Recombination between higher plant DNA and the Ti plasmid of
            <i>Agrobacterium tumefaciens</i>

Thomashow, Michael F.; Nutter, Robert C.; Postle, Kathleen; Chilton, Mary-Dell; Blattner, F. R.; Powell, Ann; Gordon, Milton P.; Nester, Eugene W.

doi:10.1073/pnas.77.11.6448

Cited by 105 publications

(33 citation statements)

References 34 publications

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“…Free IndAcOH levels were lowest in tumors incited by tns mutants 328 and 355 and highest in tumors incited by tin mutants 358 and 361 and by the parental strain A348 (Table 1) (17)(18)(19)(20)(21)(22)(23)(24). DISCUSSION The early findings of Braun (7) showed that crown gall tumors could be maintained indefinitely in culture on a simple hormone-free medium.…”

Section: Resultsmentioning

confidence: 99%

Cytokinin/auxin balance in crown gall tumors is regulated by specific loci in the T-DNA

Akiyoshi

Morris

Hinz

et al. 1983

Proc. Natl. Acad. Sci. U.S.A.

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278

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Insertion ofthe transposon Tn5 into the T-region ofthe octopine Ti plasmid ofAgrobacterium tumefiaciens gives rise to crown gall tumors having altered morphology. Three loci within the T-DNA that control tumor morphology have been detected [Garfinkel, D. J., Simpson, R. B., Ream, L. W., White, F. F., Gordon, M. P. & Nester, E. W. (1981). CeU 27, 14-3-1531. They influence tumor size (tnd), production ofroots (tmr), or production of shoots (tins). Cytokinin and auxin levels in such mutant tumors were examined by HPLC/radioimmunoassay and HPLC/fluorescence assay, respectively. Free indoleacetic acid levels (in pmol/g) were: uninfected tobacco stem tissues, 128; wild-type A348 tumors, 295; tin mutant tumors, 307; tmr mutant tumors, 129; and tns mutant tumors, 70. Average trans-ribosylzieatin levels were correspondingly: 0.97, 48, 40, 0.54, and 1,400 pmol/g. transRibosylzeatin/indoleacetic acid ratios were as high as 24 in shootproducing tumors and as low as 0.003 in root-producing tumors. The evidence strongly suggests that tumor phytohormone levels are determined by genes in the T-DNA.It is known from the work ofseveral laboratories that a segment of DNA, the transferred (T) region of a large plasmid (the Ti plasmid) harbored by the inciting bacterium, Agrobacterium tumefaciens, is integrated into the host genome during crown gall tumorigenesis (1). Although seven T-DNA transcripts have been reported (2,3) in octopine' crown gall tumors, no T-DNAcoded gene product has been identified with certainty other than octopine synthase. Other transcripts are presumably determinative in tumor growth and maintenance, but their functions are unknown (4-6). However, crown gall tumors do grow in culture in the absence of added auxin or cytokinin (7), and recent studies (8)(9)(10) indicate that cytokinin levels are increased in many, but not in all,. tumor lines.The morphology of crown gall tumors is determined by at least three factors: (i) the strain ofA. tumefaciens used to incite the tumor, (ii) the plant host, and (iii) the site ofinoculation on the host (11). The work ofSkoog and Miller (12) established that the morphology of normal tobacco tissue in culture is determined by the cytokinin/auxin ratio in the medium. High and low exogenous cytokinin/auxin ratios lead respectively to shoot and root production. It seems very plausible, therefore, that hormone overproduction and imbalance may be general characteristics also of crown gall tumors.Transpositional inactivation of regions of the T-DNA (4-6) has defined several loci that control tumor morphology. We describe here the application of some new (13-14) analytical techniques to the measurement of hormone levels in tumors that have altered morphologies as a result of Tn5 insertion in the T-DNA. The data indicate clearly that endogenous tumor hormone levels are determined by specific loci in the T-DNA that also control tumor morphology. MATERIALS AND METHODSThe strains used in these experiments have been described in detail (4). All mutants were derived from strain...

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Section: Resultsmentioning

confidence: 99%

Cytokinin/auxin balance in crown gall tumors is regulated by specific loci in the T-DNA

Akiyoshi

Morris

Hinz

et al. 1983

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

278

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“…It has been shown that a specific DNA region of the Ti plasmid, called the T-DNA region ( Fig. 1), causes tumor formation when transferred into plant chromosomes and that the T-DNA persists in the chromosomes of the tumor cells (3)(4)(5)(6). The virulence (vir) region of the Ti plasmid ( Fig.…”

mentioning

confidence: 99%

Nucleotide sequence of the insertion sequence found in the T-DNA region of mutant Ti plasmid pTiA66 and distribution of its homologues in octopine Ti plasmid.

Machida¹,

Sakurai²,

Kiyokawa³

et al. 1984

Proc. Natl. Acad. Sci. U.S.A.

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The octopine tumor-inducing (Ti) plasmid pTiA66 has an insertion mutation in its T region (the DNA region incorporated into the plant genome) that results in the slow growth of crown gall tumors. These tumors exhibit hormonal autonomy different from that of the crown gall tumors caused by wild-type Ti plasmids. In the present study, the nucleotide sequences of both the DNA segment inserted into pTiA66 and its target site have been determined. The inserted segment is 2548 base pairs long and has 20-base-pair terminal inverted repeats. An 8-base-pair sequence at the target site is duplicated at both integration junctions. These structural features of the insert suggest that it is a bacterial insertion sequence (IS) element, which we have named IS66. Blot-hybridization analyses using IS66 probes revealed that genomes of octopine Ti plasmids contain at least three sequences homologous to IS66: two homologues are located in the virulence region and one is located between the left-hand (TL-DNA) and right-hand (TR-DNA) portions of T-DNA. The chromosome of Agrobacterium tumefaciens A66 also contains two sequences highly homologous to IS66. These results suggest that the mutant pTiA66 plasmid was generated by translocation of one of the sequences showing homology with IS66 into the T region. The fact that a sequence homologous to IS66 is present between TL-DNA and TR-DNA also suggests that the octopine T region was split into two portions, TL-DNA and TR-DNA, by translocation of IS66 or its relatives. Thus, IS66 may cause genetic and structural variations of the T region and the vir region of the octopine Ti plasmids.Tumor-inducing (Ti) plasmids harbored by oncogenic strains of Agrobacterium tumefaciens cause formation of tumors on dicotyledonous plants, called crown galls (1). Cells isolated from the crown gall tumors are characterized by their unlimited proliferation in medium lacking phytohormones, such as cytokinins and auxins, that are required for the culture of normal plant cells (2). It has been shown that a specific DNA region of the Ti plasmid, called the T-DNA region (Fig. 1), causes tumor formation when transferred into plant chromosomes and that the T-DNA persists in the chromosomes of the tumor cells (3-6). The virulence (vir) region of the Ti plasmid (Fig. 1) is located outside the T region and is also required for tumorigenesis by the Ti plasmid. However, this region is probably not stably maintained in the tumor cells (7-10).The Ti plasmids are classified on the basis of the novel amino acid metabolites, such as octopine or nopaline, whose syntheses are directed by T-DNA genes in the tumor cells (11-15). The octopine T region is composed of twQ DNA segments near each other in the Ti plasmid (16) (Fig. 1), whereas the nopaline T region consists of one contiguous DNA segment (17, 18). The chromosomes of the tumor cells caused by the octopine strain contain either one or two portions of the T region (16). All tumor cells that have been analyzed contained the left portion of T-DNA (TL-DNA) but not all...

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“…Така например промоторът на Vir-C гена се индуцира от растителен фактор, който има белтъчна природа и се елюира от здрави расте ния (54). Транскрипцията на Vir-гените е в пасока към Т-ДНК (7,22 С помощта на хибридизационни експерименти е било показано, че туморните Т -ДНК, съответству ващи на Т-областта от Ti-и Ri-плазмидите, са лока лизирани в ядротона растителпата :клет:ка (6,68,69,72), като интеrрацията се наблюдава в различии слу чайни участъци на растите.ЛНата ядрена ДНК, като Т-ДНК може да присъствува в едно или ня:колко копия за клетка (20,32,56,72).…”

Section: Vir-областunclassified

Молекулярни основи на взаимодействието Agrobacterium—растение

Селеиска-Трайкова¹,

Selenska-Traikova²

1986

Biotechnology & Bioindustry

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Recombination between higher plant DNA and the Ti plasmid of Agrobacterium tumefaciens

Cited by 105 publications

References 34 publications

Cytokinin/auxin balance in crown gall tumors is regulated by specific loci in the T-DNA

Cytokinin/auxin balance in crown gall tumors is regulated by specific loci in the T-DNA

Nucleotide sequence of the insertion sequence found in the T-DNA region of mutant Ti plasmid pTiA66 and distribution of its homologues in octopine Ti plasmid.

Молекулярни основи на взаимодействието Agrobacterium—растение

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