Symptom appearance is delayed in plants infected with TGMV L148 valine mutants. N. benthamiana plants cobombarded with either wild-type or mutant TGMV A and wild-type TGMV B replicons were examined daily for the appearance of symptoms in new growth. The dpi when plants displayed unequivocal symptoms (yellow veins and leaf curling) are plotted for each construct. The symbols represent when individual plants displayed symptoms for wild type (×), L148V (○), L148V* (□), and E146A L148V (†). The total number of plants was 12 for the wild type, 8 for L148V, 10 for L148V*, and 9 for E146A L148V. The arrows indicate the average time of symptom appearance for the plants infected with each construct. The data summarize results from two independent experiments.