Figure 2.

Microscopic, subcellular localization of H₂O₂ at interaction sites in barley after inoculation with BghA6. Seven-day-old barley primary leaves of NILs were inoculated with 20 conidia mm⁻² of BghA6. At different time points after inoculation, leaves were cut off, placed in a solution of 1 mg mL⁻¹ DAB, and collected for microscopic analysis 8 h later (at the indicated time points). A, Effective papilla (PAP_eff) in formation on cv Pallas (22 hai). Papilla and vesicles (V) with DAB polymers are seen beneath the appressorial germ tube (AGT). Scale bar = 8 μm. B, Successful penetration of cv Pallas (24 hai). The fungus had formed a haustorial initial (HI). Whereas the body of the ineffective papilla shows only a faint staining, the anticlinal cell wall close to the penetration site shows typical brownish DAB polymers. Scale bar = 10 μm. C, DAB staining of chloroplasts in healthy mesophyll cells neighboring a transverse vessel in cv Pallas primary leaves. Scale bar = 40 μm. D, BCPmlo5 (30 hai). Autofluorescence under UV-light excitation of effective papilla (PAP_eff) halos and vesicles beneath primary and AGTs is indicative of the accumulation of phenolic compounds at a repulsed penetration attempt. Scale bar = 10 μm. E, BCPMla12 (48 hai): mesophyll HR subjacent to a living penetrated epidermal cell (out of focus). Dead cells show DAB staining. Scale bar = 20 μm. F, Epifluorescence microscopy of the interaction site shown in E. The cells in the center have collapsed. Accumulation of polyphenols is indicated by the yellow autofluorescence. Scale bar = 20 μm. G, BCPMla12 (48 hai): epidermal cells surrounding the penetrated, living cell show positive DAB staining, (Legend continues on facing page.)