Mulberry Latent Virus Isolated from Mulberry (Morus alba L.)

A new elongated virus was isolated from a mulberry tree. Nine species of herbaceous plants were infected with the virus by sap inoculation. It caused indistinct local lesions and systemic mosaic on Chenopodium quinoa, indistinct local lesions on C. amaranticolor, and symptomless infection on other species. The virus was not transmitted through seeds of C. quinoa and by three species of aphids. In C. quinoa juice, infectivity was lost by heating 55-65C for 10min, by diluting at 103-104, and by aging at 20C for 3 to 7 days. The virus was purified by differential centrifugation followed by sucrose density-gradient centrifugation after clarification of homogenized C. quinoa leaf tissues with carbon tetrachloride. The ratio of UV absorption at 260 and 280nm for purified virus was 1.12-1.19 (260/280). The electron microscopic examination of purified preparation showed filamentous particles of about 700nm in length. A few filamentous particles and no inclusion were observed in cytoplasm of infected C. quinoa leaf cells in ultra-thin sections. Serologically, the virus was distantly related with carnation latent virus. When healthy mulberries (cv. Kairyo-Ichinose) were inoculated with the purified virus, 5 of 12 inoculated plants showed a few indistinct local lesions on inoculated leaves and caused systemic latent infection. From these results, it is inferred that the virus belongs to carnation latent virus group, and the name of mulberry latent virus is proposed.