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Richard A. Ennos - One of the best experts on this subject based on the ideXlab platform.
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Genetic erosion of barley landrace accessions hordeum vulgare ssp vulgare conserved for different lengths of time in ex situ Gene Banks
Quantitative genetics and breeding methods: the way ahead. Proceedings of the Eleventh Meeting of the EUCARPIA Section Biometrics in Plant Breeding Pa, 2001Co-Authors: H. K. Parzies, W. Spoor, Richard A. EnnosAbstract:To secure a Gene pool for future breeding programmes huge numbers of crop plant accessions have been gathered in Gene Banks. However, at least 50 to 60% of the total Genetic variation of initial collections of barley landraces resides within individual accessions, the remainder between them. Maintenance of accessions held as seed samples in cold stores involves frequent rejuvenation cycles to ensure the viability of seeds. This has the potential to create population bottlenecks, leading to loss of Genetic diversity. Barley landraces from Syria that had been stored for 10, 39 and 72 years were compared with Genetic diversity levels in barley landraces collected recently in Syria. Genetic diversity indices assessed for morphological and isozyme markers showed very significant declines with length of time in storage. Assuming a mean time between rejuvenation of 5.3 years, Gene diversity within accessions decreased on average by approximately 10% with every cycle of rejuvenation. The effective population size N e of 4.8 suggests that only 10 unrelated parent plants contributed seeds to the following Generation. Results may have implications for Gene bank management.
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Genetic diversity of barley landrace accessions (Hordeum vulgare ssp. vulgare) conserved for different lengths of time in ex situ Gene Banks
Heredity, 2000Co-Authors: H. K. Parzies, W. Spoor, Richard A. EnnosAbstract:Genetic diversity of barley landrace accessions ( Hordeum vulgare ssp. vulgare ) conserved for different lengths of time in ex situ Gene Banks
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Genetic diversity of barley landrace accessions hordeum vulgare ssp vulgare conserved for different lengths of time in ex situ Gene Banks
Heredity, 2000Co-Authors: H. K. Parzies, W. Spoor, Richard A. EnnosAbstract:Large numbers of crop plant accessions from all over the world have been amassed in Gene Banks to secure a Gene pool for future breeding programmes. Maintenance of accessions held as seed samples in cold stores involves frequent rejuvenation cycles to ensure the viability of seeds. The practice of rejuvenation by multiplication of a sample of each accession in small field plots has the potential to create population bottlenecks, leading to loss of Genetic diversity and changes in Gene frequencies every rejuvenation cycle. In order to determine whether these undesirable effects occur, Genetic diversity levels were assessed for morphological and isozyme markers within Gene bank accessions of two barley landraces from Syria that had been stored for 10, 40 and 72 years. These were compared with Genetic diversity levels for the same markers in barley landraces collected recently at locations in Syria where they are still under cultivation. Average Gene diversity (H), alleles per locus (A) and percentage polymorphic loci (P(0.01)) all showed very significant declines with length of time in storage, and Genetic differentiation FST among accessions increased over time. If the observed differences in Genetic diversity are caused by Genetic drift in Gene bank accessions rejuvenated every 5.3 years, it was estimated that the effective population size Ne of rejuvenation populations over their period in storage was only 4.7. Implications for Gene bank management are discussed.
Karen J Maschke - One of the best experts on this subject based on the ideXlab platform.
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erratum navigating an ethical patchwork human Gene Banks
Nature Biotechnology, 2005Co-Authors: Karen J MaschkeAbstract:Nat. Biotechnol. 23, 539–545 (2005) In Table 1, page 540, the source of funding for the Singapore Tissue Network was given as the “Singapore Biomedical Research Council, Agency for Science, Technology and Research, Ministry of Health and the Genome Institute of Singapore.” It should have read the “Singapore's Biomedical Research Council of the Agency for Science Technology and Research.
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navigating an ethical patchwork human Gene Banks
Nature Biotechnology, 2005Co-Authors: Karen J MaschkeAbstract:Population Genetics research collaborations are reaching increasingly across national boundaries to access human tissue repositories. Will discrepancies in national policies on informed consent and IP rights hinder progress?
H. K. Parzies - One of the best experts on this subject based on the ideXlab platform.
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Genetic erosion of barley landrace accessions hordeum vulgare ssp vulgare conserved for different lengths of time in ex situ Gene Banks
Quantitative genetics and breeding methods: the way ahead. Proceedings of the Eleventh Meeting of the EUCARPIA Section Biometrics in Plant Breeding Pa, 2001Co-Authors: H. K. Parzies, W. Spoor, Richard A. EnnosAbstract:To secure a Gene pool for future breeding programmes huge numbers of crop plant accessions have been gathered in Gene Banks. However, at least 50 to 60% of the total Genetic variation of initial collections of barley landraces resides within individual accessions, the remainder between them. Maintenance of accessions held as seed samples in cold stores involves frequent rejuvenation cycles to ensure the viability of seeds. This has the potential to create population bottlenecks, leading to loss of Genetic diversity. Barley landraces from Syria that had been stored for 10, 39 and 72 years were compared with Genetic diversity levels in barley landraces collected recently in Syria. Genetic diversity indices assessed for morphological and isozyme markers showed very significant declines with length of time in storage. Assuming a mean time between rejuvenation of 5.3 years, Gene diversity within accessions decreased on average by approximately 10% with every cycle of rejuvenation. The effective population size N e of 4.8 suggests that only 10 unrelated parent plants contributed seeds to the following Generation. Results may have implications for Gene bank management.
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Genetic diversity of barley landrace accessions (Hordeum vulgare ssp. vulgare) conserved for different lengths of time in ex situ Gene Banks
Heredity, 2000Co-Authors: H. K. Parzies, W. Spoor, Richard A. EnnosAbstract:Genetic diversity of barley landrace accessions ( Hordeum vulgare ssp. vulgare ) conserved for different lengths of time in ex situ Gene Banks
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Genetic diversity of barley landrace accessions hordeum vulgare ssp vulgare conserved for different lengths of time in ex situ Gene Banks
Heredity, 2000Co-Authors: H. K. Parzies, W. Spoor, Richard A. EnnosAbstract:Large numbers of crop plant accessions from all over the world have been amassed in Gene Banks to secure a Gene pool for future breeding programmes. Maintenance of accessions held as seed samples in cold stores involves frequent rejuvenation cycles to ensure the viability of seeds. The practice of rejuvenation by multiplication of a sample of each accession in small field plots has the potential to create population bottlenecks, leading to loss of Genetic diversity and changes in Gene frequencies every rejuvenation cycle. In order to determine whether these undesirable effects occur, Genetic diversity levels were assessed for morphological and isozyme markers within Gene bank accessions of two barley landraces from Syria that had been stored for 10, 40 and 72 years. These were compared with Genetic diversity levels for the same markers in barley landraces collected recently at locations in Syria where they are still under cultivation. Average Gene diversity (H), alleles per locus (A) and percentage polymorphic loci (P(0.01)) all showed very significant declines with length of time in storage, and Genetic differentiation FST among accessions increased over time. If the observed differences in Genetic diversity are caused by Genetic drift in Gene bank accessions rejuvenated every 5.3 years, it was estimated that the effective population size Ne of rejuvenation populations over their period in storage was only 4.7. Implications for Gene bank management are discussed.
W. Spoor - One of the best experts on this subject based on the ideXlab platform.
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Genetic erosion of barley landrace accessions hordeum vulgare ssp vulgare conserved for different lengths of time in ex situ Gene Banks
Quantitative genetics and breeding methods: the way ahead. Proceedings of the Eleventh Meeting of the EUCARPIA Section Biometrics in Plant Breeding Pa, 2001Co-Authors: H. K. Parzies, W. Spoor, Richard A. EnnosAbstract:To secure a Gene pool for future breeding programmes huge numbers of crop plant accessions have been gathered in Gene Banks. However, at least 50 to 60% of the total Genetic variation of initial collections of barley landraces resides within individual accessions, the remainder between them. Maintenance of accessions held as seed samples in cold stores involves frequent rejuvenation cycles to ensure the viability of seeds. This has the potential to create population bottlenecks, leading to loss of Genetic diversity. Barley landraces from Syria that had been stored for 10, 39 and 72 years were compared with Genetic diversity levels in barley landraces collected recently in Syria. Genetic diversity indices assessed for morphological and isozyme markers showed very significant declines with length of time in storage. Assuming a mean time between rejuvenation of 5.3 years, Gene diversity within accessions decreased on average by approximately 10% with every cycle of rejuvenation. The effective population size N e of 4.8 suggests that only 10 unrelated parent plants contributed seeds to the following Generation. Results may have implications for Gene bank management.
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Genetic diversity of barley landrace accessions (Hordeum vulgare ssp. vulgare) conserved for different lengths of time in ex situ Gene Banks
Heredity, 2000Co-Authors: H. K. Parzies, W. Spoor, Richard A. EnnosAbstract:Genetic diversity of barley landrace accessions ( Hordeum vulgare ssp. vulgare ) conserved for different lengths of time in ex situ Gene Banks
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Genetic diversity of barley landrace accessions hordeum vulgare ssp vulgare conserved for different lengths of time in ex situ Gene Banks
Heredity, 2000Co-Authors: H. K. Parzies, W. Spoor, Richard A. EnnosAbstract:Large numbers of crop plant accessions from all over the world have been amassed in Gene Banks to secure a Gene pool for future breeding programmes. Maintenance of accessions held as seed samples in cold stores involves frequent rejuvenation cycles to ensure the viability of seeds. The practice of rejuvenation by multiplication of a sample of each accession in small field plots has the potential to create population bottlenecks, leading to loss of Genetic diversity and changes in Gene frequencies every rejuvenation cycle. In order to determine whether these undesirable effects occur, Genetic diversity levels were assessed for morphological and isozyme markers within Gene bank accessions of two barley landraces from Syria that had been stored for 10, 40 and 72 years. These were compared with Genetic diversity levels for the same markers in barley landraces collected recently at locations in Syria where they are still under cultivation. Average Gene diversity (H), alleles per locus (A) and percentage polymorphic loci (P(0.01)) all showed very significant declines with length of time in storage, and Genetic differentiation FST among accessions increased over time. If the observed differences in Genetic diversity are caused by Genetic drift in Gene bank accessions rejuvenated every 5.3 years, it was estimated that the effective population size Ne of rejuvenation populations over their period in storage was only 4.7. Implications for Gene bank management are discussed.
John Bamberg - One of the best experts on this subject based on the ideXlab platform.
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assessing changes in the Genetic diversity of potato Gene Banks 1 effects of seed increase
Theoretical and Applied Genetics, 1997Co-Authors: John Bamberg, Z HuamanAbstract:Effects of Gene bank seed-increases on the Genetic integrity of potato germ plasm is a major concern of Gene bank managers. Thus the Association of Potato Inter-Gene-bank Collaborators (APIC), a consortium of world potato Gene bank leaders, initiated this joint research project using RAPD markers to determine Genetic relationships between increased Generations within accessions. Solanum jamesii (2n=2x=24) and S. fendleri (2n=4x=48), two wild potato species native to North America, were used as plant material. These species represented two major breeding systems found among Solanum species: outcrossing diploids and inbreeding disomic tetraploids, respectively. Comparisons were made between populations one Generation apart and between sister populations Generated from a common source. Fourteen such comparisons within S. jamesii accessions had an average similarity of 96.3%, and 21 such comparisons within S. fendleri accessions had an average similarity of 96.0%. No pairs of populations were significantly different, despite the fact that RAPD markers easily separated all of these very similar accessions within their respective species. Only one of six S. jamesii accessions analyzed showed a significant change in Gene frequencies among Generations. These findings indicate that there has been minimal loss or change of Genetic diversity in ex situ germplasm using the Gene bank techniques standard at NRSP-6 and other world potato Gene Banks.
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assessing changes in the Genetic diversity of potato Gene Banks 2 in situ vs ex situ
Theoretical and Applied Genetics, 1997Co-Authors: John Bamberg, Z Huaman, Alberto Salas, Sandra E VegaAbstract:An important question in the conservation of potato germ plasm is whether germ plasm in the Gene bank, although stable, still represents the in situ populations from which it was collected, sometimes many decades ago. The answer would direct objective decisions regarding the value of re-collections and in situ preservation. The present study was undertaken as a project of the Association of Potato Inter-Gene-bank Collaborators (APIC). It measured Genetic differentiation between potato germ plasm maintained in the US Gene bank for many years and current in situ populations re-collected from the same original sites in the wild. Solanum jamesii and Solanum fendleri from the United States were used as representatives of potato germ plasm. Re-collections were carried out in 1992 at the same locations at which Gene bank-conserved accessions had been collected in 1958 and 1978. RAPD markers revealed significant Genetic differences between Gene bank-conserved and re-collected in situ populations for all seven comparisons of S. jamesii (diploid outcrosser), and 12 of 16 comparisons within S. fendleri (tetraploid inbreeder). The average Genetic similarities were 65.2% for S. jamesii and 80.4% for S. fendleri. Possible explanations and consequences of these unexpectedly large differences are discussed.