Genetics of Ustilago violacea. V. Outcrossing and Selfing in Teliospore Inocula

Baird, Michael L.; Garber, E. D.

doi:10.1086/337061

Cited by 38 publications

(37 citation statements)

References 5 publications

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“…Some data indeed indicate that a preference for selfing versus outcrossing in M. violaceum. Artificial inoculations experiments with combinations of teliospores bearing colony colour markers (Baird and Garber, 1979) detected an outcrossing rate of only 6.6%. found that mixtures of sporidia of opposite mating types conjugate more readily in selfing than outcrossing combinations.…”

Section: Discussionmentioning

confidence: 98%

Patterns of within population dispersal and mating of the fungus Microbotryum violaceum parasitising the plant Silene latifolia

Giraud

2004

Heredity

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This study explores the patterns of dispersal and mating of the anther smut Microbotryum violaceum, a model species in genetics and evolutionary biology. A French metapopulation of the fungus collected from its caryophyllaceous host Silene latifolia was analysed using microsatellites. The genetic diversity was low, populations were strongly differentiated, and there was no pattern of isolation by distance among populations. There was a strong deficit in heterozygotes, confirming the high self-fertilisation rates suggested by previous studies. Within populations there was a strong pattern of isolation by distance, with identical genotypes being highly clustered. This indicates that fungal spores are dispersed mostly between adjacent plants, and such local dispersal is important for understanding the dynamics and evolution of this disease. Local clusters of identical heterozygous genotypes did not contain significantly fewer individuals than did clusters of homozygous genotypes. As selfing between products of independent meiotic events (intertetrad selfing) rapidly reduces heterozygosity, this suggests that intratetrad matings are frequent, which helps to explain the puzzling maintenance of a sex-ratio distortion in M. violaceum. Heredity (2004) 93, 559-565.

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Section: Discussionmentioning

confidence: 98%

Patterns of within population dispersal and mating of the fungus Microbotryum violaceum parasitising the plant Silene latifolia

Giraud

2004

Heredity

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“…Estimations of intra-tetrad mating rates from controlled crosses ranged between 0.43 and 0.89 (Baird and Garber, 1979;Giraud et al, 2005Giraud et al, , 2006, with some genetic and/or environmental variability. These estimations include the range of values of intra-tetrad mating allowing the maintenance of haplo-lethal alleles even without diploid advantage, thanks to the populationlevel selection.…”

Section: Genetic Polymorphism and Antagonistic Pleiotropymentioning

confidence: 99%

“…New infectious dicaryons are rapidly produced by conjugation of two sporidia of opposite mating type. M. violaceum can perform either outcrossing or selfing (Baird and Garber, 1979;Giraud et al, 2005Giraud et al, , 2006, and selfing can occur either between cells from different tetrads of the same fungal individual (inter-tetrad conjugation) or between products of a single meiosis (intra-tetrad conjugation; Hood and Antonovics, 2000). Dicaryotic hyphae then enter the host tissue and grow along with the plants' apical meristematic regions.…”

Section: Introductionmentioning

confidence: 99%

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Antagonistic pleiotropy may help population-level selection in maintaining genetic polymorphism for transmission rate in a model phytopathogenic fungus

2006

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It has been shown theoretically that the conditions for the maintenance of polymorphism at pleiotropic loci with antagonistic effects on fitness components are rather restrictive. Here, we use a metapopulation model to investigate whether antagonistic pleiotropy could help maintain polymorphism involving common deleterious alleles in the phytopathogenic fungus Microbotryum violaceum. This fungus causes anther smut disease of the Caryophyllaceae. A previous model has shown that the sex-linked deleterious alleles can be maintained under a metapopulation structure, when intra-tetrad selfing (mating between products of the same meiosis) is high, due to founder effects and selection at the population level. Here, we add two types of pleiotropic advantages to the metapopulation model. A competitive advantage for strains carrying the sex-linked deleterious alleles did not facilitate their maintenance because competitive situations were too rare. In contrast, higher spore production did facilitate the maintenance of the deleterious alleles at low intra-tetrad mating rates and with a large advantage for spore production. These results show that antagonistic pleiotropy may promote the persistence of genetic variation, in combination with other selective forces. Heredity (2007) 98, 45-52.

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“…Multistrain infections in this association have been predicted by Bucheli & Leuchtmann (1996), but have not been documented previously for grass endophytes. However, multistrain infections of maize by the fungal pathogen Gibberella fujikuroi are reported by Kedera et al (1994), and artificial multistrain infections of Silene alba with Ustilago violacea were achieved in plants kept in the greenhouse or common garden (Baird & Garber, 1979 ;Day, 1980). Other multistrain infections are known from protozoa and viruses (e.g.…”

Section: Multistrain Infections In Brachypodium Sylvaticummentioning

confidence: 99%

Multistrain infections of the grass Brachypodium sylvaticum by its fungal endophyte Epichloë sylvatica

Meijer

Leuchtmann

1999

New Phytologist

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Endophytes of the genus EpichloeW (Clavicipitaceae, Ascomycota) are systemic symbionts of cool-season grasses. Their interactions with grass hosts may vary between mutualistic and pathogenic depending on the mode of endophyte reproduction. Sexual strains prevent flowering and seed set (choke disease) of the host and can be horizontally transmitted by ascospores, while asexual strains remain asymptomatic and are vertically transmitted through seeds. In Switzerland nearly all plants of Brachypodium sylvaticum (Huds.) P.B. are infected by EpichloeW sylvatica Leuchtmann & Schardl, but choke symptoms are formed very rarely, and are restricted to particular locations and to a minority of plants at those locations. Earlier research has revealed that E. sylvatica is genetically differentiated into sexual and asexual subpopulations. Given the high level of infection and assuming horizontal transmission of sexual strains, multiple host infections have been predicted. In this study, 25 plants out of 63 examined by isozyme analysis were found to be infected by two or three different endophyte genotypes. In most cases endophyte genotypes appeared to be correlated with the symptom type of a particular tiller, suggesting that the fungal genome controls choke formation and that the sexual and asexual subpopulations are separated at the ramet (tiller) level rather than at the genet (plant) level. These conclusions were further supported by analyses with log-linear models of the population structure of E. sylvatica at four locations where choke symptoms were present. These analyses also revealed a geographic structure in the asexual subpopulation but not in the sexual subpopulation which could be caused by the different dispersal ranges of their propagules. The rare occurrence of sexually reproducing strains and the dominance of a single genotype in asymptomatic plant populations may be explained by the colonization history of B. sylvaticum and its endophyte in Switzerland.

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Genetics of Ustilago violacea. V. Outcrossing and Selfing in Teliospore Inocula

Cited by 38 publications

References 5 publications

Patterns of within population dispersal and mating of the fungus Microbotryum violaceum parasitising the plant Silene latifolia

Patterns of within population dispersal and mating of the fungus Microbotryum violaceum parasitising the plant Silene latifolia

Antagonistic pleiotropy may help population-level selection in maintaining genetic polymorphism for transmission rate in a model phytopathogenic fungus

Multistrain infections of the grass Brachypodium sylvaticum by its fungal endophyte Epichloë sylvatica

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