Allelic mining for late blight resistance in wild Solanum species. Sanchez, M.J. and J.M. Bradeen

American Phytopathological Society Annual Meeting (Anaheim, CA Aug 2004)

The RB gene, a Late Blight (LB) resistance gene imparting broad-spectrum protection to LB pathogen races, is a valuable resource for the development of resistant potato cultivars. This work aims to mine the RB locus for the exploration of allelic diversity in geographically distant populations from the wild potato, Solanum bulbocastanum using Long Range-PCR (LR-PCR). Here, we improved three potentially limiting technical factors associated with LR-PCR: template DNA quality, amplification fidelity, and primer design. Our optimized LR-PCR method may isolate unique and putatively functional alleles useful in evolutionary analyses and eventual deployment. Our RB allelic mining efforts will test 2 proposed evolutionary hypotheses: i) RB flanking regions are conserved across genotypes within S. bulbocastanum and ii) specific RB-nucleotide sites undergo purifying/balancing selection. Moreover, the methods described and improved here may assist allelic mining research at other loci and in other plant species.