| 1. |
- Giacomello, Stefania, et al.
(författare)
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Spatially resolved transcriptome profiling in model plant species
- 2017
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Ingår i: Nature Plants. - : Springer Science and Business Media LLC. - 2055-026X .- 2055-0278. ; 3:6
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Tidskriftsartikel (refereegranskat)abstract
- Understanding complex biological systems requires functional characterization of specialized tissue domains. However, existing strategies for generating and analysing high-throughput spatial expression profiles were developed for a limited range of organisms, primarily mammals. Here we present the first available approach to generate and study highresolution, spatially resolved functional profiles in a broad range of model plant systems. Our process includes highthroughput spatial transcriptome profiling followed by spatial gene and pathway analyses. We first demonstrate the feasibility of the technique by generating spatial transcriptome profiles from model angiosperms and gymnosperms microsections. In Arabidopsis thaliana we use the spatial data to identify differences in expression levels of 141 genes and 189 pathways in eight inflorescence tissue domains. Our combined approach of spatial transcriptomics and functional profiling offers a powerful new strategy that can be applied to a broad range of plant species, and is an approach that will be pivotal to answering fundamental questions in developmental and evolutionary biology.
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| 2. |
- Müller, Niels A., et al.
(författare)
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A single gene underlies the dynamic evolution of poplar sex determination.
- 2020
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Ingår i: Nature Plants. - : Springer Nature. - 2055-0278 .- 2055-026X. ; 6:6, s. 630-637
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Tidskriftsartikel (refereegranskat)abstract
- Although hundreds of plant lineages have independently evolved dioecy (that is, separation of the sexes), the underlying genetic basis remains largely elusive. Here we show that diverse poplar species carry partial duplicates of the ARABIDOPSIS RESPONSE REGULATOR 17 (ARR17) orthologue in the male-specific region of the Y chromosome. These duplicates give rise to small RNAs apparently causing male-specific DNA methylation and silencing of the ARR17 gene. CRISPR–Cas9-induced mutations demonstrate that ARR17 functions as a sex switch, triggering female development when on and male development when off. Despite repeated turnover events, including a transition from the XY system to a ZW system, the sex-specific regulation of ARR17 is conserved across the poplar genus and probably beyond. Our data reveal how a single-gene-based mechanism of dioecy can enable highly dynamic sex-linked regions and contribute to maintaining recombination and integrity of sex chromosomes.
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| 3. |
- Apuli, Rami-Petteri, et al.
(författare)
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Inferring the Genomic Landscape of Recombination Rate Variation in European Aspen (Populus tremula)
- 2020
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Ingår i: G3. - : GENETICS SOCIETY AMERICA. - 2160-1836. ; 10:1, s. 299-309
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Tidskriftsartikel (refereegranskat)abstract
- The rate of meiotic recombination is one of the central factors determining genome-wide levels of linkage disequilibrium which has important consequences for the efficiency of natural selection and for the dissection of quantitative traits. Here we present a new, high-resolution linkage map for Populus tremula that we use to anchor approximately two thirds of the P. tremula draft genome assembly on to the expected 19 chromosomes, providing us with the first chromosome-scale assembly for P. tremula (Table 2). We then use this resource to estimate variation in recombination rates across the P. tremula genome and compare these results to recombination rates based on linkage disequilibrium in a large number of unrelated individuals. We also assess how variation in recombination rates is associated with a number of genomic features, such as gene density, repeat density and methylation levels. We find that recombination rates obtained from the two methods largely agree, although the LD-based method identifies a number of genomic regions with very high recombination rates that the map-based method fails to detect. Linkage map and LD-based estimates of recombination rates are positively correlated and show similar correlations with other genomic features, showing that both methods can accurately infer recombination rate variation across the genome. Recombination rates are positively correlated with gene density and negatively correlated with repeat density and methylation levels, suggesting that recombination is largely directed toward gene regions in P. tremula.
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| 4. |
- Christie, Nanette, et al.
(författare)
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qtlXplorer : an online systems genetics browser in the Eucalyptus Genome Integrative Explorer (EucGenIE)
- 2021
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Ingår i: BMC Bioinformatics. - : BioMed Central. - 1471-2105. ; 22:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Affordable high-throughput DNA and RNA sequencing technologies are allowing genomic analysis of plant and animal populations and as a result empowering new systems genetics approaches to study complex traits. The availability of intuitive tools to browse and analyze the resulting large-scale genetic and genomic datasets remain a significant challenge. Furthermore, these integrative genomics approaches require innovative methods to dissect the flow and interconnectedness of biological information underlying complex trait variation. The Plant Genome Integrative Explorer (PlantGenIE.org) is a multi-species database and domain that houses online tools for model and woody plant species including Eucalyptus. Since the Eucalyptus Genome Integrative Explorer (EucGenIE) is integrated within PlantGenIE, it shares genome and expression analysis tools previously implemented within the various subdomains (ConGenIE, PopGenIE and AtGenIE). Despite the success in setting up integrative genomics databases, online tools for systems genetics modelling and high-resolution dissection of complex trait variation in plant populations have been lacking.Results: We have developed qtlXplorer (https://eucgenie.org/QTLXplorer) for visualizing and exploring systems genetics data from genome-wide association studies including quantitative trait loci (QTLs) and expression-based QTL (eQTL) associations. This module allows users to, for example, find co-located QTLs and eQTLs using an interactive version of Circos, or explore underlying genes using JBrowse. It provides users with a means to build systems genetics models and generate hypotheses from large-scale population genomics data. We also substantially upgraded the EucGenIE resource and show how it enables users to combine genomics and systems genetics approaches to discover candidate genes involved in biotic stress responses and wood formation by focusing on two multigene families, laccases and peroxidases.Conclusions: qtlXplorer adds a new dimension, population genomics, to the EucGenIE and PlantGenIE environment. The resource will be of interest to researchers and molecular breeders working in Eucalyptus and other woody plant species. It provides an example of how systems genetics data can be integrated with functional genetics data to provide biological insight and formulate hypotheses. Importantly, integration within PlantGenIE enables novel comparative genomics analyses to be performed from population-scale data.
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| 5. |
- Giacomello, Stefania, et al.
(författare)
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High spatial resolution profiling in tree species
- 2019
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Ingår i: Annual Plant Reviews Online. - : Wiley. - 2639-3832. ; 2:1, s. 329-359
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Tidskriftsartikel (refereegranskat)abstract
- Until recently, the majority of genomics assays have been performed on bulk tissue samples containing multiple cell types. Tissues such as the wood formation zone in trees contain a complex mix of cell types organised in three-dimensional space. Moreover, cells within the wood formation zone represent a continual developmental progression from meristematic cambial initials through to cell death. This spatiotemporal developmental gradient and cell type information are not assayed by bulk samples. New and improved sampling methods coupled to next-generation sequencing assays are enabling the generation of high spatial resolution and single-cell transcriptomics data, offering unprecedented insight into the biology of unique cell types and cell developmental programs.We overview the application of these approaches to the study of wood development, in particular, and highlight challenges associated with the analysis of such data.
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| 6. |
- Lin, Yao-Cheng, et al.
(författare)
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Functional and evolutionary genomic inferences in Populus through genome and population sequencing of American and European aspen
- 2018
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 115:46, s. E10970-E10978
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Tidskriftsartikel (refereegranskat)abstract
- The Populus genus is one of the major plant model systems, but genomic resources have thus far primarily been available for poplar species, and primarily Populus trichocarpa (Torr. & Gray), which was the first tree with a whole-genome assembly. To further advance evolutionary and functional genomic analyses in Populus, we produced genome assemblies and population genetics resources of two aspen species, Populus tremula L. and Populus tremuloides Michx. The two aspen species have distributions spanning the Northern Hemisphere, where they are keystone species supporting a wide variety of dependent communities and produce a diverse array of secondary metabolites. Our analyses show that the two aspens share a similar genome structure and a highly conserved gene content with P. trichocarpa but display substantially higher levels of heterozygosity. Based on population resequencing data, we observed widespread positive and negative selection acting on both coding and noncoding regions. Furthermore, patterns of genetic diversity and molecular evolution in aspen are influenced by a number of features, such as expression level, coexpression network connectivity, and regulatory variation. To maximize the community utility of these resources, we have integrated all presented data within the PopGenIE web resource (PopGenIE.org).
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| 7. |
- Mannapperuma, Chanaka, et al.
(författare)
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GenIE-Sys : Genome Integrative Explorer System
- 2024
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- There are an ever-increasing number of genomes being sequenced, many of which have associated RNA sequencing and other genomics data. The availability of user-friendly web-accessible mining tools ensures that these data repositories provide maximum benefit to the community. However, there are relatively few options available for setting up such standalone frameworks. We developed the Genome Integrative Explorer System (GenIE-Sys) to set up web resources to enable search, visualization and exploration of genomics data typically generated by a genome project.GenIE-Sys is implemented in PHP, JavaScript and Python and is freely available under the GNU GPL 3 public license. All source code is freely available at the GenIE-Sys website (https://geniesys.org) or GitHub (http://github.com/plantgenie/geniesys.git). Documentation is available at http://geniesys.readthedocs.io.
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| 8. |
- Mannapperuma, Chanaka, 1982-
(författare)
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Human-computer interaction principles for developing web-based genomics resources
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Genomics projects, including genome sequencing, transcriptomics, genome-wide association mapping and epigenetics assays, producevast quantities of data. Extracting the required information from such complex datasets is a significant challenge and even where software tools do exist, these are often not intuitive or designed fornon-specialist users. This dissertation details how I have applied design principles from the field of Human-Computer Interaction (HCI) to the development of intuitive bioinformatics web-based resources for exploring genomics data. In the first part of the thesis I detail the development of a specialised genomics resource that enables non specialists who lack bioinformatics skills to access, explore and extract new knowledge from a variety of genomics data types. These tools were developed in collaboration with wet lab biologists and bioinformaticians who represent typical end-users. The tools developed have been integrated within the PlantGenIE (Plant Genome IntegrativeExplorer) web resource, which has been established as a platform for exploring genomics data for Populus, conifer, Eucalyptus and Arabidopsisgenomics data. Even though the ability to collect, store and manage data is increasing faster due to new technologies and science, our ability to understand it remains constant. To help address this, in the second part of this dissertation I focus on the usability enhancement of tools based on the HCI and User Experience (UX) practices. To achieve this, I utilised visualisation techniques and design principles in the design process for the improvement of the PlantGenIEUser Interface (UI), and applied usability methods to evaluate the UX of PlantGenIE tools. These results were then used to inform adaptations and fine-tuning of those. I show that utilisation of these research methods and practices with the development life cycle represents a framework for designing usable bioinformatics tools. Wider-scale use of these methods by future designers and developers will enable the creation of more usable bioinformatics resources.
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| 9. |
- Street, Nathaniel, 1979-
(författare)
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Genomics of forest trees
- 2019
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Ingår i: Molecular physiology and biotechnology of trees. - : Elsevier. - 9780128154656 ; , s. 1-37
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Bokkapitel (refereegranskat)abstract
- Over the past decade increasing availability and decreasing costs of "next" generation sequencing has revolutionised our ability to assay numerous aspects of genome function. Initially, massively parallel high throughput sequencing technologies resulted in a rapid increase in the number of published tree genomes and, to an even greater extent, transcriptome studies. Whereas previous genomics efforts were concentrated on a small number of model species, these new sequencing technologies have liberated the choice of species, particularly so assaying gene expression using RNA Sequencing and, more recently, for assays of epigenomics including genome structure and accessibility. These advances in sequencing throughput and cost enabled the first draft assemblies of the large (similar to 20 Gbp) genomes of a number of conifer species in addition to an ever-increasing number of angiosperm tree species, with more than 40 genomes now publicly available. The falling cost of sequencing has also enabled genome resequencing, genome wide association studies and population gene expression studies, the results of which are providing new insight into the developmental programs associated with wood formation, stress and disease tolerance, adaptive potential, population genetics and evolutionary history of tree species.
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| 10. |
- Terebieniec, Barbara, 1983-
(författare)
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Using systems genetics to explore the complexity of leaf shape variation in Populus tremula
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Leaves are essential for sustaining humanity as they function as the energy and oxygen-producing organ of plants. Intensive research on physiological processes has contributed immensely to our understanding of the function of leaves. However, comparatively little is known about how leaf size and shape is determined. The aim of my PhD was to assay leaf shape variation among individuals of Populus tremula (European aspen) sampled across the distribution range of Sweden to characterize the genetic architecture underlying variation, including elucidating contributing molecular mechanisms.In this PhD I employed an integrated systems genetics and systems biology approach to identify genetic components of variation and to assign biological function to these. We integrated population-wide data on leaf shape, gene expression and genome variation from a collection of P. tremula genotypes and used this to perform genome-wide association studies. We then integrated these results with a systems biology transcriptomics study of leaf development to provide developmental and biological context. We demonstrate that our developmental gene expression series captured known homologs of functionally characterized Arabidopsis thaliana genes and biological processes of importance during leaf development. In addition to these known genes of high importance, we also identified many novel candidate genes. Our systems genetics approach identified numerous genes with a potential role in leaf development that was supported by the developmental time series. From our association studies and population analyses we have shown that there are no large-effect loci contributing to variation in leaf shape and that highly ranked loci associated with leaf shape are primarily located in the regulatory regions of genes. Furthermore, we identified loci controlling variation in gene expression and sets of genes with significant differential expression between groups of genotypes with highly contrasting leaf shapes. We show that genes with significant associations influencing expression among genotypes are enriched in the periphery of the corresponding gene co-expression network and that they experience relaxed selective constraint. Taken together, these results suggest that leaf shape is a highly complex trait controlled by a large number of loci, each contributing only a small effect, that those loci likely act via modulation of gene expression and that they do not show signals of adaptive selection. In addition, we adapted and optimized the method of spatial transcriptomics for use in plant species. This method provides a transcriptome-wide in situ, spatially-resolved assay of transcript expression at high spatial resolution.
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