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United States Department of Agriculture

Agricultural Research Service

Research Project: Management of Temperate-Adapted Fruit, Nut, and Specialty Crop Genetic Resources and Associated Information

Location: National Clonal Germplasm Repository (Corvallis, Oregon)

Title: OHxF paternity problem perplexes pear producers

Authors
item Postman, Joseph
item Bassil, Nahla
item Kim, Daeil -

Submitted to: Journal of American Pomological Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 1, 2013
Publication Date: August 1, 2013
Citation: Postman, J.D., Bassil, N.V., Kim, D. 2013. OHxF paternity problem perplexes pear producers. Journal of American Pomological Society. 67(3):157-167.

Interpretive Summary: Early in the 20th century, a collection of fire blight resistant pears from around the world was assembled in southern Oregon in an effort to develop improved rootstocks. ‘Old Home’ and ‘Farmingdale’ are two cultivars from Illinois that exhibited strong fire blight resistance and useful horticultural traits. Both became important as interstem stocks and as parents in the development of new rootstocks. In the 1950s, an Oregon nurseryman collected seed from an ‘Old Home’ tree in British Columbia purportedly pollinated by ‘Farmingdale’, and hundreds of numbered selections of this cross ‘Old Home’ x ‘Farmingdale’ (OHxF) were evaluated. Several OHxF selections are now valued as rootstocks worldwide, and 45 unique OHxF selections are maintained at the USDA-ARS National Clonal Germplasm Repository (NCGR), in Corvallis, Oregon. DNA fingerprints were generated for ‘Old Home’, ‘Farmingdale’, 8 OHxF selections, and several reference pear cultivars at NCGR using a standard international pear fingerprinting protocol. ‘Farmingdale’ is thought to be a seedling of ‘Beurré d’Anjou’, and the fingerprint results confirmed this parental relationship. The fingerprint results also confirmed that 'Old Home' was a parent of each OHxF selection. However, it is impossible for ‘Farmingdale’ to be the pollen parent for any of the OHxF selections examined based on these fingerprinting results. DNA fingerprint evaluation of the world pear collection at NCGR established cultivar ‘Bartlett’ as the actual pollen parent of these rootstock clones. Fruit and leaf morphology is also consistent with ‘Bartlett’ and not ‘Farmingdale’ as a parent of OHxF rootstock selections. The highly fire blight resistant ‘Farmingdale’ is apparently very under-represented in the pedigrees of current pear rootstocks, and deserves renewed consideration.

Technical Abstract: Early in the 20th century, a collection of fire blight resistant pears from around the world was assembled in southern Oregon in an effort to develop improved rootstocks. ‘Old Home’ and ‘Farmingdale’ are two cultivars from Illinois that exhibited strong fire blight resistance and useful horticultural traits. Both became important as interstem stocks and as parents in the development of new rootstocks. In the 1950s, an Oregon nurseryman collected seed from an ‘Old Home’ tree in British Columbia purportedly pollinated by ‘Farmingdale’, and hundreds of numbered selections of this cross ‘Old Home’ x ‘Farmingdale’ (OHxF) were evaluated. Several OHxF selections are now valued as rootstocks worldwide, and 45 unique OHxF selections are maintained at the USDA-ARS National Clonal Germplasm Repository (NCGR), in Corvallis, Oregon. Simple Sequence Repeat (SSR) or microsatellite-based DNA profiles were generated for ‘Old Home’, ‘Farmingdale’, 8 OHxF selections, and several reference pear cultivars at NCGR using a standard fingerprinting set developed by the European Cooperative Programme for Plant Genetic Resources. ‘Farmingdale’ is thought to be a seedling of ‘Beurré d’Anjou’, and shared at least one SSR allele at each locus tested, confirming this parental relationship. All OHxF selections shared an allele with ‘Old Home’ at each locus, with one allele carrying a suspected pair of base deletions. However, based on the SSR results, it is impossible for ‘Farmingdale’ to be the pollen parent for any of the OHxF selections examined. Evaluation of the world pear collection at NCGR with this fingerprinting set established cultivar ‘Bartlett’ as the actual pollen parent of these rootstock clones. Fruit and leaf morphology is also consistent with ‘Bartlett’ and not ‘Farmingdale’ as a parent of OHxF rootstock selections. The highly fire blight resistant ‘Farmingdale’ is apparently very under-represented in the pedigrees of current pear rootstocks, and deserves renewed consideration.

Last Modified: 9/1/2014
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