FMO1 and infection: The positive interplay between NHP and SA in plant immunity is also reflected in an increased susceptibility to infection by P. syringae of both NHP- and SA-deficient ald1 sid2 or fmo1 sid2 double mutants compared to the respective single mutants that only lack one of the two immune regulators (Bernsdorff et al., 2016; Liu et al., 2020).