ABSTRACT
Gene transfer was more feasible for plant cells which were already known to express their totipotency, particularly cells from plants such as tobacco and carrot, used extensively as models in early plant transformation experiments. The discovery of bacterial plasmids and their major role in the natural process of gene transfer, prompted microbiologists to exploit deoxyribonucleic acid elements to transfer into target cells, chimaeric genes constructed in the laboratory. Knowledge of the rates of transient expression are useful in establishing procedures for the stable transformation of plant cells, to adapt them to specific plant tissues, or to determine the strain of Agrobacterium most effective for gene transfer to specific cell types. Transformation of mitochondria has been reported for yeasts and the single celled green alga, Chlamydomonas. Gene transfer, combined with other techniques of genomics, has lead to entirely new approaches to plant breeding.
