VIEW ARTICLE

Reversible Host Adaptation in Cucumber Mosaic Virus. C. E. Yarwood, Professor of Plant Pathology, University of California, Berkeley, California 94720. Phytopathology 60:1117-1119. Accepted for publication 2 March 1970. DOI: 10.1094/Phyto-60-1117.

Occasional systemic infections of cucumber mosaic virus (CMV) occurred in cowpea when over 200 primary local lesions/plant developed on inoculated primary leaves, or when the inoculated leaves were heated. Most of these mutants in cowpea were different from each other, as indicated by differences in local lesions, systemic symptoms, and injury to cowpea; by degree of injury to cucumber; and by local lesions and incidence of systemic infection in bean. Mutants were usually less injurious to cucumber and always more injurious to cowpea than the parent culture. When these mutants were passed through cucumber they usually became less injurious to cowpea, and in 21 cases they returned to the type form of CMV that produced local lesions but did not go systemic or cause injury in cowpea. When these mutants were passed through cowpea they became more injurious to cowpea. CMV was more injurious to cucumber in the winter months, or in plants subjected to reduced light in summer, than to plants with summer daylight.