Abstract: Calluses from the germinated seeds of N. tabacum were treated withstreptomycin and erthromycin. 60 regenerated plantlets from the calluses treated withstrepomycin were obtained. According to the flower shape these plantlets were classified into three kinds as follows: 1. Normal flower type, 2. Abnormal flower type, 3.Both normal and abnormal flower in same plant. It was found that the abnormal flowercould not self fertile but could be pollinated by other flower. The progenies of thenormal X abnormal flower were observed. Some of them Showed abnormal flowers. Ithad been suggested, therefore that stretomycin may not only induce mutant of chloroplast but also induce mutant of nucleus because the characters of flower axe controlledby nucleus.

Key words: Nicotiana tabacum, Mutant, Abnormal flower