Relationship of Potato Leaf Sterols to Development of Potato Late Blight Caused by Phytophthora infestans on U.S. Potato Clones and Breeding Lines. W. J. Hazel, Environmental Protection Agency, Washington, DC 20460. G. A. Bean, and R. W. Goth. Department of Botany, University of Maryland, College Park 20742; and USDA-ARS, Beltsville, MD 20705. Plant Dis. 72:203-205. Accepted for publication 23 September 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0203.

Detached leaves of Solanum tuberosum numbered clonal selections B6026-WV-5, B6039-WV-9, and B6086-WV-21 and the cultivars Irish Cobbler and Sebago inoculated with zoospore suspensions of a race 1,2,3,4 isolate of Phytophthora infestans had sporangial production at the infection sites that was correlated to their respective field resistances. However, the sterol content of the leaves did not relate to either field resistance or sporulation. The sterols sitosterol and cycloartenol were most prevalent, but cholesterol, campesterol, stigmasterol, and 24-methylene cycloartenol were present in varying concentrations in all the foliar tissues assayed. When sterol extracts from foliar tissue were added to Elliott's defined medium at rates comparable to those present in foliar tissue, sporulation of P. infestans was increased relative to medium without sterol extracts.