Improved media for testing the mating reaction and genetic complementation of Ustilago hordei

1992 ◽  
Vol 70 (4) ◽  
pp. 788-793 ◽  
Author(s):  
Alfredo D. Martinez-Espinoza ◽  
Karla J. Dugan ◽  
Michael E. Bjarko ◽  
John E. Sherwood
Keyword(s):  
Mating Type ◽  
Activated Charcoal ◽  
Rapid Identification ◽  
Sexual Cycle ◽  
Mating Test ◽  
Opposite Mating Type ◽  
Mating Reaction ◽  
Ustilago Hordei ◽  
Key Words Barley ◽  
The Stability

The sexual cycle of Ustilago hordei, which results in the formation of teliospores, requires growth on its barley host for completion. However, the early steps of mating, including conjugation and the formation of dikaryotic mycelium, can occur on artificial media. The addition of activated charcoal to a variety of media enhanced the stability and intensity of the mating reaction as measured by mycelium formation. The incubation time at which the strongest mating reaction occurred was also reduced. The dikaryotic nature of the mycelia that resulted from mating on charcoal-containing media was confirmed by fluorescence microscopy. Complementation assays using minimal medium containing activated charcoal demonstrated allelism of mutations in auxotrophic sporidial strains of opposite mating type. The ease and reliability of this mating test allow for rapid identification of the mating type of unknown isolates and progeny of crosses, as well as providing a dependable procedure for performing complementation tests. Key words: barley, covered smut, Hordeum vulgare, mating type.

A REGULATORY SYSTEM CONTROLLING INHIBITION IN THE SEXUAL CYCLE OF NEUROSPORA

1969 ◽  
Vol 11 (3) ◽  
pp. 689-705 ◽  
Author(s):  
H. Branch Howe Jr. ◽  
V. Prakash
Keyword(s):  
Mating Type ◽  
Inhibitory Activity ◽  
Regulatory System ◽  
Inhibitory Effect ◽  
Sexual Cycle ◽  
Opposite Mating Type ◽  
Partial Inhibition ◽  
Total Inhibition ◽  
Steady Rate ◽  
Rate Of Movement

A cross made by adding conidia to protoperithecia on a mycelium of opposite mating type inhibits a subsequent cross on the same mycelium, or on an adjacent mycelium connected either by hyphae or medium. The inhibitory activity reaches a steady rate of movement through the area of the second cross from the area of the first cross and brings about either total or partial inhibition of the second cross, depending upon certain controllable variables; translocation of the activity occurs primarily through the hyphae but to a lesser degree through the medium as well. Total inhibition is not a result of modification of the medium by the first cross, such as depletion of nutrients or change in pH. An uncrossed mycelium which received activity from a crossed mycelium becomes inhibited either irreversibly or, to a certain extent, reversibly, depending upon the degree of activity received; in either event, transmission of this passive activity may occur from this mycelium to an outgrowing mycelium on fresh medium. The experiments reported here were done primarily with N. tetrasperma, in which the inhibitory effect was first found, but the effect has also been observed in N. crassa.

scholarly journals A simple, cheap, and robust protocol for the identification of mating type in Saccharomyces cerevisiae

2020 ◽  
Author(s):  
Samantha D. M. Arras ◽  
Lucy Mitsugi-McHattie ◽  
Matthew A. Woods ◽  
Charlotte E. Johnson ◽  
Sylvie Hermann-Le Denmat ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
Genetic System ◽  
Rapid Identification ◽  
Culture Vessel ◽  
Diploid Strain ◽  
Liquid Media ◽  
Opposite Mating Type ◽  
Specialized Equipment ◽  
Cell Densities

AbstractSaccharomyces cerevisiae is an exceptional genetic system, with genetic crosses facilitated by its ability to be maintained in haploid and diploid forms. Such crosses are straightforward as long as the mating type and ploidy of the strains are known. Haploid S. cerevisiae cells are either MATa or MATα mating type. Several techniques can be used to determine mating type (or ploidy), but are typically time-consuming, require specialized components, and/or the results are inconsistent and transient. Here we validated a simple, cheap and robust method to enable rapid identification of S. cerevisiae mating types. When cells of opposite mating type are mixed in liquid media, they creep up culture vessel sides, a phenotype that can easily be detected visually. In contrast, mixtures of cells of the same mating type or with a diploid strain(s) simply settle out. The method does not require specialized equipment, and is robust to different media, cell densities, temperatures and strains. It can be performed in 96-well plates, and the phenotype is observable for several days. The simplicity and robustness of this method makes it ideal for routine verification of S. cerevisiae mating type, and it could be used to screen for genes underlying the creeping phenotype.

The genetics of pathogenic aggressiveness in three dikaryons of Ustilago hordei

1984 ◽  
Vol 62 (6) ◽  
pp. 1209-1219 ◽  
Author(s):  
C. E. Caten ◽  
C. Person ◽  
J. V. Groth ◽  
S. J. Dhahi
Keyword(s):  
Mating Type ◽  
Opposite Mating Type ◽  
Gene Effects ◽  
Genetic Determination ◽  
Ustilago Hordei ◽  
Number Of Genes ◽  
Polygenic System ◽  
New Races ◽  
Pathogen Populations

The genetic determination of a quantitative component of pathogenicity, aggressiveness, was examined in progeny populations derived from three parent dikaryons of Ustilago hordei. Aggressiveness was assessed as the proportion of smutted plants produced from inoculated seed of a compatible barley cultivar. The parents differed in their origins and cultural histories and this was reflected in the variability of their progenies. A standard race-10 strain appeared to be homozygous for genes affecting aggressiveness, while a dikaryon produced by mating two unrelated sporidia was heterozygous and produced highly variable progeny populations. In these populations, aggressiveness was determined by a polygenic system which involved both additive and dominance gene effects. It was not possible to estimate the number of genes involved, but segregation was apparent in individual tetrads. Furthermore, a difference between opposite mating-type segregants suggested the presence of a factor which affected aggressiveness and was linked to mating type. The dominance effects were ambidirectional suggesting that genotypes giving an intermediate level of aggressiveness are the most fit. The aggressiveness of a pathogen strain is an important factor determining the severity of epidemics on compatible hosts. It is also a major component of fitness and may influence the frequency of virulence factors in pathogen populations and the evolution of new races.

scholarly journals Uniparental sexual reproduction following cell-cell fusion of opposite mating-type partners

2020 ◽  
Author(s):  
Vikas Yadav ◽  
Sheng Sun ◽  
Joseph Heitman
Keyword(s):  
Mating Type ◽  
Genetic Material ◽  
Nuclear Genome ◽  
Sexual Cycle ◽  
Uniparental Inheritance ◽  
Opposite Mating Type ◽  
Fluorescent Reporter ◽  
Unisexual Reproduction ◽  
F1 Progeny ◽  
Opposite Sex

AbstractSome animal species require an opposite-sex partner for their sexual development but discard the partner’s genome before gamete formation, generating hemi-clonal progeny in a process called hybridogenesis. In this study, we discovered hybridogenesis-like reproduction in a basidiomycete fungus, Cryptococcus neoformans. C. neoformans has two mating types, MATa and MATα, which fuse to produce a dikaryotic zygote that completes a sexual cycle producing recombinant meiotic progeny. Here, we discovered exclusive uniparental inheritance of nuclear genetic material in a fraction of the F1 progeny produced during bisexual reproduction of two opposite mating-type partners. By analyzing strains expressing fluorescent reporter proteins, we observed that dikaryotic hyphae were produced, but only one parental nuclei was found in the terminal basidium where sporulation occurs. Whole-genome sequencing revealed the nuclear genome of the progeny was identical with one or the other parental genome, whereas the mitochondrial genome was always inherited from the MATa parent. Uniparental sporulation was also observed in natural isolate crosses occurring in concert with biparental sporulation. The meiotic recombinase Dmc1 was found to be critical for uniparental reproduction. These findings reveal an unusual mode of eukaryotic microbial unisexual reproduction that shares features with hybridogenesis in animals.

scholarly journals THE SEARCH FOR MATING-TYPE-LIMITED GENES IN THE HOMOTHALLIC ALGA CHLAMYDOMONAS MONOICA

Genetics ◽  
1986 ◽  
Vol 113 (3) ◽  
pp. 601-619
Author(s):  
Karen P VanWinkle-Swift ◽  
Jang-Hee Hahn
Keyword(s):  
Mating Type ◽  
Resistance Mutation ◽  
Mendelian Inheritance ◽  
Sexual Cycle ◽  
Uniparental Inheritance ◽  
Cell Type ◽  
Erythromycin Resistance ◽  
Type Locus ◽  
Heterothallic Species ◽  
Chlamydomonas Monoica

ABSTRACT The non-Mendelian erythromycin resistance mutation ery-u1 shows bidirectional uniparental inheritance in crosses between homothallic ery-u1 and ery-u1  + strains of Chlamydomonas monoica. This inheritance pattern supports a general model for homothallism invoking intrastrain differentiation into opposite compatible mating types and, further, suggests that non-Mendelian inheritance is under mating-type (mt) control in C. monoica as in heterothallic species. However, the identification of genes expressed or required by one gametic cell type, but not the other, is essential to verify the existence of a regulatory mating-type locus in C. monoica and to understand its role in cell differentiation and sexual development. By screening for a shift from bidirectional to unidirectional transmission of the non-Mendelian ery-u1 marker, a mutant with an apparent mating-type-limited sexual cycle defect was obtained. The responsible mutation, mtl-1, causes a 1000-fold reduction in zygospore germination in populations homozygous for the mutant allele and, approximately, a 50% reduction in germination for heterozygous (mtl-1/mtl-1  +) zygospores. By next screening for strains unable to yield any viable zygospores in a cross to mtl-1, a second putative mating-type-limited mutant, mtl-2, was obtained. The mtl-2 strain, although self-sterile, mates efficiently with mtl-2  + strains and shows a unidirectional uniparental pattern of inheritance for the ery-u1 cytoplasmic marker, similar to that observed for crosses involving mtl-1. Genetic analysis indicates that mtl-1 and mtl-2 define unique unlinked Mendelian loci and that the sexual cycle defects of reduced germination (mtl-1) or self-sterility (mtl-2) cosegregate with the effect on ery-u1 cytoplasmic gene transmission. By analogy to C. reinhardtii, the mtl-1 and mtl-2 phenotypes can be explained if the expression of these gene loci is limited to the mt  + gametic cell type, or if the wild-type alleles at these loci are required for the normal formation and/or functioning of mt  + gametes only.

ESCAPE FROM MATING-TYPE INCOMPATIBILITY IN BISEXUAL (A + a) NEUROSPORA HETEROKARYONS

1975 ◽  
Vol 17 (3) ◽  
pp. 441-449 ◽  
Author(s):  
A. M. DeLange ◽  
A. J. F. Griffiths
Keyword(s):  
Mating Type ◽  
Loss Of Function ◽  
Wild Type ◽  
Opposite Mating Type ◽  
Type Locus ◽  
Heterokaryon Incompatibility ◽  
Recessive Mutant ◽  
Type Rate ◽  
Wild Type Rate ◽  
Incompatibility Locus

In Neurospora crassa, strains of opposite mating type generally do not form stable heterokaryons because the mating type locus acts as a heterokaryon incompatibility locus. However, when one A and one a strain, having complementing auxotrophic mutants, are placed together on minimal medium, growth may occur, although the growth is generally slow. In this study, escape from such slow growth to that at a wild type or near-wild type rate was observed. The escaped cultures are stable heterokaryons, mostly having lost the mating type allele function from one component nucleus, so that the nuclear types are heterokaryon compatible. Either A or a mating type can be lost. This loss of function has been attributed to deletion since only one nuclear type could be recovered in all heterokaryons except one, but deletion spanning adjacent loci has been directly demonstrated in a minority of cases. Alternatively when one component strain is tol and the other tol+ (tol being a recessive mutant suppressing the heterokaryon incompatibility associated with mating type), escape may occur by the deletion or mutation of tol+, also resulting in heterokaryon compatibility. An induction mechanism for escape is speculated upon.

scholarly journals Isolation of Neurospora crassa A mating type mutants by repeat induced point (RIP) mutation.

Genetics ◽  
1992 ◽  
Vol 132 (1) ◽  
pp. 125-133 ◽  
Author(s):  
N L Glass ◽  
L Lee
Keyword(s):  
Neurospora Crassa ◽  
Mating Type ◽  
Single Copy ◽  
Open Reading Frame ◽  
Sexual Cycle ◽  
Reading Frame ◽  
Heterokaryon Incompatibility ◽  
Functional Regions ◽  
A Genome ◽  
Ascospore Formation

Abstract In the filamentous fungus, Neurospora crassa, mating type is regulated by a single locus with alternate alleles, termed A and a. The mating type alleles control entry into the sexual cycle, but during vegetative growth they function to elicit heterokaryon incompatibility, such that fusion of A and a hypha results in death of cells along the fusion point. Previous studies have shown that the A allele consists of 5301 bp and has no similarity to the a allele; it is found as a single copy and only within the A genome. The a allele is 3235 bp in length and it, too, is found as a single copy within the a genome. Within the A sequence, a single open reading frame (ORF) of 288 amino acids (mt A-1) is thought to confer fertility and heterokaryon incompatibility. In this study, we have used repeat induced point (RIP) mutation to identify functional regions of the A idiomorph. RIP mutations in mt A-1 resulted in the isolation of sterile, heterokaryon-compatible mutants, while RIP mutations generated in a region outside of mt A-1 resulted in the isolation of mutants capable of mating, but deficient in ascospore formation.

Sign in / Sign up

Export Citation Format

Share Document