| Characterization of plant collections with molecular markers is an ideal approach for efficient conservation of plant genetic resources. In 2003, Pelargonium was a priority genus at the Ornamental Plant Germplasm Center (OPGC), which accumulated approximately 800 Pelargonium accessions. In order to make space for other important ornamental species, the collection needed to be reduced to 25% of its peak size. The goals of this project were to use molecular marker techniques to investigate phylogenetic relationships among the accessions in OPGC's Pelargonium collection, and to assist OPGC in purging redundant accessions. The molecular screening technique selected was Target Region Amplification Polymorphism (TRAP), which combines the use of arbitrary primers and primers targeted to a gene of interest. Analyses were run to assess the utility of the TRAP technique for this genus, to evaluate the collection in terms of taxonomic sections, to compare potentially duplicated accessions, and to compare related accessions within section Ciconum using TRAP primers based on resistance genes. The first test on 46 Pelargonium accessions found the combined results from two sets of TRAP primers were sufficient to distinguish all the accessions on a dendrogram. The entire collection was analyzed using 301 TRAP markers in a neighbor joining analysis, and the dendrogram produced in the analysis revealed a division of the collection into two groups: section Ciconum and non-Ciconum accessions. Dendrograms produced by Bayesian analysis of the non-Ciconum accessions showed that section Pelargonium has the highest representation in the non-Ciconum group at OPGC, followed by section Reniformia. Ultimately, 103 accessions were found to represent most of the diversity in the non-Ciconum group. A separate Bayesian analysis of potentially duplicated accessions from section Ciconum confirmed the identity of accessions in about half the sets of potential duplicates. For the most diverse 103 accessions in the non-Ciconum group to be retained, the accessions in section Ciconum have to be reduced from over 650 to just 97, keeping the total collection size below 200 accessions. In conclusion, TRAP analyses successfully identified the taxonomic section for the previously unidentified accessions in OPGC's collection, and grouped the known accessions into the expected clusters. |
