In vitro Approaches to Extending the Host-Range of Agrobacterium for Plant Transformation

Abstract

Since the first report of successful gene transfer in 1983, engineered Agrobacterium vectors have been the most widely used means of stable plant transformation. There are host-range limitations to the utility of this approach, however, with most success in dicotyledonous species. Recent evidence has indicated that the host-range is dependent on the protocol used to infect plant tissues with Agrobacterium. Modifications of co-cultivation conditions can lead to successful gene transfer to species once thought beyond the host-range of Agrobacterium, including a number of monocots. Hence, when defining the host-range of Agrobacterium, distinction must be made between host-range for pathogenicity (oncogenicity) and host-range for transformation. Important factors in determining the ability of Agrobacterium to transfer DNA to the plant genome include genetic, physiological and physical components of the bacterium × plant interaction. Simple, empirical experiments with oncogenic strains can yield useful information regarding the importance of co-cultivation conditions. The applications of these to extending the host-range of Agrobacterium for transformation are discussed.