Submitted to: Plant and Animal Genome VX Conference Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 1/1/2005
Publication Date: 1/14/2005
Citation: Bassil, N.V., Postman, J.D. 2005. Est-ssr's utility in managing the pear collection at the national clonal germplasm repository [abstract]. Plant and Animal Genome Abstracts. p. 111. Interpretive Summary: The objective of this study was to estimate the usefulness of genetic tools (referred to as microsatellite markers) in managing the USDA-ARS pear germplasm collection, in Corvallis, Oregon. Seven previously developed markers were used in a set of 144 pear varieties. These DNA markers identified 5 sets of duplicates and 4 sets of trees that have the same name but are genetically different. The pear collection contains two Asian cultivars with the name 'Nijisseiki'. One was identified as the correct 'Nijisseiki' based on the genotypes of the reported parents. Initial analysis based on only 7 markers were useful in detecting duplications as well as incorrectly labeled genotypes in our pear collection. Future work will include additional markers with the goal of developing a unique DNA 'fingerprint' for each of the 1600 varieties in the collection.
Technical Abstract: The U.S. Department of Agriculture (USDA), Agricultural Research Service (ARS) maintains 1600 unique pear genotypes at the National Clonal Germplasm Repository in Corvallis, Oregon. The objective of this study was to use Simple Sequence Repeat (SSR) or microsatellite markers to examine the identity of potential duplicates in the collection. Ten polymorphic SSRs were developed from pear nuclear GenBank sequences. Initial results of SSR fragment analysis of seven of ten polymorphic loci using capillary electrophoresis in 144 pear accessions identified 5 sets of synonyms (4 in P. communis and one in P. ussuriensis), and 4 pairs of homonyms (3 in P. communis and one in P. pyrifolia) and confirmed 3 clonal sets. The parentage of P. pyrifolia cultivar 'Shinseiki' is reported as 'Nijisseiki' x 'Chojuro'. Our analysis of common alleles showed that while one parent 'Nijisseiki' (local accession number: 212.001) is one likely parent, alleles of our 'Chojuro' accession were absent at 6 out of 7 loci. Thus our 'Chojuro' accession cannot be the parent of our 'Shinseiki' accession. Additional microsatellite markers will be used to confirm these results, to evaluate other suspected redundancies, and to genetically document the identities of pear genotypes.