Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 15, 2008
Publication Date: June 1, 2009
Citation: Spooner, D.M., Jansky, S.H., Simon, R. 2009. Tests of Taxonomic and Biogeographic Predictivity: Resistance to Multiple Disease and Insect Pests in Wild Relatives of Cultivated Potato. Crop Science. 49:1367-1376. Interpretive Summary: Wild potato species have many natural disease resistances that can be transferred to cultivated potato. The US potato collection maintains over 5000 collections of wild and cultivated potato species for use in breeding programs. However, it is difficult to choose the disease resistant accessions from among these thousands of collections. Taxonomy (the science of grouping related organisms) and biogeography (the science of grouping organisms that share certain habitats or are grouped near each other) is sometimes used to help choose potato collections that share certain disease traits. The present study tests the ability of taxonomy and biogeography with a database of 10,758 disease evaluations, derived from the literature and genebank records, of 32 pest and diseases in five classes of organisms (bacteria, fungi, insects, nematodes, and virus) with observations. The data show that only two of the 32 pests and diseases have associations to taxonomy or biogeography in the pest (Colorado potato beetle) and the pathogen (Potato Virus M). While it is logical to initially take both taxonomy and geographic origin into account while screening genebank materials for pest and disease resistances, such associations will hold for only for a small subset of resistance traits.
Technical Abstract: A major justification for taxonomic and biogeographic research is its assumed ability to predict the presence of traits in a group for which the trait has been observed in only a representative subset of the group. Such predictors are regularly used by breeders interested in choosing potential sources of disease-resistant germplasm for cultivar improvement, by genebank managers to organize the collection, and by germplasm collectors planning to gather maximum diversity. Two prior studies in our series designed empirical tests of such predictors with resistances to foliar fungi that cause the potato diseases white mold and early blight. No consistent associations were found to species, taxonomic series, molecular-based clades, ploidy, breeding system, geographic distance, or climatic parameters. While these studies were superior in their ability to control standardized disease tests with accessions spread throughout a representative set of taxonomic and biogeographic parameters, they lacked the numbers of accessions and broad range of diseases for broader-scale tests. The present study tests taxonomic and biogeographic associations with 10,758 disease evaluations, derived from the literature and genebank records, of 32 pest and diseases in five classes of organisms (bacteria, fungi, insects, nematodes, and virus). The data show that ratings for only one pest (Leptinotarsa decemlineata) and one pathogen (Potato M Carlavirus) are reliably predicted both by host taxonomy and climatic variables. Reasons for the general lack of association are discussed. While it is logical to initially take both taxonomy and geographic origin into account while screening genebank materials for pest and disease resistances, such associations will hold for only for a small subset of resistance traits.