The embryogenic callus induction and shoot regeneration were studied systematically in elite clone GL9 of Eucalyptus cultivated widely in south China.We investigated TDZ 0.02-0.05 mg·L-1 was the proper concentration.The callus induction rate was 92.9%—100%.When TDZ concentration was higher than 0.1 mg·L-1,the axillary bud germination was completely inhibited.TDZ 0.02 mg·L-1 with combinations of CoCl2 0.125 mg·L-1 could induct the embryogenic callus.The direct regeneration rate was 13.39%±1.03%,and with combinations of NAA 0.1mg·L-1 could not differentiate directly from callus,but higher regeneration rate(20.2%±13.3%) could be obtained by transferring callus onto regeneration medium.The size of callus can increase to 1.4 fold of its original size in the first subculture in modified MS+TDZ 0.02 mg·L-1 +NAA 0.1 mg·L-1medium and the average number of deep-pink-coloured masses of embryogenic cells on each callus was 8.4.In the second and third subculture,callus stopped growing further and the number of masses of embryogenic cells decreased gradually.Regeneration system could lay a good foundation for further transformation research.
