In this study, two different approaches of regeneration systems for explants in Eucalyptus pellita have been taken to establish an efficient di ffer entiation and regeneration protocols. The somatic embryogenesis from in vitro hy pocotyls and cotyledons in Eucalyptus pellita has been investigated. The typ ical three kinds of callus types were induced from hypocotyls and cotyledons culture d on the 2,4-D containing medium with BA or kinetin. High frequency (82%) plant l et production from the friable, granular embryogenic callus derived from hypocot yls has been obtained on the differentiation medium( 1μM TDZ; 1μM BA plus 01 μMNAA ) developed in this study. The relationship between the callus types form ed on different callus induction media and their corresponding differentiation r ate was further discussed. In addition, plant regeneration through organogenesis from in vitro hypocotyls, cotyledons and mature leaves in Eucalyptus pell ita ha s also been conducted with the modified basal B 5 medium supplemented with a ra ng e of combinations of BA and NAA. The highest frequency of shoot formations for t hree kinds of explants varied on the different regeneration medium, with the reg eneration rate for leaves, cotyledons and hypocotyls in ascending order: 4167% , 6667% and 8333%, respectively. The significance of the two different plant reg eneration systems was discussed. To our knowledge, this is the first repor t on the regeneration of Eucalyptus pellita.
