Expression of Foreign Genes in Plant Cells Following Fusion of Agrobacterium Spheroplasts with Isolated Mesophyll protoplasts of Nicotiana tabacum

Agrobacterium tumefaciens and A. rhizogenes are phytopathogenic gram-negative soil bacteria causing crown gall and hairy root disease of dicotyledonous plants. Both bacteria engineer their host plant cell by transferring a part of a large plasmid (Ti Plasmid, Ri plasmid) into host genome. The transferred DNA is maintained and expressed in the engineered plant cells. Transformed cells produce new metabolites not present in normal cells (for recent review see Zambryski P. et al. 1983). With altered Ti Plasmids containing chimeric genes in the T-DNA [e.g. NOS-APH(3’)II gene] it is possible to transfer and express these foreign genes (Herrera-Estrella L. et al. 1983). Therefore the Ti plasmid can be considered as a gene vector system for dicotyledonous plants.