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Ecology and Epidemiology

Cucumber Mosaic Virus Isolates Seedborne in Phaseolus vulgaris: Serology, Host-Pathogen Relationships, and Seed Transmission. Robert F. Davis, Graduate research assistant, Department of Botany and Plant Pathology, Oregon State University, Corvallis, 97331, Current address: Assistant professor, Department of Plant Pathology, Cook College, Rutgers University, P. O. Box 231, New Brunswick, NJ 08903; Richard O. Hampton, research plant pathologist, USDA-ARS, Oregon State University. Phytopathology 76:999-1004. Accepted for publication 24 March 1986. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1986. DOI: 10.1094/Phyto-76-999.

Selected cucumber mosaic virus (CMV) isolates seedborne in bean (Phaseolus vulgaris) were compared for serological relatedness, host-pathogen relationships, and seed transmissibility. CMV strains B, Le, F, B₃₂, and Pg were found to be serologically indistinguishable by gel double-diffusion tests using antisera to formaldehyde-fixed immunogens (CMV-B and CMV-Le). Detection of CMV in infected bean leaves by gel double-diffusion tests was dependent on extraction in 0.05 M citrate buffer, pH 6.5, with 0.1% sodium thioglycollate (w/v), 0.1% Triton X-100 (v/v), and 1% formaldehyde (v/v). Time of appearance and severity of symptoms induced by CMV-B, and relative virus concentration varied among 32 bean cultivars representing diverse germ plasm. Virus titer was maximal in greenhouse-grown plants 1-2 wk after inoculation with CMV-B, -Le, and -F but declined sharply after the fourth week. CMV seed transmission varied according to variety and isolate and did not occur in seeds from plants inoculated 4 or 6 wk after planting. CMV-Pg occurred in all parts of bean seedlings infected from seed. The implications of these results for detection and diagnosis of CMV in bean plants are discussed.