Saturday, August 8, 2009

Phyla of a Fungi



Hello. Today we will be talking about "Phyla of a Fungi". Phyla of a fungi can be divided into 5 divisions. They are: Oomycota, Chytridiomycota, Zygomycota, Ascomycota, Basidiomycota. Let's us look in deeper.

Oomycota

Oomycota is a phylum of filamentous protists containing over 500 species. The majority of these organisms are in the groups commonly known as water molds or downy mildew. "Oomycota" means "egg fungi", referring to the oversize oogonia which house the female gametes (eggs). Despite the name and their superficial appearance, oomycetes are not fungi. While some members of Oomycota are relatively harmless, some species are parasitic and negatively affect aquatic plants or organisms.

Oomycete cells differ from those of true fungi in that they have walls of cellulose and the amino acid hydroxyproline. They are heterotophic, either saphropytic or parasitic. Oomycetes can reproduce asexually, by forming a structure called a sporangium or zoosporangium. Inside these sporangia, zoospores are produced, first the primary zoospore and then the secondary zoospore, which is laterally flagellated. Their flagellum allow the zoospores to move rapidly through water. This type of germination is most common among aquatic and soil-dwelling species. Oomycetes may also germinate directly on the host plant by way of a germ tube. Organisms of Oomycota may also reproduce sexually, by direct injection of the male nuclei (sperm) into the oogonium. This type of reproduction is known as "gametangical copulation".
Chytridiomycota

The name is derived from the Greek chytridion, meaning "little pot", describing the structure containing unreleased spores.Chytridiomycota are the smallest and simplest fungi. They emerged soon after the Precambrian period, and are ancestors to all Fungi. The first Chitridiomycota were found in northern Russia. There are three orders within Chytridiomycota: Chytridiales, Blastocadiales, and Monoblepharidales. They are unicellular and is attached to food-source by rhizoid. Both zoospores and gametes of the chytrids are mobile by their flagella, one whiplash per individual. Asexual spores are zoospores. Sexual spores are zygotes. They are the most primitive fungi. They kill frogs. Furthermore, they rumen fungi, in other words, they help in the digestion of a fungi.
Zygomycota
Zygomycota, or zygote fungi, is a phylum of fungi. The name comes from zygosporangia, where resistant spherical spores are formed during sexual production. Approximately 1060 species are known. They are mostly terrestrial in habitat, living in soil or on decaying plant or animal material. Some are parasites of plants, insects, and small animals, while others form symbiotic relationships with plants. Zygomycete hypae may be coenocytic, forming septa only where gametes are formed or to wall off dead hyphae.

The common example of a zygomycete is black bread mold (Rhizopus stolonifer), a member of the Mucorales. It spreads over the surface of bread and other food sources, sending hyphae inward to absorb nutrients. In its asexual phase it develops bulbous black sporangia at the tips of upright hyphae, each containing hundreds of haploid spores. As in most zygomycetes, asexual reproduction is the most common form of reproduction. Sexual reproduction in Rhizopus stolonifera, as in other zygomycetes, occurs when haploid hyphae of different mating types are in close proximity to each other. Growth of the gametangia commences after gametangia come in contact, and plasogamy, or the fusion of the cytoplasm, occurs. Karyogamy, which is the fusion of the nuclei, follows closely after. The zygosporangia are then diploid. Zygosporangia are typically thick-walled, highly resilient to environmental hardships, and metabolically inert. When conditions improve, however, they germinate to produce a sporangium or vegetative hypae.

Ascomycota

The Ascomycota are a Division/Phylum of the kingdom Fungi, and subkingdom Dikarya, whose members are commonly known as the Sac Fungi. They are the largest phylum of Fungi, with over 30,000 species.

They have sexual spores, which are Ascospores, that are borne internally in a sac (ascus). Fruiting bodies that are called ascocarp that bear these asci. However, the asexual spores are borne externally as conidia. Some examples of Ascomycota are Saprophytes, Insect Fungi (Cordyceps sp), Plant parasites (Claviceps purpurea-ergot) & Industrial fungi (Yeast).

Basidiomycota


One of two large phyla that, together with the Ascomycota, comprise the subkingdom Dikarya (often referred to as the "Higher Fungi") within the Kingdom Fungi. More specifically the Basidiomycota include mushrooms, puffballs, stinkhorns, bracket fungi, other polypores, jelly fungi, boteles, and the human pathogenic yeast, Cryptococcus. Basically, Basidiomycota are filamentous fungi composed of hypae (except for those forming yeasts), and reproducing sexually via the formation of specialized club-shaped end cells called basidia that normally bear external meiospores (usually four). These specialized spores are called basidiospores. However, some Basidiomycota reproduce asexually, and may or may not also reproduce sexually. Asexually reproducing Basidiomycota (discussed below) can be recognized as members of this phylum by gross similarity to others, by the formation of a distinctive anatomical features(clamp connection), cell wall components, and definitively by phylogenetic molecular analysis of DNA sequence data.

Well, that's basically all about the divisions in a Phyla Fungi. More will come, sooner or later.

Cheers & Have a Good Day ahead!