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Amy K. Szewc-McFadden, Warren F. Lamboy and James R. McFerson

To comprehend genetic identity and relatedness in Malus germplasm held in situ and ex situ, we are employing simple sequence repeat (SSR) DNA fragment information in combination with passport and horticultural data. SSRs offer certain advantages for characterizing large arrays of germplasm efficiently. They are abundantly dispersed throughout plant genomes and are exceedingly polymorphic. In addition, they can be PCR-amplified and detected by automated fluorescence-based technology. A size-fractionated DNA library of M. ×domestica cv Golden Delicious was screened to identify SSR loci. Eight loci were found to be reliably informative and were used to prepare locus-specific primer pairs. Characterization of the 75 M. ×domestica accessions included in the core subset of the USDA-ARS Malus germplasm collection revealed six of the eight loci were polymorphic within the array. The number of alleles per locus ranged from two to 21. Throughput was enhanced by multiplexing, allowing simultaneous use of two or three primer pairs. With improved genetic characterization of Malus germplasm, we intend to better develop and relate the core subset to the rest of the collection and to in situ Malus genetic resources. SSR markers appear to be an efficient and reliable tool to expedite this process.

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Chandra S. Thammina, Christopher von Kohn and Margaret R. Pooler

The genus Magnolia (Magnoliaceae) comprises more than 130 species distributed predominantly in temperate and tropical regions in Southeast Asia and is valued worldwide for its ornamental traits as well as for timber and medicinal products, and in trade. Despite their favored status, many species of Magnolia are faced with threats from logging, agricultural land use, development, and collection, and are at risk of extinction. Conservation of these species through habitat preservation and in ex situ collections is needed to prevent extinction. To provide a tool for conservation of Magnolia species, microsatellite markers developed previously for Magnolia ashei were tested in 10 other species of Magnolia to determine their transferability across species. Of the 64 primer pairs tested, 21 amplified alleles in the expected size range in all samples; 11 primer pairs amplified clean products in most, but not all, species; 18 primer pairs consistently amplified a polymerase chain reaction (PCR) product in most species, but had either low peak height or other amplification issues; and 14 primers showed excessive stutter, nonspecific amplification, or no amplification. Cluster analysis using the 129 alleles amplified by these 21 simple sequence repeat (SSR) primer pairs generated groups that corresponded to the known taxonomic relationships in this genus.

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Y. Gogorcena and D.E. Parfitt

32 ORAL SESSION 5 (Abstr. 034–040) Biotechnology: Germplasm Characterization

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Jan Tiväng, Jim Nienhuis and O.S Smith

32 ORAL SESSION 5 (Abstr. 034–040) Biotechnology: Germplasm Characterization

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Paul Skroch and Jim Nienhuis

32 ORAL SESSION 5 (Abstr. 034–040) Biotechnology: Germplasm Characterization

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S. Arulsekar and F. A. Bliss

32 ORAL SESSION 5 (Abstr. 034–040) Biotechnology: Germplasm Characterization

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R. Fjellstrom and D. E. Parfitt

32 ORAL SESSION 5 (Abstr. 034–040) Biotechnology: Germplasm Characterization

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Raymond J. Schnell and Robert J. Knight

32 ORAL SESSION 5 (Abstr. 034–040) Biotechnology: Germplasm Characterization

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Sriyani Rajapakse, Albert Abbott, John Kelly and Robert Ballard

32 ORAL SESSION 5 (Abstr. 034–040) Biotechnology: Germplasm Characterization

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David B. Rubino

Segregating lisianthus [Eustoma grandiflorum (Griseb.) Shinn.] progeny were evaluated to determine the inheritance of esterase (EST), diaphorase (DIA), and glucose-6-phosphate isomerase (GPI) isozymes. Phenotypic data supported the hypotheses that EST is monomeric and controlled by one locus (Est1) with at least three alleles, DIA is tetrameric and controlled by one locus (Dia2) with at least two alleles, and GPI is controlled by one locus (Gpil) with at least two alleles. The structure of the GPI isozyme could not be inferred from banding patterns. Joint segregation analyses indicated that the three loci segregate independently. These three isozymes are the first simply inherited, unlinked biochemical markers identified in lisianthus. These marker loci will be useful for genetic studies, breeding, and germplasm characterization.