John R. Raper

Genetic Analysis of the Life Cycle of Agaricus Bisporus

SUMMARYAn understanding of sexuality and life cycle has been conspicuously lacking for members of the genus Agaricus despite the prime importance of Agaricus bisporus to the edible mushroom industr...

Chemical regulation of sexual processes in the thallophytes

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 447 Extra-Specific Chemical Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451 Specific Chemical Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 464 Sexual hormones in gametic copulation . . . . . . . . . . . . . . . . . . . . . . . . . . 466 Sexual hormones in Chlamydomonas . . . . . . . . . . . . . . . . . . . . . . . . 474 The hormonal mechanism in Chlamydomonas . . . . . . . . . . . . . . . . 478 Sexual hormones in Protos iphon, Bo t ryd ium, M o n o s t r o m a . . . . 501 Sexual hormones in gamete-gametangial copulation . . . . . . . . . . . . . . 510 The hormonal mechanism in A c h l y a . . . . . . . . . . . . . . . . . . . . . . . . . 514 The Neurospora controversy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 525 Sexual hormones in gametangial copulation . . . . . . . . . . . . . . . . . . . . . . 529 Sexual hormones in somatic copulation . . . . . . . . . . . . . . . . . . . . . . . . . . 532 Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 534 Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 538

Sexual Hormones in Achlya. VII. The Hormonal Mechanism in Homothallic Species

1. A simple membrane technique is described for the study of diffusible sexual hormones in matings on a semisolid medium. 2. Sexual reactions have been shown to occur regularly between mated homothallic species and [male] and [female] strains of heterothallic species. All possible matings between two homothallic species, Achlya americana and Thraustotheca clavata, and [male] and [female] strains of two heterothallic species, A. bisexualis and A. ambisexualis, reveal relationships ranging from no reaction to complete compatibility, and presumably hybridization, between the two mated plants. 3. Matings between the homothallic and heterothallic species listed above, in a semisolid medium in which interposed membranes physically separate the mated plants, prove that the initiation and coordination of the sexual interactions result from diffusible hormones. 4. Assuming similar and interactive sexual hormonal mechanisms in homothallic and heterothallic species, the results of membrane matings confirm exactly the expectations based on the reactions observed in water and agar matings. 5. The effects of hormone-containing filtrates from homothallic and heterothallic species have been reciprocally determined on species showing both types of sexuality. 6. Homothallic plants react to hormone A in a quantitative pattern similar to the response of heterothallic [male]s to hormone A plus hormone A1. Antheridial hyphal production is but little affected by hormones A1 and A2. 7. Degeneration and/or redifferentiation of oogonial initials results from high concentrations of hormone A in nine of twelve homothallic species investigated. Oogonial development, however, is normal if delimitation of the oogonium had occurred prior to the addition of the hormone. 8. Complete inhibition of oogonial initial production results from the addition of hormone A1 in three homothallic species. 9. Three homothallic species, A. americana, T. clavata, and T. primoachlya, were each shown to secrete both acetone-soluble and water-soluble (acetone-insoluble) substances capable of inducing antheridial hyphal production on [male] heterothallic plants. Each fraction, however, induces the reaction in quantitative patterns which preclude the identities of these hormones with the hormones of the A-complex from heterothallic species. 10. The conclusion is reached that homothallic species possess a hormonal mechanism similar in broad pattern to that previously demonstrated in heterothallic species, but that striking differences in detail, possibly only as regards hormonal specificities, obtain between the mechanisms characteristic of the two types of sexuality. 11. Each homothallic species possesses, in addition to the sexual capabilities requisite to its own hermaphroditism, affinities for extra-mycelial reactions, the kind and degree of which depend upon the sexual affinities of the immediate mate. Limited evidence is presented which indicates that the homothallic species studied range, as regards extra-mycelial potentialities, from strong-[male] to weak-[male]. These correspond to the predominant-[male] intergrades of heterothallic species in that they also possess weak [female] as well as [male] potentialities. 12. The possible significance of interspecific and intergeneric reactions involving homothallic species in nature is briefly discussed.

Morphogenesis in Schizophyllum commune

SummaryIn the basidiomycete Schizophyllum commune, a mutation in a locus coh-1 prevents the formation of cohensive masses of hyphae and thus precludes the development of fruiting bodies. The mutation does not interfere with dikaryosis. coh-1- is recessive to its wild-type allele and is unlinked to either the B factor or to the modifying mutation M14.

Dikaryosis: Genetic Determination in Schizophyllum

A dominant gene, dik+, has been identified as responsible for the establishment of the dikaryon in the basidiomycetous fungus Schizophyllum commune. Interaction between compatible homokaryons, both of which carry the recessive allele dik, leads to the formation of a diploid mycelium that closely resembles the homokaryon in morphology.

Heterothailism in Biflagellate Aquatic Fungi: Preliminary Genetic Analysis

Genetic analysis of several hundred progeny from crosses of two heterothallic species of Achlya and Dictyuchus provides preliminary information about the life cycle and pattern of sexuality in the biflagellate Phycomycetes. Extensive testing of mycelial progeny indicates a diploid life cycle. Control of sexual expression and mating competence appears to be based on a complex genetic system.

Schizophyllum commune: Gene Controlling Induced Haploid Fruiting

A single gene, fis+, is essential for induced haploid fruiting in Schizophyllum commune. It appears to segregate independently of the incompatibility factors.

The identification of indigo as a pigment produced by a mutant culture of Schizophyllum commune

Abstract On the basis of solubility tests, chemical analysis, and absorption spectra, a pigment produced by a mutant culture of Schizophyllum commune has been identified as indigo. The pigment is produced on a chemically defined medium with ammonium ion as the nitrogen source.

Number and Distribution of Bipolar Incompatibility Factors in Sistotrema brinkmannii

One hundred forty-four strains, representative of four of the five known bipolar heterothallic biological species of the Sistotrema brinkmannii aggregate, were analyzed for the number and distribution of incompatibility (mating-type) factors. Although most stocks were isolated from New England, a few representatives from Europe and Canada were included. Factors appear to be randomly distributed with geography, except that on individual pieces of wood a departure from randomness exists. Similarly, specific factors appear to be equally frequent, except for possible departure also at the substratal level. The number of specific mating types identified for the groups are 21, 55, 31, and 11. Estimates for the number of factors in nature approximate 100-300 per species, but variation exists. These estimates are significantly greater than those for previously reported bipolar Hymenomycetes. The theoretical significance of the geographical region of nonrandom distribution of mating types is discussed in the context of bipolar and tetrapolar breeding systems and concomitant inbreeding and outbreeding efficiencies.

Schizophyllum commune: New Mutations in the B Incompatibility Factor

Two new mutations in the B factor of Schizophyllum commune provide additional indications regarding control by the incompatibility factors of mating and sexual morphogenesis in this and other tetrapolar fungi.