Project Number: 3655-21000-038-00
Project Type: Appropriated

Start Date: Jul 16, 2003
End Date: Jul 15, 2008

Objective:
Objective 1: Acquire, via field expeditions, potato genetic diversity currently underrepresented in US genebanks. Objective 2: Assess the amount and apportionment of genetic diversity in potato and its wild relatives via traditional and new molecular/genomic approaches. Objective 3: Elucidate the systematic relationships of domesticated potato and its wild relatives. Objective 4: Test if new taxonomic classifications and new ecogeographical information are effective tools for planning and conducting efficient, comprehensive assessments of the intrinsic horticultural merit of potato genetic resources.

Approach:
Approaches and Procedures Goal 1: Determine the wild potato species known to occur in a country to be collected through literature searches; determine countries most in need of germplasm acquisition through a comparison of genebank holdings to total distribution as determined by taxonomic names as a first proxy for diversity; present a long-range plan of collecting to the Potato Crop Germplasm Committee and get their input and concordance for this plan; prepare herbarium collections, perform seed extractions, and keep records of trip in a regular and timely manner to safeguard collections and maintain mobility in field. Approaches and Procedures Goal 2 Accurately measure morphological traits of germplasm accessions planted in replicated field trials. Three plants are measured per replicate of an accession; two replications are performed (total = six plants per accession), and up to 65 traits are measured per plant. These data are treated with univariate and multivariate analyses to investigate morphological coherence of species. Because most wild potato species are very similar and have a paucity of species-specific morphological characters (they are recognized by a complex of overlapping character states - polythetic support), cladistic analysis of morphological data have limited utility in wild potatoes. A range of molecular markers will be used to help define species limits to include nuclear RFLPs, RAPDs, nuclear microsatellites, and isozymes. The data are analyzed with appropriate cladistic and/or phenetic procedures to generate branching trees or other output (as ordination analyses) to examine species coherence. These molecular investigations are done coordinately with morphological examinations of the same accessions for a more comprehensive investigation of species limits. Data sets of different markers are combined into common analyses, if appropriate. Approaches and Procedures Goal 3 The existing chloroplast DNA phylogenies will be complimented by DNA sequence data from single copy nuclear genes (as waxy) and ITS (multiple-copy), and other genes will be investigated such as alcohol dehydrogenase genes. As well, AFLPs will be used. Approaches and Procedures Goal 4 201 accessions of 53 species that span the taxonomic, ecological, and geographical coverage of sect. Petota will be screened for various disease or other use traits. These trait data will be compared to existing and new molecular taxonomy systems of the PI, and ecogeographical data, via Chi-square tests and spatial autocorrelation statistics for the point observations and for the grids.