A program was initiated to transfer potato virus Y vein-necrosis strain resistance from N. africana to N. tabacum The Fl plants between the above species were self-sterile, but all amphidiploid plants from the Fl plants and backcrossed flowers, that is, the N. tabacum flowers crossed with amphidiploid were self-fertile. The parent, amphidiploid plants of Fl, F2 population of the amphidiploid and the backcrossed generation were screened for a resistance of potato virus Y vein-necrosis strain isolated in Korea. The Chi-square values for the F2 population of the amphidiploid and the backcrossed generation fitted 35: 1 and 5 : 1 ratios of resistant to susceptible for the potato virus Y vein-necrosis strain, respectively. Therefore, it was found that the resistance of N. tabacum for the potato virus Y vein-necrosis strain was controlled by a single dominant gene.