A chimeric DNA construction having nopaline synthase promoter, coding sequences of neomycin phosphotransferase gene conferring resistance to antibiotic kanamycin and OCS (octopine synthase) polyadenylation sequences bracketed by T-DNA ends was transferred to tobacco. Leaf discs were infected withA. tumefaciens containing disarmed, cointegrate plasmid pGV3850:: 1103 and allowed to form a callus in the presence of kanamycin. Shoots regenerated from infected leaf discs either through the callus or arising directly were further selected for their ability to root in kanamycin-containing media. Among the nine transgenic plants that were progeny tested, the transferred bacterial gene segregated as monohybrid ratio (3 KanR: 1 Kans) in seven. Segregation data of two plant progenies indicated the presence of two independent loci of KanR DNA insertion (15 KanR: 1 Kans). Back-cross segregation data were consistent with the monohybrid or independent assortment of duplicate factors. Thus in the two cases, a minimum independent integration of two copies of T-DNA each with a KanR marker is inferred.