VIEW ARTICLE

Ultrastructure at the Host-Parasite Interface of Phytophthora megasperma var. sojae in Soybean Rootlets. R. L. Slusher, Former Graduate Research Assistant, Department of Plant Pathology and Botany, University of Illinois, Urbana 61801; D. L. Haas(2), Z. B. Carothers(3), and J. B. Sinclair(4). (2)(3)(4)Graduate Teaching Assistant, Associate Professor, and Professor, respectively, Departments of Plant Pathology and Botany, University of Illinois, Urbana 61801. Phytopathology 64:834-840. Accepted for publication 12 January 1974. DOI: 10.1094/Phyto-64-834.

Ultrastructure and reactions at the host-parasite interface of Phytophthora megasperma var. sojae in soybean roots were studied. The inter- and intracellular penetration of host cells and tissues by hyphae and the formation of haustoria is described. Evidence for degradation or dissolution of host walls is presented. Lomasomes differed in structure from other Phytophthora spp., and a previously undescribed separation between host cytoplasm and host wall was found in areas of fungal contact. Two partially delineated zones within the extrahaustorial matrix are shown. The haustorial wall differed from the hyphal wall by its greater thickness, presence of an outer, dark-staining zone containing electron-dense inclusions, and an outermost granular boundary.