Vectors: Chairman’s Introduction
In this section, the authors will discuss various aspects of introducing DNA into plants. In my view, this section represents the heart of the theme of this volume. Dr. Anne DePicker, who is currently involved in active research in one of the most highly regarded laboratories of crown gall research, discusses the overall aspects of crown gall, a natural genetic engineering system in plants. In this system, a defined piece of bacterial plasmid DNA (T-region) is transferred from the inciting strain of Agrobacterium to the plant cell where it is integrated into plant nuclear DNA. By integrating foreign DNA into this defined piece of plasmid DNA, it is possible to transfer and integrate the foreign DNA into plant cells. An important feature of this system is that cells into which T-DNA is integrated can be selected on the basis that callus tissue is able to grow in the absence of exogenously added auxin and cytokinin, two phytohormones required by the untransformed tissue. Agrobacterium also has a remarkably broad host range infecting most dicotyledonous plants. At this time, the crown gall system seems to be the best vehicle for the stable incorporation of genes into plants.