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

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 virus-like particles were identified by electron microscopy in ultrathin sections or in negatively stained sap extracts, although in infected Chenopodium quinoa there were prominent membraneous inclusion bodies in the cell cytoplasm and membrane-bound structures c. 50 nm in diameter associated with the tonoplast in cell vacuoles. Double-stranded RNA species of approximately 6800, 3500 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).