Characterisation of a labile RNA virus‐like agent from white clover

Abstract

A labile virus has been identified in white clover in New Zealand. The virus was mechanically transmitted to nine species of herbaceous test plants. No viruslike particles were identified by electron microscopy in ultrathin sections or in negatively stained sap extracts, although in infected Chenopodiurn quinoa there were prominent membraneous inclusion bodies in the cell cytoplasm and membrane-bound structures c. SO nm in diameter associated with the tonoplast in cell vacuoles. Double-stranded RNA species of approximately 6800, 3.500 and 3300 bp were isolated from infected tissues. DsRNA denatured-by boiling was infectious to C. quinoa, but undenatured dsRNA was not infectious. Total nucleic acid preparations from infected leaves were highly infective without boiling, indicating that most of the infectivity was single-stranded RNA. Infectivity was recovered in the poly (A)-faction following oligo (dT)-cellulose chromatography, indicating that the RNA probably lacks a 3' tract of poly (A). The labile white clover virus is tentatively named white clover virus L (WCIVL). IntroductionMost pasture farmlands in New Zealand are mixed swards containing ryegrass and white clover. White clover (Trifolium repens) is grown for its nutritive value and for its ability to fix atmospheric nitrogen. To date, seven viruses have been identified in white clover in New Zealand: alfalfa mosaic virus (AMV; Fry, 19-52), clover yellow vein potyvirus (CYVV; Forster & Musgrave, 1985), lucerne Australian latent nepovirus (LALV; Forster & Morris-Krsinich, 198.5), red clover necrotic mosaic dianthovirus (RCNMV; Morris-Krsinich, Forster . 1990. Infectious transcripts and nuclcotide sequence of cloned cDNA of the potexvirus white clover mosaic virus. Virology 177: 152-15%. Bergh S T, Koziel M G , Huang S-C, Thomas R A, Gilley D P, Siege1 A. 1985. The nucleotide sequence of tobacco rattle virus RNA-2 (CAM strain). Nucleic Acids Research 13:8507-85 18.

Estimating the agronomic impact of white clover mosaic virus on white clover performance in the North Island of New Zealand

“…Pathogens include a number of viruses such as alfalfa mosaic alfamovirus, clover yellow vein potyvirus, lucerne Australian latent nepovirus, red clover necrotic mosaic dianthovirus, soybean dwarf luteovirus, white clover mosaic potexvirus (WC1MV) and white clover virus L (Fry 1952(Fry ,1959Smith 1966;Ashby etal. 1979;MorrisKrsinich et al 1983;Forster & Morris-Krsinich 1985;Forster & Musgrave 1985;Gardiner et al 1995).…”