Collaborative project: Enhancing resistance of winter oilseed rape (Brassica napus) against the fungal parhogen Verticillium longisporum depending on climate change. Subproject 3

Project

Project code: 2814505110
Contract period: 01.02.2011 - 31.01.2014
Budget: 327,702 Euro
Purpose of research: Experimental development

The aim of this project was the improvement of the performance stability of oilseed rape (Brassica napus) by development of molecular markers to breed resistance against Verticilli-um longisporum, a dangerous fungal pathogen that could potentially become even more widespread as a consequence to climate change. The screen-ing of comprehensive amounts of breeding materials was performed by validating two approaches, one in the greenhouse and the second in the field. As a result, it was found that the commonly used parameter of stubble scoring is not sufficiently reliable. As an alternative, a qPCR based screening method has been developed to quantify fungal DNA in the rapeseed stems from the field. The stabil-ity of quantitative trait loci (QTL) for re-sistance was investigated under different climate change scenarios using innovative transcriptomic, metabolomic and genomic techniques. With genotyping-by-sequencing (GBS) markers a high-resolution genetic map for compara-tive QTL analysis of resistance-associated stem metabolites was developed. HPLC and GC/MS methods were established to assay soluble and cell wall-bound phenolic compounds, along with the composition of lignin monomers in stem tissues. The metabolite measurements reveals resistance-related metabolites particularly among cell-wall bound phenols, and (to a much lesser extent) soluble phenolics, and also with the lignin composition. A number of cell wall-bound compounds associated with the resistance reaction were identified. The results from stress experiments show that Verticillium longisporum infection does not induce any additional drought stress in the plants, indicating that both abiotic and biotic stresses act independently without any synergistic interaction. Consequently, genotypic resistance was stable also under conditions of drought stress, while resistant rape-seed genotypes were not compromised in their drought stress tolerance under attack by V. longisporum. By comparing genes involved in the associated biochemical pathways with transcriptome data from resistant and non-resistant materials, and mapping genes of interest to the genome sequences spanning the resistance QTL, it was possible to identify candidate genes potentially responsible for resistance to V. longisporum. For selected genes high-throughput KASP markers for high-throughput genotyping of breeding populations were developed and validated. These results provide a significant basis to accelerate the breeding progress towards stress resistance and to safeguard the future of the agronomically important oilseed crop rapeseed in Germany and beyond.

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