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Etiology

Purification and Properties of a Virus from El Salvador that Causes Mild Mosaic in Bean Cultivars. H. E. Waterworth, Research Scientist, Agricultural Research Service, U. S. Department of Agriculture, Plant Introduction Station, Glenn Dale, MD 20769; J. P. Meiners(2), R. H. Lawson(3), and F. F. Smith(4). (2)(3)Research Scientists, Agricultural Research Service, U. S. Department of Agriculture, Plant Introduction Station, Glenn Dale, MD 20769; (4)Research Scientist, Agricultural Research Service, U. S. Department of Agriculture, Plant Introduction Station, BARC-W, Beltsville, MD 20705. Phytopathology 67:169-173. Accepted for publication 20 August 1976. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-169.

A virus that has been named bean mild mosaic virus (BMMV), was isolated from bean (Phaseolus vulgaris) plants imported from El Salvador. The BMMV occurred in a mixture with another virus, bean curly dwarf mosaic virus, which was primarily responsible for the field symptoms consisting of plant dwarfing and leaf curling. Alone, BMMV produced only a faint mosaic in some experimentally inoculated bean cultivars and was latent in others. It also infected six of 18 other legume species. Of 42 nonleguminous species tested, only Chenopodium quinoa and Gomphrena globosa were infected. The virus was infectious in crude bean sap after being heated 10 minutes at 84 C, after incubating at room temperature for 6 weeks, and after dilution to 1 × 10^–8. Bean mild mosaic virus was not serologically related to any of 12 other viral pathogens of legumes that were tested. The virus had particles 28 nm in diameter. It was transmitted by the Mexican bean beetle, Epilachna varivestis, and by the spotted cucumber beetle, Diabrotica undecimpunctata howardi. Extracted nucleic acid (which had a nucleotide ratio of A = 25.8, C = 31.5, G = 21.7, and U = 21.0%) was infectious at 0.01 μg/ml, but it was not infectious after incubation with RNase for 5 minutes.