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Resistance

Glyceollin Accumulation in Soybean Lines Tolerant to Phytophthora megasperma f. sp. glycinea. A. F. Olah, Research associate, Department of Plant Pathology, Ohio Agricultural Research and Development Center, Ohio State University, Wooster 44691; A. F. Schmitthenner(2), and A. K. Walker(3). (2)Professor, Department of Plant Pathology, Ohio Agricultural Research and Development Center, Ohio State University, Wooster 44691; (3)Former associate professor, Department of Agronomy, Ohio Agricultural Research and Development Center, Ohio State University, Wooster 44691, Present address: Asgrow Seed Co., Redwood Falls, MN 56283. Phytopathology 75:542-546. Accepted for publication 24 November 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/Phyto-75-542.

Wounded and unwounded hypocotyls and tap roots of soybean lines that have high or low tolerance to Phytophthora megasperma f. sp. glycinea were tested to determine whether glyceollin accumulation could account for tolerance. No correlation was shown. After inoculation into the lateral root area with compatible races, four types of lesions in the tap root were recognized. These were: no rot, 1- 10 mm rot, rot to the hypocotyl-root junction, and rot into the hypocotyl. Only plants with hypocotyl rot died within 10 days; others were stunted and recovered. Time course of accumulation and concentration of glyceollin in tap roots suggests that glyceollin does not play a role in soybean tolerance. No fungitoxic compounds other than glyceollin were detected by TLC bioassay of infected roots.