The RB gene from wild potato Solanum bulbocastanum imparts broad-spectrum late blight resistance to cultivated potato. To explore marker associations and haplotype frequencies near RB, we developed, optimized, validated, and employed a set of markers specific to the haplotype associated with the RB resistance allele. Our markers, developed using a mismatch amplification mutation assay (MAMA)-PCR approach, have single nucleotide polymorphism-level sensitivity. MAMA markers were validated via linkage mapping and applied to a collection of 60 S. bulbocastanum genotypes representing the geographic distribution of the species. Considerable marker disassociation within a 100 kb region encompassing RB was revealed. Physical distance between markers was not an effective predictor of marker disassociation. Applied to a collection of four S. bulbocastanum genotypes of known RB allelic status, a set of six MAMA markers accurately predicted the presence of the RB allele. Implications for marker aided genotype selection and association mapping in wild potato species are explored.
Bibliographical noteFunding Information:
Acknowledgements This project was partially funded by the NSF Potato Genome Project (DBI0218166). We thank Dr. John Helgeson, USDA-ARS and University of Wisconsin for providing S. bulbocas-tanum genotypes PT29 and SB22 and Dr. Chuck Brown, USDA-ARS for providing the S. bulbocastanum mapping population. Computer support from the University of Minnesota Supercomputing Institute is gratefully acknowledged. All experiments herein reported comply with current U.S. laws.
- Late blight resistance
- RB gene
- Solanum bulbocastanum