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Determining Redundancy of Short-day Onion Accessions in a Germplasm Collection Using Microsatellite and Targeted Region Amplified Polymorphic Markers

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The U.S. National Plant Germplasm System is one of the world's largest national genebank networks focusing on preserving the genetic diversity of plants by acquiring, preserving, evaluating, documenting, and distributing crop-related germplasm to researchers worldwide. Maintaining viable germplasm collections is essential to world food security but comes at a cost. Redundancy within the collection can incur needless expense and occurs as a result of donations of similar material under different names from different donors. Alternatively, similarly named accessions from different donors can actually be genetically distinct. We evaluated 35 short-day onion (Allium cepa) accessions using microsatellite and targeted region amplified polymorphic (TRAP) molecular markers to compare newly acquired germplasm with existing accessions in the collection to determine differences and redundancies and to compare the use of each marker type in distinguishing the onion accessions. Both marker types distinguished differences and found similarities, but the results did not always agree. TRAP markers found one of the Italian Torpedo entries to be different, whereas the 10 microsatellite loci analyzed found no differences. In contrast, microsatellite analysis found all three Red Grano entries to be different, whereas TRAP analysis distinguished only one accession. The eight White Grano entries were separated into four groups by microsatellite markers and five groups by the TRAP markers. Discriminating among closely related accessions using molecular markers can require a large number of random marker loci, especially when differences may be limited to a single trait. TRAP markers were more efficient, uncovering approximately =10 random polymorphic loci per primer pair, whereas microsatellite markers each uncovered differences at a single locus.
Kisha, Theodore J. , Cramer, Christopher S.
Includes references
Journal of the American Society for Horticultural Science 2011 Mar., v. 136, no. 2
Journal Articles, USDA Authors, Peer-Reviewed
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