Sexual crosses of the homothallic fungusGaeumannomyces graminis var.tritici based on use of an auxotroph obtained by transformation

Pilgeram, Alice L.; Henson, Joan M.

doi:10.1016/0147-5975(92)90039-t

Cited by 20 publications

(16 citation statements)

References 23 publications

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“…However, intraisolate crosses have been shown to occur in vitro (Zadocks et al, 1974). Ggt genotypic frequencies and disease severity 495 (Pilgeram and Henson, 1992) and sexual recombination could sometimes take place between different strains in Gg natural populations (Bryan et al, 1999). But the generation of ascospores on the base of stems at the end of the cropping season is a rare event only observed after a severe outbreak of the disease under favourable climatic conditions and doubt persists about the infectivity of the generated ascospores (Asher, 1981).…”

Section: Discussionmentioning

confidence: 99%

Linear relationship between Gaeumannomyces graminis var. tritici (Ggt) genotypic frequencies and disease severity on wheat roots in the field

Lebreton¹,

Gosme²,

Lucas³

et al. 2006

Environmental Microbiology

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In order to investigate potential links existing between Gaeumannomyces graminis var. tritici (Ggt) population structure and disease development during polyetic take-all epidemics in sequences of Ggt host cereals, seven epidemics in fields with different cropping histories were monitored during the seasons 2001/2002 (two fields), 2002/2003 (two fields) and 2003/2004 (three fields). Take-all incidence and severity were measured at stem elongation and Ggt populations were characterized. The 73 isolates collected in the two fields in 2001/2002 were distributed into two multilocus genotypes, G1 and G2 according to amplified fragment length polymorphism analysis. A monolocus molecular marker amplified by F-12 random amplification polymorphism DNA primer sizing between 1.9 and 2.0 kb that gave strictly the same distinction between the two multilocus genotypes was further applied to measure G1/G2 frequencies among Ggt populations in all fields (266 isolates). The ratios of G1 to G2 differed between fields with different cropping histories. A linear relationship between G2 frequency among Ggt populations and disease severity at stem elongation was measured during the three cropping seasons. When take-all decline was observed, G2 frequencies were low in first wheat crops, highest in short-term sequences and intermediate in longer sequences of consecutive crops of Ggt host cereals. This pattern could be the result of population selection by environmental conditions, in particular by microbial antagonism during the parasitic phase of the fungus. In order to better understand take-all epidemic dynamics, the distinction between these two genotypes could be a basis to develop models that link approaches of quantitative epidemiology and advances in population genetics of Ggt.

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Section: Discussionmentioning

confidence: 99%

Linear relationship between Gaeumannomyces graminis var. tritici (Ggt) genotypic frequencies and disease severity on wheat roots in the field

Lebreton¹,

Gosme²,

Lucas³

et al. 2006

Environmental Microbiology

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“…Because G. graminis is homothallic (self‐fertile), attempts to perform genetic crosses often result in relatively small proportions of hybrid perithecia compared with the numbers that result from selfing of each parental strain (Asher, 1981; Blanch et al ., 1981). In intra‐isolate crosses, using mutants or antibiotic‐resistant transformants, the percentage of hybrid perithecia was generally around 10–25% but sometimes higher frequencies were obtained (Hornby et al ., 1998; Musker, 1994; Pilgeram and Henson, 1992). Also, numerous vegetative incompatibility groups exist within G. graminis (Asher, 1981; Jamil and Buck, 1991; Jamil et al ., 1984) and this places restrictions on the isolate combinations that can be sucessfully paired.…”

Section: Genetics and Transformation Of G Graminismentioning

confidence: 99%

“…The stability of the integrated DNA varies. Transgenes in the majority of transformants are mitotically stable, but their stability through meiosis varies with copy number and with different genes (Pilgeram and Henson, 1990, 1992; Pilgeram et al ., 1993). For example, benomyl‐ and phleomycin‐resistant transformants of Ggt and Ggg were mitotically stable irrespective of transgene copy number.…”

Section: Genetics and Transformation Of G Graminismentioning

confidence: 99%

Gaeumannomyces graminis, the take‐all fungus and its relatives

Freeman

Ward

2004

Molecular Plant Pathology

105

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SUMMARY Take‐all, caused by the fungus Gaeumannomyces graminis var. tritici, is the most important root disease of wheat worldwide. Many years of intensive research, reflected by the large volume of literature on take‐all, has led to a considerable degree of understanding of many aspects of the disease. However, effective and economic control of the disease remains difficult. The application of molecular techniques to study G. graminis and related fungi has resulted in some significant advances, particularly in the development of improved methods for identification and in elucidating the role of the enzyme avenacinase as a pathogenicity determinant in the closely related oat take‐all fungus (G. graminis var. avenae). Some progress in identifying other factors that may be involved in determining host range and pathogenicity has been made, despite the difficulties of performing genetic analyses and the lack of a reliable transformation system.

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“…In a few cases, tagged mutations have been generated by random insertion, during transformation, of a plasmid that has no homology with the fungal genome (4)(5)(6)(7). This procedure, however, is generally inefficient because the frequency of transformation with nonhomologous plasmids is often low.…”

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confidence: 99%

Tagged mutations at the Tox1 locus of Cochliobolus heterostrophus by restriction enzyme-mediated integration.

Lyngholm

Yang

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

224

130

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We have used the restriction enzyme-mediated integration insertional mutagenesis procedure to tag the Toxl locus in the filamentous Ascomycete Cochliobolus heterostrophus. Mutations at other, unselected, loci were also identified and a high proportion (30-50%) of them were tagged. This procedure may be of general utility for simultaneously mutating and tagging genes in fungi and in other eukaryotes. The Toxl locus of C. heterostrophus has been dermed by Mendelian analysis as a single genetic element that controls production of T toxin, a linear polyketide involved in virulence of the fungus to its host plant, corn. To tag Toxi, protoplasts of a Toxl+ (T-toxin producing) strain were transformed with a linearized, nonhomologous plasmid along with an excess of the restriction enzyme used to linearize the plasmid. Of 1310 transformants recovered, two produced no detectable T toxin in culture or on corn plants. In each of these transformants, the Tox-mutation mapped at Toxi, was tagged with the selectable marker (hygB) on the transforming plasmid, and was tightly linked to the other tagged Tox-mutation. The two mutations, however, represent two different points of plasmid insertion at the Toxi locus.

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Sexual crosses of the homothallic fungusGaeumannomyces graminis var.tritici based on use of an auxotroph obtained by transformation

Cited by 20 publications

References 23 publications

Linear relationship between Gaeumannomyces graminis var. tritici (Ggt) genotypic frequencies and disease severity on wheat roots in the field

Linear relationship between Gaeumannomyces graminis var. tritici (Ggt) genotypic frequencies and disease severity on wheat roots in the field

Gaeumannomyces graminis, the take‐all fungus and its relatives

Tagged mutations at the Tox1 locus of Cochliobolus heterostrophus by restriction enzyme-mediated integration.

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