Figure 7. Fitness costs to the ToMV mutants in the absence of Tm-1.

(A) Competition of two ToMV derivatives in BY-2 protoplasts. Protoplasts isolated from non-transgenic BY-2 cells were co-inoculated with two of the six ToMV derivatives used in this study. As a control, individual derivatives were separately inoculated and the protoplasts were cocultured. At 20 hpi, RNA was extracted, and amplified cDNA was sequenced using the GS-FLX titanium. Ratios of the viral count (virus A/virus B) normalized to the respective control experiment (individual infection) are shown. *: p<0.05, **: p<0.01 based on a chi-square test for the ratio of the two derivatives in the coinfection experiment against the ratio expected from the control experiment. A result of each competition is represented twice so that each virus A histogram shows the results of competition against all the other derivatives (virus B). (B) Competition of LT1^E979K with ToMV-L or LT1 in tomato plants. Mixtures of viral RNA were mechanically inoculated onto the leaves of 16 tomato (GCR26: tm-1) plants. RNA was extracted from the inoculated leaves (IL) and upper non-inoculated leaves (UL) at 10 and 42 dpi, respectively. At least four young leaflets of each co-inoculated plant at 46 dpi were homogenized; each homogenate was inoculated onto a healthy plant, and RNA was extracted from upper non-inoculated leaves at 42 dpi (Passage). RT-PCR-amplified cDNA fragments were directly sequenced and the numbers of plants accumulating either both or one of the co-inoculated derivatives are shown.