EFFECT OF MEDIUM COMPOSITION AND DATE OF EXPLANT DRAWING ON EFFECTIVENESS OF Agrobacterium-MEDIATED TRANSFORMATION IN THE PETUNIA (Petunia hybrida pendula)

ABSTRACT An effective technique has been developed for Agrobacterium tumefaciensmediated transformation in the petunia (Petunia hybrida pendula). Leaf explants were taken from shoots cultured in vitro for at least two years. Transformation was performed on four dates (January 26, March 23, August 3, and November 26). In control explants, kanamycin significantly inhibited organogenesis and rhizogenesis at 25 mg l -1 , and totally inhibited organogenesis and rhizogenesis at 100 mg l -1 . Explants which regenerated shoots and formed roots in the presence of 100 mg l -1 kanamycin were presumed to be transgenic. Only six transgenic plants were obtained from 216 leaf explants inoculated with Agrobacterium. Incorporation of the nptII gene into the plant genome was confirmed by PCR with specific primers. Expression of the gusintron gene was confirmed histochemically. Transformation date had a significant effect on transformation effectiveness. Transformation was most efficient in November (6.15%) and least efficient in August (0%). As expected, expression of the gus-intron gene had no significant effect on the phenotype of transgenic plants