Genetic interrelationships and genome organization of double-stranded RNA elements of Fusarium poae

The similar-sized double-stranded RNA (dsRNA) elements present in vegetativ ely compatible strains of Fusarium poae were always genetically related, wh ile vegetatively incompatible strains of the fungus contained either homolo gous or non-homologous dsRNAs of the same size. Electron microscopic observ ations revealed the co-existence of encapsidated and naked dsRNA elements i n the same host. A mycovirus, named FUPO-1 was purified from strain A-11 an d was found to contain two kinds of dsRNA segments, dsRNA 1 and dsRNA 2. Th e dsRNA genome of these segments was converted to cDNA clones by reverse tr anscription and the clones were subjected to sequence analysis. The single long open reading frame deduced from the sequence of dsRNA 1 showed similar ities to the putative coat protein genes known from other mycoviruses, whil e conserved motifs of an RNA-dependent RNA polymerase were identified in th e predicted amino acid sequence of dsRNA 2. The genome organization and cer tain sequence motifs of FUPO-1 show similarities to that of the Atkinsonell a hypoxylon 2H virus and the FusoV mycovirus, members of the Partitiviridae family.