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To test the hypothesis that auxin-binding protein 1 (ABP1) is a receptor controlling auxin-mediated plant cell expansion, ABP1 complementary DNAs were expressed in a controllable fashion in tobacco plants and constitutively in maize cell lines. Induction of Arabidopsis ABP1 expression in tobacco leaf strips resulted in an increased capacity for(More)
Cloned DNA sequences encoding yeast alcohol dehydrogenase and a bacterial neomycin phosphotransferase have been inserted into the T-DNA of Agrobacterium tumefaciens plasmid pTiT37 at the "rooty" locus. Transformation of tobacco stem segments with the engineered bacterial strains produced attenuated crown gall tumors that were capable of regeneration into(More)
Mutant Agrobacterium tumefaciens strain A66 is shown to differ from its wild-type progenitor (strain A6) by a spontaneous 2.7 kb DNA insert into the T-DNA region of its Ti plasmid. Tobacco stems transformed by A66 exhibit an attenuated response characterized by slow growth and shoot proliferation. Clonal analysis demonstrates that this response is due to an(More)
Agrobacterium tumefaciens is a broad host range plant pathogen that combinatorially recognizes diverse host molecules including phenolics, low pH, and aldose monosaccharides to activate its pathogenic pathways. Chromosomal virulence gene E (chvE) encodes a periplasmic-binding protein that binds several neutral sugars and sugar acids, and subsequently(More)
A maize genomic clone containing a zein gene (Z4) was inserted into the T-region of the T37 Ti plasmid. Agrobacterium tumefaciens cells carrying this modified Ti plasmid were used to inoculate sunflower stemlets. Callus tissue active in nopaline synthesis was grown from a single transformed cell. DNA analysis of this tissue showed that the zein gene plus(More)
Naturally occurring isomers of the dehydrodiconiferyl glucosides have been isolated from Vinca rosea crown gall tumors and have been tested for cell division promoting activities in the tobacco pith and leaf assay systems. The enantiomeric isomers A and B are active, although they are required at concentrations up to 2 orders of magnitude higher than zeatin(More)
Agrobacteria carrying mutations at the auxin-biosynthesizing loci (iaaH and iaaM of the Ti plasmid) induce shoot-forming tumors on many plant species. In some cases, e.g. Nicotiana glutinosa L., tumors induced by such mutant strains exhibit an unorganized and fully autonomous phenotype. These characteristics are stable in culture at both the tissue and(More)
Agrobacterium tumefaciens initiates the expression of pathogenic genes (vir genes) in response to host-derived phenolic signals through a two-component regulatory system consisting of VirA and VirG. alpha-Bromoacetosyringone (ASBr) was developed as an inhibitor of this induction process and found to be a specific and irreversible inhibitor of vir gene(More)
The plant pathogen Agrobacterium tumefaciens responds to three main signals at the plant-bacterium interface: phenolics, such as acetosyringone (AS), monosaccharides, and acidic pH (∼5.5). These signals are transduced via the chromosomally encoded sugar binding protein ChvE and the Ti plasmid-encoded VirA/VirG two-component regulatory system, resulting in(More)
A versatile expression vector utilizing a promoter of coliphage T5, P(N25) (Gentz and Bujard, 1985. J. Bacteriol. 164, 70-77) and a derivative of the IncW broad-host-range plasmid pJB20 (Beaupré et al., 1997. J. Bacteriol. 179, 78-89) has been developed. This vector successfully expresses virulence proteins of Agrobacterium tumefaciens encoded by virG and a(More)