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1.
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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Retrovirus-like end processing of the tobacco Tnt1 retrotransposon linear intermediates of replication.
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The tobacco retrotransposon Tnt1 can transpose through an RNA intermediate in the heterologous host Arabidopsis thaliana. We report here the identification and characterization of extrachromosomal linear and circular DNA forms of Tnt1 in this heterologous host. Our results demonstrate that Tnt1 linear intermediates possess two extra base pairs at each end compared with Tnt1's integrated forms. Prior to integration into the host genome, the two terminal nucleotides at the 3' end of these linear intermediates are removed, as in the case of the yeast Ty3 retrotransposon and of retroviruses. Our data, together with those from recent studies of Ty3, reinforce the idea that 3' dinucleotide cleavage is not restricted to retroviral integrases and is probably a feature shared by many different retrotransposons' enzymes. 相似文献
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Courtial B Feuerbach F Eberhard S Rohmer L Chiapello H Camilleri C Lucas H 《Molecular genetics and genomics : MGG》2001,265(1):32-42
Tissue culture has been shown to induce the transposition of plant transposable elements; their insertion at novel sites results in somaclonal variation. Introduction of the tobacco retrotransposon Tnt1 into Arabidopsis thaliana by co-cultivation of root explants with Agrobacterium tumefaciens induces its transposition at a high frequency, but no transposed copies are found in plants transformed by the in planta procedure. Transposition occurs in the transformed root cells or in the calli derived from them, allowing the regeneration of transformed plants with up to 26 transposed copies of Tnt1. Analysis of Tnt1 integration sites in Arabidopsis shows that the Tnt1 endonuclease does not show any cleavage-site specificity at the sequence level. The insertion sites are unlinked and distributed on all five Arabidopsis chromosomes. The fact that the majority of the integration sites are located in coding regions, and none in repeated sequences, demonstrates the potential of Tnt1 as a tool for gene tagging. 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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d'Erfurth I Cosson V Eschstruth A Lucas H Kondorosi A Ratet P 《The Plant journal : for cell and molecular biology》2003,34(1):95-106
The tobacco element, Tnt1, is one of the few active retrotransposons in plants. Its transposition is activated during protoplast culture in tobacco and tissue culture in the heterologous host Arabidopsis thaliana. Here, we report its transposition in the R108 line of Medicago truncatula during the early steps of the in vitro transformation-regeneration process. Two hundred and twenty-five primary transformants containing Tnt1 were obtained. Among them, 11.2% contained only transposed copies of the element, indicating that Tnt1 transposed very early and efficiently during the in vitro transformation process, possibly even before the T-DNA integration. The average number of insertions per transgenic line was estimated to be about 15. These insertions were stable in the progeny and could be separated by segregation. Inspection of the sequences flanking the insertion sites revealed that Tnt1 had no insertion site specificity and often inserted in genes (one out of three insertions). Thus, our work demonstrates the functioning of an efficient transposable element in leguminous plants. These results indicate that Tnt1 can be used as a powerful tool for insertion mutagenesis in M. truncatula. 相似文献
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Mazier M Botton E Flamain F Bouchet JP Courtial B Chupeau MC Chupeau Y Maisonneuve B Lucas H 《Plant physiology》2007,144(1):18-31
The tobacco (Nicotiana tabacum) element Tnt1 is one of the few identified active retrotransposons in plants. These elements possess unique properties that make them ideal genetic tools for gene tagging. Here, we demonstrate the feasibility of gene tagging using the retrotransposon Tnt1 in lettuce (Lactuca sativa), which is the largest genome tested for retrotransposon mutagenesis so far. Of 10 different transgenic bushes carrying a complete Tnt1 containing T-DNA, eight contained multiple transposed copies of Tnt1. The number of transposed copies of the element per plant was particularly high, the smallest number being 28. Tnt1 transposition in lettuce can be induced by a very simple in vitro culture protocol. Tnt1 insertions were stable in the progeny of the primary transformants and could be segregated genetically. Characterization of the sequences flanking some insertion sites revealed that Tnt1 often inserted into genes. The progeny of some primary transformants showed phenotypic alterations due to recessive mutations. One of these mutations was due to Tnt1 insertion in the gibberellin 3beta-hydroxylase gene. Taken together, these results indicate that Tnt1 is a powerful tool for insertion mutagenesis especially in plants with a large genome. 相似文献
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Stress activation and genomic impact of plant retrotransposons 总被引:1,自引:0,他引:1
Grandbastien MA 《Journal de la Société de Biologie》2004,198(4):425-432
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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18.
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.
相似文献
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