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Effect of Ethylene on Phytuberin and Phytuberol Accumulation in Potato Tuber Slices. J. W. D. M. Henfling, Department of Plant Pathology, University of Kentucky, Lexington, KY 40506; N. Lisker(2), and J. Kuc(3). (2)(3) Department of Plant Pathology, University of Kentucky, Lexington, KY 40506. Phytopathology 68:587-862. Accepted for publication 14 November 1977. Copyright 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-857.

Potato slices treated with Ethrel (2-chloroethylphosphonic acid) and then inoculated with Helminthosporium victoriae, Helminthosporium carbonum, or an incompatible race of Phytophthora infestans, accumulated considerably more phytuberin and phytuberol (a deacetylated derivative of phytuberin) than did slices treated with water followed by inoculation. The accumulation of the two terpenoids also was increased in slices treated with Ethrel followed by cell-free, autoclaved sonicates of Pythium aphanidermatum or Achlya flagellata. Ethrel did not elicit consistent changes in the accumulation of rishitin and lubimin in tissue accumulating high concentrations of phytuberin and phytuberol. Ethrel did not increase the accumulation of phytuberin, phytuberol, rishitin, or lubimin in noninoculated slices, slices inoculated with compatible races of P. infestans or slices treated with sonicates of H. carbonum, H. victoriae, or Neurospora crassa. More phytuberin and phytuberol accumulated in slices treated with Ethrel followed by a sonicate of P. infestans at 19 C than at 14 or 25 C, and the terpenoids were not detected in tissues incubated at 30 and 36 C. Ethylene (100 μliters/liter) markedly increased the accumulation of phytuberin and phytuberol in slices treated with cell-free sonicates of P. infestans, but alone it did not elicit accumulation of the terpenoids. Ethrel did not alter the resistance or susceptibility of the potato cultivars Kennebec (R1) or Russet Burbank (r) to race 4 and 1,2,3,4, of P. infestans or the resistance of both cultivars to H. victoriae and H. carbonum.

Additional keywords: phytoalexins, plant-parasite interaction.