Charakterisierung der Resistenz deutscher Weizensorten gegenüber Weizenflugbrand (Ustilago tritici)

Die Resistenzzüchtung gegenüber Weizenflugbrand (Ustilago tritici) hat in den letzten Jahren aufgrund der Ausdehnung des ökologischen Landbaus, der eine Bekämpfung mittels chemischer Saatgutbeizung nicht zulässt, zunehmend an Bedeutung gewonnen. Ziel eines im Rahmen des „Bundesprogramm Ökologischer Landbau“ geförderten Projektes war es daher, Resistenzen im deutschen Weizensortiment, als Basis für eine direkte Nutzung dieser Sorten im ökologischen Anbau bzw. als Ausgangspunkt für eine gezielte Resistenzzüchtung, zu identifizieren

Kartierung der Zwergrostresistenz der Gerste MBR1012

Zusammenfassung Der Zwergrost gehört zu den wichtigsten Krankheitserregern der Gerste und kann im gemäßigten Klima Ertragsverluste von über 60 % verursachen. Auf der Suche nach neuen Resistenzquellen wurde in der aus Serbien-Montenegro stammenden Landrasse MBR1012 eine wirksame Resistenz gegenüber Zwergrost identifiziert. Um die Vererbung der Resistenz dieser Landrasse aufzuklären, wurden 76 DH-Linien aus der Kreuzung der resistenten Landrasse MBR1012 mit der anfälligen Sorte Scarlett mit der hochvirulenten Zwergrostrasse I80 künstlich inokuliert. Die Spaltung der DH-Population nach der Inokulation mit I80 zeigte, dass die Resistenz monogenetisch vererbt wird. Basierend auf den Ergebnissen der bulked segregant analysis konnte die Resistenz dem Chromosom 1H zugeordnet werden und eng gekoppelte molekulare Marker entwickelt werden, welche eine beschleunigte Übertragung dieser Resistenz in adaptierte Sorten erlauben. Die Suche nach neuen Resistenzen gegen Puccinia hordei ist von besonderer Bedeutung, da die Rostpilze durch Mutation und Rekombination zahlreiche physiologische Rassen bilden, wodurch Resistenzen relativ schnell überwunden werden können. Stichwörter: Gerste (Hordeum vulgare L.), Zwergrost (Puccinia hordei Otth), Resistenz, bulked segregant analysis (BSA), DH-Linien (doubled-haploid).   Abstract Leaf rust (Puccinia hordei Otth) is an economically important disease of barley in temperate regions, causing considerable yield losses up to about 60 %. Resistance to leaf rust has been detected in a landrace derived from Serbia Montenegro (MBR1012). To obtain information on the genetics of resistance of MBR1012 to leaf rust, 76 DH-lines derived from a cross of MBR1012 to the susceptible cv. Scarlett were inoculated using the highly virulent leaf rust isolate I80. It turned out that resistance is inherited in a monogenic manner and by bulked segregant analysis resistance was assigned to chromosome 1H. Next closely linked molecular markers were developed facilitating an efficient introgression into adapted cultivars. Broadening the genetic base of resistance to leaf rust is of special importance as this pathogen is able to overcome resistances quickly due to mutation and recombination. Keywords: Barley (Hordeum vulgare L.), leaf rust (Puccinia hordei Otth), resistance, bulked segregant analysis (BSA), DH-lines (doubled-haploid

Auftreten von Plasmodiophora brassicae als Erreger der Kohlhernie im Winterrapsanbau in Europa sowie Identifizierung, Charakterisierung und molekulare Kartierung neuer Kohlhernieresistenzgene aus genetischen Ressourcen

European monitoring of Plasmodiophora brassicae as the causal agent of clubroot disease in oilseed rape and phenotyping and molecular mapping of new resistance genes derived from genetic resourcesZusammenfassungDer Erreger der Kohlhernie (Plasmodiophora brassicae) gewinnt im europäischen Rapsanbau an Bedeutung und mittlerweile werden stark kontaminierte Flächen v.a. in Nord- und Nordostdeutschland sowie in einigen Regionen Frankreichs und Englands mit zunehmender Tendenz nachgewiesen. Starke Unterschiede in der Virulenz je nach Herkunft sind zwar bekannt, aber bisher kaum untersucht und werden daher in einem Monitoringverfahren anhand von 2 Differentialsortimenten unter kontrollierten Bedingungen detailliert analysiert. Die Kohlhernie ist aufgrund des Fehlens einer Bekämpfungsmöglichkeit mit Fungiziden und der Tatsache, dass für den praktischen Anbau aktuell nur eine einzige rassenspezifische Resistenz in agronomisch anbauwürdigen Rapssorten zur Verfügung steht, besonders problematisch. Ziel ist es daher, bisher weitgehend ungenutzte Resistenzen aus genetischen Ressourcen, z.B. Steckrübensorten, in spaltenden Populationen (RILs & DHs) zu kartieren und eng gekoppelte Marker zu entwickeln, mit deren Hilfe entsprechende Resistenzen effektiv in adaptierte Rapssorten eingelagert werden können. Stichwörter: Kohlhernie, Virulenzanalyse, pflanzengenetische RessourcenAbstractClubroot caused by the obligate biotrophic protist Plasmodiophora brassicae is a serious soilborne disease of cruciferous crops. It causes galls on roots leading to premature death of the plant. Currently, due to the raise of oilseed rape cultivation within the last decades the number of contaminated fields is increasing. The hot spots of clubroot infestation in Europe are mainly located in Northern Germany, France and in the UK. Because numerous populations and races, respectively, are known, differences in pathogenicity are being explored under greenhouse conditions. The main problem is the longevity of resting spores in the soil, the lack of reasonable control measures and that up to now only one race specific resistance is incorporated in adapted cultivars. Therefore, with the aid of segregating populations (RILs and DHs) previously unutilized resistance genes identified in genetic resources like rutabaga cv’s (B. napus ssp. napobrassica) are being mapped as a prerequisite for an efficient breeding for reistance.Keywords: clubroot disease, virulence analysis, plant genetic resource

Identifying variation in resistance to the take-all fungus, Gaeumannomyces graminis var. tritici, between different ancestral and modern wheat species

Background: Ancestral wheat relatives are important sources of genetic diversity for the introduction of novel traits for the improvement of modern bread wheat. In this study the aim was to assess the susceptibility of 34 accessions of the diploid wheat Triticum monococcum (A genome) to Gaeumannomyces graminis var. tritici (Ggt), the causal agent of take-all disease. The second aim was to explore the susceptibility of tetraploid wheat (T. durum) and the B genome progenitor species Aegilops speltoides to Ggt. Results: Field trials, conducted over 5 years, identified seven T. monococcum accessions with a good level of resistance to take-all when exposed to natural inoculum under UK field conditions. All other accessions were highly susceptible or did not exhibit a consistent phenotype across years. DArT marker genotyping revealed that whole genome diversity was not closely related to resistance to take-all within T. monococcum, suggesting that multiple genetic sources of resistance may exist within the species. In contrast the tetraploid wheat cultivars and Ae. speltoides were all highly susceptible to the disease, including those with known elevated levels of benzoxazinoids. Conclusions: The diploid wheat species T. monococcum may provide a genetic source of resistance to take-all disease that could be utilised to improve the performance of T. aestivum in high disease risk situations. This represents an extremely valuable resource to achieve economic and sustainable genetic control of this root disease

Development of an efficient method for assessing resistance to the net type of net blotch (Pyrenophora teres f. teres) in winter barley and mapping of quantitative trait loci for resistance

Breeding for resistance against Pyrenophora teres f. teres in barley is difficult due to the high virulence diversity of the pathogen and the fact that in field trials a simultaneous infection with Rhynchosporium commune, Puccinia hordei or Blumeria graminis f. sp. hordei often takes place. To avoid this, a so-called ‘‘summer hill trial’’ was developed in which winter barley is sown at the beginning of August at optimum conditions for P. teres infection. These trials allowed an unequivocal scoring of P. teres resistance. Using this approach, strong correlations of the results obtained in 3 years at two locations were observed and heritability was estimated at h2 = 0.80 for the doubled haploid (DH) population Uschi 9 HHOR3073 and h2 = 0.62 for (Post 9 Viresa) 9 HHOR9484. In parallel, genetic maps based on DArT, SSR and SNP markers were constructed, comprising 705.7 cM for the DH population Uschi 9 HHOR3073 and 1,035.8 cM for (Post 9 Viresa) 9 HHOR9484. In the population Uschi 9 HHOR3073, one quantitative trait locus (QTL) was detected on each of chromosomes 2H and 3H and two on chromosome 5H, explaining between 9.4 and 19.0 %of the phenotypic variance. In the population (Post 9 Viresa) 9 HHOR9484, three QTL were detected on chromosome 5H and one on chromosome 7H, explaining between 12.6 and 34.7 % of the phenotypic variance. These results show that the new summer hill trial design is best suited to obtain reliable phenotypic data forP. teres resistance under field conditions, as on the one hand already knownQTLwere confirmed and on the other hand new QTL were detected

Genetic resources of barley resistance to net blotch

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