Cross-Protection Studies Between Strains of Sugarcane Mosaic, Maize Dwarf Mosaic, Johnsongrass Mosaic, and Sorghum Mosaic Potyviruses. BRANKA KRSTIC, Assistant Professor, Department of Plant Protection, Faculty of Agriculture, University of Belgrade, Beograd - Zemun 11080, Yugoslavia. R. E. FORD, Professor, Department of Plant Pathology, University of Illinois, Urbana 61801; D. D. SHUKLA, Senior Principal Research Scientist, CSIRO, Division of Biomolecular Engineering, Parkville, Victoria 3052, Australia; and M. TOSIC, Professor, Department of Plant Protection, Faculty of Agriculture, University of Belgrade, Beograd - Zemun 11080, Yugoslavia. Plant Dis. 79:135-138. Accepted for publication 5 October 1994. This article is in the public domain and not copyrightable It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1995. DOI: 10.1094/PD-79-0135.

Cross-protection was studied between strains of viruses comprising the sugarcane mosaic virus (SCMV) subgroup, namely Johnsongrass mosaic, maize dwarf mosaic, sorghum mosaic, and SCMV, in 53 different combinations using differential hosts and Western blot immunoassays. Cross-protection occurred only between SCMV-MDB and SCMV-BC when the former was inoculated first and the latter used as the challenge strain, but neither vice versa nor in any other combinations including the 19 that involved recognized strains of the one virus, SCMV. The unidirectional protection between SCMV-MDB and SCMV-BC and the negative cross-protection results between other strains of SCMV appear to correlate with different sequence motifs present in the hypervariable region of the coat protein N-terminus of the SCMV strains.