The Experts below are selected from a list of 156 Experts worldwide ranked by ideXlab platform
Ludwig Triest - One of the best experts on this subject based on the ideXlab platform.
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use of rapd markers to estimate hybridization in Salix alba and Salix fragilis
2016Co-Authors: Ludwig Triest, Bart De Greef, Dirk Vanden Bossche, Ruth De Bondt, Jos Van SlyckenAbstract:The polyploid Salix alba - Salix fragilis hybrid complex is rather difficult to study when using only morphological characters. Most of the features have a low diagnostic value for identifying the hybrids, introgression patterns and population genetic structure. Molecular data from isozymes and random amplified polymorphic DNA's (RAPD) previously have been investigated in several case studies on willows from Belgium. A thorough screening with 16 decamer primers for PCR based polymorphism revealed 95 amplification products at the species level. On the basis of genetic distances, clustering and ordination analysis, a reference system for identification of clones has been established. The proposed reference system was previously checked against additional European samples of putative pure species to ensure its reliability and is currently applied to elucidate patterns of hybridization on a regional scale as well as on a local scale, this in the context of conservation genetics. The RAPD analysis suggests that hybridization is not a dominating process and that both species have kept their gene pools well separated.
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linkage mapping in tetraploid willows segregation of molecular markers and estimation of linkage phases support an allotetraploid structure for Salix alba x Salix fragilis interspecific hybrids
Heredity, 2003Co-Authors: Gianni Barcaccia, Ludwig Triest, Stefano Meneghetti, Emidio Albertini, Margherita LucchinAbstract:Salix albaSalix fragilis complex includes closely related dioecious polyploid species, which are obligate outcrossers. Natural populations of these willows and their hybrids are represented by a mixture of highly heterozygous genotypes sharing a common gene pool. Since nothing is known about their genomic constitution, tetraploidy (2n ¼ 4x ¼ 76) in willow species makes basic and applied genetic studies difficult. We have used a two-way pseudotestcross strategy and single- dose markers (SDMs) to construct the first linkage maps for both pistillate and staminate willows. A total of 242 amplified fragment length polymorphisms (AFLPs) and 50 selective amplifications of microsatellite polymorphic loci (SAMPL) markers, which showed 1:1 segregation in the F1 mapping populations, were used in linkage analysis. In S. alba ,7 3 maternal and 48 paternal SDMs were mapped to 19 and 16 linkage groups covering 708 and 339 cM, respectively. In S. fragilis, 13 maternal and 33 paternal SDMs were mapped in six and 14 linkage groups covering 98 and 321 cM, respectively. For most cosegregation groups, a comparable number of markers linked in coupling and repulsion was identified. This finding suggests that most of chromosomes pair preferentially as occurs in allotetraploid species exhibit- ing disomic inheritance. The detection of 10 pairs of marker alleles from single parents showing codominant inheritance strengthens this hypothesis. The fact that, of the 1122 marker loci identified in the two male and female parents, the vast majority (77.5%) were polymorphic and as few as 22.5% were shared between parental species highlight that S. alba and S. fragilis genotypes are differentiated. The highly difference between S. alba- and S. fragilis-specific markers found in both parental combinations (on average, 65.3 vs 34.7%, respectively) supports the (phylogenetic) hypothesis that S. fragilis is derived from S. alba-like progenitors. Heredity (2003) 90, 169-180. doi:10.1038/sj.hdy.6800213
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hybridization in staminate and pistillate Salix alba and s fragilis salicaceae morphology versus rapds
Plant Systematics and Evolution, 2001Co-Authors: Ludwig TriestAbstract:The polyploid Salix alba–Salix fragilis hybrid complex is rather difficult to study when using only morphological characters. Most of the characters have a low diagnostic value for unambiguously identifying the hybrids, introgression patterns and population structures. Morphology and molecular variation determined with random amplified polymorphic DNAs (RAPDs) were investigated in a set of staminate and pistillate willows from Belgium. A thorough screening of possible RAPD markers was done to select homologous amplification products. The selected amplified products proved to be useful in a principal coordinate analysis for the identification of individuals from a morphological continuum comprising presumed pure species and introgressants. The RAPD based identity of the individuals or clones was checked against those based on morphological characters. A correspondence analysis indicated that all pubescence related characters were associated but separated from the size related characters. The RAPDs also revealed that the S. fragilis genotypes mainly consisted of staminate individuals whereas most of the pistillate trees belonged to the S. alba genotype cluster. It was suggested that both species have kept their gene pools well separated and that morphologically intermediate plants are not necessarily genetically intermediate.
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rapd of controlled crosses and clones from the field suggests that hybrids are rare in the Salix alba Salix fragilis complex
Heredity, 2000Co-Authors: Ludwig Triest, Bart De Greef, Ruth De Bondt, Jos Van SlyckenAbstract:The polyploid Salix alba–Salix fragilis hybrid complex is rather difficult to study when using only morphological characters. Most of the features have a low diagnostic value for unambiguously identifying the hybrids, introgression patterns and population structures, though morphological traits have proved to be useful in making a hybrid index. Morphology and molecular variation from RAPDs were investigated in several case studies on willows from Belgium. A thorough screening of full-sib progenies of interspecific controlled crosses was made to select homologous amplification products. The selected amplified products proved to be useful in a principal coordinate analysis for the estimation of variability of hybrid progenies. On the basis of genetic similarities and ordination analysis, a method for the identification of clones in the field was established using presumed pure species and presumed introgressants. The chosen reference clones were checked against additional European samples of putative pure species to ensure the reliability of the method beyond a regional scale. The RAPDs suggested that both species have kept their gene pools well separated and that hybridization actually does not seem to be a dominating process. The observation that molecular markers do not always follow the morphological traits or allozyme data is discussed.
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variation and inheritance of isozyme loci in controlled crosses of Salix alba and Salix fragilis
Silvae Genetica, 1998Co-Authors: Ludwig Triest, B Degreef, M Dhaeseleer, J Vanslycken, Ghizlane Echchgadda, Els CoartAbstract:The expression of polymorphism in different enzyme systems was investigated in clones of Salix alba and Salix fragilis. Dormant buds and sprouting leaves were used but only few consistent enzyme patterns could be revealed and were retained for further testing. When considering all obtained enzyme profiles, a total of 43 genes could be scored, of which 15 may show polymorphism within S. alba or S. fragilis. Polymorphism was observed in aconitase, alcohol dehydrogenase, phosphoglucomutase, leucine aminopeptidase, glutamate oxaloacetate transaminase, β-esterase, isocitrate dehydrogenase, glutamate dehydrogenase, peroxidase, superoxide dismutase and xanthine dehydrogenase. The genetic basis of phosphoglucomutase, leucine aminopeptidase glutamate oxaloacetate transaminase and shikimate dehydrogenase could be inferred directly from intraspecific and interspecific controlled crosses. Full-sib progeny showed mendelian segregation for lap-1 and most of the pgm-2 alleles, whereas in other genes such as β-est-1 and adh-2, there was only fixed heterozygosity. Most of the isozymes can not be used directly as good markers at species level. Differences between S. alba and S. fragilis are mainly in the allele frequencies. The number of genes and alleles of the polyploid S. alba and S. fragilis were compared to those of earlier reports on diploid Salix species. The polyploids contain less genetic diversity in their soluble enzymes than the diploids. Duplicated genes did not led to a substantial increase in the heterozygosity levels in the S. alba-S. fragilis complex.
Margherita Lucchin - One of the best experts on this subject based on the ideXlab platform.
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genetic characterization of Salix alba l and Salix fragilis l by means of different pcr derived marker systems
Plant Biosystems, 2007Co-Authors: Stefano Meneghetti, Paolo Paiero, Gianni Barcaccia, Margherita LucchinAbstract:Abstract Salix alba L. and Salix fragilis L. are two closely related willow species whose phenotypic features, showing a large and continuous variation, have a low diagnostic value for identifying pure species and interspecific hybrids. In this paper, the effectiveness of different multilocus PCR-based molecular markers, such as I-SSRs, RAPDs and AFLPs in detecting genetic polymorphisms able to discriminate the two willow species was evaluated by analysing a set of 12 reference samples. Three genetic similarity indexes, Dice, Jaccard and Simple Matching coefficient, were used for all possible pairwise comparisons of individuals, revealing the same trend of variation within and between species when different marker systems were used. Cluster analysis, based on Dice genetic similarity coefficient, clustered the individuals of S. alba and S. fragilis into two distinct subgroups, indicating that the gene pools are well differentiated. Moreover, a number of private alleles for each marker system allowed the di...
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linkage mapping in tetraploid willows segregation of molecular markers and estimation of linkage phases support an allotetraploid structure for Salix alba x Salix fragilis interspecific hybrids
Heredity, 2003Co-Authors: Gianni Barcaccia, Ludwig Triest, Stefano Meneghetti, Emidio Albertini, Margherita LucchinAbstract:Salix albaSalix fragilis complex includes closely related dioecious polyploid species, which are obligate outcrossers. Natural populations of these willows and their hybrids are represented by a mixture of highly heterozygous genotypes sharing a common gene pool. Since nothing is known about their genomic constitution, tetraploidy (2n ¼ 4x ¼ 76) in willow species makes basic and applied genetic studies difficult. We have used a two-way pseudotestcross strategy and single- dose markers (SDMs) to construct the first linkage maps for both pistillate and staminate willows. A total of 242 amplified fragment length polymorphisms (AFLPs) and 50 selective amplifications of microsatellite polymorphic loci (SAMPL) markers, which showed 1:1 segregation in the F1 mapping populations, were used in linkage analysis. In S. alba ,7 3 maternal and 48 paternal SDMs were mapped to 19 and 16 linkage groups covering 708 and 339 cM, respectively. In S. fragilis, 13 maternal and 33 paternal SDMs were mapped in six and 14 linkage groups covering 98 and 321 cM, respectively. For most cosegregation groups, a comparable number of markers linked in coupling and repulsion was identified. This finding suggests that most of chromosomes pair preferentially as occurs in allotetraploid species exhibit- ing disomic inheritance. The detection of 10 pairs of marker alleles from single parents showing codominant inheritance strengthens this hypothesis. The fact that, of the 1122 marker loci identified in the two male and female parents, the vast majority (77.5%) were polymorphic and as few as 22.5% were shared between parental species highlight that S. alba and S. fragilis genotypes are differentiated. The highly difference between S. alba- and S. fragilis-specific markers found in both parental combinations (on average, 65.3 vs 34.7%, respectively) supports the (phylogenetic) hypothesis that S. fragilis is derived from S. alba-like progenitors. Heredity (2003) 90, 169-180. doi:10.1038/sj.hdy.6800213
Jos Van Slycken - One of the best experts on this subject based on the ideXlab platform.
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use of rapd markers to estimate hybridization in Salix alba and Salix fragilis
2016Co-Authors: Ludwig Triest, Bart De Greef, Dirk Vanden Bossche, Ruth De Bondt, Jos Van SlyckenAbstract:The polyploid Salix alba - Salix fragilis hybrid complex is rather difficult to study when using only morphological characters. Most of the features have a low diagnostic value for identifying the hybrids, introgression patterns and population genetic structure. Molecular data from isozymes and random amplified polymorphic DNA's (RAPD) previously have been investigated in several case studies on willows from Belgium. A thorough screening with 16 decamer primers for PCR based polymorphism revealed 95 amplification products at the species level. On the basis of genetic distances, clustering and ordination analysis, a reference system for identification of clones has been established. The proposed reference system was previously checked against additional European samples of putative pure species to ensure its reliability and is currently applied to elucidate patterns of hybridization on a regional scale as well as on a local scale, this in the context of conservation genetics. The RAPD analysis suggests that hybridization is not a dominating process and that both species have kept their gene pools well separated.
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rapd of controlled crosses and clones from the field suggests that hybrids are rare in the Salix alba Salix fragilis complex
Heredity, 2000Co-Authors: Ludwig Triest, Bart De Greef, Ruth De Bondt, Jos Van SlyckenAbstract:The polyploid Salix alba–Salix fragilis hybrid complex is rather difficult to study when using only morphological characters. Most of the features have a low diagnostic value for unambiguously identifying the hybrids, introgression patterns and population structures, though morphological traits have proved to be useful in making a hybrid index. Morphology and molecular variation from RAPDs were investigated in several case studies on willows from Belgium. A thorough screening of full-sib progenies of interspecific controlled crosses was made to select homologous amplification products. The selected amplified products proved to be useful in a principal coordinate analysis for the estimation of variability of hybrid progenies. On the basis of genetic similarities and ordination analysis, a method for the identification of clones in the field was established using presumed pure species and presumed introgressants. The chosen reference clones were checked against additional European samples of putative pure species to ensure the reliability of the method beyond a regional scale. The RAPDs suggested that both species have kept their gene pools well separated and that hybridization actually does not seem to be a dominating process. The observation that molecular markers do not always follow the morphological traits or allozyme data is discussed.
Stefano Meneghetti - One of the best experts on this subject based on the ideXlab platform.
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genetic characterization of Salix alba l and Salix fragilis l by means of different pcr derived marker systems
Plant Biosystems, 2007Co-Authors: Stefano Meneghetti, Paolo Paiero, Gianni Barcaccia, Margherita LucchinAbstract:Abstract Salix alba L. and Salix fragilis L. are two closely related willow species whose phenotypic features, showing a large and continuous variation, have a low diagnostic value for identifying pure species and interspecific hybrids. In this paper, the effectiveness of different multilocus PCR-based molecular markers, such as I-SSRs, RAPDs and AFLPs in detecting genetic polymorphisms able to discriminate the two willow species was evaluated by analysing a set of 12 reference samples. Three genetic similarity indexes, Dice, Jaccard and Simple Matching coefficient, were used for all possible pairwise comparisons of individuals, revealing the same trend of variation within and between species when different marker systems were used. Cluster analysis, based on Dice genetic similarity coefficient, clustered the individuals of S. alba and S. fragilis into two distinct subgroups, indicating that the gene pools are well differentiated. Moreover, a number of private alleles for each marker system allowed the di...
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linkage mapping in tetraploid willows segregation of molecular markers and estimation of linkage phases support an allotetraploid structure for Salix alba x Salix fragilis interspecific hybrids
Heredity, 2003Co-Authors: Gianni Barcaccia, Ludwig Triest, Stefano Meneghetti, Emidio Albertini, Margherita LucchinAbstract:Salix albaSalix fragilis complex includes closely related dioecious polyploid species, which are obligate outcrossers. Natural populations of these willows and their hybrids are represented by a mixture of highly heterozygous genotypes sharing a common gene pool. Since nothing is known about their genomic constitution, tetraploidy (2n ¼ 4x ¼ 76) in willow species makes basic and applied genetic studies difficult. We have used a two-way pseudotestcross strategy and single- dose markers (SDMs) to construct the first linkage maps for both pistillate and staminate willows. A total of 242 amplified fragment length polymorphisms (AFLPs) and 50 selective amplifications of microsatellite polymorphic loci (SAMPL) markers, which showed 1:1 segregation in the F1 mapping populations, were used in linkage analysis. In S. alba ,7 3 maternal and 48 paternal SDMs were mapped to 19 and 16 linkage groups covering 708 and 339 cM, respectively. In S. fragilis, 13 maternal and 33 paternal SDMs were mapped in six and 14 linkage groups covering 98 and 321 cM, respectively. For most cosegregation groups, a comparable number of markers linked in coupling and repulsion was identified. This finding suggests that most of chromosomes pair preferentially as occurs in allotetraploid species exhibit- ing disomic inheritance. The detection of 10 pairs of marker alleles from single parents showing codominant inheritance strengthens this hypothesis. The fact that, of the 1122 marker loci identified in the two male and female parents, the vast majority (77.5%) were polymorphic and as few as 22.5% were shared between parental species highlight that S. alba and S. fragilis genotypes are differentiated. The highly difference between S. alba- and S. fragilis-specific markers found in both parental combinations (on average, 65.3 vs 34.7%, respectively) supports the (phylogenetic) hypothesis that S. fragilis is derived from S. alba-like progenitors. Heredity (2003) 90, 169-180. doi:10.1038/sj.hdy.6800213
R.a. King - One of the best experts on this subject based on the ideXlab platform.
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characterisation and inheritance of nuclear microsatellite loci for use in population studies of the allotetraploid Salix alba Salix fragilis complex
Tree Genetics & Genomes, 2010Co-Authors: A Karp, Sarah L. Harris, R.a. King, Jacqueline H A BarkerAbstract:We present nine polymorphic di- and tri-nucleotide repeat nuclear microsatellite markers selected specifically for their use in high throughput studies concerning the dioecious allotetraploid Salix alba-Salix fragilis willow complex. These taxa and their hybrids are difficult to discriminate using morphological characters. Thus, multiplex reactions were developed for these microsatellite loci and their effectiveness to distinguish individuals, especially hybrids, and their inheritance patterns in controlled crosses were determined. All loci displayed disomic-monogenic inheritance which allowed for the genotype data to be analysed as for a diploid organism. The nine loci produced a total of 67 alleles (mean, 7.4 alleles per locus; range, 3-11 alleles) in a reference panel of 57 individuals from two germplasm collections and natural populations. Gene diversity values (as measured by the expected heterozygosity) ranged from 0.000-0.820. A total of 53 distinct multilocus genotypes were observed, and ordination analysis revealed three separate clusters corresponding to S. alba, S. fragilis and hybrids. The microsatellite loci described here will be used in population genetic studies to investigate genetic variation, gene flow, levels of hybridisation and the extent of introgression in natural populations of the S. alba-S. fragilis complex. They are also useful for clonal identification, conservation and sustainable management of germplasm collections, genetic mapping and the selection of individuals and/or certification of controlled crosses for breeding programmes.
