Abnormal accumulation of sugars and phenolics in tobacco roots expressing the Agrobacterium T-6b oncogene and the role of these compounds in 6b-induced growth.

The Agrobacterium T-DNA oncogene 6b induces tumors and modifies the growth of transgenic plants by an unknown mechanism. We have investigated changes in roots of tobacco seedlings that express a dexamethasone-inducible T-6b (dex-T-6b) gene. On induction medium with sucrose, intact or isolated dex-T-6b roots accumulated sucrose, glucose, and fructose and changed their growth, contrary to noninduced roots.

Functional diversity and mutational analysis of Agrobacterium 6B oncoproteins.

Many Agrobacterium T-DNA genes belong to a diverse family of T-DNA genes, the rolB family. These genes cause various growth abnormalities but their modes of action remain largely unknown. So far, none of the RolB-like proteins has been subjected to mutational analysis.

Structure and function of a conserved DNA region coding for tartrate utilization in Agrobacterium vitis.

Three tartrate utilization regions from Agrobacterium vitis strains involved in host specificity have been compared, to clearly define the borders of these regions and eventually identify specific sequences that could provide a mechanism of duplication of this region. A 10.8-kb conserved DNA fragment called the TAR element, found in different genetic contexts, was defined.

A T-DNA from the Agrobacterium tumefaciens limited-host-range strain AB2/73 contains a single oncogene.

Agrobacterium tumefaciens strain AB2/73 isolated from Lippia canescens has been described as a limited-host-range strain. Its tumor-inducing (Ti) plasmid has been found to lack DNA homology to known T-DNAs (L. Unger, S.

Characterization and distribution of tartrate utilization genes in the grapevine pathogen Agrobacterium vitis.

Agrobacterium vitis is a common pathogen of grapevine. Most strains utilize tartrate, an abundant compound in grapevine. Strain AB3 carries two tartrate utilization (or TAR) regions: TAR-I (on the large pTrAB3 plasmid) and TAR-II (on the AB3 Ti plasmid).

Identification of closely related Agrobacterium vitis isolates by chromosomal DNA probes.

Crown gall formation on grapevine by Agrobacterium vitis is an important plant disease in many regions of the world. On grapevine, octopine/cucumopine (o/c) strains are widely distributed. Here we describe two chromosomal sequences of o/c strains of 15 and 20 kb, which reveal a high degree of polymorphism in different o/c isolates.