A satellite RNA associated with bamboo mosaic potexvirus

Abstract

A small RNA molecule with properties of a satellite RNA was found in an isolate of bamboo mosaic potexvirus (BaMV-V) from Bambusa vulgaris McClure. This RNA (sBaMV RNA) and the genomic RNA of BaMV shared no significant sequence homology as assessed by hybridization with cDNA probes derived from the genomes of BaMV and sBaMV RNA. Replication of sBaMV RNA in barley protoplasts or Chenopodium quinoa was supported by BaMV, but not by potato virus X, the type member of the potexvirus group, or other unrelated viruses. The complete nucleotide sequence of sBaMV RNA is 836 nucleotides (excluding the poly(A) tail) and contains an open reading frame which starts after a 159-nucleotide 5'-untranslated region and encodes a 20,154-mol wt protein. In an in vitro rabbit reticulocyte lysate system, sBaMV RNA directed the synthesis of a protein estimated to be 25 kDa by SDS-polyacrylamide gel electrophoresis. The sBaMV RNA-encoded protein was not immunoprecipitated with antiserum against BaMV capsid protein. However, the sBaMV RNA was encapsidated with BaMV capsid protein to form rod-shaped particles with an average length of 60 nm as shown by immunoelectron microscopy. This is the first satellite RNA found in the potexvirus group.