Some properties of barley stripe mosaic virus*

Barley varieties differed greatly in their reactions to infection with barley stripe mosaic virus (BSMV) obtained from the variety Gloire du Velay growing in Cambridgeshire from seed imported from France. Lolium multiflorum Lam., previously considered immune, proved susceptible, as did Beta vulgaris L. and Chenopodium amaranticolor Coste & Reyn., which gave only local lesions, and Spinacea oleracea L. which became systemically infected. Heating at 65 degrees C. for 10 min. destroyed the infectivity and serological activity of BSMV. Sap was still infective after 32 days at 20 degrees C., but lost its infectivity and half of its serological activity in 3 days at - 20 degrees C.; adding sugar to the sap prevented inactivation by freezing. The virus content of inoculated barley leaves increased most rapidly in plants kept at 24-28 degrees C. At 24 degrees C. increase was most rapid during the first 5 days, and the maximum virus concentration was reached about 10 days after inoculation. The highest infection end-point of sap was 1/2048, when the precipitation end-point with virus antisera was 1/256, and sap contained 10(13) virus particles per ml. : the ratio of infectivity to serological activity and to number of virus particles is much smaller than with tobacco mosaic virus. The rod-shaped particles are about 20 m mu wide and, in fresh sap, most are between 135 and 175 m mu long. Various treatments, especially heating to 50 degrees C., cause the particles to aggregate linearly. Preparations partially purified by alternate cycles of low-and high-speed centrifugation and by precipitation with ammonium sulphate contain from 0.35 to 0.53 % P, 12.3 to 13.2 % N and 6.2 to 10.2 % carbohydrate. Such preparations are insoluble in water but dissolve in borate buffer at pH 7.5 : they inactivate below pH 4.5