RAPID DETECTION AND CHARACTERIZATION OF PLANT-VIRUSES 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 were used for the first time to detect and characterize plant viruses. PMV and some SAD strains produce 2 particles that copurify during rate zonal sedimentation, but form separate bands during agarose gel electrophoresis (forms 1 and 2). By measuring electrophoretic mobility (.mu.) as a function of agarose percentage and correcting for electroosmosis, it was found that: form 1 has a solid support-free .mu. (.mu.o) different from the .mu.o of form 2 and forms 1 and 2 have the same radius (14.6 .+-. 0.6 nm). Form 1 is indistinguishable from form 2 by either EM or sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The .mu.o 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 2 forms. The radius of the satellite of 1 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 were 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 over plant viruses.