Integration of the CP gene in calli was first
examined by PCR (19). Two 17-mers of synthetic nucleotides
were used as primers; one is located in the CaMV 35S
promoter (CTCAGAAGACCAAAGGG) and the other is
located in the cDNA of RSV RNA-3 (TCTTCCAGGGAGATATG)
(v in Fig. 1A). Genomic DNAs from hygromycin-
resistant calli were extracted (20) and the PCR was
performed at 55°C for 30 cycles. The amplified DNAs were
subsequently visualized on 1% agarose gels using ethidium
bromide.