Tools of genetic engineering in plants

Transfer and expression of foreign genes in plant cells, now routine practice in several laboratories around the world, has become a major tool to carry out gene expression studies and to obtain plant varieties of potential agricultural interest. The capacity to introduce and express diverse foreign genes in plants, first described for tobacco in 1984,[1] has been extended to many species. Transgenic crops such as tomato, cotton, maize, soybean, etc., are now available for human consumption and by complementing traditional methods of crop improvement (and thus becoming an integral part of agriculture), they will have a profound impact on food production, economic development and on the development of a sustainable agricultural system during the 21st century.

Although the capacity to introduce and manipulate specific gene expression in plants provides a powerful tool for fundamental research, much of the support for plant transformation research has been provided because of the generation of plants with useful and rapidly discernible phenotypes which are unachievable by conventional plant breeding, i.e., resistance to viruses, insects, herbicides, or post-harvest deterioration.[2–9] Plants useful for production of materials ranging from pharmaceuticals [10] to biodegradable plastics. [11] have been obtained using this new technology. Remarkably also, plant biotechnology techniques have been used to create plants overexpressing genes from human pathogens, the resulting plants accumulating proteins with immunogenic properties. These plants have been proved to be effective in causing oral immunization against diseases such as hepatitis B, cholera and rabies [12–14] which demonstrate the feasibility of using transgenic plants as expression and delivery systems for oral vaccines. In this section the technical aspects of the state of the art in plant engineering are described. It also identifies technical problems remaining in the development of systems of plant transformation applicable to crop improvement.