Virus resistance in cereals: sources of resistance, genetics and breeding
In cereals, soil-borne viruses transmitted by the plasmodiophorid Polymyxa graminis (e.g., Barley mild mosaic virus, Barley yellow mosaic virus or Soil-borne cereal mosaic virus), have increased in importance due to the increase of the acreage infested and because yield losses cannot be prevented by chemical measures. Due to global warming, it is also expected that insect transmitted viruses vectored by aphids (e.g., Barley yellow dwarf virus, Cereal yellow dwarf virus), leafhoppers (Wheat dwarf virus) or mites (e.g., Wheat streak mosaic virus), will become much more important even in cooler regions. The environmentally most sound and also most cost effective approach to prevent high yield losses caused by these viruses is breeding for resistance. Therefore, in contrast to other reviews on cereal viruses, this study briefly reviews present knowledge on cereal-infecting viruses and emphasizes especially the sources of resistance or tolerance to these viruses and their use in molecular breeding schemes.