Histology in wheat cv. 'Suwon 11' after inoculation with P. striiformis f. sp. tritici pathotype CY23 (incompatible interaction). (A) hypersensitive cell death (HR) was only observed in the mesophyll cells in contact with the haustorial mother cell at few infection sites, 18 hpi. (B) HR could be observed in most of infection sites, 24 hpi. (C) Second hyphae were formed and mesophll cells which around intercellular hyphae showed cell death, 72 hpi. (D) Host cell death and fungal spread inhibit at infection sites, 120 hpi. Bars = 50 μm, SV, substomatal vesicle; IH, infection hypha; HMC, haustorial mother cell; SH, secondary hyphae; NC, necrotic cell.