Abstract:

It is very difficult for Eucalyptus dunnii to produce roots in vitro. In order to resolve this problem, produce E. dunnii seedlings, and conduct gene engineering, an efficient and rapid micropropagation system by using seeds as explants was established for E. dunnii.The optimum medium for E. dunnii was obtained by modifying Mecown and Lloyd medium (WPM), that is: with WPM large elements, plus Murashige and Skoog (MS) trace elements, MS Fe salt, Skirvin and Chu (SC) organic compounds and 30 g ·L^-1 glucose. This modified medium was used to resolve the serious problems, such as seedling brown and shoot tip death, in E. dunnii tissue culture. A modified WPM medium supplemented with 0.5 mg ·L^-1 6-benzy1aminopurine, 0.5 mg ·L^-1 kinetin, 0.2 mg ·L^-1 napthaleneacetic acid and 30 g ·L^-1 glucose was suitable for shoot induction and proliferation from divided buds,and the shoot proliferation rate of plantlets increased by 18.43 fold. The optimum growing medium was obtained by modifying WPM medium supplemented with 0.5 mg ·L^-1 KT, 0.2 mg ·L^-1 TDZ and 0.01 mg ·L^-1 NAA. Over 84.3% regeneration plantlets were able to root after transferred to the modified half-strength MS medium supplemented with 3.0 mg ·L^-1 indole-3-butyric acid, 0.01 mg ·L^-1 napthaleneacetic acid, 0.05 mg ·L^-1 kinetin and 20 g ·L^-1 sucrose. When the micropropagated plantlets with well-developed root systems were transferred to planting bed containing a mixture of sand,soil and medium (4 ∶1 ∶1;V/V) in a greenhouse,93.8％ of the plantlets survived.

Key words: Eucalyptus dunnii, tissue culture, micropropagation