A commercial variety of cotton was transformed with a nononcogenic strain of Agrobacterium tumefaciens. The synthetic T-DNA consisted of two marker genes that encoded for neomycin phosphotransferase II (NPTII) and chloramphenicol acetyl transferase (CAT), which specify resistance to the antibiotics kanamycin and chloramphenicol, respectively. Both genes were regulated by the nopaline synthase promoter which is constitutively expressed in plant cells.

Inoculated tissues selected on kanamycin-containing medium gave rise to transformed calli that were resistant to the antibiotic and expressed the neomycin phosphotransferase enzyme. Amplified tissues produced somatic embryos which germinated into whole plants that also expressed the marker enzyme. Genetic analysis was completed on three of the transgenic cotton plants. Each carried a functional T-DNA insertion. Southern blot data of the original plants confirmed that two of the plants, #1397 and #1427, carried a portion of the synthetic T-DNA which encoded only the NPTII gene. Since both plants were derived from the same transformed cell line, it was expected they would show similar results. The data collected on #1397 and #1427 support the clonal, i.e. nonchimeric origin of their parental cell line. The third plant, #1438, was derived from a different cell line and contained a full-length T-DNA insertion which expressed both the NPTII and CAT genes. Phenotypically, #1438 also showed very low pollen viability but backcrosses could be obtained.

Results of the progeny show the expected Mendelian segregation ratios of 3:1 for selfed and 1:1 for backcrossed pollinations. Southern blot analysis of the progeny confirmed the inheritance of a single functional copy of the foreign DNA. We also observed that progeny grown on kanamycin-containing medium efficiently selected for seedlings which were NPTII expressors. We conclude that transgenic cotton plants obtained via somatic embryogenesis can transmit foreign genes to their progeny with a high degree of fidelity.