Complementary Conservation of Wild Cranberry
Food security for the world’s growing human population is one of the most pressing issues of our time. Plant breeders need diverse resources as they work to improve crops to feed people in the most efficient, effective and sustainable manner. Among these resources are the wild plants that are related to crop plants, or crop wild relatives (CWR). CWR tend to have greater genetic variability than crop plants, and their genetic identities differ from those of crop plants in significant ways. Wild species evolve in response to changes in environmental conditions, pests, pathogens and predators. When problems arise with the production of crop plants, the solutions may be found in the genes of wild relatives.
The Forest Service and the Agricultural Research Service (ARS) are uniquely positioned to cooperate with the complementary conservation of crop wild relatives native to the United States. The Forest Service has the responsibility for managing 193 million acres of National Forest System lands in 43 states. The USDA-ARS manages the U.S. National Plant Germplasm System (NPGS), which has the responsibility to collect, maintain, distribute, evaluate, and preserve genetic resources of plant species of interest to the United States. The two agencies are taking advantage of their complementary missions in a program to conserve the CWR both in their natural environments (in situ) and in gene banks (ex situ) where they are available for use in research, breeding, and restoration.
First Test Case
Wild cranberries, from which cultivated cranberries are derived, have been chosen as the first test case for the joint program. Populations of cranberry occur across the northeastern and north central United States and as far south as Tennessee and North Carolina. The large-fruited cranberry (Vaccinium macrocarpon) is the commercially important species, while the small cranberry (Vaccinium oxycoccos) is a close relative. The wild populations contain genetic diversity that may not be found in the cultivated varieties and could be important in breeding new varieties that can adapt to a changing climate and other environmental stresses.
To conserve the range of genetic diversity of wild cranberry both in situ and ex situ, representative populations across the species’ native ranges are being evaluated. Standard protocols developed by the ARS and Forest Service are used to collect leaf tissue for DNA analysis, collect fruit and seed (when present), and prepare herbarium vouchers. See "USDA Forest Service and Agricultural Research Service Strategy for the Complementary Conservation of Wild Cranberry (Vaccinium macrocarpon Ait. and V. oxycoccos) Genetic Resources and Protocols for Collecting Genetic Material, Germplasm, and Herbarium Vouchers" (PDF, 331 KB).
In 2013, ARS scientists worked with the listed Forest Service experts to visit and evaluate the following populations:
Pisgah National Forest (Collaborator: Gary Kaufman)
- Black Balsam Knob Seep Species: Vaccinium macrocarpon Activities: Seed, herbarium vouchers and leaf tissue collected
- Ivestor Gap Seep Species: Vaccinium macrocarpon Activities: Seed, herbarium vouchers and leaf tissue collected
Cherokee National Forest (Collaborator: Joe McGuiness)
- Johns Bog Species: Vaccinium macrocarpon Activities: Seed, herbarium vouchers and leaf tissue collected
- Osborne Bog Species: Vaccinium macrocarpon Activities: Seed, herbarium vouchers and leaf tissue collected
George Washington National Forest (Collaborator: Fred Huber)
- Green Pond Species: Vaccinium macrocarpon Activities: Seed, herbarium vouchers and leaf tissue collected
- Spring Pond Species: Vaccinium macrocarpon Activities: Seed, herbarium vouchers and leaf tissue collected
Monongahela National Forest (Collaborator: Kent Karriker)
- Cranberry Glades Botanical Area Species: Vaccinium macrocarpon and V. oxycoccus Activities: Herbarium vouchers and leaf tissue collected
Seed from all populations where it was collected was sent to the ARS National Clonal Germplasm Repository in Corvallis, Oregon, a component of the U.S. National Plant Germplasm System, for ex situ conservation and distribution to researchers and educators.
Leaf tissue from all populations was sent to at the ARS Cranberry Genetics and Genomics Laboratory in Madison, Wisconsin, for molecular analysis of inherent genetic variability. Thus far, analyses have been conducted for the Virginia and West Virginia populations. Results from microsatellite SSR testing of 11 unique primers across all samples showed that the V. macrocarpon and V. oxycoccos gave consistent and expected microsatellite alleles for both species. There were four unique genotypes identified in the V. macrocarpon samples: three unique genotypes identified in the George Washington National Forest and one in the Monongahela National Forest. Six unique V. oxycoccos genotypes were detected.
Over the next several years, wild populations of native cranberries of both species will be sampled from throughout their ranges and genetic variation will be measured through molecular analysis of the leaf tissue. Seeds from these populations will be maintained in the medium and long-term ex situ collections of the U.S. National Plant Germplasm System.
The ultimate goal is to identify populations on National Forests of highest priority for designation as In Situ Genetic Resource Reserves (IGRRs). Priority will be based on a number of factors used to determine their suitability as IGRRs. Factors include location, distance from other populations, sustainability, population size, genetic profile, ease of access, and cultural significance to Native Americans or others. Long-term management plans will be implemented by the Forest Service to monitor, manage, and safeguard the security of the populations.
It is anticipated that in the future many native U.S. plants important to global food security growing on land managed by the federal government will be preserved both in situ and ex situ, optimizing conservation practices and increasing the availability of essential genetic resources for the development of new varieties better adapted to the needs of the future.
USDA Agricultural Research Service
Karen Williams Plant Exploration Coordinator USDA ARS National Germplasm Resources Laboratory Beltsville, MD 20705-2350
Juan E. Zalapa Research Geneticist USDA ARS, Vegetable Crops Research Unit Madison, WI 53706
Kim E. Hummer Research Leader USDA ARS National Clonal Germplasm Repository Corvallis, Oregon
US Forest Service
Larry Stritch National Botanist US Forest Service Washington, DC
Jan Schultz Eastern Region Botanist US Forest Service Milwaukee, WI 53202
Alix Cleveland Program Manager – Non-native Invasive Species Botany US Forest Service Atlanta, GA 30309-2444