They developed a vector system for transferring foreign genes into the plant genome, by using the Ti plasmid of Agrobacterium tumefaciens. They also found a way to make plant cells resistant to the antibiotic kanamycin by transferring a bacterial neomycin phosphotransferase gene into the plant genome. PGS was the first company (in 1985) to develop genetically engineered (tobacco) plants with insect tolerance by expressing genes encoding for insecticidal proteins from Bacillus thuringiensis (Bt).