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Ascomycota

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Ascomycota
Penicillium.jpg
Scientific Classification
Classes

Subphylum: Saccharomycotina (Hemiascomycetes)

Subphylum: Pezizomycotina (Euascomycetes)

Ascomycota (formerly known as Ascomycotina) is a taxonomic class commonly called sac fungi. They are perhaps best known for their members which are considered delicacies in many cultures (morels, and truffles), and a species of yeast which is commonly used to by bakers and in alchoholic fermentation.

The class has six different sub groups separated primarily based on the type of ascocarp they possess (a reproductive structure involved with the production of spores). There are four different types of ascocarp: cleitothecium, perithecium, apothecium, and ascostroma.

Contents

Anatomy

Black pycnidia of Phomopsis developing in culture on stems of alfalfa

Ascomycetes are also called sac fungi. It is a large variety species group of fungi and contains nearly 1950 categories. The Ascus is the sexual reproductive structure which produces ascospores. (Purves, p609)

Ascomycetes is broadly divided into two major groups, the euascomycetes and hemiascomycetes. Euascomycetes have the specialized fertilizing structure and hemiascomycetes don't have this kind of structure. Saccharomyces are the most famous hemiascomycetes; used by bakers and fermentation (Baker's yeast). [2]

The hemiascomycete yeasts reproduce asexually by fission, splitting into half when mitosis is finished, and by budding.

Yeasts are the most well studied as the eukaryote because the yeast ascus always contains four or eight ascospores and these ascospores will become haploid cells. They don't have a dikaryon stage (Purves, p611).

The euascomycetes are the fungi that include many filaments and are known as molds. It is also called the pezizomycotina. The euascomyvetes is the older name for pezizomycotina in the traditional mycology. Many euascomycetes cause a lot of problems for the crops such as grapes and need to be studied for methods of controlling these fungi.[3]

Reproduction

Neurospora asci. The asci are from a cross of histone H1-GFP x wild type. Four of the eight ascospores in each ascus show glowing hH1-GFP nuclei. The remaining four ascospores contain non-glowing wild type nuclei.

Ascomycota have two ways of reproduction: sexual and asexual. The way for asexual reproduction is through budding. Sexual reproduction happens when two haploid cells of opposite mating types fuse. The sexual reproduction of ascomycota is different from Zygomycota. Zygomycota release pheromones when its sexual reproduction and those pheromones could cause the two opposite mating types to grow toward each other. (Purves, p609)

Ascospores are the product of the ascus, it forms inside the ascus when the nucleus are surrounded by the new cell walls. Ascospores and asci will not be mature at once so not every ascus could contain eight ascospores.[4](Purves, p610)

Ecology

This is a picture of Morel.

Ascomycota are one common fungi that can be found on all the continents, it includes several important genera that are useful in our life: Saccharomyces, truffles, and morels. Truffles are one kind of food for pigs, it grows underground with the roots of certain plants. Ascomycota could use the dead plants as food so it helps clean the environment by eating dead things. Yeasts also play an important role in the genetic researches.[5]

Ascomycotina

Ascomycotina could be separated into six different groups, the way it is separated is based on the ascocarp, which is an ascus-bearing structure found in ascomycetous fungi, the category of the ascocarp, and the function of ascus. Ascocarp have four different types: cleitothecium, perithecium, apothecium, and ascostroma.

Except for laboulbeniomycetes, the other five types of fungi all have relationships with the illness of plants.

  • Hemiascomycetes: It don't have ascocarp, included most of the lower level ascomycetes.
  • Plectomycetes: It's ascus growth in the middle of the cleitothecium Independently. Included aspergillus and penicillium fungi. P. digitatum and P. italicum are the main reason for the putrescence of oranges.
  • Pyrenomycetes: It has a very develpoed asexual system and could produce lots of conidia. Pyrenomycetes is the biggest part in the ascomycotina. It normally has four different categories in pyrenomycetes: Erysiphales, Sphaeriales, Coronophorales, and Melioales.
  • Loculoascomycetes: It has a double layer perithecium and is very developed in asexual period, could produce lots of conidia. It has five different categories in loculoascomycetes, and the most important three are: Myriangiales, Dothideales, and Pleosporales.
  • Discomycetes: The ascocarp of discomycetes is apothecium, and different apothecium has different size, color, and structure. Normally it's shape is like a plate. It has seven categories in discomycetes: Phacidiales, Rhytismataceae, Rhytisma, Cophodermium, Helotiales, Sclerotinia, and Monilinia.
  • Laboulbeniomycetes: It don't produce asexual conidia and they are autoeciousness fungi of arthropods. [6]

[7] [8] [9]

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