Physiological Heterothallism and Sexuality in Euascomycetes: A Partial History

Bistis, G. N.

doi:10.1006/fgbi.1998.1050

Cited by 15 publications

(9 citation statements)

References 56 publications

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“…The mfm gene was cloned by hybridization with the N. crassa clockcontrolled gene 4 (ccg-4) encoding the putative matA-specific pheromone precursor (6). When used as a probe, a DNA fragment of the ccg-4 gene coding region consistently detected a 1.6-to 2-kb fragment on Southern blots of total genomic DNA from P. anserina.…”

Section: Resultsmentioning

confidence: 99%

The Function of the Coding Sequences for the Putative Pheromone Precursors in Podospora anserina Is Restricted to Fertilization

2005

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We cloned the pheromone precursor genes of Podospora anserina in order to elucidate their role in the biology of this fungus. The mfp gene encodes a 24-amino-acid polypeptide finished by the CAAX motif, characteristic of fungal lipopeptide pheromone precursors similar to the a-factor precursor of Saccharomyces cerevisiae. The mfm gene encodes a 221-amino-acid polypeptide, which is related to the S. cerevisiae ␣-factor precursor and contains two 13-residue repeats assumed to correspond to the mature pheromone. We deleted the mfp and mfm coding sequence by gene replacement. The mutations specifically affect male fertility, without impairing female fertility and vegetative growth. The male defect is mating type specific: the mat؉ ⌬mfp and mat؊ ⌬mfm mutants produce male cells inactive in fertilization whereas the mat؊ ⌬mfp and mat؉ ⌬mfm mutants show normal male fertility. Genetic data indicate that both mfp and mfm are transcribed at a low level in mat؉ and mat؊ vegetative hyphae. Northern-blot analysis shows that their transcription is induced by the mating types in microconidia (mfp by mat؉ and mfm by mat؊). We managed to cross ⌬mfp ⌬mfm strains of opposite mating type, by complementation and transient expression of the pheromone precursor gene to trigger fertilization. These crosses were fertile, demonstrating that once fertilization occurs, the pheromone precursor genes are unnecessary for the completion of the sexual cycle. Finally, we show that the constitutively transcribed gpd::mfm and gpd::mfp constructs are repressed at a posttranscriptional level by the noncognate mating type.

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Section: Resultsmentioning

confidence: 99%

The Function of the Coding Sequences for the Putative Pheromone Precursors in Podospora anserina Is Restricted to Fertilization

2005

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“…In preliminary experiments, we tested the mixed cultivations of the MAT1-1 and MAT1-2 strains started from conidia, colonies on agar plate or mycelia in liquid medium, but perithecia could not be formed. Cell fusion in plasmogamy is one of the most critical events in mating [20]. It occurred to us that an artificial cell fusion might trigger a teleomorphic development.…”

Section: Perithecium Formation Systemmentioning

confidence: 99%

Heterothallism inCordyceps takaomontana

Yokoyama

Yamagishi

Hara

2005

FEMS Microbiology Letters

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Perithecium formation of an entomopathogenic fungus Cordyceps takaomontana was promoted by treating the mycelia with cell wall-degrading enzymes and PEG 4000. Perithecia were formed in the mixed culture of both mating-type strains MAT1 and MAT2, and not in the culture of MAT1 or MAT2 alone. The MAT1 strains did not possess a mating-type gene MAT1-1-3, but could produce perithecia. These results strongly suggested that C. takaomontana is heterothallic, and does not need MAT1-1-3 for the perithecium formation. MAT1-1-3 was also not found in another entomopathogenic fungus Cordyceps militaris. On the other hand, phytopathogenic fungi Balansia sp., Claviceps purpurea and Epichloë typhina possessed MAT1-1-3. The structures of mating-type locus MAT1-1 of these phytopathogenic fungi in the family Clavicipitaceae were similar to that of a phytopathogenic fungus Gibberella fujikuroi in the family Nectriaceae, which is closely related to Clavicipitaceae. These results suggested that phytopathogen might be more ancestral group than entomopathogen in Clavicipitaceae, and that MAT1-1-3 might be lost in the course of the host shift from plants to insects.

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“…Genetic and physiological aspects of the mating process were described in detail for model fungi such as Neurospora crassa and Podospora anserina (Bistis, 1998;Coppin et al, 1997). Mating systems are also important drivers of diversity in natural populations of fungi.…”

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confidence: 99%