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Fort Collins, CO, United States

Paiva S.R.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuaria | Mariante A.D.S.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuaria | Blackburn H.D.,National Center for Genetic Resources Preservation
Journal of Heredity | Year: 2011

Microsatellites are commonly used to understand genetic diversity among livestock populations. Nevertheless, most studies have involved the processing of samples in one laboratory or with common standards across laboratories. Our objective was to identify an approach to facilitate the merger of microsatellite data for cross-country comparison of genetic resources when samples were not evaluated in a single laboratory. Eleven microsatellites were included in the analysis of 13 US and 9 Brazilian sheep breeds (N = 706). A Bayesian approach was selected and evaluated with and without a shared set of samples analyzed by each country. All markers had a posterior probability of greater than 0.5, which was higher than predicted as reasonable by the software used. Sensitivity analysis indicated no difference between results with or without shared samples. Cluster analysis showed breeds to be partitioned by functional groups of hair, meat, or wool types (K = 7 and 12 of STRUCTURE). Cross-country comparison of hair breeds indicated substantial genetic distances and within breed variability. The selected approach can facilitate the merger and analysis of microsatellite data for cross-country comparison and extend the utility of previously collected molecular markers. In addition, the result of this type of analysis can be used in new and existing conservation programs. © 2011 The American Genetic Association. All rights reserved. Source

Perez H.E.,University of Hawaii at Manoa | Perez H.E.,University of Florida | Hill L.M.,National Center for Genetic Resources Preservation | Walters C.,National Center for Genetic Resources Preservation
Seed Science Research | Year: 2012

Assessments of seed storage physiology among Arecaceae (palm) species are often inconclusive because seeds exhibit diverse responses to low temperature and moisture conditions. Interrelationships between dry matter accumulation, cell structure and water relations during seed development of the endangered Hawaiian endemic palm, Pritchardia remota, suggest that damage from drying results from mechanical strain. Endosperm and fruits accumulate dry mass through most of the 400d gestation period, but embryos reached maximum dry mass about 250d post-anthesis (DPA). Mostly sucrose and some triacylglycerols accumulated in the cytoplasm and vacuoles of embryo cells, and organelles in mature embryo cells de-differentiated. Water content and water potential decreased as embryos matured and embryos contained about 0.45 gH2O(g dry mass) -1 (-26MPa) at shedding. Mature embryos survived drying to 0.16 g g-1 (-49MPa), but further drying was lethal. A model of allowable cell shrinkage is consistent with the substantial, but incomplete, desiccation tolerance acquired in P. remota embryos, and provides a new framework to explain variation in critical water contents as embryos develop. We suggest that desiccation tolerance, which distinguishes recalcitrant and orthodox physiologies among seeds, can be quantified by mechanical strain when embryo cells shrink during drying. © 2012 Cambridge University Press. Source

Reeves P.A.,National Center for Genetic Resources Preservation | Panella L.W.,Northern Plains Area Sugarbeet Research Unit | Richards C.M.,National Center for Genetic Resources Preservation
Theoretical and Applied Genetics | Year: 2012

The primary targets of allele mining efforts are loci of agronomic importance. Agronomic loci typically exhibit patterns of allelic diversity that are consistent with a history of natural or artificial selection. Natural or artificial selection causes the distribution of genetic diversity at such loci to deviate substantially from the pattern found at neutral loci. The germplasm utilized for allele mining should contain maximum allelic variation at loci of interest, in the smallest possible number of samples. We show that the popular core collection assembly procedure "M" (marker allele richness), which leverages variation at neutral loci, performs worse than random assembly for retaining variation at a locus of agronomic importance in sugar beet (Betavulgaris L. subsp. vulgaris) that is under selection. We present a corrected procedure ("M+") that outperforms M. An extensive coalescent simulation was performed to demonstrate more generally the retention of neutral versus selected allelic variation in core subsets assembled with M+. A negative correlation in level of allelic diversity between neutral and selected loci was observed in 42% of simulated data sets. When core collection assembly is guided by neutral marker loci, as is the current common practice, enhanced allelic variation at agronomically important loci should not necessarily be expected. © 2012 Springer-Verlag (outside the USA). Source

Bamberg J.B.,U.S. Potato Genebank | Martin M.W.,U.S. Potato Genebank | Abad J.,U.S. Department of Agriculture | Jenderek M.M.,National Center for Genetic Resources Preservation | And 5 more authors.
In Vitro Cellular and Developmental Biology - Plant | Year: 2016

The US Potato Genebank in Sturgeon Bay, Wisconsin, is the national germplasm collection for the world’s most important vegetable crop. It contains about 6,000 accessions of 100 species of tuber-bearing relatives of Solanum tuberosum. The potato of commerce is a clonal crop susceptible to many systemic pathogens, so the genebank routinely uses in vitro clonal maintenance and distribution for named cultivars. In vitro management is also the tool of choice for various breeding and genetic stocks of interest to breeders and researchers. Long-term backup cryopreservation of clones is done at the base collection in Fort Collins, Colorado. In vitro techniques also play an important role in virus elimination from clones. Recently, in vitro propagation has expanded to the temporary safekeeping of meristem propagules in antimicrobial medium during plant collecting expeditions in the southwest USA. The genebank’s mission includes promoting technology that supports expanded use of the germplasm, in particular, finding ways to overcome interspecific hybridization barriers. Thus, in vitro techniques such as pollen viability testing, ploidy manipulation, protoplast fusion, and embryo rescue have contributed technology for major advances in interspecific hybridization, utilization of noncommercial species, and introgression of genes from wild near-relatives. Finally, advancing in vitro technology holds promise as a tool for mass bioassay and selection of seeds, pollen, or somaclones for useful traits. © 2016 The Society for In Vitro Biology Source

White J.W.,Us Arid Land Agricultural Research Center | Dierig D.A.,National Center for Genetic Resources Preservation
Journal of Plant Registrations | Year: 2011

Descriptions of new germplasm published in the Journal of Plant Registrations (JPR), and previously in Crop Science, are important vehicles for informing researchers about advances in plant breeding. Launched in 2007, JPR introduced a format that allowed more detailed descriptions of registrations; however, an informal review suggests that further improvements are possible. This paper explores these suggestions. To support our arguments, we assessed the new format by reviewing 234 papers from JPR, focusing on 106 papers (53 each in the old-Crop Science-and new-JPR-formats) for cultivar releases in 14 self-pollinated crops. We examined genealogies (pedigrees), breeding processes, experimental techniques, phenotypes, and genotypes. In the new format, there was more extensive information on the chronology of the breeding process, the expected area of adaptation, experimental techniques, the quantification of phenotypes, and citation of web-based reports. Nonetheless, improvement appeared possible, including by (i) documenting genealogies in databases structured for breeding records; (ii) quantifying the degree of relatedness to other germplasm; (iii) describing the breeding process in tables that include key dates, population types and sizes, and numbers of test environments; (iv) describing adaptation through standardized scales, environmental classifications, or quantitative responses; (v) providing genotypic data; and (vi) providing access to supplementary materials from databases or Internet resources. © Crop Science Society of America. Source

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