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Etiology

Further Examination of the RNA and Coat Protein of Spring Beauty Latent Virus. Rodrigo A. Valverde, Assistant professor, Department of Plant Pathology and Crop Physiology, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge, 70803; Christopher B. Glascock, research scientist, Calgene Inc., 1920 Fifth Street, Davis, CA 95616. Phytopathology 81:401-404. Accepted for publication 1 November 1990. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/Phyto-81-401.

Spring beauty latent virus (SBLV) has been proposed as a new member of the bromovirus group. Four dsRNAs (M_r 2.2, 2.0, 1.4, and 0.5 × 10⁶) with a profile similar to those of the bromoviruses were obtained when plant tissue infected with SBLV was analyzed. A fifth dsRNA (M_r 1.2 × 10⁶) with nucleic acid similarity to the genomic RNA also was obtained. Molecular hybridization with cDNA to SBLV RNA did not show nucleic acid similarity between SBLV and four bromoviruses. Infectivity tests with SBLV ssRNAs indicated that it has a tripartite genome because RNAs 1, 2, and 3 were required for infectivity. When RNAs 1, 2, 3, and 4 were translated, 95, 48, and 23 kDa proteins were obtained. Translation of RNA 4 yielded only a 23 kDa protein that comigrated and was serologically related to SBLV and brome mosaic virus coat proteins. Western blot analysis revealed relationships among SBLV coat proteins and those of four bromoviruses. Results presented here provide further information of the properties of SBLV RNA and coat protein as well as evidence that supports placing SBLV in the bromovirus group.