A new member of the family Reoviridae may contribute to severe crumbly fruit in red raspberry, Rubus idaeus ‘Meeker’

A virus induced crumbly fruit disease of considerable importance in ‘Meeker’ and other cultivars of red raspberry has been observed in northern Washington, USA, and British Columbia, Canada and to a lesser extent in the Willamette Valley of Oregon. Raspberry bushy dwarf virus (RBDV), a pollen-borne virus, has been considered the causal agent of the disease. However, dsRNA extractions from raspberry plants exhibiting severe crumbly fruit in northern Washington revealed multiple bands in addition to those corresponding to RBDV (5.5kb and 2.2kb). Sequence analyses of these dsRNAs showed the presence of two additional viruses. One has significant amino acid identity to proteins encoded by Rice ragged stunt virus (RRSV), a ten-segmented dsRNA Oryzavirus that belongs to the family Reoviridae. Thus far, all dsRNA segments, except the one that corresponds to S6 of RRSV, have been fully sequenced and found to have characteristic features of other plant reoviruses genomes. In addition, Raspberry leaf mottle virus (RLMV), a recently characterized member of the Closteroviridae, has also been identified from raspberries with severe crumbly fruit. These findings along with the lack of severe crumbly fruit symptoms in ‘Meeker’ red raspberry singly infected with RBDV in Oregon, suggest the existence of a novel virus complex associated with severe crumbly fruit in red raspberries. The complex may involve RBDV, RLMV and/or this new reovirus, provisionally named Raspberry latent virus (RpLV).