PRODUCTION OF ROL GENE TRANSFORMED PLANTS OF ROSA-HYBRIDA L AND CHARACTERIZATION OF THEIR ROOTING ABILITY

Transgenic plants of the rootstock Rosa hybrida L. cv. Moneyway were p roduced via a two-step procedure. First, kanamycin-resistant roots wer e generated on stem slices from micropropagated shoots, which were coc ultivated with Agrobacterium tumefaciens containing the neomycin phosp hotransferase II (NPTII) gene for conferring kanamycin resistance, tog ether with individual ROL genes from A. rhizogenes. Root formation was quite efficient and up to two kanamycin-resistant roots per stem slic e were produced. In the second step, these roots were used to regenera te transgenic plants via somatic embryogenesis. Although regeneration lasted up to 12 months, production of several transformants was succes sfully accomplished. Untransformed escapes were not found, indicating that the initial selection on kanamycin resistance was reliable. The p resence of a combination of ROLA, B and C genes enhanced adventitious root formation on micropropagated shoots and explants of stems and lea ves. It appears that the auxin sensitivity was increased to such a deg ree that cells were able to respond even to endogenous auxins present in shoots and leaves. Rooting experiments in greenhouse demonstrated t hat adventitious root formation on cuttings was improved threefold upo n introduction of these ROL genes. It is concluded that a method was d eveloped for the production of ROL gene transformed roses with improve d rooting characteristics.