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Genetics

Hypovirulence Conversion in Endothia parasitica. Sandra L. Anagnostakis, Assistant scientist, Department of Genetics, The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven 06504; Peter R. Day, department head, Department of Genetics, The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven 06504. Phytopathology 69:1226-1229. Accepted for publication 1 June 1979. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-1226.

A laboratory method developed by J. Grente was used to test the abilities of seven related hypovirulent strains of E. parasitica to convert 49 virulent vegetative compatibility (v-c) tester strains to hypovirulence. The success of conversion, its rate, and the stability of the converts are all influenced by vegetative compatibility. Rapid conversions (2 days or less) always occurred between strains of the same v-c group and were common in certain incompatible pairings. In other incompatible pairings, conversion was slow and erratic, and 10 of the testers were not converted. Examination of dsRNA components in two series of replicated incompatible rapid conversions showed that variation and stability of the dsRNA patterns also were influenced by the v-c group of the recipient strains. Mechanisms for maintaining stable dsRNA genomes and for generating variants of these genomes contribute to the polymorphism and adaptability of this biological control agent.