Genetic Evidence for Hybridization in an Interspecific Cross in the Genus Sordaria

Lewis, Leslie A.

doi:10.1099/00221287-59-3-359

Cited by 13 publications

(6 citation statements)

References 6 publications

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“…Such observations have been made in crosses between heterothallic Neurospora species (Perkins, Turner & Barry, 1976;Perkins & Turner, 1988) and subgroups of Ophiostoma ulmi (Brasier,I 984). Normal perithecia were produced in an interspecific cross between Sordaria heterothallis and S. thermophila, but in this case development had proceeded as far as the delimitation of immature ascospores (Lewis, 1969). ( b ) It has been observed that mutants blocked at some point in dikaryon formation or karyogamy characteristically form only immature ascocarps, again suggesting that a signal(s) from the functional ascogenous hyphae is required for further development.…”

Section: ( I ) the Sexual Cycle And Ascocarp Developmentmentioning

confidence: 99%

The Control of Sexual Morphogenesis in the Ascomycotina

1992

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Summary (1) A series of factors controls sexual morphogenesis in the Ascomycotina, a process involving the formation of novel structures such as ascocarps (fruit bodies) and asci (sacs containing spores) during sexual reproduction. (2) Environmental and genetic factors must be correct before Ascomycetes may sexually reproduce. Compatibility in many heterothallic species is under polygenic control, with the mating type loci and also other genetic factors determining the productivity of sexual crosses. (3) Classical genetic studies have shown that sexual morphogenesis involves the expression of a series of developmentally regulated genes, and this has been confirmed by recent molecular studies which have demonstrated changes in patterns of mRNA and protein synthesis during ascocarp formation. (4) Hyphal differentiation leading to the formation of mature fruit bodies occurs in response to a series of signals, which include various physical and chemical factors. (5) Chemical sex factors have been identified which are believed to have important regulatory or nutritional roles in sexual morphogenesis. These include the following. (a) Diffusible sex hormones which may regulate developmental switching between asexual and sexual modes of reproduction, including (i) pheromones involved with the induction of gametangia and gamete attraction, and (ii) sex morphogens involved with triggering particular stages of fruit body formation. (b) Sexual growth substances which are required as nutrients, and may be precursors for the production of sex hormones, or metabolites used in the synthesis of novel sexual structures. Most of these sex factors are lipids. (6) Certain sex morphogens and sexual growth substances have been shown to exhibit activity in a variety of fungal species, suggesting that fungi of related phylogenetic descent may utilize similar metabolites or signalling factors during sexual reproduction. (7) Phenoloxidase enzymes may catalyse hyphal aggregation in developing fruit bodies. (8) Initial stages of ascocarp development may occur independently of the events of the sexual cycle. However, a link(s) with the functional ascogenous hyphae is needed for the formation of morphologically mature ascocarps. (9) Suitable environmental conditions are sufficient to trigger sexual morphogenesis in homothallic Ascomycetes. However, an extra level of control is present in heterothallic species, with a compatible partner required to complete sexual reproduction. This may be partly because novel regulatory products, formed by the combined action of the mating type loci of different partners, are required for further ascocarp development. (10) Further research is required to identify more fungal chemical sex factors and to determine the role of environmental stress in controlling sexual morphogenesis, and how this may be related to temporal patterns in the expression of mating type genes.

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Section: ( I ) the Sexual Cycle And Ascocarp Developmentmentioning

confidence: 99%

The Control of Sexual Morphogenesis in the Ascomycotina

1992

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“…Interspecific hybrids have been obtained in a number of fungi, including Neurospora (Dodge, 1936), Sordaria (Lewis, 1969), Aspergillus (Uchida et al, 1958) and Verticillium (Hastie, 1973; . Typas & Heale, 1976) by conventional sexual and parasexual processes.…”

Section: Introductionmentioning

confidence: 99%

Heterokaryon Incompatibility and Interspecific Hybridization between Verticillium albo-atrum and Verticillium dahliae Following Protoplast Fusion and Microinjection

Typas¹

1983

Microbiology

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Interspecific and intraspecific heterokaryons of Verticillium albo-atrum and Verticillium dahliae were formed by protoplast fusion or microinjection. Diploid formation was increased 1000-fold following either treatment. Combinations of auxotrophic strains which normally never form heterokaryons were obtained with both techniques. The results suggest that a variety of incompatibility factors exist in Verticillium. Compatibility and incompatibility in their strict sense did not apply to the strains used in this work, and the terms 'heterokaryon-former' and 'heterokaryon non-former' have been introduced instead. The compatibility functions are assumed to be nuclear and somehow associated with cell wall formation or components affecting the cell wall. Temperature had a profound effect on both the morphology and the nutritional marker ratio of interspecific heterokaryons. Although the frequencies of diploid formation for interspecific and intraspecific diploids were very similar, the corresponding haploidization frequencies for these diploids were markedly different. An examination of random aneuploid conidia showed that spontaneous haploidization and mitotic crossing-over occurs in interspecific diploids of Verticillium. The genetic segregation of interspecific diploids grown in the presence of haploidizing agents suggested that the two fungi are closely related and that substantial chromosomal homology may exist between them.

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“…In the Fungi interspecific hybrids have been obtained in Sordaria (Lewis, 1969), Neurospora (Dodge, 1936) and in Verticillium (Hastie, 1973) by conventional sexual and parasexual events. Developments in the field of somatic cell genetics utilizing cell fusion in animal systems (Ruddle & Creagan, 1975) and protoplast fusion in higher plants (Carlson, 1973;Cocking, 1972) have provided the impetus for similar studies in fungi.…”

Section: Introductionmentioning

confidence: 99%

Interspecific Hybridization between Aspergillus nidulans and Aspergillus rugulosus by Fusion of Somatic Protoplasts

Kevei

Peberdy

1977

Journal of General Microbiology

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~~~ ~Interspecific heterokaryons have been produced between auxotrophic mutants of Aspergillus nidulms and Aspergillus rugulosus by polyethylene glycol induced fusion of somatic protoplasts. The heterokaryons grew very slowly producing colonies of irregular shape and, on complete medium, the parental strains were readily segregated. However, during longterm cultivation on minimal medium many of the heterokaryons gave rise to vigorously growing sectors characterized by the secretion of a brown pigment and by their stability when subcultured on complete medium. Protoplasts isolated from the heterokaryons gave rise to the same new colony type when regenerated on minimal medium, and to the new colony type plus the parental types on complete medium. The new colony type was assumed to be an interspecific 'hybrid' and showed normal vegetative morphology, regular colony shape and size but produced few conidia. Conidia formed early in the development of the 'hybrid' gave rise to 'hybrid' colonies. Various sizes of conidia were observed; the largest were uninucleate and the smallest were enucleate. Comparisons of conidial size, numbers of nuclei in cells and DNA content per nucleus for 'hybrid' and parental strains indicated that the 'hybrid' was diploid. Conidia from older cultures of the 'hybrid' were heterogeneous with 'hybrid ', parental and recombinant colony types developing on germination. Cultivation of the 'hybrid' in the presence of benomyl gave segregation of parental and recombinant sectors.

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Genetic Evidence for Hybridization in an Interspecific Cross in the Genus Sordaria

Cited by 13 publications

References 6 publications

The Control of Sexual Morphogenesis in the Ascomycotina

The Control of Sexual Morphogenesis in the Ascomycotina

Heterokaryon Incompatibility and Interspecific Hybridization between Verticillium albo-atrum and Verticillium dahliae Following Protoplast Fusion and Microinjection

Interspecific Hybridization between Aspergillus nidulans and Aspergillus rugulosus by Fusion of Somatic Protoplasts

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