-throughput, massively parallel short-read sequencing (MPS) platforms. These technologies have enabled previously unimaginable studies, including draft assemblies of the massive genomes of coniferous species and population-scale resequencing. Transcriptomics studies have likewise been transformed, with RNA-sequencing enabling studies in nonmodel organisms, the discovery of previously unannotated genes (novel transcripts), entirely new classes of RNAs and previously unknown regulatory mechanisms. Here we touch upon current developments in the areas of genome assembly, comparative regulomics and population genetics as they relate to studies of forest tree species.

  • 7.
    Ingvarsson, Pär K
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Street, Nathaniel R
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Association genetics of complex traits in plants2011In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 189, no 4, p. 909-922Article in journal (Refereed)
    Abstract [en]

    Association mapping is rapidly becoming the main method for dissecting the genetic architecture of complex traits in plants. Currently most association mapping studies in plants are preformed using sets of genes selected to be putative candidates for the trait of interest, but rapid developments in genomics will allow for genome-wide mapping in virtually any plant species in the near future. As the costs for genotyping are decreasing, the focus has shifted towards phenotyping. In plants, clonal replication and/or inbred lines allows for replicated phenotyping under many different environmental conditions. Reduced sequencing costs will increase the number of studies that use RNA sequencing data to perform expression quantitative trait locus (eQTL) mapping, which will increase our knowledge of how gene expression variation contributes to phenotypic variation. Current population sizes used in association mapping studies are modest in size and need to be greatly increased if mutations explaining less than a few per cent of the phenotypic variation are to be detected. Association mapping has started to yield insights into the genetic architecture of complex traits in plants, and future studies with greater genome coverage will help to elucidate how plants have managed to adapt to a wide variety of environmental conditions.

  • 8.
    Jokipii-Lukkari, Soile
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Sveriges Lantbruksuniversitet, SE-901 83 Umeå, Sweden.
    Delhomme, Nicolas
    Schiffthaler, Bastian
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Mannapperuma, Chanaka
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Prestele, Jakob
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Nilsson, Ove
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Tuominen, Hannele
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Transcriptional Roadmap to Seasonal Variation in Wood Formation of Norway Spruce2018In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 176, no 4, p. 2851-2870Article in journal (Refereed)
    Abstract [en]

    Seasonal cues influence several aspects of the secondary growth of tree stems, including cambial activity, wood chemistry, and transition to latewood formation. We investigated seasonal changes in cambial activity, secondary cell wall formation, and tracheid cell death in woody tissues of Norway spruce (Picea abies) throughout one seasonal cycle. RNA sequencing was performed simultaneously in both the xylem and cambium/phloem tissues of the stem. Principal component analysis revealed gradual shifts in the transcriptomes that followed a chronological order throughout the season. A notable remodeling of the transcriptome was observed in the winter, with many genes having maximal expression during the coldest months of the year. A highly coexpressed set of monolignol biosynthesis genes showed high expression during the period of secondary cell wall formation as well as a second peak in midwinter. This midwinter peak in expression did not trigger lignin deposition, as determined by pyrolysis-gas chromatography/mass spectrometry. Coexpression consensus network analyses suggested the involvement of transcription factors belonging to the ASYMMETRIC LEAVES2/LATERAL ORGAN BOUNDARIES and MYELOBLASTOSIS-HOMEOBOX families in the seasonal control of secondary cell wall formation of tracheids. Interestingly, the lifetime of the latewood tracheids stretched beyond the winter dormancy period, correlating with a lack of cell death-related gene expression. Our transcriptomic analyses combined with phylogenetic and microscopic analyses also identified the cellulose and lignin biosynthetic genes and putative regulators for latewood formation and tracheid cell death in Norway spruce, providing a toolbox for further physiological and functional assays of these important phase transitions.

  • 9.
    Klevebring, Daniel
    et al.
    School of Biotechnology, Division of Gene Technology, AlbaNova University Center, Royal Institute of Technology, 106 91 Stockholm, Sweden.
    Street, Nathaniel R
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Fahlgren, Noah
    Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon 97331, USA.
    Kasschau, Kristin D
    Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon 97331, USA.
    Carrington, James C
    Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon 97331, USA.
    Lundeberg, Joakim
    School of Biotechnology, Division of Gene Technology, AlbaNova University Center, Royal Institute of Technology, 106 91 Stockholm, Sweden.
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Genome-wide profiling of populus small RNAs2009In: BMC Genomics, ISSN 1471-2164, E-ISSN 1471-2164, Vol. 10, p. 620-Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Short RNAs, and in particular microRNAs, are important regulators of gene expression both within defined regulatory pathways and at the epigenetic scale. We investigated the short RNA (sRNA) population (18-24 nt) of the transcriptome of green leaves from the sequenced Populus trichocarpa using a concatenation strategy in combination with 454 sequencing. RESULTS: The most abundant size class of sRNAs were 24 nt. Long Terminal Repeats were particularly associated with 24 nt sRNAs. Additionally, some repetitive elements were associated with 22 nt sRNAs. We identified an sRNA hot-spot on chromosome 19, overlapping a region containing both the proposed sex-determining locus and a major cluster of NBS-LRR genes. A number of phased siRNA loci were identified, a subset of which are predicted to target PPR and NBS-LRR disease resistance genes, classes of genes that have been significantly expanded in Populus. Additional loci enriched for sRNA production were identified and characterised. We identified 15 novel predicted microRNAs (miRNAs), including miRNA*sequences, and identified a novel locus that may encode a dual miRNA or a miRNA and short interfering RNAs (siRNAs). CONCLUSIONS: The short RNA population of P. trichocarpa is at least as complex as that of Arabidopsis thaliana. We provide a first genome-wide view of short RNA production for P. trichocarpa and identify new, non-conserved miRNAs.

  • 10. Lafon-Placette, Clément
    et al.
    Faivre-Rampant, Patricia
    Delaunay, Alain
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Brignolas, Franck
    Maury, Stéphane
    Methylome of DNase I sensitive chromatin in Populus trichocarpa shoot apical meristematic cells: a simplified approach revealing characteristics of gene-body DNA methylation in open chromatin state2013In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 197, no 2, p. 416-430Article in journal (Refereed)
    Abstract [en]

    DNA methylation is involved in the control of plant development and adaptation to the environment through modifications of chromatin compaction and gene expression. In poplar (Populus trichocarpa), a perennial plant, variations in DNA methylation have been reported between genotypes and tissues or in response to drought. Nevertheless, the relationships between gene-body DNA methylation, gene expression and chromatin compaction still need clarification.

    Here, DNA methylation was mapped in the noncondensed chromatin fraction from P. trichocarpa shoot apical meristematic cells, the center of plant morphogenesis, where DNA methylation variations could influence the developmental trajectory. DNase I was used to isolate the noncondensed chromatin fraction. Methylated sequences were immunoprecipitated, sequenced using Illumina/Solexa technology and mapped on the v2.0 poplar genome. Bisulfite sequencing of candidate sequences was used to confirm mapping data and to assess cytosine contexts and methylation levels.

    While the methylated DNase I hypersensitive site fraction covered 1.9% of the poplar genome, it contained sequences corresponding to 74% of poplar gene models, mostly exons. The level and cytosine context of gene-body DNA methylation varied with the structural characteristics of the genes.

    Taken together, our data show that DNA methylation is widespread and variable among genes in open chromatin of meristematic cells, in agreement with a role in their developmental trajectory.

  • 11. Laitinen, Teresa
    et al.
    Morreel, Kris
    Delhomme, Nicolas
    Gauthier, Adrien
    Schiffthaler, Bastian
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Nickolov, Kaloian
    Brader, Günter
    Lim, Kean-Jin
    Teeri, Teemu H.
    Street, Nathaniel R.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Boerjan, Wout
    Kärkönen, Anna
    A Key Role for Apoplastic H2O2 in Norway Spruce Phenolic Metabolism2017In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 174, no 3, p. 1449-1475Article in journal (Refereed)
    Abstract [en]

    Apoplastic events such as monolignol oxidation and lignin polymerization are difficult to study in intact trees. To investigate the role of apoplastic hydrogen peroxide (H2O2) in gymnosperm phenolic metabolism, an extracellular lignin-forming cell culture of Norway spruce (Picea abies) was used as a research model. Scavenging of apoplastic H2O2 by potassium iodide repressed lignin formation, in line with peroxidases activating monolignols for lignin polymerization. Time-course analyses coupled to candidate substrate-product pair network propagation revealed differential accumulation of low-molecular-weight phenolics, including (glycosylated) oligolignols, (glycosylated) flavonoids, and proanthocyanidins, in lignin-forming and H2O2-scavenging cultures and supported that monolignols are oxidatively coupled not only in the cell wall but also in the cytoplasm, where they are coupled to other monolignols and proanthocyanidins. Dilignol glycoconjugates with reduced structures were found in the culture medium, suggesting that cells are able to transport glycosylated dilignols to the apoplast. Transcriptomic analyses revealed that scavenging of apoplastic H2O2 resulted in remodulation of the transcriptome, with reduced carbon flux into the shikimate pathway propagating down to monolignol biosynthesis. Aggregated coexpression network analysis identified candidate enzymes and transcription factors for monolignol oxidation and apoplastic H2O2 production in addition to potential H2O2 receptors. The results presented indicate that the redox state of the apoplast has a profound influence on cellular metabolism.

  • 12.
    Liu, Lijun
    et al.
    Davis, CA, USA.
    Ramsay, Trevor
    Davis, CA, USA.
    Zinkgraf, Matthew
    Davis, CA, USA.
    Sundell, David
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Street, Nathaniel Robert
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Filkov, Vladimir
    Davis, CA, USA.
    Groover, Andrew
    Davis, CA, USA.
    A resource for characterizing genome-wide binding and putative target genes of transcription factors expressed during secondary growth and wood formation in Populus2015In: The Plant Journal, ISSN 0960-7412, E-ISSN 1365-313X, Vol. 82, no 5, p. 887-898Article in journal (Refereed)
    Abstract [en]

    Identifying transcription factor target genes is essential for modeling the transcriptional networks underlying developmental processes. Here we report a chromatin immunoprecipitation sequencing (ChIP-seq) resource consisting of genome-wide binding regions and associated putative target genes for four Populus homeodomain transcription factors expressed during secondary growth and wood formation. Software code (programs and scripts) for processing the Populus ChIP-seq data are provided within a publically available iPlant image, including tools for ChIP-seq data quality control and evaluation adapted from the human Encyclopedia of DNA Elements (ENCODE) project. Basic information for each transcription factor (including members of Class I KNOX, Class III HD ZIP, BEL1-like families) binding are summarized, including the number and location of binding regions, distribution of binding regions relative to gene features, associated putative target genes, and enriched functional categories of putative target genes. These ChIP-seq data have been integrated within the Populus Genome Integrative Explorer (PopGenIE) where they can be analyzed using a variety of web-based tools. We present an example analysis that shows preferential binding of transcription factor ARBORKNOX1 to the nearest neighbor genes in a pre-calculated co-expression network module, and enrichment for meristem-related genes within this module including multiple orthologs of Arabidopsis KNOTTED-like Arabidopsis 2/6.

  • 13.
    Netotea, Sergiu
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Sundell, David
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Street, Nathaniel R.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Hvidsten, Torgeir R.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    ComPlEx: conservation and divergence of co-expression networks in A. thaliana, Populus and O. sativa2014In: BMC Genomics, ISSN 1471-2164, E-ISSN 1471-2164, Vol. 15, p. 106-Article in journal (Refereed)
    Abstract [en]

    Background: Divergence in gene regulation has emerged as a key mechanism underlying species differentiation. Comparative analysis of co-expression networks across species can reveal conservation and divergence in the regulation of genes. Results: We inferred co-expression networks of A. thaliana, Populus spp. and O. sativa using state-of-the-art methods based on mutual information and context likelihood of relatedness, and conducted a comprehensive comparison of these networks across a range of co-expression thresholds. In addition to quantifying gene-gene link and network neighbourhood conservation, we also applied recent advancements in network analysis to do cross-species comparisons of network properties such as scale free characteristics and gene centrality as well as network motifs. We found that in all species the networks emerged as scale free only above a certain co-expression threshold, and that the high-centrality genes upholding this organization tended to be conserved. Network motifs, in particular the feed-forward loop, were found to be significantly enriched in specific functional subnetworks but where much less conserved across species than gene centrality. Although individual gene-gene co-expression had massively diverged, up to similar to 80% of the genes still had a significantly conserved network neighbourhood. For genes with multiple predicted orthologs, about half had one ortholog with conserved regulation and another ortholog with diverged or non-conserved regulation. Furthermore, the most sequence similar ortholog was not the one with the most conserved gene regulation in over half of the cases. Conclusions: We have provided a comprehensive analysis of gene regulation evolution in plants and built a web tool for Comparative analysis of Plant co-Expression networks (ComPlEx, http:// complex. plantgenie. org/). The tool can be particularly useful for identifying the ortholog with the most conserved regulation among several sequence-similar alternatives and can thus be of practical importance in e. g. finding candidate genes for perturbation experiments.

  • 14.
    Norman, Anita J.
    et al.
    Sveriges lantbruksuniversitet.
    Street, Nathaniel Robert
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Spong, Goran
    Sveriges lantbruksuniversitet.
    De Novo SNP Discovery in the Scandinavian Brown Bear (Ursus arctos)2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 11, p. e81012-Article in journal (Refereed)
    Abstract [en]

    Information about relatedness between individuals in wild populations is advantageous when studying evolutionary, behavioural and ecological processes. Genomic data can be used to determine relatedness between individuals either when no prior knowledge exists or to confirm suspected relatedness. Here we present a set of 96 SNPs suitable for inferring relatedness for brown bears (Ursus arctos) within Scandinavia. We sequenced reduced representation libraries from nine individuals throughout the geographic range. With consensus reads containing putative SNPs, we applied strict filtering criteria with the aim of finding only high-quality, highly-informative SNPs. We tested 150 putative SNPs of which 96% were validated on a panel of 68 individuals. Ninety-six of the validated SNPs with the highest minor allele frequency were selected. The final SNP panel includes four mitochondrial markers, two monomorphic Y-chromosome sex-determination markers, three X-chromosome SNPs and 87 autosomal SNPs. From our validation sample panel, we identified two previously known parent-offspring dyads with reasonable accuracy. This panel of SNPs is a promising tool for inferring relatedness in the brown bear population in Scandinavia.

  • 15. Nystedt, Bjorn
    et al.
    Street, Nathaniel Robert
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Wetterbom, Anna
    Zuccolo, Andrea
    Lin, Yao-Cheng
    Scofield, Douglas G.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Vezzi, Francesco
    Delhomme, Nicolas
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Giacomello, Stefania
    Alexeyenko, Andrey
    Vicedomini, Riccardo
    Sahlin, Kristoffer
    Sherwood, Ellen
    Elfstrand, Malin
    Gramzow, Lydia
    Holmberg, Kristina
    Hallman, Jimmie
    Keech, Olivier
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Klasson, Lisa
    Koriabine, Maxim
    Kucukoglu, Melis
    Kaller, Max
    Luthman, Johannes
    Lysholm, Fredrik
    Niittyla, Totte
    Olson, Ake
    Rilakovic, Nemanja
    Ritland, Carol
    Rossello, Josep A.
    Sena, Juliana
    Svensson, Thomas
    Talavera-Lopez, Carlos
    Theissen, Guenter
    Tuominen, Hannele
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Vanneste, Kevin
    Wu, Zhi-Qiang
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Zhang, Bo
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Zerbe, Philipp
    Arvestad, Lars
    Bhalerao, Rishikesh
    Bohlmann, Joerg
    Bousquet, Jean
    Gil, Rosario Garcia
    Hvidsten, Torgeir R.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    de Jong, Pieter
    MacKay, John
    Morgante, Michele
    Ritland, Kermit
    Sundberg, Bjorn
    Thompson, Stacey Lee
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Van de Peer, Yves
    Andersson, Bjorn
    Nilsson, Ove
    Ingvarsson, Pär K.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Lundeberg, Joakim
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    The Norway spruce genome sequence and conifer genome evolution2013In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 497, no 7451, p. 579-584Article in journal (Refereed)
    Abstract [en]

    Conifers have dominated forests for more than 200 million years and are of huge ecological and economic importance. Here we present the draft assembly of the 20-gigabase genome of Norway spruce (Picea abies), the first available for any gymnosperm. The number of well-supported genes (28,354) is similar to the >100 times smaller genome of Arabidopsis thaliana, and there is no evidence of a recent whole-genome duplication in the gymnosperm lineage. Instead, the large genome size seems to result from the slow and steady accumulation of a diverse set of long-terminal repeat transposable elements, possibly owing to the lack of an efficient elimination mechanism. Comparative sequencing of Pinus sylvestris, Abies sibirica, Juniperus communis, Taxus baccata and Gnetum gnemon reveals that the transposable element diversity is shared among extant conifers. Expression of 24-nucleotide small RNAs, previously implicated in transposable element silencing, is tissue-specific and much lower than in other plants. We further identify numerous long (>10,000 base pairs) introns, gene-like fragments, uncharacterized long non-coding RNAs and short RNAs. This opens up new genomic avenues for conifer forestry and breeding.

  • 16.
    Pacurar, Daniel Ioan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Pacurar, Monica Lacramioara
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Bussell, John Desmond
    Pop, Tiberia Ioana
    Gutierrez, Laurent
    Bellini, Catherine
    A collection of INDEL markers for map-based cloning in seven Arabidopsis accessions2012In: Journal of Experimental Botany, ISSN 0022-0957, E-ISSN 1460-2431, Vol. 63, no 7, p. 2491-2501Article in journal (Refereed)
    Abstract [en]

    The availability of a comprehensive set of resources including an entire annotated reference genome, sequenced alternative accessions, and a multitude of marker systems makes Arabidopsis thaliana an ideal platform for genetic mapping. PCR markers based on INsertions/DELetions (INDELs) are currently the most frequently used polymorphisms. For the most commonly used mapping combination, ColumbiaxLandsberg erecta (Col-0xLer-0), the Cereon polymorphism database is a valuable resource for the generation of polymorphic markers. However, because the number of markers available in public databases for accessions other than Col-0 and Ler-0 is extremely low, mapping using other accessions is far from straightforward. This issue arose while cloning mutations in the Wassilewskija (Ws-4) background. In this work, approaches are described for marker generation in Ws-4 x Col-0. Complementary strategies were employed to generate 229 INDEL markers. Firstly, existing Col-0/Ler-0 Cereon predicted polymorphisms were mined for transferability to Ws-4. Secondly, Ws-0 ecotype Illumina sequence data were analyzed to identify INDELs that could be used for the development of PCR-based markers for Col-0 and Ws-4. Finally, shotgun sequencing allowed the identification of INDELs directly between Col-0 and Ws-4. The polymorphism of the 229 markers was assessed in seven widely used Arabidopsis accessions, and PCR markers that allow a clear distinction between the diverged Ws-0 and Ws-4 accessions are detailed. The utility of the markers was demonstrated by mapping more than 35 mutations in a Col-0xWs-4 combination, an example of which is presented here. The potential contribution of next generation sequencing technologies to more traditional map-based cloning is discussed.

  • 17. Ratke, Christine
    et al.
    Terebieniec, Barbara K.
    Department of Forest Genetics and Plant Physiology, SLU, Umeå Plant Science Centre (UPSC), Umeå, Sweden.
    Winestrand, Sandra
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Derba-Maceluch, Marta
    Department of Forest Genetics and Plant Physiology, SLU, Umeå Plant Science Centre (UPSC), Umeå, Sweden.
    Grahn, Thomas
    Schiffthaler, Bastian
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Ulvcrona, Thomas
    Ozparpucu, Merve
    Rüggeberg, Markus
    Lundqvist, Sven-Olof
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mellerowicz, Ewa J.
    Downregulating aspen xylan biosynthetic GT43 genes in developing wood stimulates growth via reprograming of the transcriptome2018In: New Phytologist, ISSN 0028-646X, Vol. 219, no 1, p. 230-245Article in journal (Refereed)
    Abstract [en]

    Xylan is one of the main compounds determining wood properties in hardwood species. The xylan backbone is thought to be synthesized by a synthase complex comprising two members of the GT43 family. We downregulated all GT43 genes in hybrid aspen (Populus tremulaxtremuloides) to understand their involvement in xylan biosynthesis.

    All three clades of the GT43 family were targeted for downregulation using RNA interference individually or in different combinations, either constitutively or specifically in developing wood.

    Simultaneous downregulation in developing wood of the B (IRX9) and C (IRX14) clades resulted in reduced xylan Xyl content relative to reducing end sequence, supporting their role in xylan backbone biosynthesis. This was accompanied by a higher lignocellulose saccharification efficiency. Unexpectedly, GT43 suppression in developing wood led to an overall growth stimulation, xylem cell wall thinning and a shift in cellulose orientation. Transcriptome profiling of these transgenic lines indicated that cell cycling was stimulated and secondary wall biosynthesis was repressed. We suggest that the reduced xylan elongation is sensed by the cell wall integrity surveying mechanism in developing wood.

    Our results show that wood-specific suppression of xylan-biosynthetic GT43 genes activates signaling responses, leading to increased growth and improved lignocellulose saccharification.

  • 18.
    Robinson, Kathryn
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Delhomme, Nicolas
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Mahler, Niklas
    Schiffthaler, Bastian
    Önskog, Jenny
    Albrectsen, Benedicte
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Ingvarsson, Pär
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Hvidsten, Torgeir
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Populus tremula (European aspen) shows no evidence of sexual dimorphism2014In: BMC Plant Biology, ISSN 1471-2229, E-ISSN 1471-2229, Vol. 14, p. 276-Article in journal (Refereed)
    Abstract [en]

    Background:

    Evolutionary theory suggests that males and females may evolve sexually dimorphic phenotypic and biochemical traits concordant with each sex having different optimal strategies of resource investment to maximise reproductive success and fitness. Such sexual dimorphism would result in sex biased gene expression patterns in non-floral organs for autosomal genes associated with the control and development of such phenotypic traits.

    Results:

    We examined morphological, biochemical and herbivory traits to test for sexually dimorphic resource allocation strategies within collections of sexually mature and immature Populus tremula (European aspen) trees. In addition we profiled gene expression in mature leaves of sexually mature wild trees using whole-genome oligonucleotide microarrays and RNA-Sequencing.

    Conclusions:

    We found no evidence of sexual dimorphism or differential resource investment strategies between males and females in either sexually immature or mature trees. Similarly, single-gene differential expression and machine learning approaches revealed no evidence of large-scale sex biased gene expression. However, two significantly differentially expressed genes were identified from the RNA-Seq data, one of which is a robust diagnostic marker of sex in P. tremula.

  • 19. Sahlin, Kristoffer
    et al.
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Lundeberg, Joakim
    Arvestad, Lars
    Improved gap size estimation for scaffolding algorithms2012In: Bioinformatics, ISSN 1367-4803, E-ISSN 1367-4811, Vol. 28, no 17, p. 2215-2222Article in journal (Refereed)
    Abstract [en]

    Motivation: One of the important steps of genome assembly is scaffolding, in which contigs are linked using information from read-pairs. Scaffolding provides estimates about the order, relative orientation and distance between contigs. We have found that contig distance estimates are generally strongly biased and based on false assumptions. Since erroneous distance estimates can mislead in subsequent analysis, it is important to provide unbiased estimation of contig distance.

    Results: In this article, we show that state-of-the-art programs for scaffolding are using an incorrect model of gap size estimation. We discuss why current maximum likelihood estimators are biased and describe what different cases of bias we are facing. Furthermore, we provide a model for the distribution of reads that span a gap and derive the maximum likelihood equation for the gap length. We motivate why this estimate is sound and show empirically that it outperforms gap estimators in popular scaffolding programs. Our results have consequences both for scaffolding software, structural variation detection and for library insert-size estimation as is commonly performed by read aligners.

  • 20.
    Sjödin, Andreas
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Street, Nathaniel R
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Sandberg, Göran
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Gustafsson, Petter
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    The populus genome integrative explorer (PopGenIE): a new resource for exploring the populus genome2009In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 182, no 4, p. 1013-1025Article in journal (Refereed)
    Abstract [en]

    * Populus has become an important model plant system. However, utilization of the increasingly extensive collection of genetics and genomics data created by the community is currently hindered by the lack of a central resource, such as a model organism database (MOD). Such MODs offer a single entry point to the collection of resources available within a model system, typically including tools for exploring and querying those resources. * As a starting point to overcoming the lack of such an MOD for Populus, we present the Populus Genome Integrative Explorer (PopGenIE), an integrated set of tools for exploring the Populus genome and transcriptome. The resource includes genome, synteny and quantitative trait locus (QTL) browsers for exploring genetic data. * Expression tools include an electronic fluorescent pictograph (eFP) browser, expression profile plots, co-regulation within collated transcriptomics data sets, and identification of over-represented functional categories and genomic hotspot locations. A number of collated transcriptomics data sets are made available in the eFP browser to facilitate functional exploration of gene function. Additional homology and data extraction tools are provided. * PopGenIE significantly increases accessibility to Populus genomics resources and allows exploration of transcriptomics data without the need to learn or understand complex statistical analysis methods. PopGenIE is available at http://www.popgenie.org or via http://www.populusgenome.info.

  • 21. Soolanayakanahally, Raju Y
    et al.
    Guy, Robert D
    Street, Nathaniel R
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Robinson, Kathryn M
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Silim, Salim N.
    Albrectsen, Benedicte R
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Comparative physiology of allopatric Populus species: geographic clines in photosynthesis, height growth, and carbon isotope discrimination in common gardens2015In: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 6, article id 528Article in journal (Refereed)
    Abstract [en]

    Populus species with wide geographic ranges display strong adaptation to local environments. We studied the clinal patterns in phenology and ecophysiology in allopatric Populus species adapted to similar environments on different continents under common garden settings. As a result of climatic adaptation, both Populus tremula L. and Populus balsamifera L. display latitudinal clines in photosynthetic rates (A), whereby high-latitude trees of P. tremula had higher A compared to low-latitude trees and nearly so in P. balsamifera (p = 0.06). Stomatal conductance (g(S)) and chlorophyll content index (CCI) follow similar latitudinal trends. However, foliar nitrogen was positively correlated with latitude in P. balsamifera and negatively correlated in P. tremula. No significant trends in carbon isotope composition of the leaf tissue (delta C-13) were observed for both species; but, intrinsic water-use efficiency (WUEi) was negatively correlated with the latitude of origin in P. balsamifera. In spite of intrinsically higher A, high-latitude trees in both common gardens accomplished less height gain as a result of early bud set. Thus, shoot biomass was determined by height elongation duration (HED), which was well approximated by the number of days available for free growth between bud flush and bud set. We highlight the shortcoming of unreplicated outdoor common gardens for tree improvement and the crucial role of photoperiod in limiting height growth, further complicating interpretation of other secondary effects.

  • 22.
    Stachula, Paulina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Vergara, Alexander
    Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences.
    Delhomme, Nicolas
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Hurry, Vaughan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Essential processes determining life in cold in Arabidopsis thalianaManuscript (preprint) (Other academic)
  • 23.
    Street, Nathaniel Robert
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Populus Short RNAs2011In: Non Coding RNAs in Plants / [ed] Volker A. Erdmann, Jan Barciszewski, Berlin: Springer Berlin/Heidelberg, 2011, p. 375-384Chapter in book (Other academic)
    Abstract [en]

    As a model species, Populus offers opportunities to study processes unique to woody, perennial species, such as seasonal senescence, dormancy and wood production. As a long-lived species, it is also possible that different adaptive survival strategies have been selected for in comparison to annual species. To date, a number of miRNAs have been shown to be differentially expressed or induced in response to abiotic stress and to be involved in processes such as wood development. Although Populus has not yet been extensively profiled for short RNAs, the available data has been used to identify a number of phased loci and to characterise association of short RNA and repetitive elements in the genome. There appears to be a hotspot of sRNA production on chromosome 19, which contains the proposed sex-determining locus.

  • 24.
    Street, Nathaniel Robert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Hvidsten, Torgeir
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    A systems biology model of the regulatory network in Populus leaves reveals interacting regulators and conserved regulation2011In: BMC Plant Biology, ISSN 1471-2229, E-ISSN 1471-2229, Vol. 11, p. 13-Article in journal (Refereed)
    Abstract [en]

    We outline a computationally inferred model of the regulatory network of Populus leaves, and show how treating genes as interacting, rather than individual, entities identifies new regulators compared to traditional genomics analysis. Although systems biology models should be used with care considering the complexity of regulatory programs and the limitations of current genomics data, methods describing interactions can provide hypotheses about the underlying cause of emergent properties and are needed if we are to identify target genes other than those constituting the "low hanging fruit" of genomic analysis.

  • 25.
    Street, Nathaniel Robert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Sjödin, Andreas
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Bylesjö, Max
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gustafsson, Petter
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Trygg, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    A cross-species transcriptomics approach to identify genes involved in leaf development2008In: BMC Genomics, ISSN 1471-2164, E-ISSN 1471-2164, Vol. 9, no 1, p. 539-Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    Background

    We have made use of publicly available gene expression data to identify transcription factors and transcriptional modules (regulons) associated with leaf development in Populus. Different tissue types were compared to identify genes informative in the discrimination of leaf and non-leaf tissues. Transcriptional modules within this set of genes were identified in a much wider set of microarray data collected from leaves in a number of developmental, biotic, abiotic and transgenic experiments.

    Results

    Transcription factors that were over represented in leaf EST libraries and that were useful for discriminating leaves from other tissues were identified, revealing that the C2C2-YABBY, CCAAT-HAP3 and 5, MYB, and ZF-HD families are particularly important in leaves. The expression of transcriptional modules and transcription factors was examined across a number of experiments to select those that were particularly active during the early stages of leaf development. Two transcription factors were found to collocate to previously published Quantitative Trait Loci (QTL) for leaf length. We also found that miRNA family 396 may be important in the control of leaf development, with three members of the family collocating with clusters of leaf development QTL.

    Conclusion

    This work provides a set of candidate genes involved in the control and processes of leaf development. This resource can be used for a wide variety of purposes such as informing the selection of candidate genes for association mapping or for the selection of targets for reverse genetics studies to further understanding of the genetic control of leaf size and shape.

  • 26.
    Street, Nathaniel Robert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Tsai, Chung-Jui
    Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, USA.
    Populus Resources and Bioinformatics2010In: Genetics and Genomics of Populus / [ed] Stefan Jansson, Rishikesh Bhalerao, Andrew Groover, New York: Springer-Verlag New York, 2010, Vol. 8, p. 135-152Chapter in book (Other academic)
    Abstract [en]

    As a model system, Populus offers the opportunity to study biological questions pertinent to perennial growth habits such as lignocellulosic cell wall biogenesis and dormancy cycles. In the past years, much has been learnt about the transcriptional control of such processes and there is an ever-growing resource of publicly available transcriptomics data and EST sequences available. More recently greater emphasis has been placed on the study of metabolomic data and particularly in linking metabolic changes to both development and ecosystem functioning. Populus represents an ideal model system in which genetic and genomic studies can be conducted in a ecological key-stone species as well in a commercially important forest tree crop. To facilitate biological understanding a number of bioinformatics resources have become available for Populus alongside greater integration of the species in centralized sequence data sources such as NCBI and Interpro. These developments are rapidly advancing the ability to use Populus as a model system for the study of developmental, ecological and comparative genomics questions. Here we overview the current state of bioinformatics resources available for studies involving Populus as well as detailing the genetic material available to conduct studies on. Since the emergence of Populus as the model tree species, there has been a steady and rapid development of resources enabling the use of new technologies and approaches for answering biological questions. The Populus genomics resources have been, and will continue to be, instrumental in addressing biological questions pertinent to perennial growth habits (e.g., lignocellulosic cell wall biogenesis and dormancy cycles). Increasingly, genomics tools are also being incorporated into ecological investigations

  • 27. Tuskan, Gerald A.
    et al.
    DiFazio, Steve
    Faivre-Rampant, Patricia
    Gaudet, Muriel
    Harfouche, Antoine
    Jorge, Veronique
    Labbe, Jessy L.
    Ranjan, Priya
    Sabatti, Maurizio
    Slavov, Gancho
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Tschaplinski, Timothy J.
    Yin, Tongming
    The obscure events contributing to the evolution of an incipient sex chromosome in Populus: a retrospective working hypothesis2012In: Tree Genetics & Genomes, ISSN 1614-2942, E-ISSN 1614-2950, Vol. 8, no 3, p. 559-571Article, review/survey (Refereed)
    Abstract [en]

    Genetic determination of gender is a fundamental developmental and evolutionary process in plants. Although it appears that dioecy in Populus is genetically controlled, the precise gender-determining systems remain unclear. The recently released second draft assembly and annotated gene set of the Populus genome provided an opportunity to revisit this topic. We hypothesized that over evolutionary time, selective pressure has reformed the genome structure and gene composition in the peritelomeric region of the chromosome XIX, which has resulted in a distinctive genome structure and cluster of genes contributing to gender determination in Populus trichocarpa. Multiple lines of evidence support this working hypothesis. First, the peritelomeric region of the chromosome XIX contains significantly fewer single nucleotide polymorphisms than the rest of Populus genome and has a distinct evolutionary history. Second, the peritelomeric end of chromosome XIX contains the largest cluster of the nucleotide-binding site-leucine-rich repeat (NBS-LRR) class of disease resistance genes in the entire Populus genome. Third, there is a high occurrence of small microRNAs on chromosome XIX, which is coincident to the region containing the putative gender-determining locus and the major cluster of NBS-LRR genes. Further, by analyzing the metabolomic profiles of floral bud in male and female Populus trees using a gas chromatography-mass spectrometry, we found that there are gender-specific accumulations of phenolic glycosides. Taken together, these findings led to the hypothesis that resistance to and regulation of a floral pathogen and gender determination coevolved, and that these events triggered the emergence of a nascent sex chromosome. Further studies of chromosome XIX will provide new insights into the genetic control of gender determination in Populus.

  • 28.
    Wang, Jing
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Centre for Integrative Genetics, Department of Animal and Aquacultural Sciences, Faculty of Life Sciences, Norwegian University of Life Sciences, Ås, Norway.
    Ding, Jihua
    Tan, Biyue
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Stora Enso Biomaterials, 13104 Nacka, Sweden.
    Robinson, Kathryn M
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Michelson, Ingrid H.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Johansson, Anna
    Nystedt, Bjorn
    Scofield, Douglas
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Ecology and Genetics, Evolutionary Biology, Uppsala University, Uppsala, Sweden; Uppsala Multidisciplinary Center for Advanced Computational Science, Uppsala University, Uppsala, Sweden.
    Nilsson, Ove
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Street, Nathaniel R.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Ingvarsson, Pär K.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    A major locus controls local adaptation and adaptive life history variation in a perennial plant2018In: Genome Biology, ISSN 1465-6906, E-ISSN 1474-760X, Vol. 19, article id 72Article in journal (Refereed)
    Abstract [en]

    Background: The initiation of growth cessation and dormancy represent critical life history trade offs between survival and growth and have important fitness effects in perennial plants Such adaptive life history traits often show strong local adaptation along environmental gradients but, despite then importance, the genetic architecture of these traits remains poorly understood.

    Results: We integrate whole genome re sequencing with environmental and phenotypic data from common garden experiments to investigate the genomic basis of local adaptation across a latitudinal gradient in European aspen (Populus tremula). A single genomic region containing the PtFT2 gene mediates local adaptation in the timing of bud set and explains 65% of the observed genetic variation in bud set This locus is the likely target of a recent selective sweep that originated right before or during colonization of northern Scandinavia following the last glaciation Field and greenhouse experiments confirm that variation in PtFT2 gene expression affects the phenotypic variation in bud set that we observe in wild natural populations.

    Conclusions: Our results reveal a major effect locus that determines the timing of bud set and that has facilitated rapid adaptation to shorter growing seasons and colder climates in European aspen. The discovery of a single locus explaining a substantial fraction of the variation in a key life-history trait is remarkable, given that such traits are generally considered to be highly polygenic. These findings provide a dramatic illustration of how loci of large effect for adaptive traits can arise and be maintained over large geographical scales in natural populations.

  • 29.
    Wang, Jing
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Scofield, Douglas
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Ingvarsson, Pär
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Variant calling using NGS data in European aspen (Populus tremula)2015In: Advances in the Understanding of Biological Sciences Using Next Generation Sequencing (NGS) Approaches / [ed] Sablok, G., Kumar, S., Ueno, S., Kuo, J., Varotto, C. (Eds.), Springer, 2015, 1, p. 43-61Chapter in book (Refereed)
    Abstract [en]

    Analysis of next-generation sequencing (NGS) data is rapidly becoming an important source of information for genetics and genomics studies. The utility of such data does, however, rely crucially on the accuracy and quality of SNP and genotype calling. Identification of genetic variants (SNPs and short indels) from NGS data is an area of active research and many recent statistical methods have been developed to both improve and quantify the large uncertainty associated with genotype calling. The detection of genetic variants from NGS data is prone to errors, due to multiple factors such as base-calling, alignment errors and read coverage. Here we highlight some of the issues and review and exemplify some of the recent methods that have been developed for genotype calling. We also provide guidelines for their application to whole-genome re-sequencing data using a data set based on a number of European aspen (Populus tremula) individuals each sequenced to a depth of about 20x coverage per individual.

  • 30.
    Wang, Jing
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Scofield, Douglas
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Ecology and Genetics: Evolutionary Biology, Uppsala University, Uppsala; Uppsala Multidisciplinary Center for Advanced Computational Science, Uppsala University, Uppsala .
    Ingvarsson, Pär
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Natural Selection and Recombination Rate Variation Shape Nucleotide Polymorphism Across the Genomes of Three Related Populus Species2016In: Genetics, ISSN 0016-6731, E-ISSN 1943-2631, Vol. 202, no 3, p. 1185-1200Article in journal (Refereed)
    Abstract [en]

    A central aim of evolutionary genomics is to identify the relative roles that various evolutionary forces have played in generating and shaping genetic variation within and among species. Here we use whole-genome resequencing data to characterize and compare genome-wide patterns of nucleotide polymorphism, site frequency spectrum, and population-scaled recombination rates in three species of PopulusPopulus tremulaP. tremuloides, and P. trichocarpa. We find that P. tremuloides has the highest level of genome-wide variation, skewed allele frequencies, and population-scaled recombination rates, whereas P. trichocarpa harbors the lowest. Our findings highlight multiple lines of evidence suggesting that natural selection, due to both purifying and positive selection, has widely shaped patterns of nucleotide polymorphism at linked neutral sites in all three species. Differences in effective population sizes and rates of recombination largely explain the disparate magnitudes and signatures of linked selection that we observe among species. The present work provides the first phylogenetic comparative study on a genome-wide scale in forest trees. This information will also improve our ability to understand how various evolutionary forces have interacted to influence genome evolution among related species.

  • 31.
    Wang, Jing
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Scofield, Douglas
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Ecology and Genetics: Evolutionary Biology, Uppsala University, Uppsala, Sweden; Uppsala Multidisciplinary Center for Advanced Computational Science, Uppsala University, Uppsala, Sweden.
    Ingvarsson, Pär
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Variation in linked selection and recombination drive genomic divergence during allopatric speciation of European and American aspens2016In: Molecular biology and evolution, ISSN 0737-4038, E-ISSN 1537-1719, Vol. 33, no 7, p. 1754-1767Article in journal (Refereed)
    Abstract [en]

    Despite the global economic and ecological importance of forest trees, the genomic basis of differential adaptation and speciation in tree species is still poorly understood. Populus tremula and P. tremuloides are two of the most widespread tree species in the Northern Hemisphere. Using whole-genome re-sequencing data of 24 P. tremula and 22 P. tremuloidesindividuals, we find that the two species diverged ~2.2-3.1 million years ago, coinciding with the severing of the Bering land bridge and the onset of dramatic climatic oscillations during the Pleistocene. Both species have experienced substantial population expansions following long-term declines after species divergence. We detect widespread and heterogeneous genomic differentiation between species, and in accordance with the expectation of allopatric speciation, coalescent simulations suggest that neutral evolutionary processes can account for most of the observed patterns of genetic differentiation. However, there is an excess of regions exhibiting extreme differentiation relative to those expected under demographic simulations, which is indicative of the action of natural selection. Overall genetic differentiation is negatively associated with recombination rate in both species, providing strong support for a role of linked selection in generating the heterogeneous genomic landscape of differentiation between species. Finally, we identify a number of candidate regions and genes that may have been subject to positive and/or balancing selection during the speciation process.

  • 32. Xue, Weiya
    et al.
    Ruprecht, Colin
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Hematy, Kian
    Chang, Christine
    Frommer, Wolf B
    Persson, Staffan
    Niittyla, Totte
    Paramutation-like interaction of T-DNA loci in arabidopsis2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 12, p. e51651-Article in journal (Refereed)
    Abstract [en]

    In paramutation, epigenetic information is transferred from one allele to another to create a gene expression state which is stably inherited over generations. Typically, paramutation describes a phenomenon where one allele of a gene down-regulates the expression of another allele. Paramutation has been described in several eukaryotes and is best understood in plants. Here we describe an unexpected paramutation-like trans SALK T-DNA interaction in Arabidopsis. Unlike most of the previously described paramutations, which led to gene silencing, the trans SALK T-DNA interaction caused an increase in the transcript levels of the endogenous gene (COBRA) where the T-DNA was inserted. This increased COBRA expression state was stably inherited for several generations and led to the partial suppression of the cobra phenotype. DNA methylation was implicated in this trans SALK T-DNA interaction since mutation of the DNA methyltransferase 1 in the suppressed cobra caused a reversal of the suppression. In addition, null mutants of the DNA demethylase ROS1 caused a similar COBRA transcript increase in the cobra SALK T-DNA mutant as the trans T-DNA interaction. Our results provide a new example of a paramutation-like trans T-DNA interaction in Arabidopsis, and establish a convenient hypocotyl elongation assay to study this phenomenon. The results also alert to the possibility of unexpected endogenous transcript increase when two T-DNAs are combined in the same genetic background. Citation: Xue W, Ruprecht C, Street N, Hematy K, Chang C, et al. (2012) Paramutation-Like Interaction of T-DNA Loci in Arabidopsis. PLoS ONE 7(12): e51651. doi:10.1371/journal.pone.0051651

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