The susceptibility of tomato fruit to necrotrophic pathogens
increases during ripening [16, 17]. A correlation between fruit
age late in ripening and increased susceptibility was observed
in red fruit. However, in purple fruit, susceptibility to B. cinerea
did not increase from the breaker stage when anthocyanin
production was induced (Figure 1G). This observation suggested
a specific role for anthocyanins in limiting the spread
of fungal infection, as supported by the intermediate susceptibility
displayed by two different Del/Ros1 lines (C and Y) that
produce lower levels of anthocyanins than line N (used for
the initial tests) [14] (Figures S2D–S2F).