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| 2. |
- Liu, Lijun, et al.
(författare)
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A resource for characterizing genome-wide binding and putative target genes of transcription factors expressed during secondary growth and wood formation in Populus
- 2015
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Ingår i: The Plant Journal. - : Wiley. - 0960-7412 .- 1365-313X. ; 82:5, s. 887-898
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Norman, Anita, et al.
(författare)
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De Novo SNP Discovery in the Scandinavian Brown Bear (Ursus arctos)
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 8:11, s. e81012-
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 4. |
- Nystedt, Björn, et al.
(författare)
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The Norway spruce genome sequence and conifer genome evolution
- 2013
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 497:7451, s. 579-584
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
- Shi, Tian-Le, et al.
(författare)
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High-quality genome assembly enables prediction of allele-specific gene expression in hybrid poplar
- 2024
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Ingår i: Plant Physiology. - : Oxford University Press. - 0032-0889 .- 1532-2548. ; 195:1, s. 652-670
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Tidskriftsartikel (refereegranskat)abstract
- Poplar (Populus) is a well-established model system for tree genomics and molecular breeding, and hybrid poplar is widely used in forest plantations. However, distinguishing its diploid homologous chromosomes is difficult, complicating advanced functional studies on specific alleles. In this study, we applied a trio-binning design and PacBio high-fidelity long-read sequencing to obtain haplotype-phased telomere-to-telomere genome assemblies for the 2 parents of the well-studied F1 hybrid “84K” (Populus alba × Populus tremula var. glandulosa). Almost all chromosomes, including the telomeres and centromeres, were completely assembled for each haplotype subgenome apart from 2 small gaps on one chromosome. By incorporating information from these haplotype assemblies and extensive RNA-seq data, we analyzed gene expression patterns between the 2 subgenomes and alleles. Transcription bias at the subgenome level was not uncovered, but extensive-expression differences were detected between alleles. We developed machine-learning (ML) models to predict allele-specific expression (ASE) with high accuracy and identified underlying genome features most highly influencing ASE. One of our models with 15 predictor variables achieved 77% accuracy on the training set and 74% accuracy on the testing set. ML models identified gene body CHG methylation, sequence divergence, and transposon occupancy both upstream and downstream of alleles as important factors for ASE. Our haplotype-phased genome assemblies and ML strategy highlight an avenue for functional studies in Populus and provide additional tools for studying ASE and heterosis in hybrids.
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| 6. |
- Soolanayakanahally, Raju Y, et al.
(författare)
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Comparative physiology of allopatric Populus species : geographic clines in photosynthesis, height growth, and carbon isotope discrimination in common gardens
- 2015
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Ingår i: Frontiers in Plant Science. - : Frontiers Media. - 1664-462X. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 7. |
- Street, Nathaniel Robert, 1979-, et al.
(författare)
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A cross-species transcriptomics approach to identify genes involved in leaf development
- 2008
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 9:1, s. 539-
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- BackgroundWe 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.ResultsTranscription 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.ConclusionThis 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.
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| 8. |
- Street, Nathaniel Robert, 1979-, et al.
(författare)
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A systems biology model of the regulatory network in Populus leaves reveals interacting regulators and conserved regulation
- 2011
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Ingår i: BMC Plant Biology. - : Springer Science and Business Media LLC. - 1471-2229. ; 11, s. 13-
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
- Street, Nathaniel Robert, et al.
(författare)
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Populus Resources and Bioinformatics
- 2010
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Ingår i: Genetics and Genomics of Populus. - New York : Springer-Verlag New York. - 9781441915405 - 9781441915412 ; , s. 135-152
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- 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
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| 10. |
- Street, Nathaniel Robert
(författare)
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Populus short RNAs
- 2011
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Ingår i: Non coding RNAs in plants. - Berlin : Springer Berlin/Heidelberg. - 9783642194535 - 9783642194542 ; , s. 375-384
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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