Viruses of cereal crops and their vectors in the south of the Russian Far East (review)

The review presents data on the current taxonomic status and ecology of 10 viruses infecting cereals ( Poaceae ) in the South of the Russian Far East. Barley stripe mosaic virus (BSMV) ( Virgaviridae , Hordeivirus ) is the most common virus affecting about a third of crops (with the exception of oat, which is slightly infected with BSMV). The maize chlorotic stripe disease occurring in Primorye is also etiologically linked with BSMV. Unlike the European part of Russia, Brome mosaic virus (BMV) ( Bromoviridae , Bromovirus ) is slightly represented among cultivated cereals in the South of the Russian Far East since there are no its numerous vectors from perennial plants-reservoirs. In the South of the Russian Far East Poa semilatent virus (PSLV) ( Virgaviridae , Hordeivirus ) was isolated from wheat ( Triticum spp.), swamp ( Poa palustris ) and meadow ( P. pratensis ) bluegrass. Vectors for this virus have not yet been established. The epicenter of the Northern cereal mosaic virus (NCMV) ( Mononegavirales : Rhabdoviridae , Cytorhabdovirus ) strain diversity in the South of the Russian Far East is located in the Amur region whereas in the Primorsky and Khabarovsk territories this virus is much less common. Latently infected perennial wild grasses are a natural reservoir of NCMV that is effectively spread by small brown planthopper ( Laodelphax striatella ). In the body of planthopper NCMV is capable of replication as well as overwintering in larvae. Russian oat mosaic virus (ROMV) ( Bunyavirales : Phenuiviridae , Tenuivirus ) infects wide range of cereals and is known by several synonymous names. It is possible that at least some variants of this virus are a mixture with phytoplasma. In the Primorye territory this virus is mostly found together with NCMV and is also carried by small brown planthopper. The main vectors of Rice stripe virus (RSV) ( Phenuiviridae , Tenuivirus ) in the South of the Russian Far East are small brown and brown ( Nilaparvata lugens ) planthopper as well as rice beetle ( Oulema oryzae ). Rice beetle is a mechanical vector of Rice spotted mosaic virus (RSMV). Far Eastern aphid ( Hemiptera : Aphidoidea ) species are vectors of the Maize dwarf mosaic virus (MDMV) ( Potyviridae , Potyvirus ) and Barley yellow dwarf virus (BYDV) ( Luteoviridae , Luteovirus ). In the rice fields of Primorye 44 species of aphids were identified, among which green com ( Rhopalosiphum maidis ), bird cherry-oat ( Rh. padi ), English Grain ( Sitobion avenae ) and greenbug ( Schizaphis graminum ) aphids dominate. Large foci of diseases caused by Wheat streak mosaic virus (WSMV) ( Potyviridae , Tritimovirus ) were found in the far Eastern agrocenoses, which can be transmitted by herbivorous mites ( Trombidiformes : Eriophyoidea ). Spider mites ( Trombidiformes : Tetranychidae ) are presumably the carriers of BYDV, NCMV, MDMV, and WSMV. The basis of the presented review is the data of long-term (since 1962) regular monitoring of cereal crop viruses carried out by the Laboratory of Virology in the Federal Scientific Center of the East Asia Terrestrial Biodiversity, Far Eastern Branch RAS. The strains obtained during this monitoring are stored in the Russian Collection of East Asia viruses (the Federal Scientific Center of the East Asia Terrestrial Biodiversity, Far Eastern Branch RAS).