MYCOLOGY

                 WHAT ARE FUNGI?

Fungi can be single celled or very complex multicellular organisms. They are found in just about any habitat but most live on the land, mainly in soil or on plant material rather than in sea or fresh water.   A group called the decomposers grow in the soil or on dead plant matter where they play an important role in the cycling of carbon and other elements. Some are parasites of plants causing diseases such as mildews, rusts, scabs or canker. In crops fungal diseases can lead to significant monetary loss for the farmer. A very foot, ringworm and thrush

Fungi (Singular: fungus) are classified within their own kingdom - The Kingdom Fungi, while some are in The Kingdom Protista. A fungus is neither a plant nor an animal. It is similar to a plant, but it has no chlorophyll and cannot make its own food like a plant can through photosynthesis. They get their food by absorbing nutrients as from their surroundings. 

Kingdom  Fungi includes mushrooms, rusts, smuts, puffballs, truffles, morels, molds, and yeasts, and thousands of other organisms and microorganisms. They range from microscopic single-celled organisms, such yeast, to gigantic multicellular organisms.  

Many fungi play a crucial role in decomposition (breaking things down) and returning nutrients to the soil. They are also used in medicine, an example is the antibiotic penicillin, as well as in industry and food preparation. 

For a long time fungi were classified as plants, mainly because of their similar lifestyles - both are seen to grow in soil and are sessile (permanently attached; not moving). Plant and fungal cells both have a cell wall, while cells from the animal kingdom don't. Fungi are thought to have diverged from the plant and animal kingdoms about one billion years ago

GENERAL CHARATERISTICS OF FUNGI

1. Nutrition. -Heterotrophic (lacking photosynthesis), feeding by absorption rather than ingestion.

2. Vegetative status. -On or in the substratum, typically as a non-motile mycelium of hyphae showing internal protoplasmic streaming. Motile reproductive states may occur

3. Cell wall         -Typically present, usually based on glucans and chitin, rarely on glucans and cellulose (Oomycota).

4.Nuclear status.     -Eukaryotic, uni- or multi- nucleate, the thallus being homo- or hetero- karyotic, haploid, dikaryotic or diploid, the latter usually of short duration (but exceptions are known from several taxonomic groups).

5.  Life cycle -  Simple or, more usually, complex. 

6. Reproduction   - The following reproductive events may occur: sexual (i.e. nuclear fusion and meiosis) and/or parasexual (i.e. involving nuclear fusion followed by gradual de-diploidization) and/or asexual (i.e. purely mitotic nuclear division)

7.Propagules      -These are typically microscopically small spores produced in high numbers. Motile spores are confined to certain groups. 

8.Sporocarps     -Microscopic or macroscopic and showing characteristic shapes but only limited tissue differentiation.

9. Habitat  - Ubiquitous in terrestrial and fresh- water habitats, less so in the marine environment.

10. Ecology -Important ecological roles as saprotrophs, mutualistic symbionts, parasites, or hyperparasites.

                      HABITAT

Fungi exist in various habitats, including deep down in the ocean, lakes, rocks, deserts, very salty environments, and areas of extremely high or low temperatures. Some can prevail even after being exposed to intense UV and cosmic radiation as one would encounter during space travel. During the 13 years the Mir space station was in orbit, a great deal of equipment was continuously being damaged by mutated fungi that had been breeding in the space station. At first technicians were puzzled and thought the problems must have been due to faulty workmanship. The majority of fungi live on land. Fungi and bacteria are the main decomposers of organic matter in virtually all ecosystems on Earth. 

Taxonomists have classified approximately 70,000 types of fungi. Experts say there are many more - possibly 1.5 million. Fungi used to be classified according to their shape, structure, biological and biochemical characteristics. Advances in DNA sequencing have helped extend the classification of different species of fungi. Taxonomy is the classification of organisms.

                       NUTRITION

Although fungi are similar to plants in many ways, they do not have chlorophyll, the green pigment that enables plants to make their own food with the aid of sunlight (photosynthesis).

Fungi release digestive enzymes that decompose things around them, turning them into food. The fungus then absorbs the dissolved foods through Fungi have adapted various ways of doing this: the walls of its cells.  Parasitic fungi - several species of fungi exist as parasites, feeding on live hosts, which might be animals, plants or even other fungi.

 Some of these parasitic fungi damage our crops, sicken farm  animals, and harm or completely destroy trees. Dutch elm disease, caused by the fungus Ophiostoma ulmi destroyed hundreds of millions of elm tress worldwide. The rice blast fungus Magnaporthe oryzae can devastate rice crops. 

 The following fungi can cause serious diseases to humans: aspergilloses, candidoses, coccidioidomycosis, cryptococcosis, histoplasmosis, mycetomas, and paracoccidioidomycosis. An example is vaginal yeast infection.

Saprobes or saprophytes - these break down dead organisms and substances that contain organic compounds and feed on them when they have rotted. Humans welcome saprobes and also fear them. They are useful decomposers of organic material, but also damage wood products and spoil our food. When ships used to be made of wood they were often rendered unusable by wood-digesting saprobes (polypores).

Symbiosis - this is when one living thing builds up a relationship with another for the mutual survival of both. Some fungi form mycorrhizae which enhance a plant-root's capacity to absorb nutrients. 

The plant synthesizes nutrients the fungus needs and exchanges these nutrients for minerals the fungus absorbs from the soil - i.e. the plant and the fungus trade nutrients.  Some leaf-cutting ants eat nothing but a type of fungi that lives in their nests. 

The fungi live on nothing but the leaves the ants carry in for them. If the ant starved the fungi and killed them the ant would have no food and would die; if the fungi found a way of poisoning the ants and killing them off, the fungi would have no food and would die. They both depend on each other for survival.