REPLICATION OF DOUBLE-STRANDED-RNA IN MYCOVIRUS FROM THE PLANT-PATHOGENIC FUNGUS, FUSARIUM-SOLANI

A mycovirus (named FusoV) from the plant pathogenic fungus Fusarium so lani possessed two types of double-stranded (ds) RNA genome, designate d M1 and M2. RNA-dependent RNA polymerase activity was detected in Fus oV particle fractions. An in vitro RNA polymerase reaction using purif ied FusoV particles that was supplemented with NTPs revealed the synth esis of single-stranded (ss) RNA species and a subsequent formation of dsRNAs having the same size as M1 and M2. The ssRNA species synthesiz ed in the first stage were proved to be of positive polarity (coding s trand) for both M1 and M2 by dot blot hybridization analysis. These re sults suggest that FusoV genomic dsRNA replicates in a conservative ma nner.