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Genetics

Genetic Control of Symptoms, Movement, and Virus Accumulation in Cowpea Plants Infected with Cowpea Chlorotic Mottle Virus. C. W. Kuhn, Department of Plant Pathology, University of Georgia, Athens 30602; S. D. Wyatt(2), and B. B. Brantley(3). (2)Department of Plant Pathology, University of Georgia, Athens 30602, Present address: Department of Plant Pathology, Washington State University, Pullman 99164; (3)Department of Horticulture, Georgia Experiment Station, Experiment 30212. Phytopathology 71:1310-1315. Accepted for publication 24 April 1981. Copyright The American Phytopathological Society. DOI: 10.1094/Phyto-71-1310.

An inheritance study which evaluated segregating populations of cowpea plants infected with cowpea chlorotic mottle virus (CCMV) indicated that the host genotype conditioned expression of symptoms, virus accumulation, and virus movement. With certain crosses, necrotic etching on inoculated primary leaves was controlled by a single dominant gene, and virus accumulation was related to the presence or absence of necrosis. Systemic symptoms (three types) could not be differentiated objectively enough for quantitative analysis. However, symptomless plants, representing lack of viral movement, were distinguished with ease. Viral movement was controlled by a single dominant gene. Five levels of virus accumulation were found in 10 cowpea lines and in F₁, F₂, and backcross populations. Both the total accumulation of virus in plants and the rate of virus replication appeared to be controlled by the action of several genes. The viral movement gene may be closely linked with one of the genes that controls virus replication. Symptomatology, based on intensity of chlorosis, was unrelated to virus accumulation. Furthermore, yield of pods and seeds was more closely related to virus accumulation than to symptom severity. When different strains of CCMV were tested, the virus genome also was found to control the level of virus accumulation.