VIEW ARTICLE

Physiology and Biochemistry

Cell Walls of Phytophthora infestans Contain an Elicitor of Terpene Accumulation in Potato Tubers. J. W. D. M. Henfling, Department of Plant Pathology, University of Kentucky, Lexington 40546, Present address of the senior author: The International Potato Center, Apartado Postal 5969, Lima, Peru; R. M. Bostock(2), and J. Kuc(3). (2)(3)Department of Plant Pathology, University of Kentucky, Lexington 40546. Phytopathology 70:772-776. Accepted for publication 24 February 1980. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-772.

Homogenates of the mycelium of Phytophthora infestans were subjected to differential centrifugation and the fractions were applied to the upper surface of Kennebec potato slices. Lubimin and rishitin were determined in the upper 1 mm of slices 72–86 hr after application of the fractions. The fraction containing the 500-g pellet contained 70–90% of the terpene-eliciting activity, and most of the remaining activity was recovered in the fraction containing the 40,000-g supernatant. The fraction containing the 500-g pellet was also most active in eliciting browning. Living zoospores, cystospores, and sporangia of incompatible races of P. infestans caused the accumulation of high concentrations of lubimin and rishitin in potato slices. When the spores were killed by freezing followed by thawing, only cystospores and sporangia caused appreciable terpene accumulation. Empty sporangia had at least 75% of the terpene-eliciting activity of dead sporangia which had not released zoospores. Two methods were used to encyst zoospores. In one method, encystment was accomplished within 1 hr and in the other within 1.5 min. Dead cystospores produced by either method caused the accumulation of high concentrations of lubimin and rishitin in potato slices. It is concluded than an elicitor of terpene accumulation in potato tubers is associated with the cell wall of P. infestans.