| There is an emerging and fast-growing viticulture industry in Illinois and the greater Midwestern U.S.A. However, one of the greatest factors limiting the establishment of vineyards in this region is the widespread use of 2,4-D, an effective herbicide used in the control of broadleaf weeds in grain crops and home lawns. 2,4-D easily drifts and severely affects grape plantings around areas where it is used. Since grapes have no known genetic resistance to this herbicide, breeding to incorporate resistance in commercial cultivars cannot be done. Thus genetic engineering has to be employed to produce adaptable grape cultivars. The overall objective of this study was to incorporate the 2,4-D resistance gene, tfdA, from Ralstonia eutrophus into grapes and produce transgenic plants that could tolerate exposure to 2,4-D. To achieve this goal a plant regeneration system based on somatic embryogenesis was developed for the 'Chancellor' wine grape. Secondly, an Agrobacterium transformation vector was constructed and its effectiveness demonstrated by the incorporation of the tfdA gene into tobacco. The vector was used to transform 'Chancellor' grape embryogenic cells and transgenic plant regenerated from these cells. Subsequently the transgenic status of the plants was proved by PCR and southern blot techniques. Spray tests with a commercial formulation of 2,4-D showed that the plants were resistant to up to 20 times the 2,4-D application rate recommended for corn. This is the first attempt at engineering 2,4-D resistance in grapes. |
