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Zosimo Huaman - 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, Zosimo 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 1 effects of seed increase
Theoretical and Applied Genetics, 1997Co-Authors: John Bamberg, Zosimo 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, Alberto Salas, Zosimo Huaman, 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.
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, Zosimo 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 1 effects of seed increase
Theoretical and Applied Genetics, 1997Co-Authors: John Bamberg, Zosimo 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, Alberto Salas, Zosimo Huaman, 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.
Claudia Pombo Sudre - One of the best experts on this subject based on the ideXlab platform.
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Heirloom tomato Gene Bank: assessing Genetic divergence based on morphological, agronomic and molecular data using a Ward-modified location model.
Genetics and Molecular Research, 2009Co-Authors: Leandro Simões Azeredo Gonçalves, Amaral Júnior At, Mina Karasawa, Rosana Rodrigues, Claudia Pombo SudreAbstract:Accessions in Gene Banks need to be characterized and evaluated to determine their Genetic diversity. We made a joint diversity analysis of the tomato Gene Bank of the Universidade Estadual do Norte Fluminense Darcy Ribeiro in Rio de Janeiro State, using the Ward-modified location model. Forty Solanum lycopersicum accessions were characterized and evaluated for 22 morphoagronomic descriptors and 131 random amplified polymorphic DNA markers. Based on the pseudo-F and pseudo-t2 criteria, the optimal number of groups was established as five. Variability within groups was high for
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heirloom tomato Gene Bank assessing Genetic divergence based on morphological agronomic and molecular data using a ward modified location model
Genetics and Molecular Research, 2009Co-Authors: Leandro Simões Azeredo Gonçalves, Mina Karasawa, Robson Andrade Rodrigues, A Do T Amaral, Claudia Pombo SudreAbstract:: Accessions in Gene Banks need to be characterized and evaluated to determine their Genetic diversity. We made a joint diversity analysis of the tomato Gene Bank of the Universidade Estadual do Norte Fluminense Darcy Ribeiro in Rio de Janeiro state, using the Ward-modified location model. Forty Solanum lycopersicum accessions were characterized and evaluated for 22 morphoagronomic descriptors and 131 random amplified polymorphic DNA markers. Based on the pseudo-F and pseudo-t(2) criteria, the optimal number of groups was established as five. Variability within groups was high for both continuous and discrete nominal data. The first two canonical variables explained about 90% of the inter-group variability. Care should be taken in using the Ward-modified location model technique to avoid incorporating excessive and unnecessary markers, which could favor molecular markers when compared with morphoagronomic variables. However, the minimum number of markers is germplasm- dependent and must be recalculated for each new divergence analysis.
Leandro Simões Azeredo Gonçalves - One of the best experts on this subject based on the ideXlab platform.
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Heirloom tomato Gene Bank: assessing Genetic divergence based on morphological, agronomic and molecular data using a Ward-modified location model.
Genetics and Molecular Research, 2009Co-Authors: Leandro Simões Azeredo Gonçalves, Amaral Júnior At, Mina Karasawa, Rosana Rodrigues, Claudia Pombo SudreAbstract:Accessions in Gene Banks need to be characterized and evaluated to determine their Genetic diversity. We made a joint diversity analysis of the tomato Gene Bank of the Universidade Estadual do Norte Fluminense Darcy Ribeiro in Rio de Janeiro State, using the Ward-modified location model. Forty Solanum lycopersicum accessions were characterized and evaluated for 22 morphoagronomic descriptors and 131 random amplified polymorphic DNA markers. Based on the pseudo-F and pseudo-t2 criteria, the optimal number of groups was established as five. Variability within groups was high for
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heirloom tomato Gene Bank assessing Genetic divergence based on morphological agronomic and molecular data using a ward modified location model
Genetics and Molecular Research, 2009Co-Authors: Leandro Simões Azeredo Gonçalves, Mina Karasawa, Robson Andrade Rodrigues, A Do T Amaral, Claudia Pombo SudreAbstract:: Accessions in Gene Banks need to be characterized and evaluated to determine their Genetic diversity. We made a joint diversity analysis of the tomato Gene Bank of the Universidade Estadual do Norte Fluminense Darcy Ribeiro in Rio de Janeiro state, using the Ward-modified location model. Forty Solanum lycopersicum accessions were characterized and evaluated for 22 morphoagronomic descriptors and 131 random amplified polymorphic DNA markers. Based on the pseudo-F and pseudo-t(2) criteria, the optimal number of groups was established as five. Variability within groups was high for both continuous and discrete nominal data. The first two canonical variables explained about 90% of the inter-group variability. Care should be taken in using the Ward-modified location model technique to avoid incorporating excessive and unnecessary markers, which could favor molecular markers when compared with morphoagronomic variables. However, the minimum number of markers is germplasm- dependent and must be recalculated for each new divergence analysis.
Beat Keller - One of the best experts on this subject based on the ideXlab platform.
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Genetic diversity of the pm3 powdery mildew resistance alleles in wheat Gene Bank accessions as assessed by molecular markers
Diversity, 2010Co-Authors: Navreet K. Bhullar, Michael Mackay, Beat KellerAbstract:Genetic resources of crop plants are essential for crop breeding. They are conserved in Gene Banks in form of a large numbers of accessions. These accessions harbor allelic variants of agronomically important Genes and molecular tools allow a rapid assessment of this allelic diversity. Here, we have screened a collection of 1005 wheat Gene Bank accessions for powdery mildew resistance and a molecular characterization for functional alleles at the wheat powdery mildew resistance locus Pm3 was carried out mostly on the resistant accessions. The two analyzed sets of accessions consisted of 733 accessions originating from 20 different countries and 272 landraces originating specifically from Afghanistan. The Pm3 haplotype (indicating the presence of a Pm3-type of Gene, susceptible or resistant) was found to be abundantly present in both sets. The accessions with a Pm3 haplotype were further screened for the presence of the functional Pm3a to Pm3g alleles using allele-specific molecular markers. Pm3b and Pm3c were the most frequently found alleles while the other five alleles were detected only in few accessions (Pm3d, Pm3e, Pm3f) or not detected at all (Pm3a, Pm3g). The data further showed that Pm3b is the major source of Pm3-mediated powdery mildew resistance in wheat accessions from Afghanistan. Susceptible allelic variants of Pm3 were found to be widespread in the wheat Gene pool. The presented molecular analysis of Pm3 alleles in a diverse set of wheat accessions indicates that several alleles have defined geographical origins. Possibly, the widespread Pm3b and Pm3c alleles evolved relatively early in wheat cultivation, allowing their subsequent diffusion into a broad set of wheat lines.
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Wheat Gene Bank accessions as a source of new alleles of the powdery mildew resistance Gene Pm3: a large scale allele mining project
BMC Plant Biology, 2010Co-Authors: Navreet K. Bhullar, Thomas Wicker, Zhiqing Zhang, Beat KellerAbstract:Background: In the last hundred years, the development of improved wheat cultivars has led to the replacement of landraces and traditional varieties by modern cultivars. This has resulted in a decline in the Genetic diversity of agriculturally used wheat. However, the diversity lost in the elite material is somewhat preserved in crop Gene Banks. Therefore, the Gene Bank accessions provide the basis for Genetic improvement of crops for specific traits and and represent rich sources of novel allelic variation. Results: We have undertaken large scale molecular allele mining to isolate new alleles of the powdery mildew resistance Gene Pm3 from wheat Gene Bank accessions. The search for new Pm3 alleles was carried out on a geographically diverse set of 733 wheat accessions originating from 20 countries. Pm3 specific molecular tools as well as classical pathogenicity tests were used to characterize the accessions. Two new functional Pm3 alleles were identified out of the eight newly cloned Pm3 sequences. These new resistance alleles were isolated from accessions from China and Nepal. Thus, the repertoire of functional Pm3 alleles now includes 17 Genes, making it one of the largest allelic series of plant resistance Genes. The combined information on resistant and susceptible Pm3 sequences will allow to study molecular function and specificity of functional Pm3 alleles. Conclusions: This study demonstrates that molecular allele mining on geographically defined accessions is a useful strategy to rapidly characterize the diversity of Gene Bank accessions at a specific Genetic locus of agronomical importance. The identified wheat accessions with new resistance specificities can be used for marker-assisted transfer of the Pm3 alleles to modern wheat lines.