Submitted to: Journal of General Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 28, 2002
Publication Date: N/A
Interpretive Summary: Luteoviruses cause some of the most damaging virus diseases of plants. The viruses are transmitted by aphids in a persistent manner, which means that aphids retain the ability to transmit virus for days after feeding on an infected plant. While luteoviruses have had a significant impact on small grain production in the Midwest, they have not been problematic in soybeans even though viruses like Bean leafroll virus (BLRV) and Soybean dwarf virus, which produces very severe yield losses in soybeans in Asia, are commonly found in clovers growing next to soybean fields. The apparent inability of the viruses to move from clovers to soybeans has been attributed to the absence of aphid vectors that colonize soybeans and have the ability to transmit the viruses. In the summer of 2000, the Asian soybean aphid was reported in the US for the first time. These highly mobile aphids colonize soybeans and have been reported to transmit some luteoviruses. To understand the genetic structure of one of these soybean-infecting luteoviruses, we determined the nucleotide sequence of the genome of BLRV. This information showed us that BLRV is very similar to the luteovirus, Barley yellow dwarf virus (BYDV), which has been the most damaging to small grains in the Midwest. BYDV has been studied in great detail and BYDV-resistant plants have been produced through traditional breeding and genetic engineering techniques. We hope to be able to take advantage of the progress made in the studies of BYDV to develop control strategies for BLRV if it should become a problem in soybeans. The information in this paper should be useful to other scientists who are studying virus resistance, gene expression and/or transmission.
Technical Abstract: The complete nucleotide sequence of the Bean leaf roll virus (BLRV) genomic RNA and the terminus of its smallest subgenomic RNA were determined to better define its phylogenetic position within the Luteoviridae. The number and placement of open reading frames (ORFs) within the BLRV genome was Luteovirus-like. The nucleotide and predicted amino acid sequences of BLRV were most similar to those of Soybean dwarf virus (SbDV). Phylogenetic analysis employing the unweighted pair-group method using arithmetic averages and sister-scanning analysis indicated that the BLRV nonstructural proteins were closely related to those of Barley yellow dwarf virus-PAV (BYDV-PAV), a Luteovirus. The same analysis showed that the nonstructural proteins, while not closely related to those of the enomo-, luteo- or poleroviruses, were most similar to structural proteins of the poleroviruses. Consistent with the similarities in nonstructural proteins, the BLRV 5- and 3-noncoding regions and the region surrounding the frameshift at the junction between ORFs 1 and 2 contained sequences very similar to translational control elements of BYDV-PAV. Because the BLRV genomic organization and presumably strategies of expression and replication of BLRV are very similar to those of BYDV-PAV, we propose that BLRV be classified as a member of the Luteovirus genus.