Protoplast co-transformation and regeneration of transgenic 'Hamlin' sweet orange plants containing a cDNA Xa21 xanthomonas resistance gene and GFP

[...] Plasmid DNA (pARS108) encoding the non-destructive selectable marker EGFP (Enhanced Green Fluorescent Protein) gene, and the plasmid cDNA of the Xa21 gene (pXa21-mtaq) were co-transformed into 'Hamlin' orange protoplasts using polyethylene glycol. More than 150 transgenic embryoids were recovered. Over a thousand transgenic plantlets GFP positive were regenerated from 150 independent transformation events. PCR analysis revealed the presence of the cDNA of the Xa21 and the GFP genes in some of the transgenic plantlets. The recovery of transgenic plants was expedited by in vitro grafting.[...]