In order to transfer the dominant gene N , responsible for the resistance to TSWV, from Nicotiana alata to Virginia tobacco cultivars, interspecific hybridations were performed followed by in vitro culture of the immature embryos (around 7 days old), to obtain mature plants. Fertilization was achieved by applying a solution of colchicine (0.2 %) in the culture medium. Back-crossings were performed in F₂ using pollen from Virginia cultivars (Virginia 196 and Virginia 207) and the plants F₃ were obtained with an almost identical phenotype to that of the tabacum type. The artificial test on the performance vs TSWV, at the stage of 5-7 leaves, showed that the hybrid plants are resistant to infection from TSWV. Thus, out of 75 tested plants, 68 showed resistance to artificial infection with TSWV. The resistant plants were grown to maturity. Anthers from 5 of these plants were collected and cultured in vitro . Haploid plants were obtained and reached the stage of 3-4 small leaves in about eight weeks. Twenty-five haploid plants from each of the two hybrid combinations were tested for their performance against artificial infection with TSWV. It was found that almost all the plants showed resistance, by the appearance of a light necrosis on the small leaves at the bottom of the plants. The haploid plants hypersusceptible to TSWV are going to be diploidized. Through these experiments, plants of Virginia type were obtained with a resistance to TSWV acquired from Nicotiana alata . The hypersusceptibility to the artificial infection with TSWV showed by the haploid plants with a hemizygote genetic structure, emphasizes the fact that the gene for the resistance to this viral disease is dominant.