Defining a multiple-use germplasm collection for the genus Trifolium

An effective germplasm collection provides genetic variation useful to crop improvement, botanical research, and conservation of plant biodiversity. T he USDA National Trifolium germplasm collection currently limits the collec tion's effectiveness in serving multiple uses. Reflecting the historic mand ate of plant introduction, the collection is strongly biased toward the two major cultivated red and white clover species, which make up 56% of the co llection. Although many wild species are present in the collection, represe ntation is poor for species that are considered gene sources for the cultiv ated species and for species that have minor use. The objectives of this ar ticle are to demonstrate how the collection can be diversified to better se rve users and contribute to the conservation of the genus. Reflecting prior ities proposed in the 1970s, the scope was defined as containing all specie s within the genus Trifolium. Next, a broad gene-pool model was defined on the basis of ease for interspecific hybridization and the history of crop u se. Areas in the model were then identified that required more accessions t o represent diversity of specific interest to users or that were vulnerable to erosion or extinction. An essential step before making any changes to t he collection is to establish priorities by the crop curators and members o f the Crop Germplasm Committee (CGC). If a diverse set of collection stakeh olders can be included in the process, changes are more likely to result in a germplasm collection that serves diverse users and makes a significant c ontribution to conserving plant biodiversity.