A REVIEW ON WHEAT STREAK MOSAIC VIRUS (WSMV) DISEASE COMPLEX

Wheat is one of the most important staple food crop .Wheat streak mosaic virus (WSMV) was first time reported in Nebraska in 1922 as "yellow mosaic". Since then, although sporadic in its appearance and severity, wheat streak mosaic has caused losses throughout North America, Europe, North Africa and Russia. The disease was probably present in other counties, but was not detected. WSM symptoms are characterized by a yellow leaf streaking or stippled pattern and stunting, head sterility, low test weights, and poor tillering and it is a seed born or mite born disease.WSMV is transmitted by eriophyid mite in both semi persistent and circulative manners. Mostly WSMV infects the crops belonging to family graminae or Poaceae (wheat, barley) and other alternate host of the WSMV are the grassy weeds or green bridge where wheat curl mite (WCM) over winters and lay eggs in the absents of the host. Wheat production in the Great Plains is also threatened by the newly discovered wheat viruses including Wheat mosaic virus and Triticum mosaic virus (TriMV). Both viruses closely match the life cycle of WSMV and are transmitted by WCM. Genome of WSMV contains positive sense ssRNA virions and one polyprotein. The tritimovirus which is approximately of 10kb in size