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 A Model of the Effect of Pseudothecia on Genetic Recombination and Epidemic Development in Populations of Mycosphaerella graminicola

2001 ◽  
Vol 91 (3) ◽  
pp. 240-248 ◽  
Author(s):  
L. Eriksen ◽  
M. W. Shaw ◽  
H. Østergård
Keyword(s):  
Genetic Recombination ◽  
Growing Season ◽  
Mycosphaerella Graminicola ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Considerable Proportion ◽  
Initial Population ◽  
Sexual Recombination ◽  
Epidemic Development ◽  
Rain Splash

It is generally agreed that ascospores are the origin of primary infections for the disease septoria tritici blotch of wheat caused by the fungus Mycosphaerella graminicola (anamorph Septoria tritici). The epidemic during the growing season was previously ascribed to the asexual pycni-diospores dispersed over short distances by rain splash, but recent observations suggest that the airborne ascospores also may play a role. As a consequence, the composition of the pathogen population over the growing season may change through genetic recombination. In an attempt to resolve the relative importance of the two spore types to the epidemic over the growing season, a model simulating disease caused by both types of spores was constructed and analyzed. The conclusion from the analysis of this model is that sexual recombination will affect the genetic composition of the population during a growing season. A considerable proportion of spores released at the end of the growing season may be sexual descendants of the initial population. However, ascospores are unlikely to affect the severity of the epidemic during the growing season. This is due to the much longer latent period for pseudothecia compared with pycnidia, resulting in ascospores being produced too late to influence the epidemic.

scholarly journals Genome-Wide Association Study Reveals Genetic Architecture of Septoria Tritici Blotch Resistance in a Historic Landrace Collection

2021 ◽  
Author(s):  
Anik Dutta ◽  
Daniel Croll ◽  
Bruce A. McDonald ◽  
Simon G. Krattinger
Keyword(s):  
Genetic Diversity ◽  
Association Study ◽  
Genome Wide Association Study ◽  
Phenotypic Variability ◽  
Genome Wide Association ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Genome Wide ◽  
A Genome ◽  
Wheat Landraces

Abstract Septoria tritici blotch (STB), caused by the fungus Zymoseptoria tritici, is a major constraint in global wheat production. The lack of genetic diversity in modern elite wheat cultivars largely hinders the improvement of STB resistance. Wheat landraces are reservoirs of untapped genetic diversity, which can be exploited to find novel STB resistance genes or alleles. Here, we characterized 188 Swiss wheat landraces for resistance to STB using four Swiss Z. tritici isolates. We used a genome-wide association study (GWAS) to identify genetic variants associated with the amount of lesion and pycnidia production by the fungus. The majority of the landraces were highly resistant for both traits to the isolate 1E4, indicating a gene-for-gene relationship, while higher phenotypic variability was observed against other isolates. GWAS detected a significant SNP on chromosome 3A that was associated with both traits in the isolate 1E4. The resistance response against 1E4 was likely controlled by the Stb6 gene. Sanger sequencing revealed that the majority of these ~100-year-old landraces carry the Stb6 resistance allele. This indicates the importance of this gene in Switzerland during the early 1900s for disease control in the field. Our study demonstrates the importance of characterizing historic landrace collections for STB resistance to provide valuable information on resistance variability and contributing alleles. This will help breeders in the future to make decisions on integrating such germplasms in STB resistance breeding.

scholarly journals DNA Fingerprint Probe from Mycosphaerella graminicola Identifies an Active Transposable Element

2001 ◽  
Vol 91 (12) ◽  
pp. 1181-1188 ◽  
Author(s):  
Stephen B. Goodwin ◽  
Jessica R. Cavaletto ◽  
Cees Waalwijk ◽  
Gert H. J. Kema
Keyword(s):  
Transposable Elements ◽  
Reverse Transcriptase ◽  
Transposable Element ◽  
Asexual Reproduction ◽  
Dna Analysis ◽  
Mycosphaerella Graminicola ◽  
Dna Fingerprint ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Sexual And Asexual Reproduction

DNA fingerprinting has been used extensively to characterize populations of Mycosphaerella graminicola, the Septoria tritici blotch pathogen of wheat. The highly polymorphic DNA fingerprints of Mycosphaerella graminicola were assumed to reflect the action of transposable elements. However, there was no direct evidence to support that conclusion. To test the transposable element hypothesis, the DNA fingerprint probe pSTL70 was sequenced, along with three other clones from a subgenomic library that hybridized with pSTL70. Analysis of these sequences revealed that pSTL70 contains the 3′ end of a reverse transcriptase sequence plus 29- and 79-bp direct repeats. These are characteristics of transposable elements identified in other organisms. Southern analyses indicated that either the direct-repeat or reverse-transcriptase sequences by themselves essentially duplicated the original DNA fingerprint pattern, but other portions of pSTL70 contained single-copy DNA. Analysis of 60 progeny from a sexual cross between two Dutch isolates of Mycosphaerella graminicola identified several new bands that were not present in the parents. Thus, the putative transposable element probably is active during meiosis. Tests of single-spore isolates revealed gains or losses of one or more DNA fingerprint bands in 4 out of 10 asexual lines derived from isolate IPO94269. Therefore, DNA fingerprint patterns produced by the putative transposable element were capable of changes during asexual reproduction of this isolate. Probe pSTL70 did not hybridize at high stringency to genomic DNAs from other fungi related to Septoria and Mycosphaerella. These results indicate that the DNA fingerprint probe pSTL70 most likely identifies a transposable element in Mycosphaerella graminicola that may have been acquired recently, and appears to be active during both sexual and asexual reproduction.

scholarly journals Gene Encoding a c-Type Cyclin in Mycosphaerella graminicola Is Involved in Aerial Mycelium Formation, Filamentous Growth, Hyphal Swelling, Melanin Biosynthesis, Stress Response, and Pathogenicity

2011 ◽  
Vol 24 (4) ◽  
pp. 469-477 ◽  
Author(s):  
Yoon-E Choi ◽  
Stephen B. Goodwin
Keyword(s):  
Molecular Mechanisms ◽  
Fusarium Verticillioides ◽  
Aerial Mycelium ◽  
Mycosphaerella Graminicola ◽  
Filamentous Growth ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Melanin Biosynthesis ◽  
Knock Out ◽  
Tolerance Response

Mycosphaerella graminicola is an important wheat pathogen causing Septoria tritici blotch. To date, an efficient strategy to control M. graminicola has not been developed. More significantly, we have a limited understanding of the molecular mechanisms of M. graminicola pathogenicity. In this study, we attempted to characterize an MCC1-encoding c-type cyclin, a gene homologous to FCC1 in Fusarium verticillioides. Four independent MCC1 knock-out mutants were generated via Agrobacterium tumefaciens–mediated transformation. All of the MCC1 mutants showed consistent multiple phenotypes. Significant reductions in radial growth on potato dextrose agar (PDA) were observed in all of the MCC1 mutants. In addition, MCC1 gene-deletion mutants produced less aerial mycelium on PDA, showed delayed filamentous growth, had unusual hyphal swellings, produced more melanin, showed an increase in their stress tolerance response, and were reduced significantly in pathogenicity. These results indicate that the MCC1 gene is involved in multiple signaling pathways, including those involved in pathogenicity in M. graminicola.

Genetic architecture of resistance to Septoria tritici blotch (Mycosphaerella graminicola) in European winter wheat

2013 ◽  
Vol 32 (2) ◽  
pp. 411-423 ◽  
Author(s):  
Sonja Kollers ◽  
Bernd Rodemann ◽  
Jie Ling ◽  
Viktor Korzun ◽  
Erhard Ebmeyer ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Genetic Architecture ◽  
Mycosphaerella Graminicola ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
European Winter Wheat

scholarly journals Effects of Wheat Cultivar Mixtures on Epidemic Progression of Septoria Tritici Blotch and Pathogenicity of Mycosphaerella graminicola

2002 ◽  
Vol 92 (6) ◽  
pp. 617-623 ◽  
Author(s):  
Christina Cowger ◽  
Christopher C. Mundt
Keyword(s):  
Disease Progression ◽  
Mycosphaerella Graminicola ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Pure Stand ◽  
Host Genotype ◽  
Disease Response ◽  
The Mean ◽  
Pathogen Populations ◽  
Moderately Resistant

The effects of host genotype mixtures on disease progression and pathogen evolution are not well understood in pathosystems that vary quantitatively for resistance and pathogenicity. We used four mixtures of moderately resistant and susceptible winter wheat cultivars naturally inoculated with Mycosphaerella graminicola to investigate impacts on disease progression in the field, and effects on pathogenicity as assayed by testing isolate populations sampled from the field on greenhousegrown seedlings. Over 3 years, there was a correspondence between the mixtures' disease response and the pathogenicity of isolates sampled from them. In 1998, with a severe epidemic, mixtures were 9.4% less diseased than were their component pure stands (P = 0.0045), and pathogen populations from mixtures caused 27% less disease (P = 0.085) in greenhouse assays than did populations from component pure stands. In 1999, the epidemic was mild, mixtures did not reduce disease severity (P = 0.39), and pathogen populations from mixtures and pure stands did not differ in pathogenicity (P = 0.42). In 2000, epidemic intensity was intermediate, mixture plots were 15.2% more diseased than the mean of component pure stands (P = 0.053), and populations from two of four mixtures were 152 and 156% more pathogenic than the mean of populations from component pure stands (P = 0.043 and 0.059, respectively). Mixture yields were on average 2.4 and 6.2% higher than mean component pure-stand yields in 1999 and 2000, respectively, but the differences were not statistically significant. The ability of mixtures challenged with M. graminicola to suppress disease appears to be inconsistent. In this system, host genotype mixtures evidently do not consistently confer either fitness benefits or liabilities on pathogen populations.

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