Studies On The Tissue Culture Research Of Eucalyptus Dunnii Maiden

Eucalyptus dunnii Maiden is one of the introduced tree species from Australia, and it performed well in subtropical area for cold hardness in China. However, it is difficult to propagate vegetatively because of it with low rooting ability both under cutting and tissue culture. In this research, we reported the results of tissue culture to improve the mass propagation of Eucalyptus dunnii. The results are as the followings:1. The differentiation and induction for adventitious buds.Hemi-lignified shoots with buds of E. dunnii were used as the explants for this induction. Based on the studies of the impact factors on the explants, basic media, plant growth regulator (PGR) concentrations and ratios, and culture environment conditions, the optimal induction medium was confirmed as modified MS + 6-BA 0.6 mg/L+NAA0.05 mg/L +VC15mg/L+ sucrose 40g/L. Less browning symptom and more vigorous adventitious buds occurred with this medium.2. Shoot multiplication culture.Based on the analysis of every component roles of the media, the macro-elements were adjusted, and the different PGR concentrations and ratios and carbon source were selected. The best medium was confirmed as that modified MS +6-BA0.6mg/L+NAA0.10mg/L+ sucrose 30 g/L.3. Shoot elongation culture.By adjusting the sucrose concentration, supplying organic components and selecting light condition, the multiplication shoots elongated and vigorous shoots were obtained. By supplying sucrose 20 g/L and lactoflavin 450 mg/L in the medium with light intensity 30001ux, the subculture shoots grew well with the characteristics of dark green leaves and full lignified shoots which reached height 2.7 cm at most.It promoted the rooting rate in the next step.4. Rooting culture.By adjusting the different components in the media, selecting auxins and concentrations, supplying cytokinin 6-BA, medium matrix, the rooting medium was optimized as the following: modified MS +IBA0.5mg/L+6-BA0.06mg/L +sucrose 15～20g/l+ carrageenan 3.8g/L. The medium not only inhibited the basal calli growing, but also increased the joining tightness between the roots and shoots, and raised the rooting rate.