Wheat streak mosaic virus

Wheat streak mosaic virus (WSMV) is a plant pathogenic virus of the family Potyviridae that infects plants in the family Poaceae, especially wheat (Triticum spp.); it is globally distributed and vectored by the wheat curl mite, particularly in regions where wheat is widely grown. First described in Nebraska in 1922, stunted growth and the eponymous “streaks” of yellowed, non-uniform discoloration are characteristic of WSMV infection. As it has been known to cause 100% crop mortality, WSMV is a subject of ongoing scientific research.

Genome

WSMV is a flexible, rod-shaped virus composed of a positive-sense single-strand RNA genome approximately 8.5 to 12 kilobases in length, and can be either mono- or bipartite. The RNA serves as both the genome and viral messenger. The genomic RNA (or its segments) is translated into polyprotein(s) which are transformed by virus-encoded proteases into functional products.

The virions of WSMV encapsidate a single molecule of positive-sense genomic RNA. The genomic RNA has a single open reading frame encoding a large polyprotein that undergoes post-translational cleavage into at least 10 mature proteins. Researchers at USDS-ARS identified that one of these proteins, P1, as a suppressor of RNA silencing. WSMV P1 was shown to bind to dsRNA to suppress host-defensive antiviral defense.

Transmission

WSMV is semi-persistently transmitted by the wheat curl mite (Aceria tosichella), a small, cigar-shaped arthropod that can produce a single generation within 10 days under optimum temperature- approximately 27 °C. Wheat curl mites are slow crawlers, and depend on wind to disperse to other plants; they can also overwinter in abandoned infected wheat or corn heads.