Partner und Internationale Organisationen
(Englisch)
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CH, CZ, D, DK, F, FIN, H, I, N, NL, PL, S, SK, UK
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Abstract
(Englisch)
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Samples of wheat leaf rust (Puccinia recondita fsp tliticq were collected with a mobile spore trap and from infested farmers fields during summer 1998. All wheat growing areas of Switzerland were included in this survey. 111 single pustule isolates could be obtained and multiplied. Each single isolate was tested on the COST 817 core differential set for wheat leaf rust, including the Swis~ varieties Titiis and Mna. Seedlings of Titiis showed a resistant reaction to 72% of all isolates tested The genetic basis of this resistance was further elucidated with a segregating F2 populations of the reciprocal crosses between the resistant variety Titlis and the susceptible variety Mna (200 F2 plants each). with two selected pathotypes the presence of an unknown single seedling resistance gene, inherited in a recessive mode could be shown in the variety Titlis. To characterize the pathogenic diversity of the Swiss leaf rust population all isolates were tested on an extended differential set comprising 36 different leaf rust (Li) resistance genes or resistance gene combinations. Classification of pathotypes was carried out in collaboration with Dr. E. Limpert (ETH, Zurich) and showed the presence of 2 dominant pathotypes in Switzerland. No pathotypes virulent on Lrl9 were present in Switzerland, very low frequences were found for pathotypes virulent on L~, L~3, L~4, L~5, Lr28, L~9, Lr38a, Lr38b. In conclusion these resistance genes are highly effective against the current leaf rust population in Switzerland and important for the Swiss wheat breeUing program. The comparison of virulence survey data with results from neighbouring European countries permits prediction on the possible durability of single Lr genes. E.g. increasing virulence frequency on L~4 was reported from Eastern Europe and was also observed in Switzerland. The comparison with virulence survey data from 1996 revealed only minor changes in the compositio~ ol the Swiss leaf rust population. In the second part of the project we attempted to elucidate the seedling component of thet durable adult plant resistance in the Swiss winter wheat variety Forno. Using a genetically well studied recombinant inbred line (RIL) population between Forno and the susce~tible sDelt variety Samples of wheat leaf rust (Puccinia recondita fsp tliticq were collected with a mobile spore trap and from infested farmers fields during summer 1998. All wheat growing areas of Switzerland were included in this survey. 111 single pustule isolates could be obtained and multiplied. Each single isolate was tested on the COST 817 core differential set for wheat leaf rust, including the Swis~ varieties Titiis and Mna. Seedlings of Titiis showed a resistant reaction to 72% of all isolates tested The genetic basis of this resistance was further elucidated with a segregating F2 populations of the reciprocal crosses between the resistant variety Titlis and the susceptible variety Mna (200 F2 plants each). with two selected pathotypes the presence of an unknown single seedling resistance gene, inherited in a recessive mode could be shown in the variety Titlis. To characterize the pathogenic diversity of the Swiss leaf rust population all isolates were tested on an extended differential set comprising 36 different leaf rust (Li) resistance genes or resistance gene combinations. Classification of pathotypes was carried out in collaboration with Dr. E. Limpert (ETH, Zurich) and showed the presence of 2 dominant pathotypes in Switzerland. No pathotypes virulent on Lrl9 were present in Switzerland, very low frequences were found for pathotypes virulent on L~, L~3, L~4, L~5, Lr28, L~9, Lr38a, Lr38b. In conclusion these resistance genes are highly effective against the current leaf rust population in Switzerland and important for the Swiss wheat breeUing program. The comparison of virulence survey data with results from neighbouring European countries permits prediction on the possible durability of single Lr genes. E.g. increasing virulence frequency on L~4 was reported from Eastern Europe and was also observed in Switzerland. The comparison with virulence survey data from 1996 revealed only minor changes in the compositio~ ol the Swiss leaf rust population. In the second part of the project we attempted to elucidate the seedling component of thet durable adult plant resistance in the Swiss winter wheat variety Forno. Using a genetically well studied recombinant inbred line (RIL) population between Forno and the susce~tible sDelt variety Oberkulmer, phenotypic data for leaf rust infection at the seedling stage were recorded. 268 RILs and parental lines were tested with 2 different isolates avirulent on variety Forno. The two isolates showed the best differentiation in a parental screening with 17 preselected isolates. Clustering of RILs in resistant and susceptible phenotypes suggested the presence of a single seedling resistance gene in Forno. Further analysis of phenotypic data as a qualitatively inherited trail resulted in complete linkage with RFLP (restriction fragment length polymorphism) markers gIk3l 7a and ps~34, located at the short arm of chromosome I B. Therefore the hypothesis of a close relationship with Lr34 (located on chromosome 7D) could not be confirmed. However the unknown seedling resistance gene on chromosome I B might contribute to the durable field resistance of Forno, since very close linkage was found to a QTL for field resistance against leaf rust (Messmer et al., 1999). Oberkulmer, phenotypic data for leaf rust infection at the seedling stage were recorded. 268 RILs and parental lines were tested with 2 different isolates avirulent on variety Forno. The two isolates showed the best differentiation in a parental screening with 17 preselected isolates. Clustering of RILs in resistant and susceptible phenotypes suggested the presence of a single seedling resistance gene in Forno. Further analysis of phenotypic data as a qualitatively inherited trail resulted in complete linkage with RFLP (restriction fragment length polymorphism) markers gIk3l 7a and ps~34, located at the short arm of chromosome I B. Therefore the hypothesis of a close relationship with Lr34 (located on chromosome 7D) could not be confirmed. However the unknown seedling resistance gene on chromosome I B might contribute to the durable field resistance of Forno, since very close linkage was found to a QTL for field resistance against leaf rust (Messmer et al., 1999).
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