Crown Gall Disease and Prospects for Genetic Manipulation of Plants

Ream, Lloyd W.; Gordon, Milton P.

doi:10.1126/science.218.4575.854

Cited by 46 publications

(8 citation statements)

References 55 publications

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“…A widely studied method of gene transfer to dicotyledonous plants is based on the tumor-inducing (Ti) plasmid of A. tumefaciens (4,5). When a plant cell is wounded and infected with A. tumefaciens, a particular segment of the Ti plasmid, the T-DNA, is transferred and integrated into the plant nuclear genome (6)(7)(8).…”

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confidence: 99%

Cytokinin gene fused with a strong promoter enhances shoot organogenesis and zeatin levels in transformed plant cells

Smigocki

Owens

1988

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

173

103

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The isopentenyltransferase (ipt) gene associated with cytokinin biosynthesis in plants was cloned from a tumor-inducing plasmid carried by Agrobacterium tumefaciens and placed under the control of promoters of differing activities, the cauliflower mosaic virus 35S promoter and the nopaline synthase promoter. These promoter-gene constructs were introduced into wounded Nicotana stems, leafpieces, and cucumber seedlings by A. tumefaciens infection. Shoots were observed in the infection site on all responding genotypes of Nicotana plants infected with the 35S promoter construct (35S-ipt), whereas only 41% responded similarly to infection with the unmodified gene. Furthermore, shoots were observed 19 days after infection with the 35S-ipt gene but not until 28 to 45 days with the unaltered ipt gene. Shoots were more numerous (>40) on galls incited by 35S-ipt and were up to 6 times taller than shoots induced by the native gene. On Cucumis (cucumber), shoots were observed only on galls incited by the 35S-ipt construct. These galls were on the average 7.5 times larger than those incited by the nopaline synthase promoter construct (NOS-4pt) or the unmodified ipt gene. Zeatin and zeatinriboside concentrations averaged 23 times greater in the 35Spt transformed shoots than in ones transformed with the native ipt gene. These results suggest that a more active promoter on the ipt gene can enhance or change the morphogenic potential of transformed plant cells by increasing their endogenous cytokinin levels.Patternsiof differentiation in plants can be affected by several phytohormones including two major classes, the cytokinins and auxins. The relative levels of cytokinins and auxins in plants appear to be critically important. When cultured in vitro, cells of most plants require exogenous cytokinin and auxin in the medium for cell division to occur, presumably because of low endogenous pools of these phytohormones. Moreover, regeneration of shoots from cultured cells can be achieved with many plant species by increasing the cytokinin-to-auxin ratio in the medium (1, 2). However, failure of some species, among them important crop species, to respond in a morphogenic fashion to such treatment may reflect problems in hormone uptake, compartmentalization, or metabolism. The availability of phytohormone-specifying genes with plant regulatory sequences from Agrobacterium tumefaciens provides an alternate genetic approach to the study of morphogenesis through the in vivo manipulation of hormone ratios (3).A widely studied method of gene transfer to dicotyledonous plants is based on the tumor-inducing (Ti) plasmid of A.

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confidence: 99%

Cytokinin gene fused with a strong promoter enhances shoot organogenesis and zeatin levels in transformed plant cells

Smigocki

Owens

1988

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

173

103

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“…Agrobacterium tumefaciens, Agrobacterium rhizogenes, Agrobacterium rubi, Agrobacterium vitis, and Agrobacterium larrymoorei may be phytopathogens, causing diverse tumors in plants (4,45). Since A. tumefaciens is able to transform vegetal cells, it has been used to obtain genetically engineered plants (32,40). In the past 2 decades, Agrobacterium (Rhizobium) radiobacter has been recognized as an opportunistic human pathogen responsible for nosocomial infections, mainly bacteremia, peritonitis, and urinary tract infections (1,3,10,28).…”

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Multilocus Sequence-Based Analysis Delineates a Clonal Population of Agrobacterium (Rhizobium) radiobacter (Agrobacterium tumefaciens) of Human Origin

et al. 2011

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The genus Agrobacterium includes plant-associated bacteria and opportunistic human pathogens. Taxonomy and nomenclature within the genus remain controversial. In particular, isolates of human origin were all affiliated with the species Agrobacterium (Rhizobium) radiobacter, while phytopathogenic strains were designated under the synonym denomination Agrobacterium tumefaciens. In order to study the relative distribution of Agrobacterium strains according to their origins, we performed a multilocus sequence-based analysis (MLSA) on a large collection of 89 clinical and environmental strains from various origins. We proposed an MLSA scheme based on the partial sequence of 7 housekeeping genes (atpD, zwf, trpE, groEL, dnaK, glnA, and rpoB) present on the circular chromosome of A. tumefaciens C58. Multilocus phylogeny revealed that 88% of the clinical strains belong to genovar A7, which formed a homogeneous population with linkage disequilibrium, suggesting a low rate of recombination. Comparison of genomic fingerprints obtained by pulsed-field gel electrophoresis (PFGE) showed that the strains of genovar A7 were epidemiologically unrelated. We present genetic evidence that genovar A7 may constitute a human-associated population distinct from the environmental population. Also, phenotypic characteristics, such as culture at 42°C, agree with this statement. This human-associated population might represent a potential novel species in the genus Agrobacterium.

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“…With the development of genetic engineering it has become possible to break species barriers and introduce genetic information from one species to another. The original and most widely used methodology is based on the soil bacterium Agrobacterium tumefaciens, which naturally infects dicotyledonous plants and transfers a segment of its Ti plasmid into the genome of plant cells (Ream and Gordon, 1982). Using Ti plasmid vectors, it was possible to introduce and to express foreign genes in plant cells (Herrera-Estrella et al, 1983a,b) and to produce the first transgenic plants (De Block et al, 1984).…”

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confidence: 99%