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Genetics

Absence of Lethal Stem Necrosis in Select Lycopersicon spp. Infected by Cucumber Mosaic Virus Strain D and Its Necrogenic Satellite CARNA 5. James L. White, Department of Botany, University of Maryland, College Park 20742; J. M. Kaper, Microbiology and Plant Pathology Laboratory, Plant Protection Institute, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705. Phytopathology 77:808-811. Accepted for publication 17 October 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-808.

Fifty-two Lycopersicon spp. accessions were inoculated with cucumber mosaic virus (CMV) strain D containing the satellite CARNA 5 (= CMV-associated RNA 5) that induces tomato necrosis in L. esculentum ‘Rutgers’. Many exotic species showed only mosaics or chlorosis in spite of large accumulation of CMV and CARNA 5. CMV was purified from several infected accessions for further analysis of its CARNA 5. All CARNA 5s isolated from infected accessions migrated to the same position under semidenaturing polyacrylamide gel electrophoresis as necrogenic CARNA 5 from CMV-D used for inoculation. Partial nucleotide sequencing of several CARNA 5s showed them to be identical to D-CARNA 5. The observation that many Lycopersicon spp. support the replication of CMV and CARNA 5 efficiently but do not respond necrotically suggests that these accessions may have gene(s) that block the necrotic response or may lack gene(s) that induce necrosis.