VIEW ARTICLE

Factors Affecting Dissociation of Southern Bean Mosaic Virus. O. P. Sehgal, Associate Professor, Department of Plant Pathology, University of Missouri, Columbia, Missouri 65201; Phytopathology 63:629-633. Accepted for publication 8 December 1972. DOI: 10.1094/Phyto-63-629.

Treatment of southern bean mosaic virus (SBMV) with a dissociative medium (DM) comprising of an appropriate buffer (0.1 M), pH 7.5 to 10.0, 1% sodium dodecyl sulfate (SDS), 1 mM ethylenediaminetetraacetic acid (EDTA) and bentonite (50 µg/ml) resulted in its rapid dissociation into coat protein and ribonucleic acid (RNA). These virus components were then separated by density-gradient sedimentation. Presence of a buffer of suitable ionic concentration and pH, and SDS in DM were essential for virus disassembly. Absence of EDTA at pH 8.5 and 9.1 impaired SBMV dissociation but not at pH 7.5. Pretreatment of SBMV with spermine, formaldehyde, formamide, Mg⁺⁺, or several reducing agents or their presence in DM did not affect virus dissociation at pH 7.5. SBMV protein prepared by the virus dissociation method between pH 7.5 and 9.1, and sedimented by density-gradient centrifugation possessed E280/E260 ratio of 1.4 and was non-infectious. The specific infectivity of SBMV-RNA prepared by this procedure was superior to RNA isolated from SBMV by the conventional SDS-phenol method.