FIG. 4.

Infection of soybean genotypes with DsRed (DsR)-tagged avirulent SMV-N (avrN^DsR) or its experimentally evolved virulent derivative, SMV-N_{K321E+T341I+A947V} (virN^DsR) (Fig. 2). Primary leaves of susceptible (rsv1) or functionally immune (Rsv1) genotype soybeans were inoculated biolistically with molecularly cloned avrN^DsR or virN^DsR. Leaflets from the secondary leaves of the inoculated plants were visualized under white or UV lights for the expression of DsRed at 14 to 28 days postinoculation. Note that both viruses were capable of expressing DsRed in the secondary leaves from susceptible soybean Williams 82 (rsv1). Only the experimentally evolved virN^DsR, but not its progenitor avrN^DsR, expressed DsRed in noninoculated secondary leaves from all functionally immune Rsv1 genotype soybeans. Purple shading of different Rsv1 genotype soybeans is as described in the legend of Fig. 1.