Widespread occurrence of soil-borne mosaic viruses in Belgium : preferential associations of Polymyxa graminis and mosaic viruses on cereals
(2008)
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- Bymo- and furoviruses are responsible for mosaic diseases on barley, rye, triticale and wheat, and cause significant yield losses in cereal crops. They are transmitted by Polymyxa graminis, a common root-infecting parasite that ensures the long-term persistence of viruses in soils. In temperate areas, P. graminis f. sp. temperata and P. graminis f. sp. tepida, with specific ribotypes, have been associated with the transmission of these viruses. The objective of this thesis was to study the vector and viral populations in Belgium and to examine their associations with different cereal species, including barley, rye and wheat, to gain a better understanding of the host-pathogen relationships. The thesis demonstrates the wide diversity of vector and viral populations associated with cereal mosaic diseases in Belgium. It reveals the presence of both P. graminis f. sp. temperata and P. graminis f. sp. tepida on barley and wheat, and of a new P. graminis ribotype on rye. In Belgium, a pool of viruses was identified, including two Bymovirus species, Barley yellow mosaic virus (BaYMV) and Barley mild mosaic virus affecting barley, as well as furoviruses belonging to the Soil-borne cereal mosaic virus (SBCMV) species and a bymovirus, Wheat spindle streak mosaic virus (WSSMV), affecting wheat. This is the first report of P. graminis f. sp. tepida, SBCMV and WSSMV in Belgium. Hitherto, the only natural host reported for BaYMV has been barley, but this thesis shows that BaYMV can also infect rye and wheat. Similarly, SBCMV can infect barley in addition to wheat. These findings demonstrate that the BaYMV and SBCMV host ranges are larger than previously reported. The study showed that there were preferential associations of P. graminis f. sp. temperata and BaYMV on barley, and of P. graminis f. sp. tepida and SBCMV on wheat. The co-existence of bymo- and furoviruses, as well as both P. graminis f. sp. temperata and P. graminis f. sp. tepida in the same soil and the same plant was also demonstrated. This pioneering work on vector-virus-cereal associations shows the diversity of possible associations between vector, virus and cereal. It highlights the complexity of mosaic diseases affecting cereal crops and the need for more research in order to gain a better understanding of the virus-vector' interactions.
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Vaïanopoulos, C. (2008). Widespread occurrence of soil-borne mosaic viruses in Belgium : preferential associations of Polymyxa graminis and mosaic viruses on cereals. https://hdl.handle.net/2078.5/97598