Puffballs
· Division: Basidiomycota
· Mode of reproduction: Cloud of dust-like spores is emitted when mature fruiting body bursts
· Uses: Dry spores can be used as a coagulant to stop bleeding
· Uses: Human consumption – puffballs are solid white on the inside
· Avoid confusing them with deadly mushrooms by checking the insides to avoid death
Puffball mushrooms on sale at a market in England.
(Note the slices are uniform and white all the way through.)
Food
The usage of fungi for food, preservation or other purposes by humans are wide-ranging and has a rich history. For example, yeasts are used to ferment beer, wine and bread; while some other species, for example, the Aspergillus oryzae, are used in the production of soy sauce and tempeh, a food product made from soya beans, with different nutritional characteristicsa and textural qualities. Saccharomyces cerevisiae (also known as baker’s yeast), a single cell fungus, is used in the baking of bread and other wheat-based products such as pizza and dumplings. It is also used for the production of alcoholic beverages through fermentation. Several species, such as the Agaricus bisporus and the Portobello are sold as button mushrooms for consumption.
There are many more mushroom species that are harvested from the wild for personal consumption or commercial sale. Milk mushrooms, morels, chanterelles, truffles, black trumpets, and porcini mushrooms all demand a high price on the market and are often used in gourmet dishes.
For certain types of cheeses, it is also a common practice to inoculate milk curds with fungal spores to forment the growth of a specific species of mould that impart a unique flavour and textures to the cheese, this accounts for the blue colour in cheeses such as Stilton of Roquefort. The moulds used in cheese production are usually non-toxic and are thus safe for human comsumption; however, mycotoxins may accumulate due to fungal spoilage during cheese rippening or storage.
Soya sauce – Aspergillus oryzae, Pediococcus soyae, Saccharomyces rouxii
Yeasts – Saccharomyces cerevisae, e.g. wine and vodka
Cheese
Other human uses
Fungi are also used widely to produce industrial chemicals like lactic acid, antibiotics and even to make stone-washed jeans.
Fungi in the biological control of pests
In agriculture, fungi that competes for nutrients and space with, and eventually prevail over, pathogenic microorganisms, such as bacteria or other fungi, via the competitive exclusion principle, or are parasites of pathogens, may be beneficial agents for human use. Some fungi may be used to suppress growth or eliminate harmful plant pathogens, such as insects, mites, weeds, nematodes and other fungi that cause diseases of important crop plants.
Entomopathogenic fungi can be used as biopesticides, for they actively kill insects. Examples of fungi that have been used widely as biopesticides are Beauveria bassiana, Metarhizium anisopliae, Paecilomyces spp and Verticillum lecanii.
Fungi in Medicine
Antibiotics – e.g. Penicillin, Griseofulvin, Cephalosporin
Fungi are usually divided into 2 groups, filamentous and unicellular.
- Hypha : a long, branching filamentous cell of a fungus cell. Absorbs nutrients into the cell inself for nourishment.
- Organelles :
o vacuole removes unwanted structual debris, isolates materials that might be harmful to the cell,it also contains waste products, maintains the internal pressure or turgor within the cell and acidic internal pH and exports unwanted substances from the cell .
o mitochondrion produces ATP and regulates cellular metabolism.
- Septa : There is generally 2 types first is the type where there is an ingrowth of the plasma membrane with a new cell wall formation because of this a septum is tapered towards the central pore. The second type, there is a swelling around the pore region which is called dolipore septum, on each side of this septal pore caps or parenthesomes which are perforate membranes are found.
o Secondary mycelium of basidiomycetes are specialized septem known as dolipore septum. This is a specialized condition found in many but not all Basidiomycetes. This results from the fusion of 2 monokaryotic hyphae that were from single spores. The secondary mycelium holds the dikaryotic condition by clamp connection. Clamp connection is the formation of a bulge near the 2 nuclei on the hypha.
- Cell walls : It is a layer surrounding the cell and it gives the cells rigidity and strength, offering protection against mechanical stress.
Specialised Vegetative Structures
There are special functions for vegetative structures. The function may be for survival purposes.
- Appressoria : It is a specialized hyphal that is pressed against the cell surface.
- Haustoria : It is a special absorptive structure which penetrates the host cell after that it enlarges the absorptive surface area.
- Sclerotia : It is made up of hyphae that are cemented together that may be of variable shape and size. It functions as a storage for materials for survival.
- Rhizomorphs : It is compose of ropelike hyphae. It functions for the fungi’s survival.
The study of fungi is called mycology and there is a branch of mycology dealing with mushroom called mushroom biology. Mushroom is a macrofungus with a fruiting body which can be seen with human eyes on the surface of the ground or under the ground. There is specific name for both types of mushrooms, for those on the surface they are called epigeous and for those which are under the ground they are called hypogeous. These mushrooms need not be edible. There are 2 types of fruiting body the mushrooms have first is the basidiocarps for sexual fruiting bodies of the basidiomycetes and the ascocarps for the sexual fruiting body of the ascomycetes. Of all the approximate species of basidiomycetes around 10,000 had been suggested to be big enough to be considered a food source but only half of it is considered edible. Mushroom just like fungi are found almost everywhere. They can be use for a lot of purposes like medicine or food etc.
Fungi are ubiquitous – they can be found everywhere, in the air, in the swimming pool, in plants and animals, as well as in your body. Did you know that just one teaspoon of soil can contain an estimated 120,000 fungi? They also thrive in slightly acidic conditions with a pH of around 5. This explains why fungi can grow in your sweaty socks which remain unchanged for weeks. However, fungi are able to grow in areas with low moisture too. An example of such as fungus would be Podaxis PixillarisIt is found worldwide in arid places.
Sexual and asexual reproduction of the fungi is commonly via spores, often created on specialized structures or in fruiting bodies. Some species have lost the ability to form specialized reproductive structures, and thus proliferate solely by vegetative growth.
Fungi can reproduce either sexually or asexually, depending on conditions in the environment; where certain conditions trigger genetically determined developmental programs leading to the specialized structures for sexual or asexual reproduction, where they can be applicable both reproduction and efficient dissemination of spores or spore-containing propagules.
Asexual
Asexual reproduction via vegetative spores via mycelial fragmentation is common in many fungal species and permits faster dispersal than sexual reproduction. Asexual spores may form a population from the origin, and thus resulting in new colonizing.
Modes of asexual reproduction
Sexual
There are 4 types of fungi reproductive structure for sexual reproduction. They are motile gametes, gametangia, non-motile spermatia fusing with the structure of the female sex organ and compatible vegatative haphae. Fusion of matile gametes brings sexuality which forms the zygote later on. Fusion of gametangia brings about the formation of a zygospore. Spermatization is the transfer of the sperm in this case called the spermatium to a female sex organ. There is also a process called somatogamy which occurs in mushrooms, this is the pocess of the vegetative hyphae fusing.
Modes of sexual reproduction
Nonsexual
There is a few ways for fungi to reproduce for example the most common is by spores. Sporangiospores are spores that are formed in a sac-like structure it contains a lot of them in it and the sac itself is called a sporangium. There is a difference between the spores of aquatic fungi and land fungi, aquatic fungi’s spores are motile and land fungi’s spores are non motile (mostly dispersed by wind). There is another type of reproduction method it is by conidia. It is produced by chain and specialized hyphae which is called conidiophores and are generally dispersed by the wind.
Ascomycete Reproduction Cycle
Basidiomycota Reproduction Cycle
Zygomycota Reproduction Cycle
Vegetative Reproduction
Poisonous Fungi Generally, many cases of poisonings arise from people eating wild, poisonous fungi. Such happenings occur as wrong identifications of mushroom species are made, and people unknowingly consume the toxic fungi. There are numerous edible mushrooms which have toxic lookalikes. This results in people assuming the species of mushroom that they have picked is harmless and safe to eat, when they are in reality poisonous.
It has been found that a high percentage of people poisoned by mushrooms are immigrants. Often, they mistake the toxic mushroom to be a safe, edible one found in their native country. Thus, the importance of educating people on lethal fungi is absolutely vital.
Hence, it is advisable for people to consume only mushrooms after consulting an expert. They should also thoroughly search their pickings to ensure that only edible mushrooms are in the collection. Although seemingly good sense, it is prudent to remind mushroom collectors to separate their edible pickings from their non-edible ones. Again, people have to be told to always cook their collections as some wild fungi are poisonous when consumed raw. To err on the side of caution, one should retain an uncooked specimen, so that in case of poisoning, medical personnel are able to identify the medication needed. This is as different species contain varying toxins.
Furthermore, alcohol should not be consumed before or during the consumption of mushrooms as this could produce deadly effects. If the person is consuming that particular species for the first time, no more than 150 grams of mushrooms should be eaten. Allergic reactions could occur, and this acts as a precaution.
The degree of poisoning is affected by the species of mushroom consumed. Some fungi contain less debilitating toxins and thus, are not severely toxic; i.e. they will not kill you. However, some species are so poisonous, that once consumed, the time spent between the receiving of treatment is of critical importance. If the time spent without treatment is extended, the more limited the chances of survival.
Definitions
Amanitins: Cyclic peptides extracted from carpophores of various mushroom species. They are potent inhibitors of RNA polymerases in most eukaryotic species, blocking the production of mRNA and protein synthesis. These peptides are important in the study of transcription. Alpha-amanitin is the main toxin from the species Amanitia phalloides, poisonous if ingested by humans or animals.
Reference: http://medical.webends.com/kw/Amanitins
Phallotoxins: 1. A class of heterodetic cyclic heptapeptides present in Amanita phalloides; together with the amatoxins, the main toxin components of this fungus.
Reference: http://www.medilexicon.com/medicaldictionary.php?t=67697
Some Examples of poisonous Fungi
Cortinarius rubellus – A deadly species
Amanita muscaria or The Fly Agaric – This is not as poisonous as the other species and has been used by shamans in Siberia in small doses to induce trances. People with heart problems however could be killed by it. It is very common in Northern Ireland
The Death Cap, Amanita phalloides – This species causes most of the fatal poisoning cases. First of all, there are breathing problems and dizziness. Then comes severe vomiting, diarrhoea and dehydration. After three days, you begin to feel better, but actually your liver is being destroyed. Death usually happens at least 6 days after consumption. The Death Cap is not uncommon under oak.
The Destroying Angel, Amanita virosa. This causes the same problems as the Death Cap. There is one old record for it from Belvoir Park in the 1930’s, but it was refound in 1999 in Drum Manor in Tyrone.
Parasitic organisms that cause disease are called pathogens.
The survival of a parasite between cropping seasons and its effective dispersal to uninfected plants are crucial aspects of the plant disease cycle. If either of these is prevented, the disease will not occur. Most pathogens possess mechanisms to survive intercrop periods or periods of unfavourable environmental conditions. They can be spread airborne, soil-borne, water-borne, seed- or clone-borne, or vector-borne. Airborne inoculum can travel for great distances, while soil-borne inoculum is rarely spread any great distance. Many pathogens can be dispersed by more than one mechanism.
Continuous infection chains
The survival of most plant pathogens requires the repeated infection of host plants, which is known as the infection chain; it can be continuous or discontinuous. Continuous infection chains can include the same or alternative hosts. The parasite survives by repeatedly infecting plants of the same host species or infects the main crop species and another species, the alternative host. If the alternative host shows no disease symptoms, it is called a disease carrier. The parasite forms no resting structures, and is dependent on the existence of a susceptible host species.
Some plant pathogens cannot be transferred directly from one plant to another plant of the same species. They require another, completely unrelated, species to act as a vector. These vectors are usually insects, and are referred to as alternate hosts. Unlike the case of alternative hosts, the alternate host is a necessary step in the infection cycle. Without an alternative host, the infection chain breaks.
Discontinuous infection chains
Discontinuous infection chains usually involve an epiphytic, saprophytic or resting phase. During an epiphytic phase, the pathogen survives on their host or other plants in a non-parasitic relationship as an epiphyte. Pathogens that go through a saprophytic phase survive during intercrop periods on diseased plant debris or other organic matter on or in the soil.
Fungi and nematodes form resting structures that enable them to survive long periods without a suitable host, or when the environment is unfavourable. The resting spores (oospores, teliospores or chlamydospores) of some fungi can survive for twenty years or more. Some of them are triggered to germinate only by secretions from the roots of suitable plants. Other fungi produce sclerotia, which can also survive in the soil for periods ranging from months to years. Fungi can also produce sexual fruiting structures (such as cleistothecia, perithecia and pseudothecia) during the resting stage. Some fungi go through a resting stage after infection, called a latent infection.
DISPERSAL OF INOCULUM
Inoculum can be classified as primary or secondary inoculum. Primary inoculum consists of propagules of a pathogen that initiate the disease cycle in a new growing season while secondary inoculum distributes the pathogen within the main growing season of the crop.
Inoculum can be carried from plant to plant by air currents, through the soil, by water splash, or by a vector species, such as an insects or animals. Some bacteria and fungi are spread by sticking to the outside of insect vectors. Disease can also be spread in plants, such as clones and seeds. Seed-borne inoculum can be mixed in with the seed during harvesting, attached to the surface of the seed, or present inside the seed, having already infected the seed or embryo.
http://bugs.bio.usyd.edu.au/PlantPathology/survival_dispersal/survivalDispersal.html
Common fungal diseases include powdery mildew, rust, leaf spot, blight, root and crown rots, damping-off, smut, anthracnose, and vascular wilts.
These fungal diseases are very host-specific. Powdery mildew can be observed on lilacs, roses and several other plants. The symptom is a white or gray, powdery growth on leaves and stems. Powdery mildew usually would not kill a plant; it would weaken them instead. Adequate sunlight and air circulation can be provided to lower relative humidity and using fungicide sprays for high-profile plants to control powdery mildew.
Rusts are also host-specific. Masses of easily noticed, orange or dark red spore masses on leaf tissue are observed. Rusts commonly develops during cool weather. They are spread by wind and splashing water and require water to reproduce and for infection. Controls include watering early in the day and applying protective fungicidal sprays.
These diseases, which include water mould diseases, attack a wide variety of plants. They damage roots and crowns of plants. The damage to the root system results in poor growth, yellowing or stunting of the plant. Root rot fungal pathogens are found in almost all soils. However, they do not thrive in well-drained soils. They can live in soil for years in a latent state. Proper cultural practices, such as correct planting depth and improving drainage, are important controls.
Examples of Parasitic Fungi
Cordyceps ophioglossoides
Beauveria bassiana
Claviceps purpurea
Saprobic fungi are known as fungi that colonize rotting wood and dead organic matter found in the soil. Several species cannot be seen with the naked eye and are microfungi; several are edible macrofungi that breed on fallen logs and bracket fungi that grow from dead or dying parts of still standing trees. Two examples of the saprobic fungi species are the Phallus ravenelii and the Agaricus xanthodermus
The volume and value of saprobic species are used as foods are small by the comparison with the symbiotic edible fungi, though more edible saprobic species are collected. Their overall value is much higher because they are widely cultivated: a figure of US$18 billion was quoted for the annual, global trade in cultivated, saprobic species. Saprobic macrofungi are also highly valued for their medicinal properties. Most are cultivated, though the Ganoderma spp. are also collected from the wild. The list of symbiotic macrofungi with medicinal properties is a short one, though there is some indication that they have been studied less because they cannot be cultivated.
In addition, saprobic species need a constant supply of suitable organic matter to sustain production in the wild and this can be the limiting factor in their production.
Examples of saprobes
The ‘blue toadstool’ (Entoloma hochstetteri), widespread in New Zealand’s native forests
A tiny, undescribed Lachnum species, about 2 mm across, growing on dead fronds of wheki.
The basket fungus is a stink horn (Ileodictyon cibarium), producing spores in a foul-smelling slime, attracting beetles and flies to distribute its spores
The word “zygomycota” is composed of two Greek roots; yoke and fungus. It refers to the conjugation of asexual sporangiospores, also known as endospores, in the formation of zygospores.
Numerous species of molds are from this phylum of fungi. Conjugating fungi can be saprobic, but most are parasitic, depending on insects, protists and other invertebrates. Some of them are pathogenic as well. They are believed to be the most primitive of the fungi, existing from 600 to 1,400 million years ago.
6 orders, 29 families, 120 genera are found in this phylum. Fewer than 1000 species of zygomycota are known to exist.
Hyphae of zygomycota do not contain one nucleus per cell, but have mycelia composed of extended multinucleate, haploid hyphae.
Here are a few Zygomycetes:
Amoebophilus – The 3 species prey on unsuspecting amoeba. Using a spore (conidium), the fungus clings to the outer membrane of the amoeba. Then, the fungus penetrates through the amoeba through a narrow peg through the primary attack spore. A triangular- shaped feeding cell develops from the penetration peg and channels food from the amoeba to itself. Furthermore, spores are formed outside the amoeba, and are pulled along by the amoeba. These spores later break off and are engulfed by nearby bacterial cells. Advantageously, bacteria are designed to attack fungal spores, assisting the fungus in its mode of operation. Eventually, the amoeba dies due to the lack of nutrients.
Syncephalastrum racemosum: Cylindrical sporangia (=Merosporangia) with spores produced in a single column. Merosporangia are borne on a swollen vesicle on top of the sporangiophore.
Cunninghamella echinulata
