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Condensed tannins (proanthocyanidins, PAs) in the seed meal of oilseed rape can potentially have a negative impact on non-ruminant livestock nutrition, particularly because of their ability to form indigestible, astringent or bitter-tasting complexes with proteins. One option to overcome this problem is the breeding of oilseed rape varieties with reduced condensed tannins in the seed coat. This might be achievable via selection of genotypes with thinner seed coats and consequently reduced condensed tannin accumulation (seed coat structural cell mutants), or alternatively by selection of genotypes with reduced biosynthesis of condensed tannins (flavonoid biosynthesis mutants). Both types of transparent testa (TT) mutants are well-characterised in Arabidopsis; however the genetic basis of the yellow-seed trait in the polyploid genome of rapeseed is still not completely understood. In this study, genetic and chemical analyses of PAs were performed in 166 doubled haploid (DH) rapeseed lines from the segregating Brassica napus doubled haploid population YE2-DH (black seed × yellow seed). Using these analyses, the relationship between seed colour and PA fractions in B. napus was investigated with a view to improving the rapeseed meal quality. Proanthocyanidin contents were estimated by vanillin and HPLC assays and the obtained values were used to identify quantitative trait loci. Closely linked molecular markers that were identified during this study for the target traits (seed colour, condensed tannins) can be valuable tools for breeding of new oilseed rape cultivars with reduced levels of antinutritive PA compounds. [ABSTRACT FROM AUTHOR]

ociation mapping identifies quantitative trait loci (QTLs) by examining the marker-trait associations that can be attributed to the strength of linkage disequilibrium between markers and functional polymorphisms across a set of diverse germplasm. In this study, association mapping was performed to detect QTL-linked and genome wide SSR markers linked to phenolic compounds of extraction meal in a population of 49 genetically diverse oilseed rape cultivars of dark-seeded, winter-type oilseed rape accessions. Correction for population structure was performed using 559 genome wide SSR markers. Results showed that seed colour is an important contributor to seed meal quality. Totally, 52 SSR markers linked to phenolic compounds were detected, five of them being QTL linked markers. Some of these markers were already mapped on Brassica napus chromosomes that contain known QTL controlling oilseed rape meal quality traits. Our results demonstrate that association mapping is a useful approach to complement and enhance previous QTL information for marker-assisted selection. [ABSTRACT FROM AUTHOR]

Eyespot is a major disease of common wheat ( Triticum aestivum L.) in temperate climates and causes yield losses of up to 40%. The causal agents of eyespot are Oculimacula acuformis (syn. Tapesia acuformis; anamorph: Helgardia acuformis syn. Pseudocercosporella herpotrichoides var. acuformis) and O. yallundae (syn. T. yallundae; anamorph: H. yallundae syn. P. h. var. herpotrichoides). Pch1 located on chromosome 7DL is the most important and most effective resistance gene, but its use in practical breeding is limited because of difficulties in phenotyping and the fact that markers like XustSSR2001- 7DL are often population-specific in German wheat cultivars. Therefore, based on results obtained for endopeptidase Ep-D1a, which is very closely linked to Pch1, molecular markers located in the terminal region of chromosome 7DL were analysed in three DH (double haploid) populations. In a next step these molecular markers were validated on a set of German winter wheat cultivars to obtain information on their usefulness for marker assisted selection (MAS). Based on the analysis of 127 DH-lines, linkage to Pch1 ( Ep- D1) was obtained for Xorw1, Xorw5, Xorw6, Xcfd175, Xbarc76, Xwmc14, and Xcfa2040. Analyses of 104 German winter wheat cultivars showed that Xorw1, Xorw6 and the SSR Xcfd175 of these markers are well suited for MAS in German wheat breeding. [ABSTRACT FROM AUTHOR]