4. Gene vectors: Crossing natural barriers to genetic manipulations
Not available – first paragraph follows: The potential application of genetic engineering to agriculture has been predicted to be limitless. Such enthusiasm, however, should be expressed judiciously, because much information is needed before we can apply the methods to the agricultural industry. The potentials of this technology are apparent, but several important natural barriers need to be crossed before progress can be achieved. A primary limitation is the need to find an efficient means of introducing foreign genes (or DNA) into plant cells. Since 1978, U.C., Davis, scientists have devised several ways by which this can be accomplished. Foreign genes may be introduced as purified DNA directly into plant cells through the use of protoplasts (plant cells freed of their rigid cell wall material). Or these genes can be spliced to another DNA molecule, which serves as a vector. These gene vectors may be plant DNA viruses, bacterial and yeast plasmids, plant organelle DNA, and transposition elements from lower and higher cells.