MOLECULAR EVOLUTION AND PHYLOGENY OF SATELLITE RNA ASSOCIATED WITH BAMBOO MOSAIC POTEXVIRUS

Satellite RNA of bamboo mosaic potexvirus (satBaMV) is a linear RNA mo lecule which encodes a 20-kDa nonstructural protein, Sequences of seve n differ ent satBaMV isolates from bamboo hosts in three genera showed 0.7% to 7.5% base variation which spanned the whole RNA molecule, How ever, the putative 20-kDa open reading frame was all preserved in thes e isolates. The phylogenetic relationship based on the nucleotide sequ ence did not show particular grouping of satBaMV from the host in one genus; neither was the grouping of satBaMV evident by location of samp ling, Putative secondary structures of the 3' untranslated regions sho wed a basic pattern with conserved hexanucleotides (ACCUAA) and polyad enylation signal (AAUAAA) located in the loop regions. Although the sa tBaMV-encoded 20kDa protein is a nonstructural protein, its predicted secondary structure contains eight-stranded beta-sheets which may form ''jelly-roll'' structure similar to that found in capsid protein enco ded by satellite virus of panicum mosaic virus.