Plasmid tumor-inducing

Plant tumors result from uncontrolled hormone production. Crown gall tumors, for example, are due to the infection of plant wounds by certain strains of Agrobacterium. These bacteria carry a large plasmid, the tumor-inducing, or T, plasmid, part of which is incorporated into the plant genome. This DNA encodes several genes that stimu-... 

Part of the process of infection and tumor formation requires the insertion of the Tj plasmid of the bacterium into the genome of the plant, a characteristic that makes the Tj plasmid an ideal vector for the introduction of foreign DNA into the plant. The DNA of interest is spliced into the T plasmid, and then the whole segment is inserted into a plant chromosome. To achieve this objective, some modifications must be made to the Ti plasmid—for example, its attenuation (deletion of tumor-inducing genes), the insertion of cloning sites so that the DNA of interest can be inserted easily into the vector, and the addition of selectable genes. 

Tumor-Inducing Plasmids Can Be Used to Introduce New Genes into Plant Cells... 

Figure 6.33. Tumors in Plants. Crown gall, a plant tumor, is caused by a bacterium Agrobacterium tumefaciens) that carries a tumor-inducing plasmid (Ti plasmid). 

Gene disruption by RNA interference (p. 157) Tumor-inducing plasmids < p. 157)... 

DNA microarray (gene chip) (p. 159) transgenic mice (p. 161) gene disruption (gene knockout) (p. 162) tumor-inducing plasmid (Ti plasmid)... 

D-O. is also found in certain plant tumors induced by Agrobacterium tumefaciens. This bacterium induces tumors in dicotyledenous plants by transferring a large bacterial plasmid (called the Tj plasmid) to die eukaryotic cell. In the transformed tissue, the Tj plasmid determines the synthesis of novel amino acids, which serve as specific substrates for the bacterium. These may be d-O. and related compounds (the oc-topine family ), or nopaline and nopalinic acid (the nopaline family ), but not both. [F. Marines D.W.R. White Divergent Transcription and a Remote Operator Play a Role in Control of Expression of a Nopaline Catabolism Promoter in Agrobacterium tumefaciens J. Biol Chem. 270 (1995) 12339-12342]... 

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