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Asset Tag: Arabidopsis thaliana

July 7, 2019  |  

Variation of 45S rDNA intergenic spacers in Arabidopsis thaliana.

Approximately seven hundred 45S rRNA genes (rDNA) in the Arabidopsis thaliana genome are organised in two 4 Mbp-long arrays of tandem repeats arranged in head-to-tail fashion separated by an intergenic spacer (IGS). These arrays make up 5?% of the A. thaliana genome. IGS are rapidly evolving sequences and frequent rearrangements inside the rDNA loci have generated considerable interspecific and even intra-individual variability which allows to distinguish among otherwise highly conserved rRNA genes. The IGS has not been comprehensively described despite its potential importance in regulation of rDNA transcription and replication. Here we describe the detailed sequence variation in the complete IGS of A. thaliana WT plants and provide the reference/consensus IGS sequence, as well as genomic DNA analysis. We further investigate mutants dysfunctional in chromatin assembly factor-1 (CAF-1) (fas1 and fas2 mutants), which are known to have a reduced number of rDNA copies, and plant lines with restored CAF-1 function (segregated from a fas1xfas2 genetic background) showing major rDNA rearrangements. The systematic rDNA loss in CAF-1 mutants leads to the decreased variability of the IGS and to the occurrence of distinct IGS variants. We present for the first time a comprehensive and representative set of complete IGS sequences, obtained by conventional cloning and by Pacific Biosciences sequencing. Our data expands the knowledge of the A. thaliana IGS sequence arrangement and variability, which has not been available in full and in detail until now. This is also the first study combining IGS sequencing data with RFLP analysis of genomic DNA.

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July 7, 2019  |  

Assemblytics: a web analytics tool for the detection of variants from an assembly.

Assemblytics is a web app for detecting and analyzing variants from a de novo genome assembly aligned to a reference genome. It incorporates a unique anchor filtering approach to increase robustness to repetitive elements, and identifies six classes of variants based on their distinct alignment signatures. Assemblytics can be applied both to comparing aberrant genomes, such as human cancers, to a reference, or to identify differences between related species. Multiple interactive visualizations enable in-depth explorations of the genomic distributions of variants.http://assemblytics.com, https://github.com/marianattestad/assemblytics CONTACT: mnattest@cshl.eduSupplementary information: Supplementary data are available at Bioinformatics online.© The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

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July 7, 2019  |  

Chloroplast genome sequence of Arabidopsis thaliana accession Landsberg erecta, assembled from single-molecule, real-time sequencing data.

A publicly available data set from Pacific Biosciences was used to create an assembly of the chloroplast genome sequence of the Arabidopsis thaliana genotype Landsberg erecta The assembly is solely based on single-molecule, real-time sequencing data and hence provides high resolution of the two inverted repeat regions typically contained in chloroplast genomes. Copyright © 2016 Stadermann et al.

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July 7, 2019  |  

Improved long read correction for de novo assembly using an FM-index

Long read sequencing is changing the landscape of genomic research, especially de novo assembly. Despite the high error rate inherent to long read technologies, increased read lengths dramatically improve the continuity and accuracy of genome assemblies. However, the cost and throughput of these technologies limits their application to complex genomes. One solution is to decrease the cost and time to assemble novel genomes by leveraging textquotedbllefthybridtextquotedblright assemblies that use long reads for scaffolding and short reads for accuracy. To this end, we describe a novel application of a multi-string Burrows-Wheeler transform with auxiliary FM-index to correct errors in long read sequences using a set of complementary short reads. We show that our method efficiently produces significantly higher quality corrected sequence than existing hybrid error-correction methods. We demonstrate the effectiveness of our method compared to state-of-the-art hybrid and long-read only de novo assembly methods.

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