Novel Methods for Resistance Breeding in Winter Wheat

Sammanfattning: Breeding for disease resistance in winter wheat is a critical task in the agricultural industry, as plant diseases can significantly impact crop yield and quality. Traditional breeding methods are time-consuming, and disease resistance screenings are often cost and labour-demanding. Therefore, novel breeding tools are being developed to speed up winter wheat genetic gain and increase its genetic diversity.A protocol to characterize winter wheat germplasm for resistance to Fusarium head blight (FHB) under accelerated growth conditions was carried out. The results showed that it is possible to reduce the time necessary to characterize germplasm for FHB resistance by growing up to three generations per year. In a genome-wide association study (GWAS), several markers were identified that were significantly associated with FHB resistance. These markers overlapped with previously known markers contributing to FHB resistance. Novel phenomic methods, the low throughput and affordable SmartGrain and the high throughput Cgrain ValueTM were implemented to predict FHB severity in the tested germplasm. Both methods showed good correlation to visual scoring, suggesting a potential alternative for the traditional visual assessment methods with machine-based methods that offer higher throughput and lower cost. The study also investigated seedling resistance to Septoria tritici blotch (STB) using association mapping and genomic prediction (GP). The study identified 20 QTL for STB seedling resistance of which nine were potentially novel QTL for STB seedling resistance and four overlapped with previously identified genomic regions at the adult stage. The identified QTL could be exploited in winter wheat marker-assisted selection (MAS) against STB and promote the seedling stage for early selection instead of the adult stage. Furthermore, the study investigated the genotypic responses of winter wheat seedlings infected with STB to the fungal biocontrol agent Clonostachys rosea. SNP markers associated with C. rosea biocontrol efficacy and disease resistance were identified, laying the groundwork for further research in genotype-specific-biocontrol compatibility in disease resistance breeding. The thesis provides useful insights into developing novel breeding tools for disease resistance in winter wheat and emphasizes the importance of industry collaboration to transfer knowledge from research to application.