Presence of the HC-Pro cistron in susceptible (SL) and resistant (RL) maize lines. (A) The positions of the viral inoculated area and four relative positions from this site: two apical, one proximal (AP), and one distal (AD); and two basal, one proximal (BP), and one distal (BD), closer to the stem. (B) RT-PCR reactions showing either the presence or absence of the positive (+) or negative (-) amplified SCMV-HC-Pro cistron from the maize isolate (SCMV-VER1) at 3, 6, and 12 dpi in different positions, relative to the inoculation site. S4A and S4B are apical proximal and basal distal regions on a systemic leaf number 4. Noninoculated leaves are indicated as NI.