AGROBACTERIUM-TUMEFACIENS-MEDIATED TRANSFORMATION OF EUCALYPTUS-CAMALDULENSIS AND PRODUCTION OF TRANSGENIC PLANTS

An efficient system for Agrobacterium-mediated transformation of Eucal yptus camaldulensis and production of transgenic plants was developed. Transformation was accomplished by cocultivation of hypocotyl segment s with Agrobacterium tumefaciens containing a binary Ti-plasmid vector harboring chimeric neomycin phosphotransferase and beta-glucuronidase (GUS) genes. A modified Gamborg's B5 medium used in this study was ef fective for both callus induction and regeneration of transgenic shoot s. This medium could also effectively maintain the organogenic capabil ity of callus for more than a year. Culturing transgenic shoots in Mur ashige and Skoog medium supplemented with 0.1 mg.l(-1) benzylaminopuri ne prior to root induction in rooting medium markedly increased the ro otability of shoots that were recalcitrant to rooting. Histochemical a ssay revealed the expression of the GUS gene in leaf, stem, and root t issues of transgenic plants. Insertion of the GUS gene in the nuclear genome of transgenic plants was verified by genomic Southern hybridiza tion analysis, further confirming the integration and expression of T- DNA in these plants.