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Physiology and Biochemistry

In Vitro Effects of Glyceollin on Phytophthora megasperma f. sp. glycinea. P. Stössel, Nestlé Research Department, CH-1814 La Tour-de-Peilz, Switzerland; Phytopathology 73:1603-1607. Accepted for publication 3 June 1983. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-1603.

Inhibition of Phytophthora megasperma f. sp. glycinea (Pmg) races 1, 4, and 6 by glyceollin was examined in several bioassays. On absorbent pads impregnated with bean broth or soybean broth, the ED₅₀ for inhibition of mycelial growth of Pmg race 4 was about 100 μg of glyceollin per milliliter; with race 6, the ED₅₀ was 70 μg/ml using pads impregnated with bean broth and 100 μg/ml using pads impregnated with a sucrose-asparagine medium. For inhibition of germ tube growth in liquid media, however, the ED₅₀ was approximately 15 μg of glyceollin per milliliter for race 4 and 25 μg/ml for races 1 and 6. Germ tube growth of cysts and sporelings (cysts allowed to germinate for 8 hr prior to exposure to glyceollin) was equally affected by glyceollin. Pre-exposure of cysts to noninhibitory concentrations of glyceollin, phaseollin or kievitone induced some tolerance to glyceollin. There was no evidence for glyceollin metabolism.