VIEW ARTICLE

Ecology and Epidemiology

Concentration and Infectivity of Barley Stripe Mosaic Virus in Barley. Manuel K. Palomar, Cooperative Investigations, Agricultural Research Service, U.S. Department of Agriculture and Plant Pathology, Department, Nebraska Agricultural Experiment Station, Lincoln 68583; M. K. Brakke, Cooperative Investigations, Agricultural Research Service, U.S. Department of Agriculture and Plant Pathology Department, Nebraska Agricultural Experiment Station, Lincoln 68583. Phytopathology 66:1422-1426. Accepted for publication 2 June 1976. Copyright © 1976 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-66-1422.

Barley stripe mosaic virus (BSMV) was extracted by grinding infected barley (Hordeum vulgare) leaves in 0.5 M sodium orthoborate, pH 9.0, and purified by differential and density-gradient centrifugation. The concentration of extractable virions in the youngest two leaves of infected plants grown at 13, 17, 21, and 25 C was approximately the same for plants from the two-leaf to the flag-leaf stage, suggesting that the infected plant has no long-lasting acquired immunity from the virus. In plants pretreated for 3 days at 25 C, symptoms were more severe at a lower temperature than at a higher temperature, but this difference was not correlated with virion concentration. Polyacrylamide gel electrophoresis of BSMV RNA showed two RNA components for the Type strain, three for the ND18 strain, and four for the AM strain. Component I had the largest molecular weight RNA and component IV, the smallest. The ratio of component I to II in AM strain increased to about 1:1 when infected barley plants were maintained at 13 C, but reverted to the normal 1:3 ratio when plants were returned to 25 C. Component IV could not be recovered from flag leaves of plants infected with AM strain. No changes in proportion of components I to II or loss of any components were observed with plants infected with ND18 or Type strain kept at 13 C until maturity.