S. plymuthica IC1270 primes rice for enhanced accumulation of autofluorescent phenolics upon challenge inoculation. Intact leaf sheaths of the susceptible cv. CO39 and its resistant near-isogenic line C101LAC were challenged by injecting a conidial suspension of M. oryzae VT7. (A) Epifluorescence image of IC1270-induced sheath cells at 24 hpi. Ap = appressorium. Scale bar = 20 μm. (B) Quantitative analysis of autofluorescence under blue light excitation in water-treated susceptible (CO39), susceptible yet ISR-expressing (CO39 + IC1270), and genetically resistant (C101LAC) plants. Each bar represents the mean and SD of six replications stemming from three plants. At least 50 single-cell interaction sites originating from representative sheath sections were examined per replication. Data from one experiment is presented. Repetition of experiments led to results very similar to those shown.