Mating Type and Morphogenesis in Ustilago violacea

1979 ◽  
Vol 140 (1) ◽  
pp. 94-101 ◽  
Author(s):  
Alan W. Day
Keyword(s):  
Mating Type ◽  
Ustilago Violacea

scholarly journals Evidence for a new kind of regulatory gene controlling expression of genes for morphogenesis during the cell cycle in Ustilago violacea

1975 ◽  
Vol 25 (3) ◽  
pp. 253-266 ◽  
Author(s):  
A. W. Day ◽  
J. E. Cummins
Keyword(s):  
Cell Cycle ◽  
Mating Type ◽  
Cell Cycle Control ◽  
Regulatory Gene ◽  
Type Locus ◽  
Ustilago Violacea ◽  
Temporal Properties ◽  
Expression Of Genes ◽  
Separate Control ◽  
A Cell

SUMMARYThe first part of the paper provides strong supportive evidence for the previous findings (Cummins & Day, 1973; Day & Cummins, 1973) that the two alleles of the mating-type locus of the basidiomycete Ustilago violacea have different periods of inducibility during a cell cycle, and that the cell cycle characteristics of each allele are maintained in freshly isolated diploids. This difference in temporal properties of the alleles appears to be the basis of the dominance of allele a2 as it is inducible during a phase of the cell cycle when allele a1 is non-inducible. During G1 both alleles appear to be inducible and apparently ‘neutralize’ each other so that the cell cannot mate.The second part of the paper provides evidence for a unique genetic control mechanism. The evidence suggests that the period of cell cycle inducibility of a locus governing a morphogenetic pathway may be regulated by a separate control gene the cc locus, with two known alleles ccstr(a stringent or restricted period of inducibility) and ccrel (a relaxed or non-restricted period of inducibility). This hypothesis stems from analysis of a diploid that was a1· ccstr/a2· ccrel and showed dominance of allele a2 during the S and G2 phases when freshly isolated, but which became incapable of mating after a period of subculturing. Analysis of haploids derived from this diploid strain showed that both mating-type alleles were functional but that it was now homozygous for ccstr, i.e. of genotype a1· ccstr/a2·ccstr· Thus the temporal and functional aspects of the mating type alleles are determined by different loci. It is postulated that cell cycle control loci may be widespread and serve to regulate the action of genes concerned with morphogenesis in relation to other cell cycle events.

Conjugation in Ustilago violacea. I. Morphology

1974 ◽  
Vol 20 (2) ◽  
pp. 187-191 ◽  
Author(s):  
N. H. Poon ◽  
J. Martin ◽  
A. W. Day
Keyword(s):  
Cell Cycle ◽  
Mating Type ◽  
Electron Micrographs ◽  
Cell Walls ◽  
Plasma Membranes ◽  
Smut Fungus ◽  
Type Ii ◽  
Opposite Mating Type ◽  
Ustilago Violacea ◽  
Anther Smut

Conjugation in the anther smut fungus, Ustilago violacea, is described and five stages are characterized viz. (i) intimate pairing of cells of opposite mating type; (ii) development of bumps from each cell at the point of pairing. The cell walls of opposing pegs are fused, but the plasma membranes are not yet affected; (iii) elongation of the bumps into pegs; (iv) dissolution of the walls and plasma membranes of opposing pegs at the point of contact, and the formation of a tube; (v) elongation of the tube to the mature mating configuration (about 5 μm). Electron micrographs and Nomarski interference contrast micrographs of this sequence are illustrated. The assembly of the conjugation tube begins as early as 1.5 h after the cells are mixed on mating medium and is completed in about 45 min. Even in asynchronous populations there is a burst of synchronous mating, followed by later asynchronous mating. Observations on the ability to mate of unbudded and budded cells support the evidence from cell cycle work that allele a1 mates only in the G1 phase (unbudded) while allele a2 is competent to mate during all phases.

scholarly journals The Distribution of Mating-Type Bias in Natural Populations of the Anther-Smut Ustilago violacea on Silene alba in Virginia

Mycologia ◽  
1998 ◽  
Vol 90 (3) ◽  
pp. 372 ◽  
Author(s):  
P. V. Oudemans ◽  
H. M. Alexander ◽  
J. Antonovics ◽  
S. Altizer ◽  
P. H. Thrall ◽  
...  
Keyword(s):  
Mating Type ◽  
Natural Populations ◽  
Ustilago Violacea ◽  
Silene Alba ◽  
Anther Smut

THE ISOLATION AND IDENTIFICATION OF POLYPLOID STRAINS OF USTILAGO VIOLACEA

1972 ◽  
Vol 14 (4) ◽  
pp. 925-932 ◽  
Author(s):  
Alan W. Day
Keyword(s):  
Growth Rate ◽  
Stationary Phase ◽  
Cell Volume ◽  
Mating Type ◽  
Dominant Allele ◽  
Isolation And Identification ◽  
Volume Stability ◽  
Type Allele ◽  
Rate Decrease ◽  
Ustilago Violacea

A method for the synthesis of polyploid strains of Ustilago violacea and the criteria for their identification are described. Cell length increases directly in proportion to the ploidy and thus the volume of the cell increases very rapidly at higher ploidies. The volume of the nucleus also increases but remains at a constant 3-4% of the cell volume. Stability and growth rate decrease with increasing ploidy. The a2 mating-type allele acts as a simple dominant allele in log phase cells, but there is no dominance in stationary phase cells.

Fungal fimbriae. II. Their role in conjugation in Ustilago violacea

1975 ◽  
Vol 21 (4) ◽  
pp. 547-557 ◽  
Author(s):  
A. W. Day ◽  
N. H. Poon
Keyword(s):  
Cell Surface ◽  
Mating Type ◽  
Electron Micrographs ◽  
Essential Role ◽  
Smut Fungus ◽  
Mating Types ◽  
Opposite Mating Type ◽  
Sensitive Material ◽  
Ustilago Violacea ◽  
Anther Smut

During conjugation in the anther smut fungus Ustilago violacea cells of opposite mating type first pair tightly and then develop a conjugation tube or bridge between them. The cells of both mating types are covered in long fine hairs or fimbriae, some of which appear to end in knobs. Experiments involving enzyme treatments of the cell surface indicate that these fimbriae do not play an essential role in cell pairing, instead pairing seems to be initiated when one or both mating types produce amorphous masses of α-amylase-sensitive material. Electron micrographs, enzyme and inhibitor studies, and experiments using restrictive temperatures suggest, however, that fimbriae may be essential for the later stages of conjugation i.e. development of the conjugation tube. If so, it is suggested that they may permit the exchange of macromolecules between the conjugating cells, initiating localized wall-softening and wall-breakdown.

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