Molecular Plant Pathology – Pathogen Profiles

Beet yellows virus: the importance of being different

Valerian V. Dolja

Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA

Taxonomic relationship:Type member of the genus Closterovirus, family Closteroviridae. A member of the alphavirus-like supergroup of positive-strand RNA viruses.

Physical Properties:Virions are flexuous filaments of ~1300 nm in length and ~12 nm in diameter that are made up of a ~15.5 kb RNA and five proteins. The major capsid protein forms virion body of helical symmetry that constitutes ~95% of the virion length. The short virion tail is assembled by the minor capsid protein, Hsp70-homologue, ~64-kDa protein, and ~20-kDa protein.

Viral proteins: The 5′-most ORFs 1a and 1b encode leader proteinase and RNA replicase. The remaining ORFs 2-8 are expressed by subgenomic mRNAs that encode 6-kDa membrane protein, Hsp70 homologue, ~64-kDa protein, minor and major capsid proteins, ~20-kDa protein, and ~21-kDa protein, respectively.

Hosts:The principal crop plants affected by Beet yellows virus (BYV) are sugar beet (Beta vulgaris) and spinach (Spinacea oleracea). In addition, BYV was reported to infect ~120 species in 15 families. Most suitable propagation species are Nicotiana benthamianaTetragonia expansa, and Claytonia perfoliata.