GENETIC-TRANSFORMATION BY AGROBACTERIUM-TUMEFACIENS IN THE INTERSPECIFIC HYBRID HELIANTHUS-ANNUUS X HELIANTHUS-TUBEROSUS

A genetic transformation method has been developed in the interspecific hybrid Helianthus annuus x Helianthus tuberosus using Agrobacterium tumefaciens. Leaf explants of a clone with an efficient tissue culture regeneration capacity were inoculated with A. tumefaciens carrying a disarmed Ti plasmid containing the Cauliflower Mosaic Virus (CaMV) 35S-GUS fusion gene with the nopaline sinthase (NOS) neomycin phosphotransferase II (NPT II) gene. On selection medium containing 25 mg/l of kanamycin, the inoculated leaf explants formed meristematic centers with buds and embryo-like structures that successively developed into putative transformed shoots, when transferred onto medium without growth regulators. Under suitable conditions, three days of cocultivation on medium containing BAP and NAA, the highest transformation frequency was 5.4%. Histochemical staining for the beta-glucuronidase (GUS) activity provided evidence for transformation in different tissues and organs of transgenic plants. Integration of foreign DNA into genomic H. annuus x H. tuberosus DNA was demonstrated by Southern analysis.