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Etiology

Properties of Blackgram Mottle Virus. H. A. Scott, Department of Plant Pathology, University of Arkansas, Fayetteville, AR 72701; H. C. Phatak, Department of Plant Pathology, Kasetsart University, Bangkhen, Bangkok, Thailand. Phytopathology 69:346-348. Accepted for publication 10 October 1978. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-346.

Blackgram mottle virus was purified from infected Black Valentine bean plants by a chloroform-butanol procedure. Purified preparations contained polyhedral particles 28 nm in diameter and exhibited a single immunoelectrophoretic component that migrated toward the anode at pH 8.8. Analytical ultracentrifugation showed a single component with a sedimentation coefficient of 122S and a density of 1.364 gm/cm³. Polyacrylamide gel electrophoresis demonstrated one nucleic acid component and one coat protein subunit with estimated molecular weights of 1.4 × 10⁶ and 38,200 daltons, respectively. Phenol-extracted nucleic acid was infectious on Pinto bean and sensitive to ribonuclease and had a nucleotide ratio of G = 24.9%; A = 25.9%; C = 25.3%; U = 24.0%. Blackgram mottle virus was transmitted by the bean leaf beetle, Cerotoma trifurcata, and the Mexican bean beetle, Epilachna varivestis. Reciprocal serologic tests failed to show relationships between blackgram mottle virus and members of other beetle-transmitted legume virus groups.