Genetic diversity in Brassica napus and association studies with seed glucosinolate content
Lade...
Datum
Autor:innen
Betreuer/Gutachter
Weitere Beteiligte
Beteiligte Institutionen
Herausgeber
Zeitschriftentitel
ISSN der Zeitschrift
Bandtitel
Verlag
Lizenz
Zitierlink
Zusammenfassung
Today oilseed rape (B. napus ssp. napus) is the most important source of vegetable oil in Europe and the second most important oilseed crop in the world after soybean. However, breeding of oilseed rape has evoked a strong bottleneck selection towards double-low (00, canola) seed quality with zero erucic acid and low seed glucosinolate content. Genetic diversity throughout the rapeseed primary gene pool was examined by obtaining detailed molecular genetic information at simple sequence repeat (SSR) loci for a broad range of winter and spring oilseed, fodder and leaf rape gene bank accessions. A set of 96 genotypes was characterised using publicly available mapped SSR markers spread over the B. napus genome. Allelic information from 30 SSR primer combinations amplifying 220 alleles at 51 polymorphic loci provided unique genetic fingerprints for all genotypes. UPGMA clustering enabled the Überidentifikation of four general groups with increasing genetic diversity as follows (1) spring oilseed and fodder; (2) winter oilseed; (3) winter fodder; (4) vegetable genotypes. The diverse spring and winter oilseed genotypes identified in the study may represent a useful resource for improving heterotic potential in spring and winter oilseed rape, respectively. In this regard the highly genetically distinct winter oilseed varieties "Mytnickij", "Kromerska", "Mestnij" and "Krapphauser" represent a potentially valuable resource for winter oilseed rape breeding, whereas "Dux" (Germany) and "Wesway" (Australia) could be of interest for diversifying the spring oilseed rape gene pool. Moreover a considerable genetic variation was identified in B. napus vegetable and fodder rape genotypes compared to the gene pools of conventional spring and winter oilseed material. The molecular genetic information gained enables the identification of untapped genetic variability for rapeseed breeding and is potentially interesting with respect to increasing heterosis in oilseed rape hybrids. The results of this study demonstrate the suitability of SSR data for analysis of genetic diversity in B. napus genotypes.Using this set of genetically diverse genotypes, structure-based allele-trait association studies were conducted to identify potentially gene-linked markers for important seed glucosinolate loci. The analyses included a set of new SSR markers whose orthologs in Arabidopsis thaliana are physically closely linked to promising candidate genes for glucosinolate biosynthesis. Using 62 polymorphic SSR primer combinations, a total of 348 polymorphic SSR marker alleles were amplified in the 94 gene bank accessions. Associations between the marker data and the total seed glucosinolate content were tested using the logistic regression approach. A total of 51 marker alleles from 29 SSR primer combinations were found to exhibit a significant association (P≤0.05) to total seed glucosinolate content. The results indicate that four genes involved in the biosynthesis of indole, aliphatic and aromatic glucosinolates might be associated with known QTL for total seed glucosinolate content in B. napus. Markers linked to homoeologous loci of these genes in the paleopolyploid B. napus genome were found to be associated with a significant effect on the seed glucosinolate content. Inter-crossing of different high-glucosinolate genotypes that contain complementary marker alleles associated with reduced total glucosinolate content at different gene loci should result in transgressive segregation with the possibility for marker-assisted pyramiding of positive alleles at all major loci. This could open the way for the development of new, genetically-diverse heterotic pools for hybrid breeding.Genome-wide SSR marker data and population structure information were generated that provide a useful starting point for structure-based association analyses of other phenotypic traits in this B. napus core collection. Furthermore, a new procedure was developed and successfully applied for the identification of potentially gene-linked SSR markers based on Brassica-Arabidopsis comparative genome analysis. In the future, this method could be applied for marker development, allele-trait association studies and marker-assisted selection for numerous important quantitative traits in B. napus and other Brassica crop species.Verknüpfung zu Publikationen oder weiteren Datensätzen
Beschreibung
Anmerkungen
Erstpublikation in
Genetic Resources and Crop Evolution, (2006) , S. 793 802 / Theor Appl Genet, 116 (2008) S. 1035 1049