Abstract
Both hypersensitive flecks and susceptible lesions were produced on the potato leaves of resistant interspecific hybrid 1506-(b) 9 and susceptible variety Norin No.1, by placing on the leaves the DNA-containing fraction from leaves of susceptible variety Norin No.1, and resistant hybrid 1506-(b) 9, respectively.
The same flecks and lesions were recognized on these plants by placing the DNA-containing fraction from susceptible variety, Norin No.1, and resistant hybrid 1506-(b) 9 after treating the fraction with RNase and after purifying the DNA through Sepharose 6B. By grafting of susceptible variety, Norin No.1, scions on resistant hybrids 1506-(b) 9 and 96-56 stocks or vice versa, both susceptible lesions and hypersensitive flecks coexisted by inoculating the leaves with zoospores of Phytophthora infestans, race 0. Whereas, the leaves of susceptible and resistant potato varieties, not grafted, showed the susceptible lesions and hypersensitive flecks only, respectively.
