Association Mapping of Black Spot Resistance Genes in Roses

In this work we focuse on the association of resistance to several important fungal rose pathogens (Diplocarpon rosae, Podosphaera pannosa, Peronospora sparsa and Sphaceloma rosarum) and different phenotypic traits like scent, anthocyanin and carotinoid content and plant architecture to molecular markers. A panel of 96 rose cultivars were planted in five different field locations in the north, middle and western part of germany. Rose diseases were scored in 2012 and 2013. Additionally, one set of the association panel was cultivated under controlled conditions under glass and plants were used to estimate scent, flower colour and flower size. In a detached leaf assay susceptibility of all 96 cultivars was determined to different races of black spot and downy mildew. The studies included the generation of AFLP- and SSR- markers and markers for candidate genes as well as 68,893 SNPs of the WagRhSNP Axiom array for genome wide association studies.

To achieve this the molecular markers were also useful to estimate population structure (Structure 2.3.4) and genetic diversity of our association panel. Associations between markers and phenotypic traits were calculated with Tassel 4.1.10. A testcross progeny was developed to verify the identified marker-trait associations.