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. The USDA National Trifolium germplasm collection currently limits the collection's effectiveness in serving multiple uses. Reflecting the historic mandate of plant introduction, the collection is strongly biased toward the two major cultivated red and white clover species, which make up 56% of the collection. Although many wild species are present in the collection, representation is poor for species that are considered gene sources for the cultivated species and for species that have minor use. The objectives of this article are to demonstrate how the collection can be diversified to better serve users and contribute to the conservation of the genus. Reflecting priorities proposed in the 1970s, the scope was defined as containing all species 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 use. Areas in the model were then identified that required more accessions to represent diversity of specific interest to users or that were vulnerable to erosion or extinction. An essential step before making any changes to the collection is to establish priorities by the crop curators and members of the Crop Germplasm Committee (CGC). If a diverse set of collection stakeholders can be included in the process, changes are more likely to result in a germplasm collection that serves diverse users and makes a significant contribution to conserving plant biodiversity.