Genetic Analysis in Gibberella pulicaris: Rishitin Tolerance, Rishitin Metabolism, and Virulence on Potato Tubers. Anne E. Desjardins. Northern Regional Research Center, Agricultural Research Service, U. S. Department of Agriculture, Peoria, IL 61604 U.S.A. Harold W. Gardner. Northern Regional Research Center, Agricultural Research Service, U. S. Department of Agriculture, Peoria, IL 61604 U.S.A. MPMI 2:26-34. Accepted 27 December 1988. This article is in the public domain and not copryightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1989.

Twenty-fix field strains of Gibberella pulicaris were tested for tolerance of the potato phytoalexin rishitin, for ability to metabolize rishitin, and for virulence on potato (Solanum tuberosum) tubers. All highly virulent strains were tolerant of rishitin and able to metabolize rishitin. A cross was made between strains that differed in rishitin tolerance, rishitin, metabolism, and virulence. These traits were followed through one generation of random ascospore progeny and a second, backcrossed generation of tetrad progeny. All highly virulent progeny were tolerant of and able to metabolize rishitin, and all rishitin-sensitive progeny were of low virulence. These results support the hypotheses that rishitin metabolism is required for a high level of rishitin tolerance and is either required for or closely linked to genes for a high level of virulence.