VIEW ARTICLE

Physiology and Biochemistry

Effect of the R-3 Gene in Resistance of the Wauseon Potato Tuber to Phytophthora infestans. R. M. Zacharius, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Philadelphia, Pennsylvania 19118; S. F. Osman(2), E. G. Heisler(3), and J. C. Kissinger(4). (2)(3)(4)Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Philadelphia, Pennsylvania 19118. Phytopathology 66:964-966. Accepted for publication 17 February 1976. Copyright © 1976 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-66-964.

Tuber tissue of potato cultivar Wauseon, which has R₁R₃ resistance genes, was compatible with Phytophthora infestans race 1, even though incompatibility was predicted from its foliar reaction to that pathogen. When challenged by P. infestans race 4, Wauseon tuber slices developed a penetrating necrosis and showed a high accumulation of the terpenoids, phytuberin, and katahdinone. The susceptibility of Wauseon tubers to race 1 exemplify van der Plank’s contention that the tubers of R₃ potato cultivars may not be as resistant as is its foliage to this race. In the compatible interaction of Wauseon with race 1, production of rishitin is almost equal to that produced during the hypersensitive response of Kennebec (R₁) to race 4. This suggests that rishitin is not the primary factor involved in the resistance of potato tubers to races of P. infestans.