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Imprint
Viruses in grasses as potential threat for cereal crops
Project
Project code: JKI-EP-08-2255
Contract period: 01.01.2014
- 31.12.2015
Purpose of research: Applied research
Grasses can be infected by a wide range of different viruses but so far there is very limited knowledge on the importance of infected grasses as infection reservoirs for cereal crops. Besides the direct effect on the yield of grasslands (forage grasses, meadows and pastures) the corresponding viruses can potentially threaten the different cereal species grown in Germany, too. Aim of the project is to analyze the occurrence and the distribution of the spectrum of grasses infecting viruses. Moreover, biological, serological and genetic characterization of viruses that were recently isolated from tall oatgrass and brome within boundary ridges will be performed. If not already available, specific diagnostic methods have to be developed for the newly discovered virus species.
Most of the viruses occurring in fodder or wild grasses (s. Table 1 in Rabenstein, 2014) are able to infect experimentally also cereals. Except for the insect transmitted viruses of the Barley yellow dwarf virus/Wheat dwarf complex, these other viruses seem so far hardly to play a role for cultivation of cereals in Germany. This includes, inter alia, the Brome mosaic virus (BMV), which is occasionally observed on various fodder and wild grasses. About the occurrence of BMV in wheat in Germany has been hitherto reported only once (Rabenstein & Proeseler 1982). All the more surprising has been that this virus appeared in 2013 not only in field plots of several breeding companies in Germany and Austria, but also in DH lines of wheat breeding material grown in the greenhouse of one company, so that all the material had to be destroyed. Unclear is the economic importance of a new satellite virus of BMV that was isolated from winter wheat samples from a German breeding station from Russia (Rabenstein et al. 2013). Further research seems to be required in this connection. A number of other isometric viruses that in part not yet been finally characterized, were isolated from forage grasses (Lolium species L. perenne, L. multiflorum, L. westerwoldicum and Datylis glomerata) and from wild grass grow on field edges. This is firstly the Ryegrass mottle virus (genus Sobemovirus), which could be isolated from both ryegrass and cocksfoot. The virus seems to be potentially especially harmful for winter barley since all varieties were highly susceptible and the inoculated plants died completely about 28 dpi. Further viruses with isometric particle morphology of the genus Sobemovirus (Cocksfoot mottle virus, Cynosurus mottle virus, CyMoV) or Panicovirus (Cocksfoot mild mosaic virus, Brome strem leaf mottle virus, and Phleum mottle virus) caused after inoculation on wheat and barley clearly visible symptoms, but were not lethal. All virus isolates with spherical particle structure found in tall oatgrass (Arrhenatherum elatius) reacted with two antisera to CyMoV, but differed in their host range from two CyMoV-isolates from crested dog’s tail (Cynosurus cristatus). While the both CyMoV-isolates CV-123 and CV-104 caused onto the oat variety 'Jumbo' only mild symptoms, caused all Arrhenatherum-isolates a dieback of the inoculated oat plants. All antisera against the mentioned viruses from the JKI collection were checked in DAS-ELISA. In addition, further antisera were produced against new spherical viruses from grasses and added to the serum bank of JKI. Viruses with flexible, filamentous morphology of the grasses genera Dactylis, Festuca and Arrhenatherum were less aggressive towards cereals. Significant symptoms were only visible on Avena-species (Avena barbata, A. fatua, A. sativa), while in winter wheat and winter barley no or latent infections occurred. From cocksfoot (D. glomerata, two samples from Germany, one sample from Austria) and from giant fescue (Festuca gigantea, originating from the Harz region), two new virus species could be isolated, which both belonging to different genera within the family Potyviridae. The complete RNA sequence was determined of the virus isolated from orchard grass in Germany. This virus, for which the designation 'cocksfoot streak mosaic virus' is proposed, can be assigned to the genus Tritimovirus. Likewise, the complete sequence of the virus from giant fescue was determined and assigned to the new genus Poacevirus. Tall oatgrass samples from field margins contained more different flexible viruses that could also be isolated, propagated and purified. Against all virus isolates antisera have been produced in rabbits and then added to the antisera collection of the JKI. Previous results suggest that the filamentous viruses isolated from Arrhenatherum represent two different (new) potyviruses and a further unknown virus that does not belong to this family, because it does not induce characteristic pinwheel inclusion bodies.
Section overview
Subjects
- Crop Protection
Framework programme
Funding programme
Excutive institution
Institute for Epidemiology and Pathogen Diagnostics (JKI-EP)
