Metabolic profiling by MALDI-Q-TOF analysis of P. cucumerina-infected Arabidopsis leaves following spray and droplet inoculation. Principal component analysis (PCA) of ions (m/z values) that show a statistically significant difference between treatments (n = 4; ANOVA, P < 0.01). Five-week-old leaves were collected at 2 d after mock or P. cucumerina inoculation (106 spores mL−1). Leaf extracts were analyzed by MALDI-Q-TOF in negative (MALDI−) and positive (MALDI+) ionization mode. Pie charts show statistically significant (red) and nonsignificant (black) fractions of all detected ions. Each data point in the PCA plots represents the profile of one biologically replicated sample, which was derived from the average of six technical replicates. Percentages of variation explained by each principal component (PC) are shown in parentheses.
