ABSTRACT
Agrobacterium rhizogenes transfers a segment of its plasmid to the plant genome. The transferred DNA contains genes which are involved in the synthesis of plant hormones. These genes express in the plant cell and give rise to rooty-tumors at the infection site. Transgenic plants can be readily regenerated from the rooty-tumors and the transferred DNA is transmitted to progeny plants. High regeneration potential and sustained maintenance of transferred DNA makes the bacterium a suitable vector for plant genetic engineering. DNA sequences homologous to the transferred DNA of Agrobacterium rhizogenes were detected in some untransformed plant species suggesting a past infection by Agrobacterium rhizogenes during evolution of some genera, notably Nicotiana.