Authors: Hilal İLARSLAN, A. Sülün ÜSTÜN, Reyhan YILMAZER
Abstract: A histopathological examination of resistant and susceptible host-pathogen interactions was conducted in three pepper genotypes, Thin Long-35 (TL-35), PM 217 and PM 702 (=CM 334) with isolate of Phytophthora capsici Leon. from Antalya (1x104 zoospor/ml), Inoculated plants were characterized and compared with healthy controls at 2, 4 and 6 days after inoculation. Crowns of the resistant pepper cultivars (PM 217 and PM 702) formed limited symptom when inoculated with P. capsici after 2 days But, in the crown of susceptible genotype revealed that intra- and intercellulary growing fungal hyphae colonized the epidermis, cortical parenchymatic pith cells. The host cell walls were palely stained, thinned and swollen, possibly being biochemically altered by the action of fungal macerating enzymes. At the 6 days after inoculation, in susceptible cultivar, the epidermis, cortical parenchyma and parenchymatic pith were completely destroyed and cytoplasm of all infected cells were plasmolysed. On the other hand, in PM 702 and PM 217, the damage began respectable after 4th and 6th days inoculation. Papilla-like material (callose) was produced in the inner surface of host walls directly in contact with fungal cell more than susceptible genotype. At the 6 days after inoculation, the tissue of resistance genotypes was characterized by general histology of epidermis, cortical parenchyma and parenchymatic pith, which showed no sign of cellular distruption or wall degredation.