601
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Rutter MT, Cross KV, Van Woert PA. Birth, death and subfunctionalization in the Arabidopsis genome. TRENDS IN PLANT SCIENCE 2012; 17:204-12. [PMID: 22326563 DOI: 10.1016/j.tplants.2012.01.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 01/12/2012] [Accepted: 01/16/2012] [Indexed: 05/08/2023]
Abstract
Arabidopsis thaliana is now a model system, not just for plant biology but also for comparative genomics. The completion of the sequences of two closely related species, Arabidopsis lyrata and Brassica rapa, is complemented by genomic comparisons among A. thaliana accessions and mutation accumulation lines. Together these genomic data document the birth of new genes via gene duplication, transposon exaptation and de novo formation of new genes from noncoding sequence. Most novel loci exhibit low expression, and are undergoing pseudogenization or subfunctionalization. Comparatively, A. thaliana has lost large amounts of sequence through deletion, particularly of transposable elements. Intraspecific genomic variation indicates high rates of deletion mutations and deletion polymorphisms across accessions, shedding light on the history of Arabidopsis genome architecture.
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Affiliation(s)
- Matthew T Rutter
- Department of Biology, College of Charleston, Charleston, SC 29401, USA.
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602
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Harrison RJ. Understanding genetic variation and function- the applications of next generation sequencing. Semin Cell Dev Biol 2012; 23:230-6. [DOI: 10.1016/j.semcdb.2012.01.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 01/10/2012] [Accepted: 01/12/2012] [Indexed: 12/31/2022]
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603
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604
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Hamilton JP, Buell CR. Advances in plant genome sequencing. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 70:177-90. [PMID: 22449051 DOI: 10.1111/j.1365-313x.2012.04894.x] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The study of plant biology in the 21st century is, and will continue to be, vastly different from that in the 20th century. One driver for this has been the use of genomics methods to reveal the genetic blueprints for not one but dozens of plant species, as well as resolving genome differences in thousands of individuals at the population level. Genomics technology has advanced substantially since publication of the first plant genome sequence, that of Arabidopsis thaliana, in 2000. Plant genomics researchers have readily embraced new algorithms, technologies and approaches to generate genome, transcriptome and epigenome datasets for model and crop species that have permitted deep inferences into plant biology. Challenges in sequencing any genome include ploidy, heterozygosity and paralogy, all which are amplified in plant genomes compared to animal genomes due to the large genome sizes, high repetitive sequence content, and rampant whole- or segmental genome duplication. The ability to generate de novo transcriptome assemblies provides an alternative approach to bypass these complex genomes and access the gene space of these recalcitrant species. The field of genomics is driven by technological improvements in sequencing platforms; however, software and algorithm development has lagged behind reductions in sequencing costs, improved throughput, and quality improvements. It is anticipated that sequencing platforms will continue to improve the length and quality of output, and that the complementary algorithms and bioinformatic software needed to handle large, repetitive genomes will improve. The future is bright for an exponential improvement in our understanding of plant biology.
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Affiliation(s)
- John P Hamilton
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
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605
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Cubillos FA, Coustham V, Loudet O. Lessons from eQTL mapping studies: non-coding regions and their role behind natural phenotypic variation in plants. CURRENT OPINION IN PLANT BIOLOGY 2012; 15:192-8. [PMID: 22265229 DOI: 10.1016/j.pbi.2012.01.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 12/17/2011] [Accepted: 01/03/2012] [Indexed: 05/24/2023]
Abstract
Even if considerable progress has been achieved towards the understanding of natural variation in plant systems, the contribution of transcript abundance variation to phenotypic diversity remains unappreciated. Over the last decade, efforts to characterise the genome-wide expression variation in natural accessions, structured populations and hybrids have improved our knowledge of the contribution of non-coding polymorphisms to gene expression regulation. Moreover, new studies are helping to unravel the role of expression polymorphisms and their orchestrated performance. Recent advances involving classical linkage analysis, GWAS and improved eQTL mapping strategies will provide a greater resolution to determine the genetic variants shaping the broad diversity in plant systems.
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Affiliation(s)
- Francisco A Cubillos
- Institut Jean-Pierre Bourgin, UMR1318 INRA-AgroParisTech, F-78000 Versailles, France
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606
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Alcázar R, Pecinka A, Aarts MGM, Fransz PF, Koornneef M. Signals of speciation within Arabidopsis thaliana in comparison with its relatives. CURRENT OPINION IN PLANT BIOLOGY 2012; 15:205-211. [PMID: 22265228 DOI: 10.1016/j.pbi.2012.01.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 12/06/2011] [Accepted: 01/03/2012] [Indexed: 05/31/2023]
Abstract
The species within the now well-defined Arabidopsis genus provide biological materials suitable to investigate speciation and the development of reproductive isolation barriers between related species. Even within the model species A. thaliana, genetic differentiation between populations due to environmental adaptation or demographic history can lead to cases where hybrids between accessions are non-viable. Experimental evidence supports the importance of genome duplications and genetic epistatic interactions in the occurrence of reproductive isolation. Other examples of adaptation to specific environments can be found in Arabidopsis relatives where hybridization and chromosome doubling lead to new amphidiploid species. Molecular signals of speciation found in the Arabidopsis genus should provide a better understanding of speciation processes in plants from a genetic, molecular and evolutionary perspective.
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Affiliation(s)
- Rubén Alcázar
- Department of Plant Breeding and Genetics, Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Cologne, Germany
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607
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Joshi HJ, Christiansen KM, Fitz J, Cao J, Lipzen A, Martin J, Smith-Moritz AM, Pennacchio LA, Schackwitz WS, Weigel D, Heazlewood JL. 1001 Proteomes: a functional proteomics portal for the analysis of Arabidopsis thaliana accessions. ACTA ACUST UNITED AC 2012; 28:1303-6. [PMID: 22451271 DOI: 10.1093/bioinformatics/bts133] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
MOTIVATION The sequencing of over a thousand natural strains of the model plant Arabidopsis thaliana is producing unparalleled information at the genetic level for plant researchers. To enable the rapid exploitation of these data for functional proteomics studies, we have created a resource for the visualization of protein information and proteomic datasets for sequenced natural strains of A. thaliana. RESULTS The 1001 Proteomes portal can be used to visualize amino acid substitutions or non-synonymous single-nucleotide polymorphisms in individual proteins of A. thaliana based on the reference genome Col-0. We have used the available processed sequence information to analyze the conservation of known residues subject to protein phosphorylation among these natural strains. The substitution of amino acids in A. thaliana natural strains is heavily constrained and is likely a result of the conservation of functional attributes within proteins. At a practical level, we demonstrate that this information can be used to clarify ambiguously defined phosphorylation sites from phosphoproteomic studies. Protein sets of available natural variants are available for download to enable proteomic studies on these accessions. Together this information can be used to uncover the possible roles of specific amino acids in determining the structure and function of proteins in the model plant A. thaliana. An online portal to enable the community to exploit these data can be accessed at http://1001proteomes.masc-proteomics.org/
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Affiliation(s)
- Hiren J Joshi
- Joint BioEnergy Institute and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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608
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Díaz A, Zikhali M, Turner AS, Isaac P, Laurie DA. Copy number variation affecting the Photoperiod-B1 and Vernalization-A1 genes is associated with altered flowering time in wheat (Triticum aestivum). PLoS One 2012; 7:e33234. [PMID: 22457747 PMCID: PMC3310869 DOI: 10.1371/journal.pone.0033234] [Citation(s) in RCA: 237] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 02/06/2012] [Indexed: 11/18/2022] Open
Abstract
The timing of flowering during the year is an important adaptive character affecting reproductive success in plants and is critical to crop yield. Flowering time has been extensively manipulated in crops such as wheat (Triticum aestivum L.) during domestication, and this enables them to grow productively in a wide range of environments. Several major genes controlling flowering time have been identified in wheat with mutant alleles having sequence changes such as insertions, deletions or point mutations. We investigated genetic variants in commercial varieties of wheat that regulate flowering by altering photoperiod response (Ppd-B1 alleles) or vernalization requirement (Vrn-A1 alleles) and for which no candidate mutation was found within the gene sequence. Genetic and genomic approaches showed that in both cases alleles conferring altered flowering time had an increased copy number of the gene and altered gene expression. Alleles with an increased copy number of Ppd-B1 confer an early flowering day neutral phenotype and have arisen independently at least twice. Plants with an increased copy number of Vrn-A1 have an increased requirement for vernalization so that longer periods of cold are required to potentiate flowering. The results suggest that copy number variation (CNV) plays a significant role in wheat adaptation.
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Affiliation(s)
- Aurora Díaz
- John Innes Centre, Norwich Research Park, Norwich, Norfolk, United Kingdom
| | - Meluleki Zikhali
- John Innes Centre, Norwich Research Park, Norwich, Norfolk, United Kingdom
| | - Adrian S. Turner
- John Innes Centre, Norwich Research Park, Norwich, Norfolk, United Kingdom
| | - Peter Isaac
- iDNA Genetics Ltd., The Norwich BioIncubator, Norwich Research Park, Norwich, United Kingdom
| | - David A. Laurie
- John Innes Centre, Norwich Research Park, Norwich, Norfolk, United Kingdom
- * E-mail:
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609
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Hansey CN, Vaillancourt B, Sekhon RS, de Leon N, Kaeppler SM, Buell CR. Maize (Zea mays L.) genome diversity as revealed by RNA-sequencing. PLoS One 2012; 7:e33071. [PMID: 22438891 PMCID: PMC3306378 DOI: 10.1371/journal.pone.0033071] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 02/08/2012] [Indexed: 11/18/2022] Open
Abstract
Maize is rich in genetic and phenotypic diversity. Understanding the sequence, structural, and expression variation that contributes to phenotypic diversity would facilitate more efficient varietal improvement. RNA based sequencing (RNA-seq) is a powerful approach for transcriptional analysis, assessing sequence variation, and identifying novel transcript sequences, particularly in large, complex, repetitive genomes such as maize. In this study, we sequenced RNA from whole seedlings of 21 maize inbred lines representing diverse North American and exotic germplasm. Single nucleotide polymorphism (SNP) detection identified 351,710 polymorphic loci distributed throughout the genome covering 22,830 annotated genes. Tight clustering of two distinct heterotic groups and exotic lines was evident using these SNPs as genetic markers. Transcript abundance analysis revealed minimal variation in the total number of genes expressed across these 21 lines (57.1% to 66.0%). However, the transcribed gene set among the 21 lines varied, with 48.7% expressed in all of the lines, 27.9% expressed in one to 20 lines, and 23.4% expressed in none of the lines. De novo assembly of RNA-seq reads that did not map to the reference B73 genome sequence revealed 1,321 high confidence novel transcripts, of which, 564 loci were present in all 21 lines, including B73, and 757 loci were restricted to a subset of the lines. RT-PCR validation demonstrated 87.5% concordance with the computational prediction of these expressed novel transcripts. Intriguingly, 145 of the novel de novo assembled loci were present in lines from only one of the two heterotic groups consistent with the hypothesis that, in addition to sequence polymorphisms and transcript abundance, transcript presence/absence variation is present and, thereby, may be a mechanism contributing to the genetic basis of heterosis.
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Affiliation(s)
- Candice N. Hansey
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, United States of America
- Department of Energy Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, Michigan, United States of America
| | - Brieanne Vaillancourt
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, United States of America
- Department of Energy Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, Michigan, United States of America
| | - Rajandeep S. Sekhon
- Department of Agronomy, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Energy Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Natalia de Leon
- Department of Agronomy, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Energy Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Shawn M. Kaeppler
- Department of Agronomy, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Energy Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - C. Robin Buell
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, United States of America
- Department of Energy Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, Michigan, United States of America
- * E-mail:
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610
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A genome-wide association study identifies variants underlying the Arabidopsis thaliana shade avoidance response. PLoS Genet 2012; 8:e1002589. [PMID: 22438834 PMCID: PMC3305432 DOI: 10.1371/journal.pgen.1002589] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 01/25/2012] [Indexed: 12/30/2022] Open
Abstract
Shade avoidance is an ecologically and molecularly well-understood set of plant developmental responses that occur when the ratio of red to far-red light (R∶FR) is reduced as a result of foliar shade. Here, a genome-wide association study (GWAS) in Arabidopsis thaliana was used to identify variants underlying one of these responses: increased hypocotyl elongation. Four hypocotyl phenotypes were included in the study, including height in high R∶FR conditions (simulated sun), height in low R∶FR conditions (simulated shade), and two different indices of the response of height to low R∶FR. GWAS results showed that variation in these traits is controlled by many loci of small to moderate effect. A known PHYC variant contributing to hypocotyl height variation was identified and lists of significantly associated genes were enriched in a priori candidates, suggesting that this GWAS was capable of generating meaningful results. Using metadata such as expression data, GO terms, and other annotation, we were also able to identify variants in candidate de novo genes. Patterns of significance among our four phenotypes allowed us to categorize associations into three groups: those that affected hypocotyl height without influencing shade avoidance, those that affected shade avoidance in a height-dependent fashion, and those that exerted specific control over shade avoidance. This grouping allowed for the development of explicit hypotheses about the genetics underlying shade avoidance variation. Additionally, the response to shade did not exhibit any marked geographic distribution, suggesting that variation in low R∶FR–induced hypocotyl elongation may represent a response to local conditions. The goal of this work was to identify genetic variants underlying a well-characterized environmental response, the elongation of Arabidopsis thaliana hypocotyls (seedling stems) in response to shade, otherwise known as shade avoidance. We performed a genome-wide association study with four phenotypes: absolute hypocotyl height of plants grown in both simulated sun and shade and two measures of how height responded to shade. With this study, we confirmed previous findings that variants in two photoreceptors were associated with hypocotyl height variation. We also found associations with genetic variants in previously-identified shade avoidance genes, as well as with variants in genes not typically considered part of the shade avoidance pathway. By examining patterns of which of the four phenotypes were associated with each gene, we were then able to discriminate between genetic variants that have a general role in hypocotyl height variation and variants that are specifically involved in the shade avoidance response. We also found that shade avoidance was not broadly associated with geography, suggesting that variation in this trait may be due to local differences in light quality.
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611
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Oh DH, Dassanayake M, Bohnert HJ, Cheeseman JM. Life at the extreme: lessons from the genome. Genome Biol 2012. [DOI: 10.1186/gb4003] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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612
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Schmitz RJ, Ecker JR. Epigenetic and epigenomic variation in Arabidopsis thaliana. TRENDS IN PLANT SCIENCE 2012; 17:149-54. [PMID: 22342533 PMCID: PMC3645451 DOI: 10.1016/j.tplants.2012.01.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 12/23/2011] [Accepted: 01/04/2012] [Indexed: 05/04/2023]
Abstract
Arabidopsis thaliana (Arabidopsis) is ideally suited for studies of natural phenotypic variation. This species has also provided an unparalleled experimental system to explore the mechanistic link between genetic and epigenetic variation, especially with regard to cytosine methylation. Using high-throughput sequencing methods, genotype to epigenotype to phenotype observations can now be extended to plant populations. We review the evidence for induced and spontaneous epigenetic variants that have been identified in Arabidopsis in the laboratory and discuss how these experimental observations could explain existing variation in the wild.
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Affiliation(s)
- Robert J Schmitz
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
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613
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Conn SJ, Berninger P, Broadley MR, Gilliham M. Exploiting natural variation to uncover candidate genes that control element accumulation in Arabidopsis thaliana. THE NEW PHYTOLOGIST 2012; 193:859-66. [PMID: 22403822 DOI: 10.1111/j.1469-8137.2011.03977.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The plant ionome varies both inter- and intraspecifically despite the highly conserved roles for particular elements across the plant kingdom. Element storage requires transport across the plasma membrane and commonly deposition within the central vacuole. Therefore, tonoplast transport characteristics can be highly influential in controlling the plant ionome. As a result, individual cell types of the same plant, each with unique transcriptomes and vacuolar proteomes, can display very different elemental profiles. Here we address the use of natural variation in Arabidopsis thaliana for identifying genes involved in elemental accumulation. We present a conceptual framework, exploiting publicly available leaf ionomic and transcriptomic data across 31 Arabidopsis accessions, that promises to accelerate conventional forward genetics approaches for candidate gene discovery. Utilizing this framework, we identify numerous genes with documented roles in accumulation of calcium, magnesium and zinc and implicate additional candidate genes. Where appropriate, we discuss their role in cell-specific elemental accumulation. Currently, this framework could represent an alternate approach for identifying genes suitable for element biofortification of plants. Integration of additional cell-specific and whole-plant 'omics' datasets across Arabidopsis accessions under diverse environmental conditions should enable this concept to be developed into a scalable and robust tool for linking genotype and phenotype.
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Affiliation(s)
- Simon J Conn
- European Molecular Biology Laboratory, Grenoble Outstation, 38042 Grenoble, France.
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614
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Simon M, Simon A, Martins F, Botran L, Tisné S, Granier F, Loudet O, Camilleri C. DNA fingerprinting and new tools for fine-scale discrimination of Arabidopsis thaliana accessions. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 69:1094-1101. [PMID: 22077701 DOI: 10.1111/j.1365-313x.2011.04852.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
One of the main strengths of Arabidopsis thaliana as a model species is the impressive number of public resources available to the scientific community. Exploring species genetic diversity--and therefore adaptation--relies on collections of individuals from natural populations taken from diverse environments. Nevertheless, due to a few mislabeling events or genotype mixtures, some variants available in stock centers have been misidentified, causing inconsistencies and limiting the potential of genetic analyses. To improve the identification of natural accessions, we genotyped 1311 seed stocks from our Versailles Arabidopsis Stock Center and from other collections to determine their molecular profiles at 341 single nucleotide polymorphism markers. These profiles were used to compare genotypes at both the intra- and inter-accession levels. We confirmed previously described inconsistencies and revealed new ones, and suggest likely identities for accessions whose lineage had been lost. We also developed two new tools: a minimal fingerprint computation to quickly verify the identity of an accession, and an optimized marker set to assist in the identification of unknown or mixed accessions. These tools are available on a dedicated web interface called ANATool (https://www.versailles.inra.fr/ijpb/crb/anatool) that provides a simple and efficient means to verify or determine the identity of A. thaliana accessions in any laboratory, without the need for any specific or expensive technology.
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Affiliation(s)
- Matthieu Simon
- Institut Jean-Pierre Bourgin, UMR1318 INRA-AgroParisTech, F-78000 Versailles, France.
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615
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616
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Buschiazzo E, Ritland C, Bohlmann J, Ritland K. Slow but not low: genomic comparisons reveal slower evolutionary rate and higher dN/dS in conifers compared to angiosperms. BMC Evol Biol 2012; 12:8. [PMID: 22264329 PMCID: PMC3328258 DOI: 10.1186/1471-2148-12-8] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 01/20/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Comparative genomics can inform us about the processes of mutation and selection across diverse taxa. Among seed plants, gymnosperms have been lacking in genomic comparisons. Recent EST and full-length cDNA collections for two conifers, Sitka spruce (Picea sitchensis) and loblolly pine (Pinus taeda), together with full genome sequences for two angiosperms, Arabidopsis thaliana and poplar (Populus trichocarpa), offer an opportunity to infer the evolutionary processes underlying thousands of orthologous protein-coding genes in gymnosperms compared with an angiosperm orthologue set. RESULTS Based upon pairwise comparisons of 3,723 spruce and pine orthologues, we found an average synonymous genetic distance (dS) of 0.191, and an average dN/dS ratio of 0.314. Using a fossil-established divergence time of 140 million years between spruce and pine, we extrapolated a nucleotide substitution rate of 0.68 × 10(-9) synonymous substitutions per site per year. When compared to angiosperms, this indicates a dramatically slower rate of nucleotide substitution rates in conifers: on average 15-fold. Coincidentally, we found a three-fold higher dN/dS for the spruce-pine lineage compared to the poplar-Arabidopsis lineage. This joint occurrence of a slower evolutionary rate in conifers with higher dN/dS, and possibly positive selection, showcases the uniqueness of conifer genome evolution. CONCLUSIONS Our results are in line with documented reduced nucleotide diversity, conservative genome evolution and low rates of diversification in conifers on the one hand and numerous examples of local adaptation in conifers on the other hand. We propose that reduced levels of nucleotide mutation in large and long-lived conifer trees, coupled with large effective population size, were the main factors leading to slow substitution rates but retention of beneficial mutations.
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Affiliation(s)
- Emmanuel Buschiazzo
- Department of Forest Sciences, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada.
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617
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Abstract
More than 70 years after the first ex situ genebanks have been established, major efforts in this field are still concerned with issues related to further completion of individual collections and securing of their storage. Attempts regarding valorization of ex situ collections for plant breeders have been hampered by the limited availability of phenotypic and genotypic information. With the advent of molecular marker technologies first efforts were made to fingerprint genebank accessions, albeit on a very small scale and mostly based on inadequate DNA marker systems. Advances in DNA sequencing technology and the development of high-throughput systems for multiparallel interrogation of thousands of single nucleotide polymorphisms (SNPs) now provide a suite of technological platforms facilitating the analysis of several hundred of Gigabases per day using state-of-the-art sequencing technology or, at the same time, of thousands of SNPs. The present review summarizes recent developments regarding the deployment of these technologies for the analysis of plant genetic resources, in order to identify patterns of genetic diversity, map quantitative traits and mine novel alleles from the vast amount of genetic resources maintained in genebanks around the world. It also refers to the various shortcomings and bottlenecks that need to be overcome to leverage the full potential of high-throughput DNA analysis for the targeted utilization of plant genetic resources.
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Affiliation(s)
- Benjamin Kilian
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Genebank/Genome Diversity, Corrensstrasse 3, 06466 Gatersleben, Germany.
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618
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Genome-wide patterns of genetic variation in worldwide Arabidopsis thaliana accessions from the RegMap panel. Nat Genet 2012; 44:212-6. [PMID: 22231484 PMCID: PMC3267885 DOI: 10.1038/ng.1042] [Citation(s) in RCA: 390] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 11/29/2011] [Indexed: 11/24/2022]
Abstract
Arabidopsis thaliana is native to Eurasia and naturalized across the world due to human disturbance. Its easy propagation and immense phenotypic variability make it an ideal model system for functional, ecological and evolutionary genetics. To date, analyses of its natural variation have involved small numbers of individuals or genetic markers. Here we genotype 1,307 world-wide accessions, including several regional samples, at 250K SNPs, enabling us to describe the global pattern of genetic variation with high resolution. Three complementary tests applied to these data reveal novel targets of selection. Furthermore, we characterize the pattern of historical recombination and observe an enrichment of hotspots in intergenic regions and repetitive DNA, consistent with the pattern observed for humans but strikingly different from other plant species. We are making seeds for this Regional Mapping (RegMap) panel publicly available; they comprise the largest genomic mapping resource available for a naturally occurring, non-human, species.
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619
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Shindo T, Misas-Villamil JC, Hörger AC, Song J, van der Hoorn RAL. A role in immunity for Arabidopsis cysteine protease RD21, the ortholog of the tomato immune protease C14. PLoS One 2012; 7:e29317. [PMID: 22238602 PMCID: PMC3253073 DOI: 10.1371/journal.pone.0029317] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 11/24/2011] [Indexed: 01/02/2023] Open
Abstract
Secreted papain-like Cys proteases are important players in plant immunity. We previously reported that the C14 protease of tomato is targeted by cystatin-like EPIC proteins that are secreted by the oomycete pathogen Phytophthora infestans (Pinf) during infection. C14 has been under diversifying selection in wild potato species coevolving with Pinf and reduced C14 levels result in enhanced susceptibility for Pinf. Here, we investigated the role C14-EPIC-like interactions in the natural pathosystem of Arabidopsis with the oomycete pathogen Hyaloperonospora arabidopsidis (Hpa). In contrast to the Pinf-solanaceae pathosystem, the C14 orthologous protease of Arabidopsis, RD21, does not evolve under diversifying selection in Arabidopsis, and rd21 null mutants do not show phenotypes upon compatible and incompatible Hpa interactions, despite the evident lack of a major leaf protease. Hpa isolates express highly conserved EPIC-like proteins during infections, but it is unknown if these HpaEPICs can inhibit RD21 and one of these HpaEPICs even lacks the canonical cystatin motifs. The rd21 mutants are unaffected in compatible and incompatible interactions with Pseudomonas syringae pv. tomato, but are significantly more susceptible for the necrotrophic fungal pathogen Botrytis cinerea, demonstrating that RD21 provides immunity to a necrotrophic pathogen.
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Affiliation(s)
- Takayuki Shindo
- The Plant Chemetics Laboratory, Chemical Genomics Centre of the Max Planck Society and Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Johana C. Misas-Villamil
- The Plant Chemetics Laboratory, Chemical Genomics Centre of the Max Planck Society and Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Anja C. Hörger
- The Plant Chemetics Laboratory, Chemical Genomics Centre of the Max Planck Society and Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Jing Song
- Center for Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Renier A. L. van der Hoorn
- The Plant Chemetics Laboratory, Chemical Genomics Centre of the Max Planck Society and Max Planck Institute for Plant Breeding Research, Cologne, Germany
- * E-mail:
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van Straalen NM, Feder ME. Ecological and evolutionary functional genomics--how can it contribute to the risk assessment of chemicals? ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:3-9. [PMID: 22043966 DOI: 10.1021/es2034153] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Affiliation(s)
- Nico M van Straalen
- Department of Ecological Science, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands.
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621
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Muñoz-Diez C, Vitte C, Ross-Ibarra J, Gaut BS, Tenaillon MI. Using Nextgen Sequencing to Investigate Genome Size Variation and Transposable Element Content. PLANT TRANSPOSABLE ELEMENTS 2012. [DOI: 10.1007/978-3-642-31842-9_3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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622
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Chavigneau H, Goué N, Delaunay S, Courtial A, Jouanin L, Reymond M, Méchin V, Barrière Y. QTL for floral stem lignin content and degradability in three recombinant inbred line (RIL) progenies of <i>Arabidopsis thaliana</i> and search for candidate genes involved in cell wall biosynthesis and degradability. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/ojgen.2012.21002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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623
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Weigel D. Natural variation in Arabidopsis: from molecular genetics to ecological genomics. PLANT PHYSIOLOGY 2012; 158:2-22. [PMID: 22147517 PMCID: PMC3252104 DOI: 10.1104/pp.111.189845] [Citation(s) in RCA: 242] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 12/05/2011] [Indexed: 05/18/2023]
Affiliation(s)
- Detlef Weigel
- Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany.
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624
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Janitza P, Ullrich KK, Quint M. Toward a comprehensive phylogenetic reconstruction of the evolutionary history of mitogen-activated protein kinases in the plant kingdom. FRONTIERS IN PLANT SCIENCE 2012; 3:271. [PMID: 23230446 PMCID: PMC3515877 DOI: 10.3389/fpls.2012.00271] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 11/19/2012] [Indexed: 05/06/2023]
Abstract
The mitogen-activated protein kinase (MAPK) pathway is a three-tier signaling cascade that transmits cellular information from the plasma membrane to the cytoplasm where it triggers downstream responses. The MAPKs represent the last step in this cascade and are activated when both tyrosine and threonine residues in a conserved TxY motif are phosphorylated by MAPK kinases, which in turn are themselves activated by phosphorylation by MAPK kinase kinases. To understand the molecular evolution of MAPKs in the plant kingdom, we systematically conducted a Hidden-Markov-Model based screen to identify MAPKs in 13 completely sequenced plant genomes. In this analysis, we included green algae, bryophytes, lycophytes, and several mono- and eudicotyledonous species covering >800 million years of evolution. The phylogenetic relationships of the 204 identified MAPKs based on Bayesian inference facilitated the retraction of the sequence of emergence of the four major clades that are characterized by the presence of a TDY or TEY-A/TEY-B/TEY-C type kinase activation loop. We present evidence that after the split of TDY- and TEY-type MAPKs, initially the TEY-C clade emerged. This was followed by the TEY-B clade in early land plants until the TEY-A clade finally emerged in flowering plants. In addition to these well characterized clades, we identified another highly conserved clade of 45 MAPK-likes, members of which were previously described as Mak-homologous kinases. In agreement with their essential functions, molecular population genetic analysis of MAPK genes in Arabidopsis thaliana accessions reveal that purifying selection drove the evolution of the MAPK family, implying strong functional constraints on MAPK genes. Closely related MAPKs most likely subfunctionalized, a process in which differential transcriptional regulation of duplicates may be involved.
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Affiliation(s)
- Philipp Janitza
- Department of Molecular Signal Processing, Leibniz Institute of Plant BiochemistryHalle (Saale), Germany
| | - Kristian Karsten Ullrich
- Department of Molecular Signal Processing, Leibniz Institute of Plant BiochemistryHalle (Saale), Germany
| | - Marcel Quint
- Department of Molecular Signal Processing, Leibniz Institute of Plant BiochemistryHalle (Saale), Germany
- *Correspondence: Marcel Quint, Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, Weinberg 03, 06120 Halle (Saale), Germany. e-mail:
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625
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Okumoto S, Jones A, Frommer WB. Quantitative imaging with fluorescent biosensors. ANNUAL REVIEW OF PLANT BIOLOGY 2012; 63:663-706. [PMID: 22404462 DOI: 10.1146/annurev-arplant-042110-103745] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Molecular activities are highly dynamic and can occur locally in subcellular domains or compartments. Neighboring cells in the same tissue can exist in different states. Therefore, quantitative information on the cellular and subcellular dynamics of ions, signaling molecules, and metabolites is critical for functional understanding of organisms. Mass spectrometry is generally used for monitoring ions and metabolites; however, its temporal and spatial resolution are limited. Fluorescent proteins have revolutionized many areas of biology-e.g., fluorescent proteins can report on gene expression or protein localization in real time-yet promoter-based reporters are often slow to report physiologically relevant changes such as calcium oscillations. Therefore, novel tools are required that can be deployed in specific cells and targeted to subcellular compartments in order to quantify target molecule dynamics directly. We require tools that can measure enzyme activities, protein dynamics, and biophysical processes (e.g., membrane potential or molecular tension) with subcellular resolution. Today, we have an extensive suite of tools at our disposal to address these challenges, including translocation sensors, fluorescence-intensity sensors, and Förster resonance energy transfer sensors. This review summarizes sensor design principles, provides a database of sensors for more than 70 different analytes/processes, and gives examples of applications in quantitative live cell imaging.
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Affiliation(s)
- Sakiko Okumoto
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA 24061, USA
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626
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Todesco M, Balasubramanian S, Cao J, Ott F, Sureshkumar S, Schneeberger K, Meyer RC, Altmann T, Weigel D. Natural variation in biogenesis efficiency of individual Arabidopsis thaliana microRNAs. Curr Biol 2011; 22:166-70. [PMID: 22206705 DOI: 10.1016/j.cub.2011.11.060] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 10/28/2011] [Accepted: 11/29/2011] [Indexed: 10/14/2022]
Abstract
Like protein-coding genes, loci that produce microRNAs (miRNAs) are generally considered to be under purifying selection, consistent with miRNA polymorphisms being able to cause disease. Nevertheless, it has been hypothesized that variation in miRNA genes may contribute to phenotypic diversity. Here we demonstrate that a naturally occurring polymorphism in the MIR164A gene affects leaf shape and shoot architecture in Arabidopsis thaliana, with the effects being modified by additional loci in the genome. A single base pair substitution in the miRNA complementary sequence alters the predicted stability of the miRNA:miRNA(∗) duplex. It thereby greatly reduces miRNA accumulation, probably because it interferes with precursor processing. We demonstrate that this is not a rare exception and that natural strains of Arabidopsis thaliana harbor dozens of similar polymorphisms that affect processing of a wide range of miRNA precursors. Our results suggest that natural variation in miRNA biogenesis resulting from cis mutations is a common contributor to phenotypic variation in plants.
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Affiliation(s)
- Marco Todesco
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
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627
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Mochida K, Shinozaki K. Advances in omics and bioinformatics tools for systems analyses of plant functions. PLANT & CELL PHYSIOLOGY 2011; 52:2017-38. [PMID: 22156726 PMCID: PMC3233218 DOI: 10.1093/pcp/pcr153] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Omics and bioinformatics are essential to understanding the molecular systems that underlie various plant functions. Recent game-changing sequencing technologies have revitalized sequencing approaches in genomics and have produced opportunities for various emerging analytical applications. Driven by technological advances, several new omics layers such as the interactome, epigenome and hormonome have emerged. Furthermore, in several plant species, the development of omics resources has progressed to address particular biological properties of individual species. Integration of knowledge from omics-based research is an emerging issue as researchers seek to identify significance, gain biological insights and promote translational research. From these perspectives, we provide this review of the emerging aspects of plant systems research based on omics and bioinformatics analyses together with their associated resources and technological advances.
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Affiliation(s)
- Keiichi Mochida
- RIKEN Biomass Engineering Program, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045 Japan.
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628
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Guo YL, Fitz J, Schneeberger K, Ossowski S, Cao J, Weigel D. Genome-wide comparison of nucleotide-binding site-leucine-rich repeat-encoding genes in Arabidopsis. PLANT PHYSIOLOGY 2011; 157:757-69. [PMID: 21810963 PMCID: PMC3192553 DOI: 10.1104/pp.111.181990] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Accepted: 08/01/2011] [Indexed: 05/18/2023]
Abstract
Plants, like animals, use several lines of defense against pathogen attack. Prominent among genes that confer disease resistance are those encoding nucleotide-binding site-leucine-rich repeat (NB-LRR) proteins. Likely due to selection pressures caused by pathogens, NB-LRR genes are the most variable gene family in plants, but there appear to be species-specific limits to the number of NB-LRR genes in a genome. Allelic diversity within an individual is also increased by obligatory outcrossing, which leads to genome-wide heterozygosity. In this study, we compared the NB-LRR gene complement of the selfer Arabidopsis thaliana and its outcrossing close relative Arabidopsis lyrata. We then complemented and contrasted the interspecific patterns with studies of NB-LRR diversity within A. thaliana. Three important insights are as follows: (1) that both species have similar numbers of NB-LRR genes; (2) that loci with single NB-LRR genes are less variable than tandem arrays; and (3) that presence-absence polymorphisms within A. thaliana are not strongly correlated with the presence or absence of orthologs in A. lyrata. Although A. thaliana individuals are mostly homozygous and thus potentially less likely to suffer from aberrant interaction of NB-LRR proteins with newly introduced alleles, the number of NB-LRR genes is similar to that in A. lyrata. In intraspecific and interspecific comparisons, NB-LRR genes are also more variable than receptor-like protein genes. Finally, in contrast to Drosophila, there is a clearly positive relationship between interspecific divergence and intraspecific polymorphisms.
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629
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Double-strand break repair processes drive evolution of the mitochondrial genome in Arabidopsis. BMC Biol 2011; 9:64. [PMID: 21951689 PMCID: PMC3193812 DOI: 10.1186/1741-7007-9-64] [Citation(s) in RCA: 176] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 09/27/2011] [Indexed: 11/12/2022] Open
Abstract
Background The mitochondrial genome of higher plants is unusually dynamic, with recombination and nonhomologous end-joining (NHEJ) activities producing variability in size and organization. Plant mitochondrial DNA also generally displays much lower nucleotide substitution rates than mammalian or yeast systems. Arabidopsis displays these features and expedites characterization of the mitochondrial recombination surveillance gene MSH1 (MutS 1 homolog), lending itself to detailed study of de novo mitochondrial genome activity. In the present study, we investigated the underlying basis for unusual plant features as they contribute to rapid mitochondrial genome evolution. Results We obtained evidence of double-strand break (DSB) repair, including NHEJ, sequence deletions and mitochondrial asymmetric recombination activity in Arabidopsis wild-type and msh1 mutants on the basis of data generated by Illumina deep sequencing and confirmed by DNA gel blot analysis. On a larger scale, with mitochondrial comparisons across 72 Arabidopsis ecotypes, similar evidence of DSB repair activity differentiated ecotypes. Forty-seven repeat pairs were active in DNA exchange in the msh1 mutant. Recombination sites showed asymmetrical DNA exchange within lengths of 50- to 556-bp sharing sequence identity as low as 85%. De novo asymmetrical recombination involved heteroduplex formation, gene conversion and mismatch repair activities. Substoichiometric shifting by asymmetrical exchange created the appearance of rapid sequence gain and loss in association with particular repeat classes. Conclusions Extensive mitochondrial genomic variation within a single plant species derives largely from DSB activity and its repair. Observed gene conversion and mismatch repair activity contribute to the low nucleotide substitution rates seen in these genomes. On a phenotypic level, these patterns of rearrangement likely contribute to the reproductive versatility of higher plants.
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630
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631
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Spontaneous epigenetic variation in the Arabidopsis thaliana methylome. Nature 2011; 480:245-9. [PMID: 22057020 DOI: 10.1038/nature10555] [Citation(s) in RCA: 466] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 09/13/2011] [Indexed: 11/09/2022]
Abstract
Heritable epigenetic polymorphisms, such as differential cytosine methylation, can underlie phenotypic variation. Moreover, wild strains of the plant Arabidopsis thaliana differ in many epialleles, and these can influence the expression of nearby genes. However, to understand their role in evolution, it is imperative to ascertain the emergence rate and stability of epialleles, including those that are not due to structural variation. We have compared genome-wide DNA methylation among 10 A. thaliana lines, derived 30 generations ago from a common ancestor. Epimutations at individual positions were easily detected, and close to 30,000 cytosines in each strain were differentially methylated. In contrast, larger regions of contiguous methylation were much more stable, and the frequency of changes was in the same low range as that of DNA mutations. Like individual positions, the same regions were often affected by differential methylation in independent lines, with evidence for recurrent cycles of forward and reverse mutations. Transposable elements and short interfering RNAs have been causally linked to DNA methylation. In agreement, differentially methylated sites were farther from transposable elements and showed less association with short interfering RNA expression than invariant positions. The biased distribution and frequent reversion of epimutations have important implications for the potential contribution of sequence-independent epialleles to plant evolution.
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632
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Gan X, Stegle O, Behr J, Steffen JG, Drewe P, Hildebrand KL, Lyngsoe R, Schultheiss SJ, Osborne EJ, Sreedharan VT, Kahles A, Bohnert R, Jean G, Derwent P, Kersey P, Belfield EJ, Harberd NP, Kemen E, Toomajian C, Kover PX, Clark RM, Rätsch G, Mott R. Multiple reference genomes and transcriptomes for Arabidopsis thaliana. Nature 2011; 477:419-23. [PMID: 21874022 PMCID: PMC4856438 DOI: 10.1038/nature10414] [Citation(s) in RCA: 528] [Impact Index Per Article: 40.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 08/05/2011] [Indexed: 01/07/2023]
Abstract
Genetic differences between Arabidopsis thaliana accessions underlie the plant's extensive phenotypic variation, and until now these have been interpreted largely in the context of the annotated reference accession Col-0. Here we report the sequencing, assembly and annotation of the genomes of 18 natural A. thaliana accessions, and their transcriptomes. When assessed on the basis of the reference annotation, one-third of protein-coding genes are predicted to be disrupted in at least one accession. However, re-annotation of each genome revealed that alternative gene models often restore coding potential. Gene expression in seedlings differed for nearly half of expressed genes and was frequently associated with cis variants within 5 kilobases, as were intron retention alternative splicing events. Sequence and expression variation is most pronounced in genes that respond to the biotic environment. Our data further promote evolutionary and functional studies in A. thaliana, especially the MAGIC genetic reference population descended from these accessions.
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Affiliation(s)
- Xiangchao Gan
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
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