Genetic fingerprinting identifies apple (Malus domestica Borkh.) fruit cultivars in historic orchards on public lands

The National Historic Preservation Act of 1966 mandates that historic resources, including orchards, on federal lands be evaluated for potential significance. Evaluations include assessments and documentation of an orchard’s layout and location, as well as the architecture, ages, conditions, and cultivars of trees. These factors may reveal an orchard’s history and uniqueness and determine an orchard’s historic importance. Fruit tree cultivar identities are a key piece of this puzzle. They reveal information about an orchard’s use, origin, and uniqueness. In the past, historic preservationists relied on pomologists to identify cultivars based primarily on the phenotypic traits of the tree. DNA fingerprinting technologies, in combination with high-quality reference cultivar collections, have dramatically improved the accuracy of heritage cultivar identification. We demonstrate the utility of using DNA technologies for cultivar identifications on federal lands using examples from trees in orchards of Redwood National and State Parks and the Eldorado National Forest. A total of 87 historic apple trees from these locations were genotyped and cultivar names were determined for 35 trees, using a reference set of 1319 apple cultivars from the USDA National Plant Germplasm System, Washington State University, Seed Savers Exchange, and Temperate Orchard Conservancy. Some of the trees that were not identified may be cultivars that are not included in the reference sets and others may be unique trees derived from seeds. The information derived from genetic fingerprinting analyses will aid in the determination of the historic significance of orchards on public lands.