Purification of a Tasmanian isolate of subterranean clover red leaf virus, and its serological interactions with a New Zealand isolate and other luteoviruses

Abstract

A Tasmanian isolate of subterranean clover red leaf virus (SCRLV) was purified and concentrated from pea (Pisum sativunz L. cv. Puget) by tissue extraction with cellulase followed by heat clarification, precipitation with polyethylene glycol in salt, and differential and density gradient centrifugation. Virus particles were isometric and 27 nm in diameter. Aulacorthum solani (Kalt.) acquired virus particles from the preparations through Parafilm membranes and transmitted them to healthy subterreanean clover test seedlings, causing disease symptoms of SCRLV. Isolates of SCRLV from Tasmania appeared identical with those from New Zealand on the basis of particle morphology and serological tests. Tasmanian SCRLV was distantly related serologically to Californian isolates of beet western yellows (BWYV) and legume yellows (LYV) viruses. Tests indicated that the relationship was closest with a potato isolate of BWYV and most distant with LYV. Virus particles in sap extracts from infected pea plants were readily detected by electron microscopy following adsorption onto grids coated with SCRLV antiserum, but not on grids coated with antisera to BWYV and LYV. These data confirm that SCRLV is a new, distinct member of the luteovirus group.