Comparative structural genomics of the potato tertiary genepool: improving access to disease resistance genes

James M. Bradeen¹, Massimo Iorizzo^1,2, Liangliang Gao¹, Riccardo Aversano², Edmund A. Quirin¹, and Domenico Carputo²

¹University of Minnesota, Department of Plant Pathology, 495 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN 55108 USA

²University of Naples “Federico II”, Department of Soil, Plant, Environmental, and Animal Production Sciences, Via Università 100, 80055 Portici (NA) Italy

The potato tertiary genepool includes 20 species, each a source of disease resistance genes. Due to sexual incompatibilities with cultivated potato, these genes have been mostly unavailable for crop improvement. Gene cloning and transgenic technologies are changing that. To facilitate gene mapping and recovery, this research project focuses on the structural genomics of the potato tertiary genepool. Detailed molecular maps will be constructed for three wild potato species, Solanum bulbocastanum, S. commersonii, and S. pinnatisectum, using RFLP, Conserved Orthologous Sequence (COS), and Diversity Array Technology (DArT) markers. RFLP and COS markers mapped in potato and tomato will be used to compare gross genome structure within genus Solanum. Finer detailed comparisons will be facilitated by sequencing 600 DArT markers mapped in S. bulbocastanum, followed by alignment with burgeoning potato and tomato genome sequences. A collection of 116 putative disease resistance gene fragments has been amassed for wild potato. Using these fragments as molecular probes, S. bulbocastanum BAC clones are identified and mapped onto S. bulbocastanum linkage maps. Comparison of genome-wide distribution of disease resistance genes in wild potato, cultivated potato, and tomato will ensue, revealing trends in the origin and diversification of disease resistance in genus Solanum. The resulting system of integrated linkage maps, disease resistance gene physical maps, and associated markers will be used to map one disease resistance gene in a potato tertiary genepool species. This project is supported by the National Research Initiative (NRI) Plant Genome Program of the USDA Cooperative State Research, Education and Extension Service (CSREES).