Fig. 3

Comparative development of powdery mildew on in vitro leaves of genotypes containing different combinations of R loci introgressed from Vitis piasezkii. Detached leaves were inoculated with powdery mildew using a settling tower, harvested 5 dpi and stained with Coomassie Brilliant blue to visualize the development of fungal structures on the leaf surface. (a) Ren6 ⁻/Ren7 ⁻, (b) Ren6 ⁻/Ren7 ⁺, (c) Ren6 ⁺/Ren7 ⁻, and (d) Ren6 ⁺/Ren7 ⁺ genotypes. The brown cells beneath the appressoria of germinated fungal spores are the result of a hypersensitive response induced by the R loci. Scale bars represent 50 μm