<p style="text-align: justify;">A number of transgenic lines were produced by transformation of the plum cultivar &lsquo;Bluebyrd&rsquo; with <i>Agrobacterium tumefaciens</i> strain C58/Z707 containing a binary T-DNA plasmid. Seeds of the plum cultivar were sterilised and soaked in sterile water overnight before the seed coat was removed and the cotyledons slit open. The embryonic axis was removed and the hypocotyl segment cut into slices approximately 1mm thick. These slices were immersed in a liquid culture of the the <i>Agrobacterium</i> strain and then cultured on medium containing various plant hormones to induce shoot formation and regeneration.</p>

<p style="text-align: justify;">The binary plasmid was derived from pGA482GG and contains the <i>nptII</i> and <i>uidA</i> (gus) marker genes, as well as tetracycline and gentamicin antibiotic resistance genes. The <i>nptII</i> gene is under control of the nopaline synthase promoter (nos) and nos terminator. The <i>uidA</i> gene is under control of the 35S promoter and nos terminator. The tetracycline and gentamicin marker genes are under control of prokaryotic promoters and therefore are not expressed in plants. In addition to these intact genes, pGA482GG contains an interrupted &szlig;-lactamase gene. Sequencing analysis shows that this gene is interrupted by a cos site that renders the gene non-functional. The <i>nptII</i> gene codes for the neomycin phosphotransferase enzyme (NPT) which provides resistance to the antibiotic kanamycin as a selectable marker. The <i>uidA</i> gene codes for the &szlig;-glucuronidase enzyme (GUS) as another marker gene.</p>

<p style="text-align: justify;">The coat protein gene of the plum pox virus containing the 35S promoter and the nos terminator, from plasmid pBIPCP was subcloned into <i>Hind</i>III-digested pGA482GG and the resulting plasmid was designated pGA482GG/PPV-CP-33. This plasmid was used to electrotransform <i>A. tumefaciens</i> strain C58/Z707 and used for transformation of plum tissue.</p>
