Submitted to: Theoretical and Applied Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/5/2005
Publication Date: 8/2/2005
Citation: Villamon, F.G., Spooner, D.M., Orrillo, M., Mihovilovich, E., Bonierbale, M. 2005. Late blight resistance linkages in a novel cross of the wild potato solanum series piurana clade. Theoretical and Applied Genetics. 111:1201-1214. Interpretive Summary: The cultivated potato, technically known as Solanum tuberosum, is affected by a variety of diseases. The most serious potato disease is late blight, caused by the organism technically known as Phytophthora infestans, the disease that caused the Irish potato famine. This study examines a natural resistence to late blight disease in a wild species relative of potato technically known as Solanum paucissectum, through a technique called genetic mapping. We discovered that Solanum paucissectum has strong resistance to late blight and showed that the greatest degree of late blight resistance was found on one of the 12 potato chromosomes called chromosome 11. We tried to transfer this disease to cultivated potato through a sexual cross but have not been able to do so because of sexual incompatibility of these two species, but we are still trying to make this cross. If we are successful, it will provide a source of novel resistance to late blight in cultivated potato.
Technical Abstract: The cultivated potato, Solanum tuberosum, is affected by a variety of diseases with late blight, caused by Phytophthora infestans, being the most severe. Wild potato species have proven to be a continuing source of resistance, sometimes of an extreme type, to this disease. The present study constructs a genetic map of a previously uncharacterized wild, tuber-bearing South American relative of potato, Solanum paucissectum, using probes for conserved sequences from potato and tomato. Eight probes mapped to unexpected linkage groups, but syntenic differences with prior maps of potato were not supported by any blocks of rearranged chromosome segments. All 12 linkage groups were resolved, and significant associations with late blight resistance were found on chromosomes 10, 11 and 12. A major quantitative trait locus on chromosome 11 accounts for more than 25% of the phenotypic variance measured in a field trial. Crossing of S. paucissectum with cultivated potato resulted in very few seeds indicating partial reproductive barriers. Differential reactions of accessions of this potential donor species with simple and complex isolates of P. infestans suggest that it carries major resistance genes that are not those previously described from the Mexican species, S. demissum. However, the additivity of the quantitative trait loci effects argues for the quantitative nature of resistance in this cross.