Evolution of CMV seed transmission, virus accumulation and virulence across passages of vertical transmission.

Seed transmission rate (A) was estimated from the number of infected seedlings out of 100 seeds per plant. Virus accumulation (B) was measured as µg of viral RNA per g of fresh leaf tissue. Virulence (C) is represented as one minus the ratio of seed weight in infected to mock-inoculated plants: 1−(SW_i/SW_m). Data are plotted as mean±standard error of the five independent lineages in each passage for Fny-CMV (blue squares), De72-CMV (red triangles) and LS-CMV (green diamonds). The black line in each panel represents the fitted regression line for lineages of all three strains combined.