An efficient regeneration/transformation system was developed for `Beurre Bosc' pear. Young leaves were harvested from in vitro shoots proliferated on a medium containing MS basal salts and 5 BAP, 0.5 μM IBA, and 0.6M3. Shoot regeneration was optimized using a modification of the medium of Chevreau and Leblay (1993). Explants were cultured on shoot induction medium contained 10 μM TDZ and 1 μM IBA for 4 weeks in the dark, and then transfered to a similar, but auxinless, regeneration medium until shoots developed, usually after an additional 4 to 8 weeks. Leaf tissues were transformed by co-cultivation for 3 days with Agrobacterium tumefaciens EHA101 carrying a pGA482 plasmid containing NPTII, GUS, and rolC genes, followed by cultivation on SIM containing 300 mg/L timentin. Putative transgenic plants were selected on shoot induction medium containing 80mg/L kanamycin, and multiplied on shoot proliferation medium. Four clones were confirmed as transgenic using the GUS histochemical assay and Southern blots for the NPTII and rolC genes. Plants of each clone have been rooted and successfully transfered to the greenhouse for further analysis of gene expression.
Highly efficient protoplast transformation system for Streptococcus faecalis and a new Escherichia coli-S. faecalis shuttle vector.
