Abstract
Agronomic performances of the male sterile tobacco (Nicotiana tabacum cv. Consolation 402) obtained by protoplast fusion between Consolation 402 and X-irradiated N.debneyi were evaluated. A majority of the male sterile lines in the BC1 generation exhibited almost equivalent field performances to the selfed lines of normal fertile Consolation 402, and stable performances of these male sterile lines were also recorded in the following generation. In the BCI generation, however, there were a few lines showing late maturity and smaller stature. These lines did not carry a specific type of chloroplast genom.e, thus suggesting little participation of chloroplast genomes in the observed deviations. Also, such deviated traits appeared to be recovered in the subsequent generations of backcrosses. This indicates that the deviated traits are resulted from mutational events in the nuclear genome during in vitro culture. None of the male sterile lines segregeted any fertile plants. The observed stability of fusion-derived male sterile tobacco both in agronomic traits and in the male sterility indicates that the protoplast fusion method can be incorporated into a practical breeding program as an alternative for obtalning male sterile tobacco.
