scholarly journals Inheritance of Race-Specific Resistance to Mycosphaerella graminicola in Wheat

2002 ◽  
Vol 92 (2) ◽  
pp. 138-144 ◽  
Author(s):  
C. A. McCartney ◽  
A. L. Brûlé-Babel ◽  
L. Lamari
Keyword(s):  
Resistance Genes ◽  
Tetraploid Wheat ◽  
Gene Interaction ◽  
Mycosphaerella Graminicola ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Controlled Environment ◽  
High Level ◽  
Wheat Lines ◽  
Level Resistance

Mycosphaerella graminicola causes Septoria tritici blotch of hexaploid and tetraploid wheat. The inheritance of high-level resistance to Septoria tritici blotch was studied in controlled environment experiments. Intraspecific reciprocal crosses were made between hexaploid wheat lines Salamouni, ST6, Katepwa, and Erik, and the tetraploid wheat lines Coulter and 4B1149. Parental, F1, F2, F3, BC1F1, and BC1F2 populations were evaluated for reaction to isolates MG2 and MG96-36 of M. graminicola. Resistance was controlled by incompletely dominant nuclear genes in all cases. Salamouni had three independent resistance genes to isolate MG2, two of which also controlled resistance to isolate MG96-36. ST6 had a single resistance gene to isolate MG2 and none to isolate MG96-36. The resistance genes in Salamouni and ST6 were not allelic. Two independent genes control resistance to isolate MG2 in Coulter, one of which also controlled resistance to isolate MG96-36. These data are consistent with a gene-for-gene interaction in the wheat-M. graminicola pathosystem.

scholarly journals A Gene-for-Gene Relationship Between Wheat and Mycosphaerella graminicola, the Septoria Tritici Blotch Pathogen

2002 ◽  
Vol 92 (4) ◽  
pp. 439-445 ◽  
Author(s):  
Penny A. Brading ◽  
Els C. P. Verstappen ◽  
Gert H. J. Kema ◽  
James K. M. Brown
Keyword(s):  
Specific Resistance ◽  
Mycosphaerella Graminicola ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Avirulence Gene ◽  
Breeding Line ◽  
Wheat Lines ◽  
Homozygous Resistant ◽  
F2 Progeny ◽  
Gene For Gene

Specific resistances to isolates of the ascomycete fungus Mycosphaerella graminicola, which causes Septoria tritici blotch of wheat, have been detected in many cultivars. Cvs. Flame and Hereward, which have specific resistance to the isolate IPO323, were crossed with the susceptible cv. Longbow. The results of tests on F1 and F2 progeny indicated that a single semidominant gene controls resistance to IPO323 in each of the resistant cultivars. This was confirmed in F3 families of Flame × Longbow, which were either homozygous resistant, homozygous susceptible, or segregating in tests with IPO323 but were uniformly susceptible to another isolate, IPO94269. None of 100 F2 progeny of Flame × Hereward were susceptible to IPO323, indicating that the resistance genes in these two cultivars are the same, closely linked, or allelic. The resistance gene in cv. Flame was mapped to the short arm of chromosome 3A using microsatellite markers and was named Stb6. Fifty-nine progeny of a cross between IPO323 and IPO94269 were used in complementary genetic analysis of the pathogen to test a gene-for-gene relationship between Stb6 and the avirulence gene in IPO323. Avirulence to cvs. Flame, Hereward, Shafir, Bezostaya 1, and Vivant and the breeding line NSL92-5719 cosegregated, and the ratio of virulent to avirulent was close to 1:1, suggesting that these wheat lines may all recognize the same avirulence gene and may all have Stb6. Together, these data provide the first demonstration that isolate-specific resistance of wheat to Septoria tritici blotch follows a gene-for-gene relationship.

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.

Multiple-Antibiotic Resistance of Enterococcus faecalis and Enterococcus faecium from Cecal Contents in Broiler Chicken and Turkey Flocks Slaughtered in Canada and Plasmid Colocalization of tetO and ermB Genes

2011 ◽  
Vol 74 (10) ◽  
pp. 1639-1648 ◽  
Author(s):  
CINDY-LOVE TREMBLAY ◽  
ANN LETELLIER ◽  
SYLVAIN QUESSY ◽  
MARTINE BOULIANNE ◽  
DANIELLE DAIGNAULT ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Enterococcus Faecalis ◽  
Resistance Genes ◽  
Enterococcus Faecium ◽  
Broiler Chicken ◽  
Multidrug Resistant ◽  
Poultry Meat ◽  
Antimicrobial Resistance Genes ◽  
High Level ◽  
Level Resistance

This study was conducted to characterize the antimicrobial resistance determinants and investigate plasmid colocalization of tetracycline and macrolide genes in Enterococcus faecalis and Enterococcus faecium from broiler chicken and turkey flocks in Canada. A total of 387 E. faecalis and E. faecium isolates were recovered from poultry cecal contents from five processing plants. The percentages of resistant E. faecalis and E. faecium isolates, respectively, were 88.1 and 94% to bacitracin, 0 and 0.9% to chloramphenicol, 0.7 and 14.5% to ciprofloxacin, 72.6 and 80.3% to erythromycin, 3.7 and 41% to flavomycin, 9.6 and 4.3% (high-level resistance) to gentamicin, 25.2 and 17.1% (high-level resistance) to kanamycin, 100 and 94% to lincomycin, 0 and 0% to linezolid, 2.6 and 20.5% to nitrofurantoin, 3 and 27.4% to penicillin, 98.5 and 89.7% to quinupristin-dalfopristin, 7 and 12.8% to salinomycin, 46.7 and 38.5% (high-level resistance) to streptomycin, 95.6 and 89.7% to tetracycline, 73 and 75.2% to tylosin, and 0 and 0% to vancomycin. One predominant multidrug-resistant phenotypic pattern was identified in both E. faecalis and E. faecium (bacitracin, erythromycin, lincomycin, quinupristin-dalfopristin, tetracycline, and tylosin). These isolates were further examined by PCR and sequencing for the genes encoding their antimicrobial resistance. Various combinations of vatD, vatE, bcrR, bcrA, bcrB, bcrD, ermB, msrC, linB, tetM, and tetO genes were detected, and ermB, tetM, and bcrB were the most common antimicrobial resistance genes identified. For the first time, plasmid extraction and hybridization revealed colocalization of tetO and ermB genes on a ca. 11-kb plasmid in E. faecalis isolates, and filter mating experiments demonstrated its transferability. Results indicate that the intestinal enterococci of healthy poultry, which can contaminate poultry meat at slaughter, could be a reservoir for quinupristin-dalfopristin, bacitracin, tetracycline, and macrolide resistance genes.

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 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 Resistance of Wheat Line Kavkaz-K4500 L.6.A.4 to Septoria Tritici Blotch Controlled by Isolate-Specific Resistance Genes

2005 ◽  
Vol 95 (6) ◽  
pp. 664-671 ◽  
Author(s):  
L. Chartrain ◽  
S. T. Berry ◽  
J. K. M. Brown
Keyword(s):  
Resistance Genes ◽  
Specific Resistance ◽  
Field Resistance ◽  
Field Conditions ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
High Susceptibility ◽  
Sources Of Resistance ◽  
Wheat Improvement ◽  
The Uk

The International Maize and Wheat Improvement Center (CIMMYT), Mexico, germplasm-derived wheat (Triticum aestivum) Kavkaz-K4500 L.6.A.4 (KK) is one of the major sources of resistance to Septoria tritici blotch (STB). KK is resistant to STB in field conditions in the UK even though a large majority of Mycosphaerella graminicola isolates are virulent to it. The genetics of the resistance of KK to four isolates of M. graminicola were investigated. KK has at least five isolate-specific resistance genes including Stb6 on chromosome 3A plus a second gene for resistance to isolate IPO323, two genes on chromosome 4A, both in the region where Stb7 is located with one designated as Stb12, and a gene designated Stb10 on chromosome 1D. Taken together, the widespread use of KK as a source of resistance to STB, its high resistance in field conditions, and its high susceptibility to M. graminicola isolates, which are virulent to all its resistance genes, suggest that high levels of field resistance to STB might be achieved by pyramiding several isolate-specific resistance genes.

scholarly journals Genetic Mapping of Loci for Resistance to Stem Rust in a Tetraploid Wheat Collection

2018 ◽  
Vol 19 (12) ◽  
pp. 3907 ◽  
Author(s):  
Antonietta Saccomanno ◽  
Oadi Matny ◽  
Daniela Marone ◽  
Giovanni Laidò ◽  
Giuseppe Petruzzino ◽  
...  
Keyword(s):  
Association Mapping ◽  
Resistance Genes ◽  
Stem Rust ◽  
Tetraploid Wheat ◽  
Resistance Qtls ◽  
Mapping Panel ◽  
Genome Wide ◽  
Broad Spectrum Resistance ◽  
High Level ◽  
Or Genes

Stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is a major biotic constraint to wheat production worldwide. Disease resistant cultivars are a sustainable means for the efficient control of this disease. To identify quantitative trait loci (QTLs) conferring resistance to stem rust at the seedling stage, an association mapping panel consisting of 230 tetraploid wheat accessions were evaluated for reaction to five Pgt races under greenhouse conditions. A high level of phenotypic variation was observed in the panel in response to all of the races, allowing for genome-wide association mapping of resistance QTLs in wild, landrace, and cultivated tetraploid wheats. Twenty-two resistance QTLs were identified, which were characterized by at least two marker-trait associations. Most of the identified resistance loci were coincident with previously identified rust resistance genes/QTLs; however, six regions detected on chromosomes 1B, 5A, 5B, 6B, and 7B may be novel. Availability of the reference genome sequence of wild emmer wheat accession Zavitan facilitated the search for candidate resistance genes in the regions where QTLs were identified, and many of them were annotated as NOD (nucleotide binding oligomerization domain)-like receptor (NLR) genes or genes related to broad spectrum resistance.

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