Transfer, Maintenance and Expression of Genes Introduced into Plant Cells via the Ti Plasmid
The capacity of a microorganism to establish itself successfully in a particular ecological niche often seems to depend upon the activities of a very small number of genes that are absent in competiting species. This additional DNA is frequently part of a plasmid that allows its host to metabolize rarely exploited carbon or nitrogen sources. Because of the presence of such genes, these plasmids have been called degradative or catabolic plasmids1. We believe that the Ti plasmids of Agrobacterium tumefaciens form a special class of catabolic plasmids2,3. In addition to encoding for proteins’ that catabolize several common amino acids4,5 and some polyphenols5, these plasmids also carry genes whose products catabolize compounds calles opines. Opines are unusual amino acids, such as nopaline6, octopine6 or agropine7 and phosphorylated sugars, such as the agrocinopines8. These opines have only been found in plant cells transformed by Ti plasmids into crown gall tumor cells. by inducing crown gall tumors, Agrobacterium tumefaciens forces a plant to synthesize compounds which only the same virulent strains can use.
KeywordsHairy Root Agrobacterium Tumefaciens Crown Gall Unusual Amino Acid Restriction Endonuclease Mapping
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