Abstract
Artificial clonal tetraploids were induced with colecmid using tissue cultured shoot primordia in an annual plant, Haplopappus gracilis (2n=4). The method for the successful induction of tetraploid in tissue cultured shoot primordia was treatment with 0.5mg/ml of colcemid in liquid medium for 3 days. During the treatment the frequency of the tetraploid cells in shoot primordia increased gradually. On 30 days after the treatment, the majority (about 85%) of the metaphase cells in each shoot primordium were tetraploid. The shoot primordia on 30 days after the treatment were regenerated into plants, of which the almost all were tetraploid. Tetraploid plants obtained by this method seem to be one clone. It is concluded that direct induction of clonal tetraploids is possible by using the shoot primordia.
