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Physiology and Biochemistry

Effects of Glyphosate on Glyceollin Production and the Expression of Resistance to Phytophthora megasperma f. sp. glycinea in Soybean. N. T. Keen, Department of Plant Pathology, University of California, Riverside 92521; M. J. Holliday(2), and M. Yoshikawa(3). (2)(3)Department of Plant Pathology, University of California, Riverside 92521; (2)Current address: E. I. du Pont de Nemours & Co., Biochemistry Department, Experimental Station, Wilmington, DE 19898; (3)Present address: Laboratory of Plant Pathology, Faculty of Agriculture, Kyoto Prefectural University, Kyoto 606, Japan. Phytopathology 72:1467-1470. Accepted for publication 14 April 1982. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-1467.

The phenylalanine ammonia-lyase inhibitors aminooxyacetate and aminooxyphenyl propionate did not block resistance expression or glyceollin accumulation in soybean hypocotyls inoculated with an incompatible race of Phytophthora megasperma f. sp. glycinea. However, low, nonphytotoxic concentrations of the herbicide glyphosate (N-phosphonomethyl glycine) effectively inhibited both processes. The results support other data indicating that glyceollin accumulation accounts for the expression of resistance to incompatible races of the fungus.

Additional keywords: herbicides, phenylpropanoid pathway, phytoalexin.