VIEW ARTICLE

Physiology and Biochemistry

Stimulation of Oospore Production in Phytophthora megasperma f. sp. medicaginis by Medicarpin. Ahmad Vaziri, Graduate research assistant, Department of Plant Pathology, University of California, Riverside 92521; N. T. Keen(2), and D. C. Erwin(3). (2)(3)Professors, respectively, Department of Plant Pathology, University of California, Riverside 92521. Phytopathology 73:730-734. Accepted for publication 4 January 1983. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-730.

Medicarpin inhibited mycelial growth of Phytophthora megasperma f. sp. medicaginis (Pmm) isolates from alfalfa but stimulated oospore production (correlation coefficient = 0.98 for the number of oospores produced as a function of medicarpin concentration in the medium). However, medicarpin (75- 125 μg·ml^{- 1}) did not stimulate oospore production in isolates of P. megasperma from other hosts or in Phytophthora cinnamomi. Oospore production was not stimulated by the soybean phytoalexins, glyceollin and glycinol, in either Pmm or P. cinnamomi.