The population genetics of Septoria tritici (teleomorph Mycosphaerella graminicola)

1995 ◽  
Vol 73 (S1) ◽  
pp. 292-301 ◽  
Author(s):  
B. A. McDonald ◽  
R. E. Pettway ◽  
R. S. Chen ◽  
J. M. Boeger ◽  
J. P. Martinez
Keyword(s):  
Population Genetics ◽  
Genetic Markers ◽  
Population Biology ◽  
Mycosphaerella Graminicola ◽  
Septoria Tritici ◽  
Gametic Disequilibrium ◽  
Length Polymorphisms ◽  
Wheat Gene ◽  
High Degree ◽  
Analytical Tools

The DNA-based markers of molecular genetics were combined with the analytical tools of population genetics to learn about the population biology of the wheat pathogen Mycosphaerella graminicola. DNA-based genetic markers, including restriction fragment length polymorphisms in nuclear and mitochondrial DNA, DNA fingerprints, and electrophoretic karyotypes were used in combination to show that the amount and distribution of genetic variation within and among field populations of M. graminicola is similar around the world. Measures of gametic disequilibrium suggested that the sexual stage of reproduction has a more significant impact on the genetic structure of M. graminicola populations than asexual reproduction. A field experiment conducted over a 3-year period showed that populations had a high degree of genetic stability over time. The potential effects of selection were quantified in a cultivar mixture experiment with four wheat cultivars that varied in resistance to M. graminicola. In combination, these experiments demonstrated the utility of selectively neutral genetic markers to elucidate the population genetics of fungi. Key words: genetic diversity, wheat, gene flow, RFLPs, DNA fingerprinting.

scholarly journals Measuring Immigration and Sexual Reproduction in Field Populations of Mycosphaerella graminicola

1998 ◽  
Vol 88 (12) ◽  
pp. 1330-1337 ◽  
Author(s):  
J. Zhan ◽  
C. C. Mundt ◽  
B. A. McDonald
Keyword(s):  
Genetic Structure ◽  
Sexual Reproduction ◽  
Random Mating ◽  
Growing Season ◽  
Mycosphaerella Graminicola ◽  
Dna Fingerprints ◽  
Gametic Disequilibrium ◽  
Late Season ◽  
Length Polymorphisms ◽  
Restriction Fragment Length

A field experiment was conducted to determine the relative contributions of immigration and sexual reproduction to the genetic structure of Mycosphaerella graminicola populations during the course of an epidemic. The genetic structure of M. graminicola populations sampled from wheat plots inoculated artificially with 10 isolates was compared with control plots infected naturally by airborne ascospores. Restriction fragment length polymorphisms (RFLPs) were used to test the randomness of associations among loci, and DNA fingerprints were used to identify clones. All isolates in the control plots had unique genotypes and RFLP loci were at gametic equilibrium, findings consistent with random mating. The proportion of isolates in the inoculated plots with DNA fingerprints that differed from the 10 inoculated isolates increased from 3% in the early to 39 and 34% in the mid- and late season, respectively. The degree of gametic disequilibrium was higher in the mid-season than in the late-season population. By the end of the growing season, we estimate that 66% of the isolates in the inoculated plots were asexual progeny of the 10 inoculated isolates, 10% were immigrants, and 24% were sexual recombinants. The proportion of infections caused by ascospores increased over the growing season.

Microsatellite markers provide evidence for sexual reproduction of Mycosphaerella graminicola in Saskatchewan

Genome ◽  
2004 ◽  
Vol 47 (5) ◽  
pp. 789-794 ◽  
Author(s):  
M Razavi ◽  
G R Hughes
Keyword(s):  
Genetic Diversity ◽  
Genetic Variability ◽  
Sexual Reproduction ◽  
Primary Source ◽  
Mycosphaerella Graminicola ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Allelic Series ◽  
Evolutionary Potential ◽  
Wheat Field

This study examined the genetic structure of a Saskatchewan population of Mycosphaerella graminicola, cause of the foliar disease Septoria tritici blotch of wheat. Such knowledge is valuable for understanding the evolutionary potential of this pathogen and for developing control strategies based on host resistance. Nine pairs of single-locus microsatellite primers were used to analyze the genomic DNA of 90 isolates of M. graminicola that were collected using a hierarchical sampling procedure from different locations, leaves, and lesions within a wheat field near Saskatoon. Allelic series at eight different loci were detected. The number of alleles per locus ranged from one to five with an average of three alleles per locus. Genetic diversity values ranged from 0.04 to 0.67. Partitioning the total genetic variability into within- and among-location components revealed that 88% of the genetic variability occurred within locations, i.e., within areas of 1 m2, but relatively little variability occurred among locations. Low variability among locations and a high degree of variability within locations would result if the primary source of inoculum was airborne ascospores, which would be dispersed uniformly within the field. This finding was confirmed by gametic disequilibrium analysis and suggests that the sexual reproduction of M. graminicola occurs in Saskatchewan.Key words: Mycosphaerella graminicola, SSR markers, sexual reproduction, genetic diversity.

scholarly journals mixIndependR: a R package for statistical independence testing of loci in database of multi-locus genotypes

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Bing Song ◽  
August E. Woerner ◽  
John Planz
Keyword(s):  
Population Genetics ◽  
Linkage Disequilibrium ◽  
Genetic Markers ◽  
Software Package ◽  
Tandem Repeats ◽  
Population Data ◽  
Real Data ◽  
R Package ◽  
Nucleotide Polymorphisms ◽  
Mutual Independence

Abstract Background Multi-locus genotype data are widely used in population genetics and disease studies. In evaluating the utility of multi-locus data, the independence of markers is commonly considered in many genomic assessments. Generally, pairwise non-random associations are tested by linkage disequilibrium; however, the dependence of one panel might be triplet, quartet, or other. Therefore, a compatible and user-friendly software is necessary for testing and assessing the global linkage disequilibrium among mixed genetic data. Results This study describes a software package for testing the mutual independence of mixed genetic datasets. Mutual independence is defined as no non-random associations among all subsets of the tested panel. The new R package “mixIndependR” calculates basic genetic parameters like allele frequency, genotype frequency, heterozygosity, Hardy–Weinberg equilibrium, and linkage disequilibrium (LD) by mutual independence from population data, regardless of the type of markers, such as simple nucleotide polymorphisms, short tandem repeats, insertions and deletions, and any other genetic markers. A novel method of assessing the dependence of mixed genetic panels is developed in this study and functionally analyzed in the software package. By comparing the observed distribution of two common summary statistics (the number of heterozygous loci [K] and the number of share alleles [X]) with their expected distributions under the assumption of mutual independence, the overall independence is tested. Conclusion The package “mixIndependR” is compatible to all categories of genetic markers and detects the overall non-random associations. Compared to pairwise disequilibrium, the approach described herein tends to have higher power, especially when number of markers is large. With this package, more multi-functional or stronger genetic panels can be developed, like mixed panels with different kinds of markers. In population genetics, the package “mixIndependR” makes it possible to discover more about admixture of populations, natural selection, genetic drift, and population demographics, as a more powerful method of detecting LD. Moreover, this new approach can optimize variants selection in disease studies and contribute to panel combination for treatments in multimorbidity. Application of this approach in real data is expected in the future, and this might bring a leap in the field of genetic technology. Availability The R package mixIndependR, is available on the Comprehensive R Archive Network (CRAN) at: https://cran.r-project.org/web/packages/mixIndependR/index.html.

scholarly journals Reaction of winter wheat genotypes to infection by Mycosphaerella graminicola(Fuckel) Schroeter

2013 ◽  
Vol 55 (1) ◽  
pp. 233-246
Author(s):  
Ewa Mirzwa-Mróz ◽  
Czesław Zamorski
Keyword(s):  
Winter Wheat ◽  
Broad Spectrum ◽  
Mycosphaerella Graminicola ◽  
Wheat Breeding ◽  
Septoria Tritici ◽  
Wheat Cultivars ◽  
Breeding Lines ◽  
Wheat Genotypes ◽  
Winter Wheat Cultivars

The response of Polish winter wheat genotypes to <i>M.graminicola</i> (preliminary experiments and cultivar collections) was observed in different regions of Poland. Observations were carried out in 1995-1999. The winter wheat genotypes showed a broad spectrum of reaction to this pathogen. Between 1997 and 1999 the highest degree of infection on winter wheat breeding lines was noted in Kończewice. During this time no genotypes free from infection were observed (preliminary breeding experiments). Cultivars with no symptoms of <i>Septoria tritici</i> blotch (Leszczyńska Wczesna and Żelazna) were found among old genotypes in Słupia Wielka only in earlier experiments (1995-1996). In the years 1997-1999 the winter wheat cultivars were classified into groups on the basis of their response to the pathogen. The degree of infection for the majority cultivars was quite high.

scholarly journals Development of a multiplex system for determining 11 genetic markers of predisposition to obesity

2021 ◽  
Vol 57 (3) ◽  
pp. 300-309
Author(s):  
G. V. Sergeev ◽  
I. V. Haidukevich ◽  
A. M. Gorkavaya ◽  
M. D. Ameliyanovich ◽  
I. B. Mosse ◽  
...  
Keyword(s):  
Genetic Markers ◽  
Fto Gene ◽  
Lepr Gene ◽  
High Degree ◽  
Multiplex System

A system has been developed to identify 11 genetic markers associated with the risk of obesity: rs10852521, rs11075990, rs1121980, rs1421085, rs1477196, rs17817449, rs3751812, rs7206790, rs8047395, rs9940128 (FTO gene) and rs1137101 (LEPR gene) by minisequencing (SNaPshot analysis). The conditions for carrying out the amplification and minisequencing reactions, as well as the compositions of the reaction mixtures, were optimized so that the analysis was carried out for all 11 markers simultaneously. The resulting system was tested and showed a high degree of reproducibility and sensitivity required for the detection of these polymorphisms.

Modern DNA and the Ancient Mediterranean

2019 ◽  
pp. 224-248
Author(s):  
Roy J. King ◽  
Peter A. Underhill
Keyword(s):  
Population Genetics ◽  
Dna Sequence ◽  
Genetic Markers ◽  
Human History ◽  
Ancient History ◽  
Dna Variation ◽  
Mutational Change

This chapter takes a look at genetics and its role in the study of ancient history. Genetics is the study of inheritance, and DNA variation is the essence of heredity. DNA sequence differences underpin genetics overall and population genetics is the study of such diversity in populations and how it changes through time. Reconstructing human history using modern DNA has been a longstanding endeavor rooted in sampling practicality. If a mutational change does not negatively affect the individual's ability to reproduce, it may be passed down to each succeeding generation, eventually becoming established in a population. Such mutations, whether beneficial, harmful, or neutral, can serve as genetic markers.

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