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Hyphal Interactions and Antagonism Among Field Isolates and Single-Basidiospore Strains of Athelia (Sclerotium) rolfsii. Z. K. Punja, Postdoctoral research associate, Department of Plant Pathology, University of California, Davis 95616, Present title and address of senior author: Visiting assistant professor, Department of Plant Pathology, North Carolina State University, Raleigh 27650-5397; R. G. Grogan, professor, Department of Plant Pathology, University of California, Davis 95616. Phytopathology 73:1279-1284. Accepted for publication 13 April 1983. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-1279.

Seventy-two field isolates of Athelia rolfsii from 19 hosts and 15 geographical areas were paired in culture in all possible combinations. On the basis of antagonism zones (also called barrage zones) that developed in 86.5% of these pairings, the isolates were assigned to 25 interaction groups (i-groups). Within an i-group, all of the isolates grew together when paired and the hyphae intermingled with little or no cell death. In pairings between members from any two groups, antagonism zones developed; this was accompanied by the plasmolytic killing of hyphal cells. Isolates within a given i-group varied in morphological characteristics and frequently were isolated from different hosts or geographical areas. Antagonism zones also developed in 80- 92% of sibling pairings and in 86% of non-sibling pairings among 50 single-basidiospore (S1) strains obtained from five parent field isolates from California that belonged to i-group I. Similar antagonism zones developed in all pairings between the S1 strains and these field isolates. Formation of antagonism zones in sibling and non-sibling pairings was not significantly influenced by media or by different incubation temperatures. The implications of these findings are discussed relative to similar observations reported for wood-decaying basidiomycetes.

Additional keywords: aversion, cytoplasmic incompatibility, heterogenic incompatibility, heterokaryon incompatibility, vegetative isolation, vegetative incompatibility.