Pathogen Profiles

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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 benthamiana, Tetragonia expansa, and Claytonia perfoliata.


Morphology of the BYV virions. (A) Electron micrograph of two BYV virions. Virion tails marked by arrows were immunogold labelled using anti-CPm serum (courtesy of Alberto J. Napuli). (B) Atomic force microscopy image of a single BYV virion. The white appearance of the body and the grey appearance of the tail are due to a larger depth of the body compared to that of the tail. (C and D) 3D reconstruction of the virion ends obtained using atomic force microscopy. Images B-D are courtesy of Igor Andreev and Michael E. Taliansky.

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