Production of phytoalexins, glycoalkaloids and phenolics in leaves and tubers of potato cultivars with different degrees of field resistance after infection with Phytophthora infestans

The kinetics of accumulation of phytoalexins, glycoalkaloids and phenolics was studied in two potato cultivars differing in their degrees of field res istance when infected with Phytophthora infestans. Tuber slices and leaves of cvs Pampeana INTA (high degree of field resistance, free of R genes) and Bintje (susceptible) were infected with race C (complex race 1, 3, 5, 7, 1 1) of Phytophthora infestans. Phytoalexins and phenolics accumulated in tub er and leaf tissues which had been inoculated. The levels of these compound s in the susceptible cv. Bintje were relatively low and similar to those fo und before inoculation. Leaves of cv. Pampeana INTA had a very high glycoal kaloid content, suggesting that glycoalkaloids may play a role in protectio n of leaves against the fungus. However, we could find no correlation betwe en resistance and glycoalkaloid content of tubers. Our results suggest a ma jor role of phytoalexins, phenolics and glycoalkaloids in the complex mecha nisms of held resistance.