TRANSFER OF KANAMYCIN RESISTANCE FROM NICOTIANA-TABACUM TO NICOTIANA-PLUMBAGINIFOLIA BY FUSION OF X-IRRADIATED PROTOPLASTS

Nuclear hybrids have been obtained by fusion of mesophyll protoplasts of Nicotiana plumbaginifolia and x-irradiated or iodoacetate-treated mesophyll protoplasts of a kanamycin-resistant line of N. tabacum. The effect of irradiation on the recovery of asymmetric hybrids was evaluated by analysis of their morphology, fertility, chromosome number, isozyme patterns, restriction patterns in their organelle DNAs, and presence of the kanamycin-resistance gene. The results presented in this paper show that x-ray irradiation leads to a significant reduction in the amount of N. tabacum genome present in the hybrids and demonstrates, once more, the power of this technique to induce directional loss of genomic traits of the irradiated parent.