Fig. 1.

Nonhost response of pepper (Capsicum annuum) against Phytophthora infestans is associated with hypersensitive cell death. (a) Detached leaves of nonhost pepper landrace CM334 and host plants (potato (Solanum tuberosum) cv Daeji and tomato (S. lycopersicum) cv Heinz) were infected with a zoospore suspension of P. infestans 88069 (5 × 10⁴ ml⁻¹). Leaf pieces containing zoospore droplet were excised at 5 d post-inoculation, examined for hypersensitive cell death and sporangia development under UV illumination, and visualized by trypan blue staining. White arrows indicate sporangia formation on potato and tomato leaves. Zp, zoospore; gt, germ tube. (b) Hypersensitive cell death was confirmed by interactions between pepper accessions and four isolates of P. infestans 40707, 40718, 43071 and 43072. Bars, 50 μm.