AGROBACTERIUM-MEDIATED TRANSFORMATION OF SWEET ORANGE AND REGENERATION OF TRANSGENIC PLANTS

Transgenic sweet orange (Citrus sinensis L. Osbeck) plants have been o btained by Agrobacterium tumefaciens-mediated gene transfer. An hyperv irulent A. tumefaciens strain harboring a binary vector that contains the chimeric neomycin phosphotransferase II (NPT II) and beta-glucuron idase (GUS) genes was cocultivated with stem segments from in vivo gro wn seedlings. Shoots regenerated under kanamycin selection were harves ted from the stem segments within 12 weeks. Shoot basal portions were assayed for GUS activity and the remaining portions were shoot tip gra fted in vitro for production of plants. Integration of the GUS gene wa s confirmed by Southern analysis. This transformation procedure showed the highest transgenic plant production efficiency reported for Citru s.