Influence of treatment with S. plymuthica IC1270 on M. oryzae -induced H
-generation in epidermal sheath cells. Intact leaf sheaths of the susceptible rice cv. CO39 and its resistant near-isogenic line C101LAC were challenged by injecting a conidial suspension of M. oryzae VT7. (A), Micrographs depicting distinct H2O2 accumulation patterns at 48 hpi in inoculated leaf sheaths supplied with 3,3'-diaminobenzidine (DAB): (I), successful fungal colonization of living epidermal cells in the absence of DAB staining (CO39; Control treatment); (II) DAB accumulation in the first-invaded cell following fungal invasion of adjacent cells (CO39; IC1270 treatment); (III) accumulation of DAB-positive vesicle-like bodies in the vicinity of the invasive hyphae (CO39; IC1270 treatment); (IV) DAB-positive cytoplasmic granules in hypersensitively reacting cells (C101LAC; Control treatment); (V) whole-cell DAB staining (CO39; Control treatment). Ap, appressorium or appressorial site; IH, invading hyphae; Vs, vesicles. Scale bars = 20 μm. (B), Frequencies of abovementioned DAB patterns at 36 and 48 hours post inoculation. In all graphs, bars represent the mean and SD of six replications originating 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.