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8/4/2019 Genome Sequencing in is Thaliana.
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A. thaliana is a small flowering plant that is
widely used as a model organism in plant
biology.
Member of the mustard (Brassicaceae) familyCommon name- Wall cress or Mouse-ear cress
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Small genome -125 Mb, sequenced in the year2000
Extensive genetic and physical maps of all 5chromosomes
A rapid life cycle (about 6 weeks fromgermination to mature seed)
Prolific seed production and easy cultivation inrestricted space.
Efficient transformation methods utilizingAgrobacterium tumefaciens.
A large number of mutant lines and genomicresources many of which are available fromStock Centers(ABRC, Ohio;NASC,UK)
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A. thaliana was discovered by Johannes Thal
in the Harz mountains in Germany
He called it Pilosella siliquosa, later name
changed toA. thaliana F. Laibach first summarized the potential of
A. thaliana as a model organism for genetics
in 1943.
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Bacterial artificial chromosome (BAC), phage
(P1) and Transformation-competent artificial
chromosome (TAC) libraries as the primary
substrates for sequencing.
Physical maps of the genome of accession
Columbia was first assembled by BAC clones.
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Total length of sequenced regions, which
extend from telomeres to the 180-base-pair
centromeric repeats, is 115,409,949 (bp)
The unsequenced centromeric and rDNArepeat regions measure roughly 10
megabases (Mb), yielding a genome size of
about 125Mb
Features such as gene density, expressionlevels and repeat distribution are very
consistent across the five chromosomes
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Arabidopsis has a significantly greater extent
of tandem gene duplications and segmental
duplications, which account for its larger
gene set.
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To assess the similarities and differences of
the Arabidopsis gene complement compared
with other sequenced eukaryotic genomes,
functional categories were assigned to thecomplete set of Arabidopsis genes.
The functions of 69% of the genes were
classified according to sequence similarity to
proteins of known function in all organisms.
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17.6% and 11.4% of gene products were
predicted to be targeted to the secretory
pathway and mitochondria in Arabidopsis
14% of the gene products are likely to betargeted to the chloroplast
Significant proportion of genes with
predicted functions involved in metabolism,
gene regulation and defence.
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The Arabidopsis genome sequence provides a
complete view of chromosomal organization
and clues to its evolutionary history
The majority of the Arabidopsis genome isrepresented in duplicated segments, it
appears most likely that Arabidopsis, like
maize, had a tetraploid ancestor.
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To identify commonly occurring changes in
genome microstructure.
Enables the development of new molecular
markers for genetic mappingComparative analysis was done between
accession Columbia (Col-0) and accession
Landsberg erecta
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They identified two classes of differences
between the sequences: single nucleotide
polymorphisms (SNPs), and insertion-
deletions (InDels). Sequence polymorphisms between accessions
of Arabidopsis in both coding and non-coding
regions.
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Transposons in Arabidopsis account for at
least 10% of the genome
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For more information log on to:
http://www.arabidopsis.org/index.jsp
Analysis of the genome sequence of the
flowering plantArabidopsis thaliana :Nature:408
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