Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 2, 2006
Publication Date: December 1, 2006
Citation: Jansky, S.H., Simon, R., Spooner, D.M. 2006. Testing taxonomic predictivity: a test with disease resistance data. Crop Science. 46:2561-2570. Interpretive Summary: Taxonomy is the theory and practice of describing, naming, and classifying organisms into related groups. Taxonomy has many uses, but perhaps one of the most useful is to serve as a predictive tool. That is, it is assumed that related organisms share traits, and breeders interested in choosing potential sources of disease resistant plants use taxonomy as a guide. This study was designed to test this prediction idea by associating disease resistance of wild potatoes to a fungus called white mold. We also tested associations of potato taxonomy to biogeography, with the potential that closely spaced populations or populations sharing habitats shared disease resistances. No consistent association was observed between white mold resistance and taxonomy or biogeography. Although we did find some species or individual populations that generally had high resistance to white mold, variation in these populations or species reduced the prediction of overall resistance. This study is useful because it alerts breeders interested in white mold resistance that taxonomy and biogeography have limitations in planning their breeding work.
Technical Abstract: A major justification for taxonomic research is its assumed ability to predict the presence of traits in a group for which the trait has been observed in a representative subset of the group. There are many examples of the predictive component of taxonomy, but these overlook non-associations. Taxonomy is regularly used by breeders interested in choosing potential sources of disease resistant germplasm for cultivar improvement. This study was designed as an empirical test of prediction by associating white mold resistance (caused by the fungal pathogen Sclerotinia sclerotiorum) to diverse potato taxonomies, and biogeography, using 144 accessions of 34 wild relatives of potato in Solanum sections Petota and Etuberosum. Tremendous variation for resistance to white mold was observed both within and among species. No consistent association was observed between white mold resistance and taxonomic series (based on a phenetic concept), clades (based on a cladistic concept), ploidy, breeding system, geographic distance, or climate parameters. Species and individual accessions with high proportions of white mold resistant plants have been identified in this study, but both often have extensive variation, and designation of either as resistant or susceptible must take this variation into account. Therefore, taxonomic relationships and ecogeographic data can not be used to predict where additional sources of white mold resistance genes will be found.