Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 7, 2001
Publication Date: December 31, 2001
Interpretive Summary: Germplasm collections are important repositories that help ensure that valuable plant traits are saved and will be available for future uses by plant breeders and those interested in preserving biodiversity. Many times these collections are large, so it may be difficult to easily select specific kinds of germplasm that are needed. This research shows a way different birdsfoot trefoil germplasm, a popular forage legume, can be examined efficiently. By examining a broad range of genetic characteristics, four distinct genetic pools that originate from different regions of the world were identified. These pools can be used as standards for evaluating future acquisitions to be sure that only unique materials are added to the collection. The procedures developed will help plant breeders make good choices when looking for new sources of natural pest resistance, ways to improve the quality of forage used by livestock or wildlife, and identifying unique germplasm that is not presently being used to develop new cultivars. This research will also help germplasm collection managers reduce the costs for maintaining this collection. The principles developed in this research can also be applied to other plant germplasm collections.
Technical Abstract: Through systematic evaluations, information is emerging that describes the range of genetic variation and association among trait characters in the National Plant Germplasm System (NPGS) core subset collections, including that for birdsfoot trefoil. The 48 accession subset was evaluated for seed globulin polypeptide and random amplified polymorphic DNA polymorphisms, herbage tannin content, leaf size, seed pod weight, flowering habit characteristics, and seed chalcid resistance. Collection site coordinates and a geographic information system data bases were used to estimate the ecogeography of wild and naturalized accession collection sites. Interpretive groups were constructed using cluster analysis and verified by disciminant analysis to describe the range of variation in plant descriptors. Associations among descriptors and with ecogeography were determined using Pearson's correlation coefficient or the Mantel Z statistic. Using parsimony analysis, the accessions were classified into four distinct genetic diversity pools that were described using ecogeographic characteristics of the collecting sites. Three distinct accessions not originally included with the core subset accessions were classified using disciminant analysis to determine their placement in the genetic diversity pools. The present birdsfoot trefoil core subset adequately represents a range of variation found in the NPGS base collection, and can be used as a standard tool to evaluate future acquisitions.