Rapid detection and characterization of plant virused by agarose gel electrophoresis: Size, surface charge and heterogeneity of panicum mosaic and related viruses

Using panicum mosaic virus (PMV) and several St. Augustine decline strains of PMV (SAD) as test viruses, previously developed procedures of agarose gel electrophoresis (reviewed in P. Serwer, Electrophoresis 1983, 3, 375–382) have been used for the first time to detect and characterize plant viruses. PMV and some SAD strains produce two particles that copurify during rate zonal sedimentation, but form separate bands during agarose gel electrophoresis (forms 1 and 2). By measuring electrophoretic mobility (μ) as a function of agarose percentage and correcting for electroosmosis, it was found that: (a) form 1 has a solid support‐free μ (μ₀) different from the μ₀ of form 2, and (b) forms 1 and 2 have the same radius (14.6 ± 0.6nm). Form 1 is indistinguishable from form 2 by either electron microscopy or sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. The μ₀ of form 1 and the relative amount of forms 1 and 2 vary with the virus strain and can be used to help identify strains. A previously described satellite of PMV and some SAD strains also has two forms. The radius of the satellite of one SAD strain was found to be 7.6 ± 0.3 nm. A procedure of differential gel staining was developed for distinguishing the 14.6 nm virus from its 7.6 nm satellite. After agarose gel electrophoresis of either totally unfractionated or partially fractionated, infected grass extracts, virus particles wer detected without interference from host components. The procedures used here should be useful for rapid disease diagnosis and strain typing of the above and possibly other plant viruses.