Resource development
for efficient mapping of disease resistance traits in Solanum
Harpartap Mann1, Edmund A. Quirin1, Liangliang Gao1, Riccardo Aversano2, Massimo Iorizzo1,2, Domenico Carputo2, and James M.
Bradeen1
1Department of Plant Pathology, University of
Minnesota, St. Paul, MN 55108 (USA)
2Department
of Soil, Plant, Environmental and Animal Production Sciences, University of Naples ÒFederico IIÓ, Portici
(Italy)
Despite being a rich source of genetic resistance to various potato pathogens, species of the wild potato taxon superseries Stellata remain a largely inaccessible resource for improvement of potato disease resistance due to sexual incompatibility and lack of information on their genomic structure. Towards improving access to resistance (R) genes in Stellata species via gene cloning and transformation, our laboratory is characterizing genome structure in key Stellata species. Currently, one of these species, Solanum bulbocastanum is being genetically mapped in our lab using Diversity Arrays Technology (DArT). Here we detail efforts to augment the burgeoning S. bulbocastanum genetic map with BAC clones harboring resistance gene homologs (RGAs). Several R genes have been cloned from the genus Solanum and the majority belong to the nucleotide binding site-leucine rich repeat (NBS-LRR) class. Conserved regions of the NBS domain of known R genes were used to develop primers to amplify RGAs from S. bulbocastanum. 107 RGAs thus identified were assembled into nine contigs at 90 % sequence identity. PCR amplified DNA from the members of each contig was pooled and used as a probe to identify BAC clones harboring RGA sequences. DArT markers and PCR-based markers developed from BAC ends were used to integrate the BAC clones into the S. bulbocastanum genetic map. The resulting integrated genetic and RGA physical map can be further used 1) for positional cloning of resistance genes, 2) as a resource for mapping additional resistance loci in a population-independent manner, and 3) as a resource for mapping disease resistance loci in other members of the of the superseries Stellata by exploiting their syntenic relationship with S. bulbocastanum.