Figure 4.

RT-PCR product size comparisons. Total RNA from a BSMV-infected plant was converted to cDNA using the cDNA primer BSMV8 followed by amplification with primers 5′BSMV2 and 3′BSMV5 (lane 2, see Table 1 for primers). Total RNA from individual plants infected by MStV (lane 3) and doubly infected by MStV plus BSMV (lane 4) was converted to cDNA by primer MStV50 followed by amplification with primers 5′MStV-CON and 3′NCP or 5′BSMV2 and 3′NCP, respectively. The RT-PCR products were electrophoretically separated in 15% nondenaturing polyacrylamide gel followed by ethidium bromide staining. Included on the gel was the BRL 1-kb DNA ladder (lane 1) and in lane 5, a mixture of portions of the RT-PCR products shown in lanes 3 and 4.