The Genetic Structure of Field Populations of Rhynchosporium secalis from Three Continents Suggests Moderate Gene Flow and Regular Recombination

2000 ◽  
Vol 90 (8) ◽  
pp. 901-908 ◽  
Author(s):  
S. Salamati ◽  
J. Zhan ◽  
J. J. Burdon ◽  
B. A. McDonald
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Genetic Variability ◽  
Gene Diversity ◽  
Regional Scale ◽  
Genetic Distances ◽  
Rflp Markers ◽  
Rhynchosporium Secalis ◽  
Genotype Diversity ◽  
Average Gene

Restriction fragment length polymorphism (RFLP) markers were used to compare the genetic structure of field populations of Rhynchosporium secalis from barley. A total of 543 isolates representing 8 field populations were sampled from Australia, California, Finland, and Norway. Gene and genotype diversity were high in all populations. Nei's average gene diversity across seven RFLP loci was 0.513. Hierarchical gene diversity analysis showed that 9% of the total genetic variability was distributed among continents, 4% was distributed among fields within continents, and 13% was distributed among collection stations within a field. The majority (74%) of genetic variability was distributed within collection areas of approximately 1 m2 within fields. Gene flow appears to be significant on a regional scale but more restricted among continents. Allele frequencies were significantly different at several RFLP loci. Genetic distances were small among populations within regions and large between regions. Pairwise comparisons of genotype diversity in the populations revealed significant differences among populations that were related mainly to differences in sampling strategies. Isolates from Norway and Finland showed a lower copy hybridization pattern with probe pRS26. This probe functioned as a fingerprint probe for the California and Australian isolates. Seven out of the eight populations studied were at gametic equilibrium for RFLP loci, suggesting that R. secalis populations in Norway, Finland, and Australia undergo regular recombination, although a teleomorph has not yet been recognized.

scholarly journals Genetic Structure of Rhynchosporium secalis in Australia

1999 ◽  
Vol 89 (8) ◽  
pp. 639-645 ◽  
Author(s):  
B. A. McDonald ◽  
J. Zhan ◽  
J. J. Burdon
Keyword(s):  
Genetic Structure ◽  
Gene Diversity ◽  
Sampling Site ◽  
Geographic Distance ◽  
South Australia ◽  
Rflp Markers ◽  
Rhynchosporium Secalis ◽  
Fungal Isolates ◽  
Fungal Populations ◽  
Average Gene

Restriction fragment length polymorphism (RFLP) markers were used to determine the genetic structure of Australian field populations of the barley scald pathogen Rhynchosporium secalis. Fungal isolates were collected by hierarchical sampling from five naturally infected barley fields in different geographic locations during a single growing season. Genetic variation was high in Australian R. secalis populations. Among the 265 fungal isolates analyzed, 214 distinct genotypes were identified. Average genotype diversity within a field population was 65% of its theoretical maximum. Nei's average gene diversity across seven RFLP loci was 0.54. The majority (76%) of gene diversity was distributed within sampling site areas measuring ≈1 m2; 19% of gene diversity was distributed among sampling sites within fields; and 5% of gene diversity was distributed among fields. Fungal populations from different locations differed significantly both in allele frequencies and genotype diversities. The degree of genetic differentiation was significantly correlated with geographic distance between populations. Our results suggest that the R. secalis population in Western Australia has a different genetic structure than populations in Victoria and South Australia.

scholarly journals Genetic variability in the peach palm genebank with RAPD markers

2010 ◽  
Vol 10 (3) ◽  
pp. 211-217 ◽  
Author(s):  
Michelly de Cristo Araújo ◽  
Doriane Picanço Rodrigues ◽  
Spartaco Astolfi Filho ◽  
Charles Roland Clement
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Genetic Variability ◽  
Genetic Analysis ◽  
Rapd Markers ◽  
Genetic Distances ◽  
Peach Palm ◽  
Fruit Species ◽  
High Gene ◽  
Average Gene

Peach palm is a native Amazonian fruit species with broad genetic diversity in its wild and domesticated populations. This study completed the molecular characterization and genetic analysis of the accessions in the Peach Palm genebank, Brazil, using RAPD markers. Eight primers generated 132 markers, of which 128 were polymorphic. Average heterozigosity was 0.35, with 95.5% polymorphism. The genetic variability within the landraces (H S) was 0.32, while genetic divergence (G ST) was 0.09 among the four well-represented landraces. The average gene flow was 5.0, with high gene flow between the Solimões and Pampa Hermosa (Nm=10.07), and between the Putumayo and Solimões (Nm=10.73) landraces, all western landraces. The dendrograms of the Nei's and Rogers' genetic distances of the well-represented landraces presented similar groupings to previous analyses, with the Solimões, Putumayo and Pampa Hermosa landraces grouped together in western Amazonia, and distant from the Pará landrace in central and eastern Amazonia.

scholarly journals Genetic structure and gene flow of Eugenia dysenterica natural populations

2005 ◽  
Vol 40 (10) ◽  
pp. 975-980 ◽  
Author(s):  
Maria Imaculada Zucchi ◽  
José Baldin Pinheiro ◽  
Lázaro José Chaves ◽  
Alexandre Siqueira Guedes Coelho ◽  
Mansuêmia Alves Couto ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Variability ◽  
Pearson Correlation ◽  
Natural Populations ◽  
Similarity Index ◽  
Genetic Distances ◽  
Strong Positive Correlation ◽  
Randomly Amplified Polymorphic Dna ◽  
Jaccard Similarity ◽  
Eugenia Dysenterica

This study was carried out to assess the genetic variability of ten "cagaita" tree (Eugenia dysenterica) populations in Southeastern Goiás. Fifty-four randomly amplified polymorphic DNA (RAPD) loci were used to characterize the population genetic variability, using the analysis of molecular variance (AMOVA). A phiST value of 0.2703 was obtained, showing that 27.03% and 72.97% of the genetic variability is present among and within populations, respectively. The Pearson correlation coefficient (r) among the genetic distances matrix (1 - Jaccard similarity index) and the geographic distances were estimated, and a strong positive correlation was detected. Results suggest that these populations are differentiating through a stochastic process, with restricted and geographic distribution dependent gene flow.

scholarly journals Genetic Diversity and Variability in Endangered Pantesco and Two Other Sicilian Donkey Breeds Assessed by Microsatellite Markers

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Salvatore Bordonaro ◽  
Anna Maria Guastella ◽  
Andrea Criscione ◽  
Antonio Zuccaro ◽  
Donata Marletta
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Variability ◽  
Genetic Information ◽  
Gene Diversity ◽  
Genetic Distances ◽  
Conservation Strategies ◽  
Population Structure Analysis ◽  
The Mean ◽  
Differentiation Index

The genetic variability of Pantesco and other two Sicilian autochthonous donkey breeds (Ragusano and Grigio Siciliano) was assessed using a set of 14 microsatellites. The main goals were to describe the current differentiation among the breeds and to provide genetic information useful to safeguard the Pantesco breed as well as to manage Ragusano and Grigio Siciliano. In the whole sample, that included 108 donkeys representative of the three populations, a total of 85 alleles were detected. The mean number of alleles was lower in Pantesco (3.7), than in Grigio Siciliano and Ragusano (4.4 and 5.9, resp.). The three breeds showed a quite low level of gene diversity (He) ranging from 0.471 in Pantesco to 0.589 in Grigio. The overall genetic differentiation index (Fst) was quite high; more than 10% of the diversity was found among breeds. Reynolds’ () genetic distances, correspondence, and population structure analysis reproduced the same picture, revealing that, (a) Pantesco breed is the most differentiated in the context of the Sicilian indigenous breeds, (b) within Ragusano breed, two well-defined subgroups were observed. This information is worth of further investigation in order to provide suitable data for conservation strategies.

scholarly journals Isozyme and RAPD studies in Prosopis glandulosa and P. Velutina (Leguminosae, Mimosoideae)

2000 ◽  
Vol 23 (3) ◽  
pp. 639-648 ◽  
Author(s):  
Cecilia Bessega ◽  
Beatriz O. Saidman ◽  
Juan C. Vilardi
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Genetic Variability ◽  
Genetic Differentiation ◽  
Rapd Markers ◽  
Random Amplified Polymorphic Dna ◽  
Mantel Test ◽  
Prosopis Glandulosa ◽  
Geographical Distance ◽  
Taxonomic Studies

Allozyme and random amplified polymorphic DNA (RAPD) techniques have been compared for their usefulness for genetic and taxonomic studies in Prosopis glandulosa and P. velutina populations. Isozymes and RAPDs yielded similarly high estimates of genetic variability. Genetic structure and differentiation were analyzed through non-hierarchical Wright's F DT. For all populations considered, both markers produced low gene flow (Nm < 1) estimates. When only P. glandulosa populations were analyzed, isozyme data yielded higher gene flow estimates (Nm > 1), in agreement with that expected for conspecific populations. However, in RAPD data the expected reduction in F DT and the increase in Nm were not observed. Correlation between F DT and geographical distance matrices (Mantel test) for all populations was significant (P = 0.02) when based on isozymes, but not so (P = 0.33) when based on RAPDs. No significant associations among genetic and geographical or climatic variables were observed. Two isoenzyme systems (GOT and PRX) enabled us to distinguish between P. glandulosa and P. velutina, but no diagnostic band for recognition of populations or species studied here were detected by RAPD. However, RAPD markers showed higher values for genetic differentiation among conspecific populations of P. glandulosa and a lower coefficient of variation than those obtained from isozymes.

scholarly journals Analysis of Genetic Diversity within Nepalese Maize Populations Using SSR Markers

1970 ◽  
Vol 11 ◽  
pp. 1-8 ◽  
Author(s):  
Dil Bahadur Gurung ◽  
Maria Luz C George ◽  
Quirino D Dela Cruz
Keyword(s):  
Genetic Diversity ◽  
Ssr Markers ◽  
Gene Diversity ◽  
Genetic Distances ◽  
Maize Breeding ◽  
Maize Populations ◽  
Maize Varieties ◽  
Ssr Loci ◽  
Average Gene ◽  
Hybrid Maize

Information on genetic diversity and relationships among breeding materials is necessary for hybrid maize breeding. Four open-pollinated varieties were analyzed using SSR markers to determine the genetic diversity within the varieties. In each variety, 15 individuals were genotyped with 30 SSR markers. Average heterozygosity percentage of the varieties was 45.07%, ranging from 35.23% in Rampur Composite to 54.64% in Khumal Yellow, indicating the higher level of heterozygosity in these two varieties. An average PIC value across all the polymorphic SSR loci was 0.50; which ranged from 0.47 in Manakamana-2 to 0.52 in Khumal Yellow and Arun-4. At the genotype level, the range was from 0.07 in umc1161 to 0.84 in umc1136. The total number of alleles detected was 415 for 30 SSR markers in 60 genotypes. The unique and common alleles detected respectively were 27 and 71. The average number of alleles per locus was 3.45 among the varieties, ranging from 3.21in Manakamana-2 to 3.76 in Khumal Yellow. Average gene diversity across the varieties was 0.54 and ranged from 0.51 in Manakamana-2 to 0.56 in Khumal Yellow and Arun-4. The genetic similarity coefficient of all individuals among the varieties was seen at 0.35.The MRD values were higher between Arun-4 and Manakamana-2 (0.290) and low between Khumal Yellow and Rampur Composite (0.221). Estimate of genetic distances among the varieties showed that Rampur Composite, Khumal Yellow, and Manakamana-2 were closely related sharing the similar genetic backgrounds, whereas Arun-4 was genetically more distantly related. Efforts are being made for the development and evaluation of inbred lines from these distantly related maize varieties for developing high yielding maize hybrids. Key Words: genetic diversity; maize hybrid; SSR markers DOI: 10.3126/njst.v11i0.4082Nepal Journal of Science and Technology 11 (2010) 1-8

scholarly journals Genetic Variability and Distribution of Mating Type Alleles in Field Populations of Leptosphaeria maculans from France

2006 ◽  
Vol 72 (1) ◽  
pp. 185-191 ◽  
Author(s):  
Lilian Gout ◽  
Maria Eckert ◽  
Thierry Rouxel ◽  
Marie-Hélène Balesdent
Keyword(s):  
Genetic Structure ◽  
Genetic Variability ◽  
Mating Type ◽  
Gene Diversity ◽  
Spatial Scales ◽  
Leptosphaeria Maculans ◽  
Genotypic Diversity ◽  
Stem Canker ◽  
Field Population ◽  
Sexual And Asexual Reproduction

ABSTRACT Leptosphaeria maculans is the most ubiquitous fungal pathogen of Brassica crops and causes the devastating stem canker disease of oilseed rape worldwide. We used minisatellite markers to determine the genetic structure of L. maculans in four field populations from France. Isolates were collected at three different spatial scales (leaf, 2-m2 field plot, and field) enabling the evaluation of spatial distribution of the mating type alleles and of genetic variability within and among field populations. Within each field population, no gametic disequilibrium between the minisatellite loci was detected and the mating type alleles were present at equal frequencies. Both sexual and asexual reproduction occur in the field, but the genetic structure of these populations is consistent with annual cycles of randomly mating sexual reproduction. All L. maculans field populations had a high level of gene diversity (H = 0.68 to 0.75) and genotypic diversity. Within each field population, the number of genotypes often was very close to the number of isolates. Analysis of molecular variance indicated that >99.5% of the total genetic variability was distributed at a small spatial scale, i.e., within 2-m2 field plots. Population differentiation among the four field populations was low (GST < 0.02), suggesting a high degree of gene exchange between these populations. The high gene flow evidenced here in French populations of L. maculans suggests a rapid countrywide diffusion of novel virulence alleles whenever novel resistance sources are used.

Genetic diversity between Italian and Greek buffalo populations

2001 ◽  
Vol 29 ◽  
pp. 31-40 ◽  
Author(s):  
B. Moioli ◽  
A. Georgoudis ◽  
F. Napolitano ◽  
G. Catillo ◽  
S. Lucioli ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Diversity ◽  
Genetic Distances ◽  
Allele Frequency Distribution ◽  
Average Gene Diversity ◽  
Polymorphic Microsatellite ◽  
Average Gene ◽  
Degree Of Differentiation ◽  
Two Populations ◽  
Global Project

SummaryThe present study is a first step of a global project aiming at the estimation of the genetic distances and relationships among buffalo breeds and sub-populations and the investigation of the production potential and adaptability of different buffalo genotypes in various environments.Genetic diversity of Italian and Greek buffalo populations was estimated on the basis of allele frequencies at nine polymorphic microsatellite loci: CSSM43, CSSM38, DRB3, D21S4, CYP21, CSSM47, CSSM60, CSSM36 and CSSM33. The number of detected alleles per locus varied from two (D21S4) to thirteen (CSSM47). Allele frequency distribution was similar in the two populations, which have the same alleles at the highest frequency at all loci, except loci CSSM47 and CSSM60. Average gene diversity over all loci was 0.60. Across-loci average gene diversity increased with the number of alleles. Observed average heterozygosity was 0.167 and 0.177 in the Italian and Greek populations, respectively. The degree of differentiation between Italian and Greek buffalo was moderate and estimated at 0.021 ± 0.009.

Structure et variabilité génétique de populations d'épinette noire (Piceamariana (Mill.) B.S.P.) dans la zone hémiarctique du Nouveau-Québec

1987 ◽  
Vol 17 (9) ◽  
pp. 1006-1012 ◽  
Author(s):  
Mireille Desponts ◽  
Jean-Pierre Simon
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Genetic Variability ◽  
Gel Electrophoresis ◽  
Black Spruce ◽  
Geographic Isolation ◽  
Marginal Populations ◽  
Isolated Populations ◽  
Subarctic Region ◽  
Enzyme Systems

The genetic structure of five populations of black spruce located at l'Eau Claire Lake, in the subarctic region of Nouveau-Québec, were analysed by acrylamide gel electrophoresis of seven enzyme systems. The analysis of 25 loci disclosed an average polymorphism of 0.80 and a level of heterozygosity of 0.351. Results indicate that there is no loss of genetic variability in these marginal populations that could be attributed to genetic drift. Data based on Wright's statistics indicate an excess of heterozygotes for most loci. Populations share the same alleles at most loci and are only slightly differentiated from each other (Fst = 0.06). Results suggest that gene flow between these isolated populations remains sufficiently high to override the effect of geographic isolation.

Landscape genetic structure of Pinus banksiana: allozyme variation

2001 ◽  
Vol 79 (8) ◽  
pp. 871-878 ◽  
Author(s):  
Cuauhtemoc Saenz-Romero ◽  
Raymond P Guries ◽  
Andrew I Monk
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Genetic Structure ◽  
Pinus Banksiana ◽  
Allozyme Variation ◽  
Jack Pine ◽  
Genetic Distances ◽  
Jack Pine Forests ◽  
Forest Mosaic ◽  
Landscape Genetic

Many of Wisconsin's jack pine forests originated following fire or agricultural abandonment creating a forest mosaic fragmented by a history of disturbance and past land use. The extent and patterning of genetic diversity at a landscape scale (30 × 30 km) was investigated in 82 natural Pinus banksiana Lamb. (jack pine) stands in Wisconsin using 14 polymorphic allozymes. Most measures of genetic diversity and overall allelic frequencies varied little among these stands, and Reynolds' (coancestry) genetic distances were small (mean = 0.026). Genetic differentiation among stands was limited but significant ([Formula: see text]ST = 0.022). Gene flow (Nm) is extensive, estimated to be slightly more than 11 migrants per generation. Autocorrelation analysis provided evidence for a weak pattern of genetic structure at a few loci with a spatial scale of 8–15 km. However, when all loci were examined together the populations did not present a clear spatial pattern across the landscape, probably because of extensive gene flow among stands.Key words: jack pine, allozymes, genetic diversity, population differentiation, spatial autocorrelation, gene flow.

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