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Etiology

Confirmation that Fourteen Potyvirus Isolates from Soybean Are Strains of One Virus by Comparing Coat Protein Peptide Profiles. R. K. Jain, visiting scientist, Commonwealth Scientific and Industrial Research Organisation, Division of Biomolecular Engineering, 343 Royal Parade, Parkville 3052, Australia; Permanent address: Advance Centre for Plant Virus Education and Research, Division of Mycology and Plant Pathology, Indian Agricultural Research Institute, New Delhi 110012; N. M. McKern(2), S. A. Tolin(3), J. H. Hill(4), O. W. Barnett(5), M. Tosic(6), R. E. Ford(7), R. N. Beachy(8), M. H. Yu(9), C. W. Ward(10), and D. D. Shukla(11). (2)(10)(11)Principal research scientist, chief research scientist, and senior principal research scientist, respectively, Commonwealth Scientific and Industrial Research Organisation, Division of Biomolecular Engineering, 343 Royal Parade, Parkville 3052, Australia; (3)Professor, Department of Plant Pathology, Physiology and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg 24061-0330; (4)Professor, Department of Plant Pathology, Iowa State University, Ames 50011; (5)Professor, Department of Plant Pathology and Physiology, Clemson University, Clemson, SC 29634-0377; (6)Professor, Faculty of Agriculture, University of Belgrade, Beograd-Zemun-11080, Yugoslavia; (7)Professor/head, Department of Plant Pathology, University of Illinois, Urbana 61801; (8)Professor, Department of Biology, Washington University, St. Louis, MO 63130; and (9)Professor, Department of Biochemistry, August 1st Agricultural College, Xinjiang, China. Phytopathology 82:294-299. Accepted for publication 23 September 1991. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/Phyto-82-294.

A number of potyvirus isolates have been identified as strains of soybean mosaic virus (SMV) on the basis of host range, symptomatology, vector specificity, and antigenic properties. Comparison of recently established coat protein gene sequences of two of the strains, SMV-N and SMV-VA, suggested that they represent two distinct potyviruses. The taxonomic status of other strains relative to these two strains is uncertain at present. To address this question we have compared high-performance liquid chromatographic peptide profiles of coat protein tryptic digests from 14 such strains, including SMV-N and SMV-VA. Our results, including amino acid composition of some peptides, show that these 14 strains are all related to SMV-N and that no evidence could be found for the reported coat protein sequence of SMV-VA, implying that the sequenced SMV-VA clone was a minor contaminant of the original SMV-VA isolate. Our results also confirm that SMV-N and watermelon mosaic virus 2 (WMV 2) are closely related, and the question of whether WMV 2 is a distinct virus or an SMV pathotype is discussed.