Abstract:

Using mature zygotic embryos as initial explants, the effect factors including basal medium and plant hormone on organogenesis, somatic embryogenesis and adventitious buds induction roots were investigated respectively. The origin and development of somatic embryos and adventitious buds were observed through the paraffin method. The results indicated that the medium of DCR+6-BA 1.0 mg·L^{-1 +TDZ 0.002 mg·L-1 +NAA 0.1 mg·L-1 was optimal for mature zygotic embryos to induce adventitious buds. The optimal medium for mature zygotic embryos to induce somatic embryos was DCR+6-BA 1.0 mg·L-1+TDZ 0.003 mg·L-1 + NAA 0.1 mg·L-1 . Adventitious buds can elongate effectively on the DCR medium without plant hormone. 1/4MS+IBA 0.2 mg·L-1 +NAA 0.1 mg·L-1 was the optimal medium for adventitious buds to root. Histological observation indicated that there were two ways in which adventitious buds originate. The first way of origination was from meristematic tissue developed from epiderm cells and three or four liners under epiderm. The other was that the little vascular bundle dedifferentiated into meristematic tissue, which in turn developed into adventitious buds. Both of the two ways were direct organogenesis.}

Key words: Cunninghamia lanceolata, mature zygotic embryos, organogenesis, somatic embryogenesis