Identification, characterization, and relatedness of luteovirus isolates from forage legumes

Virus isolates from forage legumes collected from eight different states we re identified as luteoviruses closely related to soybean dwarf luteovirus d warfing (SbDV-D) and yellowing (SbDV-Y) described in Japan. All isolates pr oduced reddened leaf margins in subterranean clover and were transmitted in a persistent manner by Acrythosiphon pisum, but not by Aulacorthum solani. Specific monoclonal antibodies raised against SbDV-Y were differentially r eactive with endemic isolates. Immunoblots probed with a SbDV-D polyclonal antiserum showed single 26-kDa coat protein bands, confirming close serolog ical relatedness to SbDV. Analyses of genomic and subgenomic double-strande d RNAs and northern blot analyses confirmed genomic relatedness to SbDV. Ba sed on our results, we conclude that the U.S. luteovirus isolates studied c omprise a strain or strains of the soybean dwarf virus that have clovers as common hosts and the pea aphid as a common vector.