Function of heterologous and pseudo border repeats in T region transfer via the octopine virulence system of Agrobacterium tumefaciens

Haaren, M. J. J. Van; Sedee, N. J. A.; Krul, M. R. L.; Schilperoort, R. A.; Hooykaas, Paul J. J.

doi:10.1007/bf00019517

Cited by 18 publications

(7 citation statements)

References 30 publications

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“…If combined with the overdrive sequence both types of repeats can mediate T-region transfer to plants equally well [29,31]. This justifies the formulation of a consensus sequence for a border repeat from the sequence data obtained so far for both left-and right-border repeats [3,16,35].…”

Section: The Border Repeatmentioning

confidence: 92%

Mutational analysis of the conserved domains of a T-region border repeat of Agrobacterium tumefaciens

Haaren

Sedee

Boer³

et al. 1989

Plant Mol Biol

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Left- and right-border repeats, which surround the T-region, contain two conserved regions separated by 5 bp that are not conserved. At the onset of T-DNA processing virD-encoded proteins introduce a nick in the largest of these conserved regions (12 bp) at a specific position in the bottom strand between a guanine and thymine nucleotide [2, 33]. In this paper we describe the effect of several site-directed mutations in the right-border repeat on tumorigenicity of Agrobacterium in plants. Our data show that mutations introduced directly around the nick site do not seriously affect the tumorigenicity of Agrobacterium, whereas mutations in the right part of this 12 bp conserved region do so. Furthermore, it appeared that the second conserved region (5 bp) is also essential for border activity and that the distance between the two conserved regions is important to obtain optimal border activity.

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Section: The Border Repeatmentioning

confidence: 92%

Mutational analysis of the conserved domains of a T-region border repeat of Agrobacterium tumefaciens

Haaren

Sedee

Boer³

et al. 1989

Plant Mol Biol

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“…To determine the end point of the T-DNA borders, the T-DNA region was aligned against the T-DNA plasmid sequence. We will refer throughout to a correct nicking process of the T-strand when the T-DNA is cleaved between the third and fourth base of the 24-bp border repeat (Van Haaren et al, 1988).…”

Section: Methodsmentioning

confidence: 99%

T-DNA Integration in Arabidopsis Chromosomes. Presence and Origin of Filler DNA Sequences

et al. 2003

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To investigate the relationship between T-DNA integration and double-stranded break (DSB) repair in Arabidopsis, we studied 67 T-DNA/plant DNA junctions and 13 T-DNA/T-DNA junctions derived from transgenic plants. Three different types of T-DNA-associated joining could be distinguished. A minority of T-DNA/plant DNA junctions were joined by a simple ligation-like mechanism, resulting in a junction without microhomology or filler DNA insertions. For about one-half of all analyzed junctions, joining of the two ends occurred without insertion of filler sequences. For these junctions, microhomology was strikingly combined with deletions of the T-DNA ends. For the remaining plant DNA/T-DNA junctions, up to 51-bp-long filler sequences were present between plant DNA and T-DNA contiguous sequences. These filler segments are built from several short sequence motifs, identical to sequence blocks that occur in the T-DNA ends and/or the plant DNA close to the integration site. Mutual microhomologies among the sequence motifs that constitute a filler segment were frequently observed. When T-DNA integration and DSB repair were compared, the most conspicuous difference was the frequency and the structural organization of the filler insertions. In Arabidopsis, no filler insertions were found at DSB repair junctions. In maize (Zea mays) and tobacco (Nicotiana tabacum), DSB repair-associated filler was normally composed of simple, uninterrupted sequence blocks. Thus, although DSB repair and T-DNA integration are probably closely related, both mechanisms have some exclusive and specific characteristics.

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“…Alignment of T-DNA border sequences from a diverse range of Agrobacterium strains reveals two strongly conserved motifs of 12-13 bp and 6-7 bp that flank a variable region of 5 bp (Table 1). The importance of these two conserved motifs for T-strand transfer has been confirmed by mutational analysis (van Haaren et al 1988(van Haaren et al , 1989. By contrast, the end point of the T-DNA sequence transferred at the left border is far less precise and may occur at or about the left border, or even well beyond this sequence.…”

Section: Mechanism Of Gene Transfermentioning

confidence: 96%

Intragenic vectors for gene transfer without foreign DNA

et al. 2006

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The intragenic vector system involves identifying functional equivalents of vector components from the genome of a specific crop species (or related species to which it can be hybridised) and using these DNA sequences to assemble vectors for transformation of that plant species. This system offers an attractive alternative to current genetic engineering strategies where vectors are based on DNA sequences that usually originate from bacteria. The construction of intragenic vectors enables the well-defined genetic improvement of plants with all transferred DNA originating from within the gene pool already available to plant breeders. In this manner genes can be introgressed into elite cultivars in a single step without linkage drag and without the incorporation of foreign DNA. The resulting plants are non-transgenic, although they are derived using the tools of molecular biology and plant transformation. The use of intragenic vectors for the transfer of genes from within the gene pools of crops may help to alleviate some of the major public concerns over the deployment of GM crops in agriculture, notably the ethical issue associated with the transfer of DNA across wide taxonomic boundaries. This paper reviews the progress toward the development and use of intragenic vectors and the implications of their use for the genetic improvement of crops.

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Function of heterologous and pseudo border repeats in T region transfer via the octopine virulence system of Agrobacterium tumefaciens

Cited by 18 publications

References 30 publications

Mutational analysis of the conserved domains of a T-region border repeat of Agrobacterium tumefaciens

Mutational analysis of the conserved domains of a T-region border repeat of Agrobacterium tumefaciens

T-DNA Integration in Arabidopsis Chromosomes. Presence and Origin of Filler DNA Sequences

Intragenic vectors for gene transfer without foreign DNA

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