Novel transformation vectors may be used for the genetic modification of plant cells, plant tissue or plant organs. These transformation vectors are double-stranded DNA molecules which include a gene foreign to said plant cell, plant tissue or plant organ and associated with a selectable or identifiable trait when present therein and at least one DNA sequence substantially identical to a DNA sequence which is present in said plant cell, plant tissue or plant organ and capable or homologous recombination with said plant DNA sequence when the transformation vector is introduced into the plant cell, plant tissue or plant organ. Double-stranded DNA molecules which additionally include a gene associated with expression of a desired agronomic property or production of a desired product in plant cells, plant tissues, plant organs or in plants derived therefrom can be used to create plants having desirable properties or to produce commercially valuable products. These transformation vectors are especially useful for modifying the genetic make-up of cereals, including barley, wheat, rice and maize.
