共查询到20条相似文献,搜索用时 31 毫秒
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M. E. Manetti M. Rossi M. Nakabashi M. A. Grandbastien Marie Anne Van Sluys 《Molecular genetics and genomics : MGG》2009,281(3):261-271
Eukaryotic genome expansion/retraction caused by LTR-retrotransposon activity is dependent on the expression of full length
copies to trigger efficient transposition and recombination-driven events. The Tnt1 family of retrotransposons has served
as a model to evaluate the diversity among closely related elements within Solanaceae species and found that members of the
family vary mainly in their U3 region of the long terminal repeats (LTRs). Recovery of a full length genomic copy of Retrosol
was performed through a PCR-based approach from wild potato, Solanum oplocense. Further characterization focusing on both LTR sequences of the amplified copy allowed estimating an approximate insertion
time at 2 million years ago thus supporting the occurrence of transposition cycles after genus divergence. Copy number of
Tnt1-like elements in Solanum species were determined through genomic quantitative PCR whereby results sustain that Retrosol in Solanum species is a low copy number retrotransposon (1–4 copies) while Retrolyc1 has an intermediate copy number (38 copies) in
S. peruvianum. Comparative analysis of retrotransposon content revealed no correlation between genome size or ploidy level and Retrosol
copy number. The tetraploid cultivated potato with a cellular genome size of 1,715 Mbp harbours similar copy number per monoploid
genome than other diploid Solanum species (613–884 Mbp). Conversely, S. peruvianum genome (1,125 Mbp) has a higher copy number. These results point towards a lineage specific dynamic flux regarding the history
of amplification/activity of Tnt1-like elements in the genome of Solanum species.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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Maria E Manetti Magdalena Rossi Ana PP Costa Andrea M Clausen Marie-Anne Van Sluys 《BMC evolutionary biology》2007,7(1):34
Background
Tnt1 was the first active plant retrotransposon identified in tobacco after nitrate reductase gene disruption. The Tnt1 superfamily comprises elements from Nicotiana (Tnt1 and Tto1) and Lycopersicon (Retrolyc1 and Tlc1) species. The study presented here was conducted to characterise Tnt1-related sequences in 20 wild species of Solanum and five cultivars of Solanum tuberosum. 相似文献4.
Raquel A. Kriedt Guilherme M. Q. Cruz Sandro L. Bonatto Loreta B. Freitas 《Plant Molecular Biology Reporter》2014,32(1):142-152
Transposable elements (TEs) are widespread in eukaryotic genomes. The diversity and abundance of TEs are highly variable among species and may correspond to particular relationships between a species and the elements in its genome. There are often many TE families within a single genome; thus, the amplification of one TE family may influence the amplification of other families. LTR retrotransposons (LTR-RTs) are extremely abundant in flowering plants, and Tnt1 is one of the most well known. First characterized in tobacco, Tnt1-related sequences have since been reported in other genera of Solanaceae. In this study, we investigated the profile of Tnt1-related sequences among the species of three Solanaceae genera through genomic amplification and the cloning of partial sequences. The analysis of these sequences revealed high levels of diversity and showed that the sequences are not as closely related to Tnt1 as had been previously hypothesized. The classification of the sequences yielded ten possible families of LTR-RTs, which are, in addition to Tnt1, all members of the Tork clade within the Copia superfamily. However, the sequences did not follow the phylogeny of the species and were not homogeneously distributed. One family includes only sequences of taxa that inhabit dry areas. These findings were consistent with previous suggestions of an early association of Tnt1-related elements with the evolution of several Solanaceae species. 相似文献
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Retroviruses consist of populations of different but closely related genomes referred to as quasispecies. A high mutation rate coupled with extremely rapid replication cycles allows these sequences to be highly interconnected in a rapid equilibrium. It is not known if other retroelements can show a similar population structure. We show here that when the tobacco Tnt1 retrotransposon is expressed, its RNA is not a unique sequence but a population of different but closely related sequences. Nevertheless, this highly variable population is not in a rapid equilibrium and could not be considered as a quasispecies. We have thus named the structure presented by Tnt1 RNA quasispecies-like. We show that the expression of Tnt1 in different situations gives rise to different populations of Tnt1 RNA sequences, suggesting an adaptive capacity for this element. The analysis of the variability within the total genomic population of Tnt1 elements shows that mutations frequently occur in important regulatory elements and that defective elements are often produced. We discuss the implications that this population structure could have for Tnt1 regulation and evolution. 相似文献
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Distribution dynamics of the Tnt1 retrotransposon in tobacco 总被引:1,自引:0,他引:1
Le QH Melayah D Bonnivard E Petit M Grandbastien MA 《Molecular genetics and genomics : MGG》2007,278(6):639-651
Retrotransposons contribute significantly to the size, organization and genetic diversity of plant genomes. Although many
retrotransposon families have been reported in plants, to this day, the tobacco Tnt1 retrotransposon remains one of the few
elements for which active transposition has been shown. Demonstration that Tnt1 activation can be induced by stress has lent
support to the hypothesis that, under adverse conditions, transposition can be an important source of genetic variability.
Here, we compared the insertion site preference of a collection of newly transposed and pre-existing Tnt1 copies identified
in plants regenerated from protoplasts or tissue culture. We find that newly transposed Tnt1 copies are targeted within or
close to host gene coding sequences and that the distribution of pre-existing insertions does not vary significantly from
this trend. Therefore, in spite of their potential to disrupt neighboring genes, insertions within or near CDS are not preferentially
removed with age. Elimination of Tnt1 insertions within or near coding sequences may be relaxed due to the polyploid nature
of the tobacco genome. Tnt1 insertions within or near CDS are thus better tolerated and can putatively contribute to the diversification
of tobacco gene function.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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DELPHINE MELAYAH † K. YOONG LIM ERIC BONNIVARD ‡ BOULOS CHALHOUB § FRANÇOIS DORLHAC DE BORNE CORINNE MHIRI REW R. LEITCH MARIE-ANGÈLE GRANDBASTIEN 《Biological journal of the Linnean Society. Linnean Society of London》2004,82(4):639-649
Transposable elements can generate considerable genetic diversity. Here we examine the distribution of the Tnt1 retrotransposon family in representative species of the genus Nicotiana . We show that multiple Tnt1 insertions are found in all Nicotiana species. However, Tnt1 insertions are too polymorphic to reveal species relationships. This indicates that Tnt1 has amplified rapidly and independently after Nicotiana speciation. We compare patterns of Tnt1 insertion in allotetraploid tobacco ( N. tabacum ) with those in the diploid species that are most closely related to the progenitors of tobacco, N. sylvestris (S-genome donor) and N. tomentosiformis (T-genome donor). We found no evidence for Tnt1 insertion sites of N. otophora origin in tobacco. Nicotiana sylvestris has a higher Tnt1 content than N. tomentosiformis and the elements are distributed more uniformly across the genome. This is reflected in tobacco where there is a higher Tnt1 content in S-genome chromosomes. However, the total Tnt1 content of tobacco is not the sum of the two modern-day parental species. We also observed tobacco-specific Tnt1 insertions and an absence of tobacco Tnt1 insertion sites in the diploid relatives. These data indicate Tnt1 evolution subsequent to allopolyploidy. We explore the possibility that fast evolution of Tnt1 is associated with 'genomic-shock' arising out of interspecific hybridization and allopolyploidy. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 639–649. 相似文献
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The evolutionary analysis of the Tnt1 retrotransposon in Nicotiana species reveals the high variability of its regulatory sequences 总被引:2,自引:0,他引:2
We studied the evolution of the tobacco Tnt1 retrotransposon by analyzing
Tnt1 partial sequences containing both coding domains and U3 regulatory
sequences obtained from a number of Nicotiana species. We detected three
different subfamilies of Tnt1 elements, Tnt1A, Tnt1B, and Tnt1C, that
differ completely in their U3 regions but share conserved flanking coding
and LTR regions. U3 divergence between the three subfamilies is found in
the region that contains the regulatory sequences that control the
expression of the well-characterized Tnt1-94 element. This suggests that
expression of the three Tnt1 subfamilies might be differently regulated.
The three Tnt1 subfamilies were present in the Nicotiana genome at the time
of species divergence, but have evolved independently since then in the
different genomes. Each Tnt1 subfamily seems to have conserved its ability
to transpose in a limited and different number of Nicotiana species. Our
results illustrate the high variability of Tnt1 regulatory sequences. We
propose that this high sequence variability could allow these elements to
evolve regulatory mechanisms in order to optimize their coexistence with
their host genome.
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Regulation of expression of the tobacco Tnt1 retrotransposon in heterologous species following pathogen-related stresses 总被引:2,自引:0,他引:2
Corinne Moreau-Mhiri Jean-Benoît Morel Colette Audeon Madina Ferault Marie-Angéle Grandbastien Hélène Lucas 《The Plant journal : for cell and molecular biology》1996,9(3):409-419
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