Agrobacterium Ti Plasmids as a Tool for Genetic Engineering in Plants

Abstract

The technology of cloning poses issues and presents possibilities that were almost unimaginable only a few years ago. With the aid of restriction endonucleases and ligase, the biochemist can literally be a genetic architect. If a means can be devised for detecting its presence, a desired gene can be cloned in Escherichia coli, and plasmid DNA can be isolated that contains the gene in high concentration and purity. The gene can then be excised from the E. coli vector plasmid and inserted into other vectors for introduction into a eukaryotic cell. Monkey kidney tissue culture cells, for example, have been shown to produce mouse globulin after introduction of the mouse globulin gene attached to SV40 viral DNA (Hamer and Leder, 1979). In the view of some critics (Goodfield, 1977? Packard, 1977) experiments of this sort pose ethical question and raise the specter of manipulation of the human gene pool. However, the application of recombinant DNA technology to agricultural crop improvement has not been subjected to such criticism. Man has been manipulating the genomes of crop plants for centuries by more traditional methods. Crop improvement by direct manipulation of DNA appears to be a socially acceptable extension of plant breeding efforts. Thus the obstacles that beset the plant genetic engineer are chiefly technical rather than social ones.