NPR1 and infection: The concerted negative impact of functional NPR1 on the meta-substituted SA- and BA-derivatives, SA, SA conjugates (SGE, SA-Mal, SA-Asp), and SA biosynthetic intermediates (IC-Glu, Pyr-Glu) indicates that NPR1 negatively regulates the isochorismate pathway at an early step upstream of isochorismate production, which could lead to an over-accumulation of isochorismate in npr1 mutants, and consequently, enhanced production of isochorismate-derived compounds under pathogen infection conditions (Fig. 9).