Ryegrass Mottle Virus, a New Virus from Lolium multiflorum in Japan

Abstract

Ryegrass mottle virus (RMotV), a previously undescribed mechanically transmissible virus, was obtained from field infected Italian ryegrass (Lolium multiflorum) and cocksfoot (Dactylis glomerata) in Japan. The virus causes mottling and necrotic symptoms in leaves and readily infects wheat (Triticum aestivum), barley (Hordeum vulgare), oat (Avena sativa), rye (Secale cereale), Italian ryegrass and Italian millet (Setaria italica). Cocksfoot, chewing fescue (Festuca rubra) and perennial ryegrass (Lolium perenne) were less readily infected. The virus particle is isometric and ca. 28nm in diameter. The particles have a sedimentation coefficient (S_{20, w}) of 108 S and a buoyant density of 1.366g/ml in CsCl. They contain a single RNA component of mol. wt ca. 1.5×10⁶, representing about 23% of the particle weight, a major protein of mol. wt 26, 000 and possibly two minor proteins of 17, 500 and 16, 500. In double-diffusion tests, antiserum to RMotV reacted weakly with cocksfoot mottle virus and phleum mottle virus, apparently not to a common antigen. No relationship to RMotV was detected with antisera to cocksfoot mild mosaic, phleum mottle, cocksfoot mottle and cynosurus mottle viruses. RMotV is considered to be a newly discovered virus and a member of the phleum mottle virus group. Its present cryptogram is R/1:1.5/23:S/S:S/*.