FIG 2.

Influence of UpA dinucleotide and U+A mononucleotide contents on SD-PPV fitness. (A and C) Images taken with an epifluorescence microscope of N. benthamiana leaves infected with the indicated viruses. Inoculated leaves at 6 days postinoculation (dpi) and upper noninoculated leaves at 10 and 20 dpi are shown. Bars, 5 mm. (B and D) PPV CP-specific immunoblot analyses of extracts from upper noninoculated N. benthamiana leaves (four individual plants) infected with the indicated mutant viruses (F4_) and their parental control (SD-PPV), at 10 (two upper membranes) and 20 (two lower membranes) dpi. Membranes stained with Ponceau red showing the RubisCO large subunit were included as loading controls. Bar graphs showing the mean ± SD (n = 4) of immunoblot signals in arbitrary units are shown on the right (for comparison, we considered the average for SD-PPV to be 1). In panel D, the number of UpAs in the whole fragment F4 from each virus is indicated in parentheses above its corresponding bar. Different letters indicate significant differences (P < 0.05), by one-way ANOVA and Tukey’s HSD test.