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

A genetic transformation method has been developed in the interspecifi c 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 phosphotran sferase II (NPT II) gene. On selection medium containing 25 mg/l of ka namycin, the inoculated leaf explants formed meristematic centers with buds and embryo-like structures that successively developed into puta tive transformed shoots, when transferred onto medium without growth r egulators. Under suitable conditions, three days of cocultivation on m edium containing BAP and NAA, the highest transformation frequency was 5.4%. Histochemical staining for the beta-glucuronidase (GUS) activit y provided evidence for transformation in different tissues and organs of transgenic plants. Integration of foreign DNA into genomic H. annu us x H. tuberosus DNA was demonstrated by Southern analysis.