Molecular Fingerprints Identify Historic Pear Trees in Two U.S. National Parks

Authors: Bassil, Nahla; Postman, Joseph; Hummer, Kim; DOLAN, SUSAN - US DEPT. OF INTERIOR; LAWLISS, LUCY - US DEPT. OF INTERIOR; ODA, ADRIENNE - WASHINGTON S. U.

Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2007
Publication Date: 10/20/2008
Citation: Bassil, N.V., Postman, J.D., Hummer, K.E., Dolan, S., Lawliss, L., Oda, A. 2008. Molecular Fingerprints Identify Historic Pear Trees in Two U.S. National Parks. Acta Horticulturae. 800:417-422.

Interpretive Summary: The U.S. Department of Interior, National Park Service (NPS), has developed conservation plans for historical orchards within National Park boundaries. Variety identification of significant fruit trees is an important part of these plans. The U.S. Department of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository (NCGR), in Corvallis, Oregon, maintains a genebank of world pear germplasm and uses simple sequence repeat (SSR) markers to fingerprint cultivars. These two agencies are collaborating to identify historic pear trees in U.S. National Parks using SSR fingerprints. The San Juan Island National Historical Park (NHP) north of Seattle, Washington, contains several remnant orchards with large surviving European pear trees planted in the late 19th to early 20th centuries. The John Muir National Historic Site (NHS) in Martinez, California, also contains many old pear trees. Young leaf samples were collected from 31 pear trees at San Juan NHP and John Muir NHS in May, 2006, and sent to the USDA genebank in Oregon for analysis. DNA was extracted and microsatellite fragments were amplified using 11 SSR primer pairs. Several known pear cultivars were also included that were suspected to be identical to NPS pears or that were available from nurseries at the time these locations were settled. Four pear trees growing at the English Camp at San Juan NHP had SSR fingerprints identical to ‘Pound Pear’. Four other San Juan NHP pears were found to be identical to ‘Bartlett’ and one was identical to ‘White Doyenne’. Other pear trees at San Juan NHS were identical to each other, but did not match any of the standards. Seven pear trees at John Muir NHS were indistinguishable from ‘Bartlett’, and two trees were identical to each other but we were unable to match them to the standards. About 20 pear trees remain in an orchard where John Muir was buried in 1915 and are now a part of the National Historic Site. A large tree growing by his gravesite was confirmed as ‘Bartlett’. DNA fingerprinting using SSRs is a promising technology for rapid identification of historical fruit trees even when no fruit is present. As additional pear accessions at the USDA genebank become fingerprinted more unknown historical trees will be identifiable.

Technical Abstract: The U.S. Department of Interior, National Park Service (NPS), has developed conservation plans for historical orchards within National Park boundaries. Variety identification of significant fruit trees is an important part of these plans. The U.S. Department of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository (NCGR), in Corvallis, Oregon, maintains a genebank of world pear germplasm and uses simple sequence repeat (SSR) markers to fingerprint cultivars. These two agencies are collaborating to identify historic pear trees in U.S. National Parks using SSR fingerprints. The San Juan Island National Historical Park (NHP) north of Seattle, Washington, contains several remnant orchards with large surviving European pear (Pyrus communis L.) trees planted in the late 19th to early 20th centuries. The John Muir National Historic Site (NHS) in Martinez, California, also contains many old pear trees. Young leaf samples were collected from 31 pear trees at San Juan NHP and John Muir NHS in May, 2006, and sent to the USDA genebank in Oregon for analysis. DNA was extracted and microsatellite fragments were amplified using 11 SSR primer pairs. Several known pear cultivars were also included that were suspected to be identical to NPS pears or that were available from nurseries at the time these locations were settled. Four pear trees growing at the English Camp at San Juan NHP had SSR fingerprints identical to ‘Pound Pear’. Four other San Juan NHP pears were found to be identical to ‘Bartlett’ and one was identical to ‘White Doyenne’. Other pear trees at San Juan NHS were identical to each other, but did not match any of the standards. Seven pear trees at John Muir NHS were indistinguishable from ‘Bartlett’, and two trees were identical to each other but we were unable to match them to the standards. About 20 pear trees remain in an orchard where John Muir was buried in 1915 and are now a part of the National Historic Site. A large tree growing by his gravesite was confirmed as ‘Bartlett’. DNA fingerprinting using SSRs is a promising technology for rapid identification of historical fruit trees even when no fruit is present. As additional pear accessions at the USDA genebank become fingerprinted more unknown historical trees will be identifiable.