Abnormal flower formation of tobacco plants regenerated from callus cultures

The plantlets regenerated from tobacco calluses, subcultured for prolonged periods, were weak and generally could not be cultivated into mature flowering specimens. However, some of them flowered and various kinds of abnormal flowers as well as leaves were observed in all the tobacco plants bearing flowers. They were sterile at had abnormal immature pollen grains. Some of them occasionally germinated in the anther. Abnormalities were also found in the nucleus of immmature pollen grains. Such drastic floral abnormalities were not found in tobacco plants derived from seeds and callus cultures subcultured for a relatively short period under the same conditions of cultivation. Part XVIII in the series “studies on plant tissue cultures”; for Part XVII, see Chem. Pharm. Bull., in press (1972).