Genomic-led potato breeding

Abstract: Most cultivated potatoes (Solanum tuberosum L.) are polyploids with tetrasomic inheritance (2n = 4x = 48), which makes breeding for new improved cultivars more complicated compared to diploid crops. In addition to this, the potato market is much more fragmented compared to other staple crops such as maize or wheat, where yield and dry matter are by far the most important traits. A conventional potato breeder needs to consider a number of important breeding traits, including plant maturity, tuber and cooking quality, host plant resistance to pests and pathogens, and starch content. In the scope of this thesis, genomic-led breeding approaches for tetraploid potato are explored using high throughput genotypic data acquired from single nucleotide polymorphism (SNP) markers. Quantitative trait loci (QTL) for host plant resistance to Alternaria solani are mapped to chromosomes 5 and 11 using a segregating bi-parental crossing population. The application of genomic selection (GS) is tested in a potato breeding program situated in Sweden by predicting genomic estimated breeding values (GEBVs) for eight important breeding traits, such as tuber yield and quality, and host plant resistance to Phytophthora infestans. The predictive ability of GEBVs across clonal generations in the breeding program is poor for most breeding traits, however, the approach of predicting GEBVs within and across half-sib families results in higher predictive ability. Lastly, the genetic diversity of the potato germplasm at the Nordic Genetic Resource Centre (NordGen) is compared to newly bred clones in Sweden. These results suggest a close genetic relationship between the accessions from NordGen (local farmer’s cultivars and obsolete cultivars), and the modern breeding clones from the potato breeding program based in Sweden.

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