Agrobacterium-Mediated Gene Transfer Results Mainly in Transgenic Plants Transmitting T-DNA as a Single Mendelian Factor.

Forty-four independent transformed tobacco plants were obtained from a cocultivation experiment with Agrobacterium tumefaciens strains carrying modified Ti-plasmids. The transformed plants were either self-fertilized or crossed with nontransformed plants or with other transformed plants. The segregation of a phenotypic marker (kanamycin resistance) in the progenies of these plants was determined. In 40 cases out of 44, the segregation of the kanamycin resistance marker is consistent with Mendelian genetics. Among these 40 clones, 35 contain a single kanamycin resistance locus. The five others segregate two independent resistance loci. In two of the single insert clones, the segregation ratio after selfing indicates that the T-DNA insertion may have caused a recessive lethal mutation.

An Agrobacterium-transformed cell culture from the monocot Asparagus officinalis.

Cultured stem fragments from the monocotyledonous plant Asparagus officinalis infected by the oncogenic bacterium Agrobacterium tumefaciens developed tumorous proliferations. This tissue was propagated in vitro on hormone-free culture medium. The T-DNA-encoded markers nopaline and agrocinopine were unambiguously detected in these tissues. The data demonstrate that stable T-DNA transfer as well as expression of T-DNA genes is possible in at least some monocotyledonous plants. This opens new possibilities for plant genetic engineering using the Ti plasmid as a gene vector.