Mating in fungi

Mating in fungi

Mating in fungi is a complex process governed by mating types. Research on fungal mating has focused on only a few model species[1]. Since not all of the fungi reproduce sexually and many that do are isogamous, the terms male and female do not apply to this kingdom. Homothallic species are able to mate with themselves, while in heterothallic species only isolates of opposite mating types can mate.

Mating between isogamous fungi may consist only of a transfer of nuclei from one cell to another.[citation needed] Vegetative incompatibility within species often prevent a fungal isolate from mating with another isolate. Isolates of the same incompatibility group do not mate or mating does not lead to successful offspring. High variation has been reported[citation needed] including same chemotype mating, sporophyte to gametophyte mating and biparental transfer of mitochondria.

Contents

Mating type

A picture of the mating type mechanism has begun to emerge from studies of particular fungi such as yeast. The mating type genes are located in homeobox and encode enzymes for production of pheromones and pheromone receptors. Sexual reproduction thereby depends on pheromones produced from variant alleles of the same gene. Since sexual reproduction takes place in haploid organisms, it cannot proceed until complementary genes are provided by a suitable partner through cell or hyphal fusion. The number of mating types depends on the number of genes and the number of alleles for each.[citation needed]

Depending of the species, sexual reproduction takes place through gametes or hyphal fusion. When a receptor on one haploid detects a pheromone from a complementary mating type, it approaches the source through chemotropic growth or chemotactic movement if it is a gamete.

Zygomycete

Mating zygomycetes form progametangia with suspensors

A zygomycete hypha grows towards a compatible mate and they both form a bridge, called a progametangia, by joining at the hyphal tips via plasmogamy. A pair of septa forms around the merged tips, enclosing nuclei from both isolates. A second pair of septa forms two adjacent cells, one on each side. These adjacent cells, called suspensors provide structural support. The central cell is destined to become a spore. The nuclei join in a process called karyogamy to form a zygote.

Sac fungi

Sac fungi form ascogonium and antheridium with trichogyne bridge

As it approaches a mate, a haploid sac fungus develops one of two complementary organs, a "female" ascogonium or a "male" antheridium. These organs resemble gametangia except that they contain only nuclei. A bridge, the trichogyne forms, that provides a passage for nuclei to travel from the antheridium to the ascogonium. A dikaryote grows from the ascogonium, and karyogamy occurs in the fruiting body.

Club fungi

Fusion of club fungi

In club fungi, cells from compatible hyphae fuse upon contact.[citation needed] The donor nuclei divide and travel from cell to cell of the receiver hypha. Septa open to allow the passage. The exchange may or may not be reciprocal. As with sac fungi, karyogamy is deferred until a fruiting body forms.


See also


References

  1. ^ Turgeon B.G. -1998- Application of mating type gene technology to problems in fungal biology. Annual review of Phytopathology. 36:115-137

Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Mating type — Mating types occur in eukaryotes that undergo sexual reproduction via isogamy. Since the gametes of different mating types look alike, they are often referred to by numbers, letters, or simply + and instead of male and female. Mating… …   Wikipedia

  • mating type — n a strain or clone or other isolate made up of organisms (as certain fungi or protozoans) incapable of sexual reproduction with one another but capable of such reproduction with members of other strains of the same organism and often capable of… …   Medical dictionary

  • Mating — Dragonflies mating Tortoises mating …   Wikipedia

  • Mating of yeast — The yeast Saccharomyces cerevisiae is a simple single celled eukaryote with both a diploid and haploid mode of existence. The mating of yeast only occurs between haploids, which can be either the a or α (alpha) mating type and thus display simple …   Wikipedia

  • Fungi — Pilze Anistrichterling (Clitocybe odora) Systematik Klassifikation: Lebewesen …   Deutsch Wikipedia

  • Mating-type region — The mating type region is a specialized region in the genomes of some yeast and other fungi, usually organized into heterochromatin and possessing unique histone methylation patterns. The genes in this region regulate the mating type of the… …   Wikipedia

  • Fungi Imperfecti — A phylum of fungi in which sexual reproduction is not known or in which one of the mating types has not yet been discovered. Formerly, most fungi causing disease in humans were considered asexual and were placed in this class, but studies have… …   Medical dictionary

  • mating type — noun : a strain or clone or other isolate made up of organisms (as certain fungi or protozoans) incapable of sexual reproduction with one another but capable of such reproduction with members of other strains of the same organism and often… …   Useful english dictionary

  • Sexual reproduction — is the creation of a new organism by combining the genetic material of two organisms. The two main processes are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the… …   Wikipedia

  • Fungus — Fungi redirects here. You may be looking for Fungi (music) or Fungus (XM). Fungi Temporal range: Early Devonian–Recent (but see text) …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”