Sequence of the iaa and ipt region of different Agrobacterium tumefaciens biotype III octopine strains: reconstruction of octopine Ti plasmid evolution

Paulus, François; Canaday, Jean; Vincent, Florence; Bonnard, Géraldine; Kares, Christa; Otten, Léon

doi:10.1007/bf00023425

Cited by 27 publications

(17 citation statements)

References 36 publications

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“…This result therefore suggests that the biosynthesis of 3-indoleacetic acid is dispensable for the production of tumors in cherry but essential for the production of tumors in tomato in this strain. A similar effect on host range was observed in Agrobacterium vitis strains, which suffered a reduction in host range capabilities when this gene was removed, due to the insertion of an IS (40). The insertion sequence IS426 has been previously found to be associated with spontaneous mutations in the pTi of strain C58 that lead to nonpathogenic variants (14,52).…”

Section: Vol 75 2009 Virulence Of a Tumefaciens Strains From Tumormentioning

confidence: 57%

Recovery of Nonpathogenic Mutant Bacteria from Tumors Caused by Several Agrobacterium tumefaciens Strains: a Frequent Event?

Llop

Murillo

Lastra

et al. 2009

Appl Environ Microbiol

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We have evaluated the interaction that bacterial genotypes and plant hosts have with the loss of pathogenicity in tumors, using seven Agrobacterium tumefaciens strains inoculated on 12 herbaceous and woody hosts. We performed a screening of the agrobacteria present inside the tumors, looking for nonpathogenic strains, and found a high variability of those strains in this niche. To verify the origin of the putative nonpathogenic mutant bacteria, we applied an efficient, reproducible, and specific randomly amplified polymorphic DNA analysis method. In contrast with previous studies, we recovered a very small percentage (0.01%) of nonpathogenic strains that can be considered true mutants. Of 5,419 agrobacterial isolates examined, 662 were nonpathogenic in tomato, although only 7 (from pepper and tomato tumors induced by two A. tumefaciens strains) could be considered to derive from the inoculated strain. Six mutants were affected in the transferred DNA (T-DNA) region; one of them contained IS426 inserted into the iaaM gene, whereas the whole T-DNA region was apparently deleted in three other mutants, and the virulence of the remaining two mutants was fully restored with the T-DNA genes as well. The plasmid profile was altered in six of the mutants, with changes in the size of the Ti plasmid or other plasmids and/or the acquisition of new plasmids. Our results also suggest that the frequent occurrence of nonpathogenic clones in the tumors is probably due to the preferential growth of nonpathogenic agrobacteria, of either endophytic or environmental origin, but different from the bacterial strain inducing the tumor.Agrobacterium tumefaciens is the causal agent of crown gall, a neoplastic disease induced in a large number of dicotyledonous and some monocotyledonous plants, as well as in gymnosperms, in this case artificially (9,32,34,35). Many studies have focused on the molecular understanding of the process that involves the tumorous growth of plant tissue by means of the transfer of specific genes from a plasmid harbored by the bacterium, called tumor-inducing plasmid (pTi) (7,18,30,43). This transfer system has significant importance for pathogenicity and epidemiology studies, as well as for biotechnology, because this unique mechanism of pathogenicity has allowed the development of a diverse and efficient methodology for the transformation of eukaryotic cells. Other studies have concentrated on the ecology and epidemiology of Agrobacterium spp. to obtain a better knowledge of the spread and stability of the bacterium as a pathogen in tumors, hosts, and soil habitats (5,11,36).The pathogenicity of A. tumefaciens seems to be somewhat unstable both in association with plants and under free-living conditions. Several studies demonstrated that A. tumefaciens populations from tumors induced under natural conditions in several plants consisted mostly of nonpathogenic strains (2, 33, 38), and loss of pathogenicity has been proposed as a likely cause to explain the predominance of nonpathogens over pathogenic strains. Lik...

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Section: Vol 75 2009 Virulence Of a Tumefaciens Strains From Tumormentioning

confidence: 57%

Recovery of Nonpathogenic Mutant Bacteria from Tumors Caused by Several Agrobacterium tumefaciens Strains: a Frequent Event?

Llop

Murillo

Lastra

et al. 2009

Appl Environ Microbiol

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“…Further comparison of the four sequences revealed some other common features such as inverted repeats at the ends of the elements. Moreover, comparison of the insertion point flanking regions revealed in all cases a small duplication of a host sequence, which in several cases has an interesting similarity, as the dinucleotide 5'-TA-3' can be found in the centre of this sequence (De Meirsman et al, 1990;Ferrante & Lessie, 1991;Paulus et al, 1991;Scordilis et al, 1987;Vanderleyden et al, 1986).…”

Section: Features Of the Nucleotide Sequencementioning

confidence: 92%

Characterization of an IS-like element from Mycobacterium tuberculosis

Mariani

Piccolella

Colizzi

et al. 1993

Journal of General Microbiology

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A DNA sequence, present in members of the Mycobacterium tuberculosis complex, has been identified and characterized. The distribution of this DNA sequence among mycobacterial species was analysed by DNA hybridization and PCR experiments. As the sequence was detected only in bacteria belonging to the M. tuberculosis complex, it may be useful for the rapid discrimination of mycobacteria. Interestingly, the sequence has some characteristics of an insertion element (IS) and codes for a hypothetical protein with significant homologies to proteins encoded by several IS elements of other organisms, namely IS427 and IS869 from Agrobacterium tumefaciens, IS402 from Pseudomonas cepacia, Tn4811 from Streptomyces liuidans and ISRm4 from Rhizobium meliloti. Together, these elements form a previously unrecognized family of transposable elements. This finding suggests the possibility of horizontal gene transfer between pathogenic mycobacteria and other organisms including Gram-negative plant-pathogenic bacteria.

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“…(viii) Small TA plasmids such as pTiAB3 carry the IS element IS869 on their TA region (23). An [26]).…”

Section: Methodsmentioning

confidence: 99%

IS870 requires a 5'-CTAG-3' target sequence to generate the stop codon for its large ORF1

1993

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The TB regions of the Agrobacterium vitis octopine/cucumopine Ti plasmids constitute a family of related structures. All contain a bacterial insertion element downstream of the TB-iaaM gene, IS870.1. Whereas 43 isolates with octopine/cucumopine Ti plasmids carry only one IS870 copy, strain Ag57 carries a second copy (IS870.2) 3.9 kb to the right of IS870.1 and part of the same TB region. Two other octopine/cucumopine strains carry an IS870 copy on their chromosome (IS870.3). A study of the unmodified insertion sites of IS870.2 and IS870.3, cloned from closely related strains, enabled us to delimit the IS870 elements. IS870 has a size of 1,152 bp and is terminated by inverted repeats. It contains a large open reading frame without a stop codon. However, a stop codon is generated by insertion into the target sequence 5'-CTAG-3'. IS870 is related to five other insertion sequence elements. For two of these, the stop codon of the largest open reading frame is also created by insertion into a CTAG target site.Bacterial insertion sequences (IS) play an important role in bacterial evolution (32). Their transposition into new locations may cause mutations by gene disruption but can also create potentially useful variability within a population. We are interested in the role of IS elements in the evolution of Agrobacterium Ti plasmids. Part of the Ti plasmid (its T-DNA or T region) is transferred to the plant cell during tumor induction. Expression of T-DNA genes then leads to tumor formation (for a review, see reference 42). The various octopine/cucumopine (o/c) Ti plasmids found in Agrobacterium vitis (20) isolates code for tumor induction on grapevine. They are particularly suited for evolutionary studies, since they are closely related to each other but nevertheless show considerable variation (for a review, see reference 21). All o/c plasmids harbor two independent T regions: TA and TB. The o/c plasmids have been divided into five different types on the basis of their TA region structure. These structures are derived from an ancestor TA region by insertion of different IS elements (IS866, IS868, and IS869) and by deletions caused by insertion of and recombination between different copies of the same IS element (IS868 and IS867). Two large o/c Ti plasmid groups can be distinguished: the "small TA" group (with its representatives pTiAB3 and pTiAg57) and the "large TA" group (pTiTm4 and pTiHml); they correspond to the limited-and wide-host-range Ti plasmids, respectively (15, 41).The TB regions have an average size of about 20 kb and carry two auxin genes, TB-iaaM and TB-iaaH, together responsible for indoleacetic acid synthesis in the tumor cells (3,11,41)

show abstract

Sequence of the iaa and ipt region of different Agrobacterium tumefaciens biotype III octopine strains: reconstruction of octopine Ti plasmid evolution

Cited by 27 publications

References 36 publications

Recovery of Nonpathogenic Mutant Bacteria from Tumors Caused by Several Agrobacterium tumefaciens Strains: a Frequent Event?

Recovery of Nonpathogenic Mutant Bacteria from Tumors Caused by Several Agrobacterium tumefaciens Strains: a Frequent Event?

Characterization of an IS-like element from Mycobacterium tuberculosis

IS870 requires a 5'-CTAG-3' target sequence to generate the stop codon for its large ORF1

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