Crop Wild Relatives of the United States

a blog about their conservation and use

Priority U.S. Crop Genepools

Priority wild relatives for a national CWR conservation strategy

Wild and weedy plant species belonging to the priority genera identified in the World’s Top Crops list, that occur in the United States (listed in the national inventory1 and in GRIN taxonomy), were identified as U.S. priority crop wild relative (CWR) taxa. Important agricultural crops with rich native genepools included onion (Allium), squash (Cucurbita), strawberry (Fragaria), sunflower (Helianthus), sweet potato (Ipomoea), bean (Phaseolus), cherry, almond, peach, etc. (Prunus), current and gooseberry (Ribes), raspberry and blackberry (Rubus), blueberry and cranberry (Vaccinium), and grape (Vitis), among others. 

The initial priority CWR list was reviewed by crop researchers, germplasm curators, and plant breeders, who submitted edits and proposed additions to the priorities, resulting in a combined list of over 2000 taxa within 176 genera.

Given the wealth of CWR and other utilized species in the U.S., it was considered necessary to further refine the immediate priorities for a national conservation strategy. To this end we focused first on the Priority 1 genepools, which are largely comprised of taxa that have the greatest potential to contribute to food crop improvement. Approximately 821 taxa from 69 genera are included (inclusive both of species and subspecies/varieties of species).
IMG_0831Within these genepools, we prioritized taxa by degree of relatedness to the crop (i.e. genepool concepts(2,3). Those closely related native taxa (generally GP1 and GP2), plus any additional taxa recorded as useful in crop breeding, are given the greatest attention in the gap analysis for identification of collecting priorities and for in situ conservation considerations (Priority 1A). Taxa identified as rare or threatened are given particular emphasis. Approximately 285 taxa from 30 genera comprise the highest priority list.

Distantly related and/or non-native (introduced) taxa that have not been specifically identified by the research community as a priority for utilization are covered more superficially (Priority 1B). This includes approximately 536 taxa within 57 genera.

The current scope of priorities leaves a number of potentially significant CWR resources for future work. These include minor or emerging wild crops and CWR, medicinal taxa, and ornamentals. Many of these crops are economically important and the genetic resources inhabiting the U.S. may have very high potential use value. Further efforts will be necessary to ensure that these species are adequately conserved and available to the research community.

1Khoury CK, Greene S, Wiersema J, Maxted N, Jarvis A, and Struik P (2013) An Inventory of Crop Wild Relatives of the United States. Crop Sci. 53(4): 1496.
2Harlan JR and de Wet JMJ (1971) Toward a Rational Classification of Cultivated Plants. Taxon 20 (4): 509.
3Maxted N, Ford-Lloyd BV, Jury SL, Kell SP and Scholten MA (2006) Towards a definition of a crop wild relative. Biodiversity and Conservation 15(8): 2673–2685.
Photos: serpentine sunflower (Helianthus exilis A. Gray) by K. Stepiens, and eastern gama grass (Tripsacum dactyloides (L.) L.) by C. K. Khoury