The production of transgenic plants depends on the stable introduction
of foreign DNA into the plant genome, followed by regeneration to pro
duce intact plants, and the subsequent expression of the introduced ge
ne(s). A Variety of transformation methods have been developed, and th
is has allowed many of the world's important crop plants to be transfo
rmed. Transformation mediated by Agrobacterium has provided a reliable
means of creating transgenics in a wide variety of species that are a
menable to tissue culture and regeneration. Vectorless gene-transfer s
ystems include particle bombardment (biolistics), electroporation and
membrane permeabilization using chemicals. Of these, biolistics has pr
oved to be particularly successful with plants that are less amenable
to tissue culture, such as cereals and legumes.