Selective Degradation of Proteins by Cercospora kikuchii and Phomopsis longicolla in Soybean Seed Coats and Cotyledons. R. K. Velicheti, Research Associate, Department of Plant Pathology, University of Illinois at Urbana-Champaign, 1102 S. Goodwin Avenue, Urbana, IL 61801-4709. K. P. Kollipara, J. B. Sinclair, and T. Hymowitz. Graduate Research Assistant, Department of Agronomy, Professor, Department of Plant Pathology, and Professor, Department of Agronomy, University of Illinois at Urbana-Champaign, 1102 S. Goodwin Avenue, Urbana, IL 61801-4709. Plant Dis. 76:779-782. Accepted for publication 3 February 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0779.

Soybean seeds infected with Cercospora kikuchii showed degradation of seed coat proteins but not cotyledonary proteins, whereas seeds infected with Phomopsis longicolla showed degradation of seed coat and cotyledonary proteins. Lipoxygenase, conglycinins (α, α’, β, β’), and glycinins (A₁, A₄), which are cotyledonary proteins degraded by P. longicolla, were tentatively identified by their molecular weights. Lipoxygenase was degraded only in seed coats infected with C. kikuchii and in cotyledons infected with P. longicolla. ?-Amylase was partially degraded in seed coats and cotyledons infected with P. longicolla but not in seeds infected with C. kikuchii. Soybean seed lectins were found in seed coats infected with P. longicolla but not in seeds infected with C. kikuchii or in the uninfected control. Soybean seed lectins were not degraded in cotyledons of seeds infected with either fungus.