Viroid-like RNA encapsidated in lucerne transient streak virus

Abstract

Lucerne transient streak virus (LTSV) has been isolated from lucerne crops in Australia and New Zealand [ 121. The virus was characterised and shown to share many properties with members of the southern bean mosaic virus group [3]. Velvet tobacco mottle virus (VTMOV), solanum nodiflorum mottle virus (SNMV) and subterranean clover mottle virus (SCMoV) have properties similar to those of southern bean mosaic virus (SBMV), but have an unusual RNA complement [4,.5]. In addition to virus-like linear single-stranded (ss)-RNA molecules, viroid-like circular ss-RNA molecules were also present [4-61. Virusand viroid-like RNA molecules of VTMoV and SNMV have no base sequence homology and both are essential for infection [7,8]. Here we examine the RNA complement of highly purified preparations of LTSV and show it to consist of both virusand viroid-like RNA molecules. instrument, virus preparations were stained with 2% uranyl acetate and RNA preparations were spread under denaturing conditions and rotary shadowed [4]. Preparations of RNA 2 and RNA 3 were isolated by polyacrylamide gel electrophoresis under denaturing conditions followed by sucrose density-gradient centrifugation [7]. Thermal denaturation of the RNAs in 1 X SSC buffer (0.15 M NaCl t 0.015 M sodium citrate pH 7.0) was determined as in [7].