Location: Vegetable Crops Research Unit
Project Number: 3655-21000-050-00
Start Date: Mar 12, 2008
End Date: Mar 11, 2013
For objective 1, the PI has obtained a list of current germplasm holdings of Daucus and is actively planning germplasm collecting expeditions. Through GRIN, he obtained accepted taxonomic names for carrot and associated taxonomic information. For Solanum, he will collect in Peru as a priority country if permits can be obtained. He will discuss collection needs with personnel from the National Germplasm Resources Laboratory, and seek collecting permits. He will attend the annual meetings of the Root and Bulb Crop Germplasm Committee to present a collecting plan and seek their concordance and support, and submit collecting proposals to the U.S. Germplasm Laboratory and conduct collecting expeditions based on available permits and funding. Based on current collecting needs and potential collaborations carrot expeditions are planned for Pakistan, Tunisia, and the United States. He will obtain locality data from herbarium and genebank curators. He will survey taxonomic treatments of carrot and floras worldwide and visit key herbaria to assess collection needs. For objective 2, the PI will gather information about species boundaries of carrot from taxonomic treatments. Morphological studies will be conducted at the Ames germplasm station using species-specific morphological characters, and the data will be analyzed with standard multivariate techniques. For interspecific relationships, DNA phylogenies will be generated for a subset (50) of wild and cultivated potato and all available (12) carrot species. In addition, outgroups identified as possibly congeneric with Daucus will be examined using COSII (nuclear DNA) markers, and be examined with standard cladistic techniques. While COSII genes will be explored as new markers, plastid rpoC1 intron and rpl16 intron sequences, and plastid matK coding sequences also will be examined. The PI will write a taxonomic monograph of the wild potato species from the Southern Cone of South America and will write taxonomic treatments of Solanum series Conicibaccata and the Solanum series Piurana group. For objective 3, associations will be made of potato taxonomy to the potato diseases late blight, Colorado potato beetle, and potato virus Y Disease resistance data will then be associated to taxonomic variables by nonparametric methods based on rank scores using the Mann–Whitney test when comparisons between two groups are made and the Kruskal–Wallis test when comparisons among more than two groups are made. Post hoc pairwise comparisons following a significant Kruskal–Wallis test will be performed using the Mann–Whitney test with an appropriate Bonferroni correction. To determine the relative contributions of species, accessions, and individual plants of days to infection or insect pressure, a linear model will be fit with random effects of species and accession. These statistical tests for associations of disease and biogeography are standard. To test the question of whether geographic provenance of samples is a predictor of disease resistance, we will analyze biogeographic variables using spatial autocorrelation, followed by a regression analysis against possible predictors using Moran’s I.