NPR1 and infection: Plants primed through SAR equip themselves with pattern recognition receptors (Tateda et al., 2014; Hartmann et al., 2018) and pathogen-responsive MPKs (Beckers et al., 2009) which are then activated upon a second infection by elicitors such as the flagellin-derived peptide flg22 and depend on NPR1 (Yi et al., 2015).