Supercoiled circular DNA in crown-gall inducing Agrobacterium strains

Zaenen, Ivo; Larebeke, N. Van; Teuchy, H.; Montagu, M. van; Schell, J.

doi:10.1016/s0022-2836(74)80011-2

Cited by 446 publications

(146 citation statements)

References 34 publications

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“…Later, the biotypes were changed to biovars (26,32). In the meantime, other researchers who discovered megaplasmids showed that the megaplasmids induced tumors or hairy roots (22,23, 30, 33, 46, 49,52). These plasmids are believed to be transferable among Agrobacterium strains (22, 23, 30).…”

Section: Discussionmentioning

confidence: 99%

“…Most of the genes associated with tumor and hairy root formation are located on Ti or Ri plasmids (22, 23, 30,33,46,49,50,52), and therefore the present system used for differentiation of species in the genus Agrobacterium is not based on chromosomal DNA. However, the taxonomy of bacteria should be grounded upon chromosomal DNA.…”

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confidence: 99%

“…Many non-tumorforming strains closely related to the tumor formers which have been found in soil or in the rhizospheres of plants (3,4) and in clinical specimens (13) have been identified as Agrobacterium radiobacter strains (4,26). Later, molecular biological studies have revealed that the tumor-or hairy-rootforming ability is due to the presence of large indigenous plasmids (22,23,30,33,46,49,52), and the inclusion of the organisms that do not form tumors in the genus Agrobacterium has been confirmed. Also, recent rRNA-DNA homology studies (9,19) have revealed the close relationship between the non-tumor-forming strains and the tumor formers.…”

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confidence: 99%

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Proposal for Rejection of Agrobacterium tumefaciens and Revised Descriptions for the Genus Agrobacterium and for Agrobacterium radiobacter and Agrobacterium rhizogenes

Sawada

Ieki

Oyaizu

et al. 1993

International Journal of Systematic Bacteriology

220

153

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The 16s rRNA sequences of seven representative Agrobacterium strains, eight representative Rhizobium strains, and the type strains of Azorhizobium caulinodans and Bradyrhizobium japonicum were determined. These strains included the type strains of Agrobacterium tumefaciens, Agrobacterium rhizogenes, Agrobacterium radiobacter, Agrobacterium vitis, Agrobacterium rubi, Rhizobium fredii, Rhizobium galegae, Rhizobium huukuii, Rhizobium leguminosarum, Rhizobium loti, Rhizobium meliloti, and Rhizobium tropici. A phylogenetic analysis showed that the 15 strains of Agrobacterium and Rhizobium species formed a compact phylogenetic cluster clearly separated from the other members of the alpha subclass of the Proteobacteria. However, Agrobacterium species and Rhizobium species are phylogenetically entwined with one another, and the two genera cannot be separated. In the Agrobacterium species, the strains of biovar 1, biovar 2, Agrobacterium rubi, and Agrobacterium vitis were clearly separated. The two biovars exhibited homogeneity in their phenotypic, chemotaxonomic, and phylogenetic characteristics, and two species should be established for the two biovars. We considered the nomenclature of the two biovars, and revised descriptions of Agrobacterium radwbacter (for the biovar 1 strains) and Agrobacterium rhizogenes (for the biovar 2 strains) are proposed. The name Agrobacterium tumefaciens is rejected because the type strain of this species was assigned to Agrobacterium radiobacter, and consequently the description of the genus Agrobacterium is revised.The genus Agrobactenum was established by Conn (4) in 1942. This genus has been a member of the family Rhizobiaceae since it was first established. The members of the family Rhizobiaceae have a unique ability to induce cortical hypertrophies on plants (26). The genera Rhizobium and Bradyrhizobium are well-known nitrogen-fixing noduleforming bacteria associated with legumes. The members of genus Phyllobactenum induce the formation of nodules on the leaves of certain plant species.All of the members of the genus Agrobactenum except Agrobacterium radiobacter induce cortical hypertrophy of the upper parts of roots (Agrobacterium tumefaciens and Agrobacterium rubi) or abnormal root growth Cllgrobacterium rhizogenes) on many kinds of plants. Many non-tumorforming strains closely related to the tumor formers which have been found in soil or in the rhizospheres of plants (3,4) and in clinical specimens (13) have been identified as Agrobacterium radiobacter strains (4, 26). Later, molecular biological studies have revealed that the tumor-or hairy-rootforming ability is due to the presence of large indigenous plasmids (22, 23, 30,33,46,49,52), and the inclusion of the organisms that do not form tumors in the genus Agrobacterium has been confirmed. Also, recent rRNA-DNA homology studies (9, 19) have revealed the close relationship between the non-tumor-forming strains and the tumor formers.The separation of the genus Agrobacterium from allied genera and also the separation of species in...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Proposal for Rejection of Agrobacterium tumefaciens and Revised Descriptions for the Genus Agrobacterium and for Agrobacterium radiobacter and Agrobacterium rhizogenes

Sawada

Ieki

Oyaizu

et al. 1993

International Journal of Systematic Bacteriology

220

153

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“…Virulent Agrobacterium turnefaciens strains carry large plasmids (TI plasmids) that are essential for the oncogenic properties of the bacteria (Zaenen et al, 1974). The mechanism whereby agrobacteria transform normal cells into tumour cells is unknown.…”

Section: Introductionmentioning

confidence: 99%

Regulation of the Transfer of TI Plasmids of Agrobacterium tumefaciens

Hooykaas

Roobol

Schilperoort

1979

Journal of General Microbiology

146

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Octopine-utilizing agrobacteria could be distinguished from non-utilizers on a solid medium containing octopine as the only added nitrogen source if a pH indicator such as bromothymolblue were present. On green bromothymolblue plates, octopine-utilizing strains formed orange-yellow colonies, while those of non-utilizers were translucent. Strains could be tested for utilization of other nitrogen sources such as nopaline by substituting these for octopine in the same medium.Using bromothymolblue plates, it was found that TI plasmids of octopine-utilizing strains of Agrobacterium turnefaciens were transferable in the presence of octopine, octopinic acid or lysopine, but not in the presence of the analogues nor-octopine, homo-octopine or desmethylhomo-octopine. Transfer in the presence of ' inducer' was not detected when bacteria were mated at 37 "C instead of 29 "C, or when either methionine, cysteine or cystine was present in the mating medium. Mutant plasmids were obtained that were conjugative in the absence of an inducer; these were insensitive to methionine and cysteine but, like the wild-type plasmid, were thermosensitive for transfer.The TI plasmid of an octopine-utilizing strain was introduced into a strain that carried a deleted nopaline TI plasmid. These plasmids were found to be compatible. The properties of this transconjugant showed that the octopine oxidase does not accept nopaline as a substrate. Tumours induced on Kalanchoz daigremontiana by this bacterium were rough and contained octopine. Exclusion of phage S18 was found to be a marker specific for the TI(Kerr 14) plasmid. I N T R O D U C T I O NVirulent Agrobacterium turnefaciens strains carry large plasmids (TI plasmids) that are essential for the oncogenic properties of the bacteria (Zaenen et al., 1974). The mechanism whereby agrobacteria transform normal cells into tumour cells is unknown. However, recently it was shown that a small fragment of the TI plasmid is present in transformed plant cells and is transcribed into RNA (Drummond et al., 1977). How this bacterial DNA enters the plant cell is unknown. Since tumour induction can be inhibited by preventing attachment of the virulent bacteria to the plant cells (Schilperoort, 1969;Lippincott & Lippincott, 1969;Lippincott et al., 1977; Whatley et al., 1976), it is possible that DNA is transferred from the bacteria to plant cells by a conjugation-like mechanism. It is well known that TI plasmids can act as conjugative plasmids in crown gall tumours, i.e. avirulent Agrobacterium strains can become oncogenic by acquisition of the TI plasmid from a virulent strain in mixed infections of plants (van Larebeke et al., 1975; Watson et ul., 1975; Kerr et al., 1977). Explanta, however, transfer of TI plasmids was not observed, although they could be mobilized by the R plasmid RP4 (Bomhoff et al., 1976; Chilton et ul., 1976;Hooykaas et al., 1977; on a synthetic medium containing high concentrations of octopine or nopaline (Kerr et aZ,, 1977;Genetello et al., 1977).Tumours induced by octopine-utilizi...

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“…In 1974, they showed that an Agrobacterium plasmid, which they called the Ti plasmid, was responsible for causing the tumor in plants (Zaenen et al, 1974;Van Montagu, 2011). 1 They then tried to develop methods for altering Agrobacterium so as to use it as a vehicle for genetically modifying plants.…”

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confidence: 99%

Anomalías en los comienzos de la transgénesis vegetal: intereses e interpretaciones en torno a las primeras plantas transgénicas

Pellegrini

2013

Hist. cienc. saude-Manguinhos

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The origins of plant transgenesis are discussed and the experiments that led to the first transgenic plants are analyzed. This process involved a series of actors, practices and interests specific to biotechnology. Consensus about the meaning of fundamental experiments was also at issue here. These events illustrate some of the conflicts related to genetically modified organisms, since scientists had different responses to plant transgenesis at the time of the first experiments, and opinions of the anomalies in those experiments varied. Thus, this article analyzes the interests and interpretations surrounding the first experiments involving transgenic plants.

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Supercoiled circular DNA in crown-gall inducing Agrobacterium strains

Cited by 446 publications

References 34 publications

Proposal for Rejection of Agrobacterium tumefaciens and Revised Descriptions for the Genus Agrobacterium and for Agrobacterium radiobacter and Agrobacterium rhizogenes

Proposal for Rejection of Agrobacterium tumefaciens and Revised Descriptions for the Genus Agrobacterium and for Agrobacterium radiobacter and Agrobacterium rhizogenes

Regulation of the Transfer of TI Plasmids of Agrobacterium tumefaciens

Anomalías en los comienzos de la transgénesis vegetal: intereses e interpretaciones en torno a las primeras plantas transgénicas

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