The project uses as input the results, tools and resources of the first project phase from 1999 to 2004. Our aims are:

• To identify at the molecular level genes controlling quantitative resistance to pathogens, which are highly relevant for potato cultivation. These pathogens are Phytophthora infestans causing the late blight disease and the root cyst nematode Globodera pallida.
• To develop and test molecular diagnostic tools for the assessment of phenotypic and genotypic biodiversity in potato germ plasm with respect to pathogen resistance in general and to quantitative resistance against Phytophthora infestans and Globodera pallida in particular.
• To evaluate marker-assisted breeding strategies for quantitative resistance to Phytophthora infestans and Globodera pallida in the context and under the conditions of commercial potato breeding programs.
• To develop a local database application tool, which allows storage of structured data and efficient data analysis, e.g. computational haplotyping and correlation between haplotype and phenotype in polyploid crops.

A population of distantly related tetraploid potato breeding clones is genotyped for SNP/InDel and other PCR-based markers linked to potato resistance loci. All genotypic data are integrated in the GABI Primary Database (GabiPD). The same population of tetraploid breeding clones is evaluated in replicated field trials for quantitative resistance to P. infestans in combination with other agronomic characteristics. Genotypic data are then tested for association with quantitative field resistance.

The annotated putative genes in 400 kb genomic sequence from the resistance hot spot on potato chromosome V are analysed for expression in response to infection with P. infestans. Based on expression analysis and/or putative function assignment, candidate genes are selected for association mapping and further functional analysis, for example gene silencing experiments.