KINGDOM FUNGI
“Fungi are a group of unicellular to multicellular, thalloid, heterotrophic, eukaryotic living organisms having a body called MYCELLIUM, made up of HYPHAE which are non-chlorophyllous & have cell wall (made up of chitin). Reproduction is usually ASEXUAL by means of spores”.
FUNGI ARE NEITHER COMPLETELY PLANTS NOR ANIMALS
Previously fungi were regarded as plants as they resemble the plants in many characteristics. But in addition fungi have many qualities just like the animals. So they are regarded in the midway between plants and animals.
PLANT LIKE CHARACTERISTICS OF FUNGI
Fungi resemble the plants in
But Fungi also resemble with animals as they are
Fungi are neither completely plants nor animals.
CONFIRMATION
Detail studies also confirm that Fungi are different from all other organisms.
NUCLEAR MITOSIS
They have a characteristic mitosis called Nuclear-mitosis, during which nuclear membrane does not break & spindle is formed with in the nucleus.
SOME REPRESENTATIVES OF KINGDOM FUNGI
Some imp. Examples are as follows:-
MYCELIUM
The complete multicellular body of fungus is called MYCELIUM, which is composed of white fluffy mass of branched hyphae.
HYPHAE
A few of true fungi are unicellular (such as yeast) but most have multicellular body (mycelium) consisting of long, slender, branched, tubular, thread like filaments called as Hyphae which spread extensively over the surface of substrate.
HYPHAE
TYPES OF HYPHAE
Hyphae can be divided in to two types:
1. Septate or Multicellular Hyphae
2. Non-septate or multinuclear or coenocytic hyphae.
1.SEPTATE HYPHAE
DEFINITION
“Those hyphae which are separated by cross-walls called “septa” into individual cells containing one or more nuclei , are called “Septate Hyphae”
EXAMPLE: Mushrooms
2. NON-SEPTATE HYPHAE
DEFINITION
Those hyphae, which lack septa & are not divided into individual cells, instead these are in the form of long, multinucleated large cells are called Non-septate or Coenocytic Hyphae.
EXAMPLE Mucor & Rhizopus
CELL WALL OF HYPHAE
CHITIN is the chief component present in the cell wall of most fungi, Because it is more resistant to decay than are the Cellulose & lignin which make up plant cell wall.
CYTOPLASM OF HYPHAE
In septate Hyphae —– Cytoplasm flows through the pores of septa from cell to cell, carrying the materials to growing tips & enabling the hyphae to grow rapidly, under favorable conditions. In non-septate hyphae —— cytoplasm moves effectively, distributing the materials throughout.
NUCLEI OF HYPHAE
All fungal nuclei are HAPLOID except for transient diploid zygote that forms during sexual reproduction.
MAIN FUNCTION OF HYPHAE
Extensive spreading system of Hyphae provides enormous surface area for absorption.
NUTRITION IN FUNGI
ABSORPTIVE HETEROTROPHS
All fungi lack chlorophyll & are heterotrophs ( obtain carbon & energy from organic matter, They obtain their food by direct absorption from immediate environment & are thus “ABSORPTIVE HETEROTROPHS”.
DIFFERENT MODES OF HETEROTROPHIC NUTRITION IN FUNGI
Being Heterotrophic, fungi can exist as
1- Saprotrophs or saprobes ( Decomposers )
2- Parasites
3- Predators
4- Mutualists
1. SAPROBIC OR SAPROTROPHIC FUNGI ( DECOMPOSERS)
Saprobic fungi along with bacteria, are the major decomposers of biosphere, contributing to the recycling of the elements (C,N,P,O,H & etc) used by living things.
DEFINITION
“Those fungi which obtain their food (energy, carbon & nitrogen), directly by digesting the dead organic matter are called “SAPROBIC FUNGI” OR “DECOMPOSERS”
MECHANISM OF ABSORBING FOOD (DEVELOPMENT OF RHIZOIDS)
These fungi anchor to the substrate by modified hyphae, the RHIZOID, which provide enormous surface area for absorptive mode of nutrition.
SECRETION OF DIGESTIVE JUICES
Saprobic fungi secrete digestive juices, which digest organic matter & the organic molecules thus produced are absorbed, back into the fungus.
2. PARASITIC FUNGI
DEFINITION
Those fungi which absorb nutrients directly from living host cytoplasm are called PARASITIC FUNGI.
MECHANISM
For obtaining, their food requirements, these fungi develop specialized hyphal tips called as HAUSTORIA which penetrate the host tissues for absorbing nutrients.
TYPES OR PARASITIC FUNGI
Parasitic fungi may be of two types
A. OBLIGATE PARASITES
B. FACULTATIVE PARASITES.
(A) OBLIGATE PARASITES
DEFINITION
Those parasitic fungi which can grow only in their living host & cannot be grown on available defined growth culture medium, are called “ Obligate Parasites”.
EXAMPLES
Many mildews
Most of Rust species.
(B) FACULTATIVE PARASITES
DEFINITION
“Those parasitic fungi which can grow parasitically on their host as well as by themselves on artificial growth media, are called “ Facultative Parasites”.
3. PREDATORY FUNGI
DEFINITION
“Those fungi which obtain their food by killing other living organisms are called PREDATORY FUNGUS
EXAMPLES
1. Oyster Mushrooms ( Pleurotus astreatus ).
2. Some species of Arthrobotrys.
MECHANISM OF OBTAINING FOOD
1. IN OYSTER MUSHROOMS
Oyster mushroom is a carnivorous fungus. It Paralyses the nematodes (that feed on this fungus), penetrate them & absorb their nutritional contents, primarily to fulfill nitrogen requirements. It fulfill it glucose requirements by breaking the woods.
2. IN ARTHROBOTRYS
Constrictor ring development
Some species of Arthrobotrys trap soil nemotodes by forming CONSTRICTING RING, their hyphae invading & digesting the unlucky victim.
4. MUTUALISTIC FUNGI
DEFINITION
“Those fungi which form such symbiotic associations with other living organisms in which both partners of association get benefit from each other are called MUTUALISTIC FUNGI & Such association are called as “MUTUALISTIC SYMBIOTIC ASSOCIATIONS”
TWO MUTUALISTIC SYMBIOTIC ASSOCIATIONS FORMED BY FUNGI
Fungi form two key mutualistic symbiotic associations. These are:
1. LICHENS
2.MYCORRHIZAE
1. LICHENS
SYMBIOTIC PARTNERS IN LICHENS
Lichens are mutualistc & have symbiotic associations b/w certain fungi (mostly Ascomycetes) & imperfect fungi & few Basidiomycetes (about 20 out of 15000 species of lichens) & certain photoautotroph either green algae or cynobacterium or sometimes both.
MUTUAL BENEFIT
In lichens, fungi protect the algal partner from strong light & desiccation & itself gets food through the courtesy of alga.
AREAS WHERE LICHENS GROW
Lichens can grow at such places such as bare rocks & etc, where neither of the components alone can grow.
ECOLOGICAL IMPORTANCE OF LICHENS
From ecological point of view, lichens are very important because they serve as BIO INDICATORS of AIR POLLUTION.
2. MYCORRHIZAE
SYMBIOTIC PARTNERS
Mycorrhizae are mutualistic association b/w certain fungi & roots of vascular plants (about 95% of all kinds of vascular plants).
MUTUAL BENEFIT
The fungal hyphae dramatically increase the amount of soil contact & total surface area for absorption & help in direct absorption of nutrients from soil. The plant on the other hand, supplies organic carbon to fungal hyphae.
TYPES OF MYCORRHIZAE
There are two main types of mycorrhizae.
1. Endomycorrhizae
2. Ectomycorrhizae
1. ENDOMYCORRHIZAE
In Endomycorrhizae, the fungal hyphae penetrate the outer cells of plant root, forming coils, swellings & minute branches, & also extend out into surrounding soil.
2.ECTOMYCORRHIZAE
In Ectomycorshizae the hyphae surround & extend between the cell but don’t penetrate the cell walls of roots.
EXAMPLE
Mutualistic association between fungi & pines & firs
REPRODUCTION IN FUNGI
Two kinds of reproduction are usually found in Fungi
1. ASEXUAL REPRODUCTION
2. SEXUAL REPRODUCTION
Except In perfect Fungi in which sexual reproduction has not been observed.
1. ASEXUAL REPRODUCTION
DEFINITIION
The most common means of reproduction in fungi which does not involve sexes, reduction division & fertilization is called A SEXUAL REPRODUCTION
DIFFERENT MODES OF ASEXUAL REPRODUCTION
In fungi , asexual reproduction take place by following ways:
1- SPORE FORMATION
2- CONIDIA FORMATION
3- FRAGMENTATION
4- BUDDING.
1- SPORE FORMATION
INTRODUCTION
It is the most common type of asexual reproduction in fungi in which large no of spores are developed with in the sporangia. Each spore on generation produces another mycelium.
EXPLANATION OF THE PROCESS
SPORES
Spores may be produced by sexual or asexual process, are haploid, thick walled, non-motile & not needing water for their dispersal, They are very small & produced in very large no. with in the SPORANGIUM.
SPORANGIUM
Spores are produced inside the reproductive structures called SPORANGIA, which develop as swellings at the tips of SPORANGIOPHORES.
SEPARATION OF SPORANGIUM FROM HYPHAE
After the formation of spores, sporangium becomes separated from hypae by a complete septa.
BREAKAGE OF SPORANGIAL WALL
On maturity of the spores, the outer wall of sporangium breaks down & spores are dispersed.
DISPERSION OF SPORES
Spores are usually dispersed by air currents to great distances & cause wide distribution of many kinds of fungi. They may also be dispersed by small animals & insects & by rain splashes.
GERMINATION OF SPORES
In a favorable condition, on a proper substrate, the spore germinates giving rise to new fungal hyphae.
2.CONIDIA FORMATION
INTRODUCTION
The type of asexual reproduction in fungi in which large number of asexual spores called “CONIDIA are formed, each on germination giving rise to new mycelium is known as CONIDIAL REPRODUCTION.
EXPLANATION
CONIDIA
Conidia are non-motile, asexual spores which may be produced in very large number & can survive for weeks, causing rapid colonization on new food.
CONIDIOPHORES
Conidia are not developed inside the sporangium but they are usually cut off at the end of modified hyphae called CONIDIOPHORES, commonly in chains or clusters.
EXAMPLE
Asexual reproduction by conidia formation is very common in ASCOMYCETES.
3.FRAGMENTATION
It is the type of asexual reproduction in which mycelium of some fungal hyphae breaks into pieces or fragments. Each fragment develops into a new mycelium.
4. BUDDING
INTRODUCTION
Budding is an asymmetric asexual division in which tiny outgrowth or bud is produced which may separate & grow by simple relatively equal cell division into new mycelium.
EXAMPLE
Unicellular yeasts reproduce by budding
SEXUAL REPRODUCTION
INTRODUCTION
Details of sexual reproduction very in different groups of fungi on the basis of which fungi can be divided into four major phyla, However the fusion of haploid nuclei & meiosis are common to all.
EXPLANATION
Sexual reproduction in fungi takes place through several stages, which are as follows.
PLASMOGAMY
When fungi reproduce sexually, hyphae of two genetically different but compatible mating types come together & their cytoplasm fuse. This process is called PLASMOGAMY, This step is common in all types of fungi.
IN ZYGOMYCOTA
In Zygomycota after Plasmogamy following steps occur.
KARYOGAMY
In zygomycetes, Plasmogamy is followed by fusion of nuclei, called as KARYOGAMY
ZYGOT FOMATION & MEIOSIS
In ZYGOMYCETES, fusion of nuclei, leads directly to the formation of zygot, which divides by meiosis when it germinates.
IN ASCOMYCOTA AND BASIDIOMYCOTA
In these groups of fungi, following steps after plasmogamy.
FORMATION OF DIKARYOTIC NYPHAE
In these groups, the two genetic types of haploid nuclei from two individuals my coexist & divide in the same hyphae for most of the life of fungus. Such as fungal hyphae is called DIKARYOTIC OR HETEROKARYOTIC HYPHA/CELL.
FORMATION OF FRUITING BODIES
Extensive growth of dikaryotic hyphae may lead to the formation of massive structures of interwoven hyphae called as Fruiting Bodies, such as
Fusion of two haploid nuclei occurs with in the fruiting bodies forming a zygote, This is called as SYNGAMY, followed immediately by meiosis.
FORMATION OF HAPLOID SEXUAL SPORES
Each zygote divides immediately by meiosis to form four haploid spores, which when release are dispersed, some of them giving rise to new hyphae.
CLASSIFICATION OF FUNGI
There are four major divisions of fungi, which are divided on the basis of their sexual reproduction.
1- ZYGOMYCOTA
2- ASCOMYCOTA
3- BASIDIOMYCOTA
4- DEUTEROMYCOTA
1- ZYGOMYCOTA
INTRODUCTION
Zygomycota are by far the smallest of four groups of fungi, with only about 600 named species. This group includes more frequently bread molds as well as a variety of other microscopic fungi found on decaying organic material.
CHARACTERISTIC FEATURE
The group is named after a characteristic feature of the life cycle of its member, the production of temporalily dormant structures called ZYGOSPORES.
The zygomycetes lack septa in their hyphae i.e coenocytic hyphae, except when they form sporangia or gametangia.
LIFE CYCLE OF ZYGOMYCOTA
In the life cycle of zygomycota, two types of reproduction occurs:
A- SEXUAL REPRODUCTION IN ZYGOMYCOTA
B- ASEXUAL REPRODUCTION IN ZYGOMYCOTA
(A) SEXUAL REPRODUCTION IN ZYGOMYCOTA
Sexual reproduction takes place by fusion of GAMETANGIA in following steps:
FORMATION OF PROGAMETANGIUM
When two hyphae came in contact with each other, each of them gives a lateral progametangium, facing each other.
DIFFERENTIATION OF PROGAMETANGIA INTO GAMETANGIA & SUSPENSORS
Later on, each of the progametangium differentiates into two parts
The gametangia may be formed on hyphae of different mating types or on a single hyphae. If different mating types are involved, fusion between pairs of haploid nuclei occurs immediately.
ZYGOT FORMATION
Fusion of haploid nuclei results in formation of diploid zygote nuclei, Except for the zygote nuclei, all nuclei of zygomycota are haploid.
ZYGOSPORE FORMATION
After the formation of diploid zygote nuclei, the fused portion of hyphae develops into ZYGOSPORES.
GERMINATION OF ZYGOSPORE
Under favorable condition zygospore germinates & giving rise to new mycelium. Meiosis occurs during germination.
(B) ASEXUAL REPRODUCTION IN ZYGOMYCOTA (BY SPORE FORMATION )
Asexual reproduction occurs much more frequently than sexual reproduction in the zygomycetes.
EXPLANATION
As previously discussed in spore formation
EXAMPLES OF ZYGOMYCETES
1- MUCOR
2- RHIZOPUS STOLONIPER
2-ASCOMYCOTA
INTRODUCTION
The second division of fungi, the ASCOMYCOTA is a very large group of about 30,000 named species with many more being discovered each year.
CHARACTERISTIC FEATURE
The ascomycota are named for their characteristic reproductive structure, the microscopic, club shaped ASCUS.
TYPE OF HYPHAE
The hyphae of ascomycetes are divided by septa i.e septate hyphae, but the septa are perforated & the cytoplasm flows along the length of each hyphae. The septa that cut off the asci & conidia are initially perforated like all other septa, but later they often become blocked.
LIFE CYCLE OF ASCOMYCOTA
In life cycle of ascomycota, Both sexual & asexual reproduction occurs.
(A) SEXUAL REPRODUCTION IN ASCOMYCOTA
Sexual reproduction occurs through following steps.
1-FORMATION OF MALE GAMETANGIUM OR ANTHERIDIUM
The hyphae of ascomycetes may be either homokaryotic & heterokaryotic. The cells of these hyphae usually contain from several to many nuclei. These cells form Antheridium or male gametangium.
2-FEMALE GAMETANGIUM OR ASCOGONIUM
The gametangium which develop beak like out growth called as TRICHOGYNE, is called female gametangium or Ascogonium.
3-FUSION OF MALE & FEMALE GAMETANGIUM
When antheridium is formed , it fuses with trichogyne of an adjacent ascogonium. Fusion of cytoplasm or plasmogamy occurs.
4-PAIRING OF NUCLEI
After plasmogamy, nuclei from antheridium then migrate through the trichogyne into the ascogonium, & pair with nuclei of opposite mating types.
5-FORMATION OF DIKARYOTIC HYPHAE & DIKARYOTICY
Dikarytic hyphae then arise from the area of fusion. Throughout such hyphae, nuclei that represent the two different original mating types occur ( DIKARYOTICY ) Such hyphae are also called as HETEROKARYOTIC HYPHAE.
6-FORMATION OF ASCOCARPS OR FRUITING BODIES
Excessive growth of monokaryotic or dikaryotic hyphae results in formation of massive structures of tightly interwoven hyphae, called as FRUITING BODIES OF ASCOCARPS, which corresponds to the visible portions of a morel or cup fungus.
7- ASCI FORMATION
Asci are special reproductive structures which are formed on special fertile layers of dikaryotic hyphae with in the Ascocarps.
8- SEPARATION OF ASCI
-+The asci are cut off by the formation of septa at the tips of heterokaryotic hyphae.
9- SYNGAMY
There are two haploid nuclei with in each ascus one of each of which belongs to different mating type. Fusion of these two nuclei occurs within each ascus called as SYNGAMY.
10-ZYGOT FORMATION
Syngamy results in zygote formation, which divides immediately by meiosis, forming four haploid daughter cells.
11- FORMATION OF ASCOSPORES
Four haploid daughter nuclei, usually divide again by mitosis , producing 8 haploid nuclei that become walled & called ASCOSPORES.
12-BURSTING OF ASCUS
In most Ascomycetes, the ascus becomes highly turgid at maturity and ultimately bursts, often at a perforated area, which may be pore or slit or lid
13- DESPERSION & GERMINATION OF ASCOSPORES
After bursting, the ascospores may be thrown as far as 30 cm. Under favorable circumstances they germinate giving new hyphae.
TYPES OF ASCOCARPS IN ASCOMYCETES
According to their shape, Ascocarps are of following three types:
1- OPOTHECIUM
The ascocarps of cup fungi & the morels are open, with the asci lining the open cups called OPOTHECIUM.
2- CLEISTOTHECIUM
Some ascocarps are closed & called as ‘CLESTOTHECIUM’
3- PERITHECIUM
Some ascocarps have small opening at the apex called as PERITHECIUM. Ascocarps of NEUROSPORA are of this type.
(B) ASEXUAL REPRODUCTION IN ASCOMYCOTA (BY CONDIA FORMATION)
INTRODUCTION
The type of asexual reproduction in fungi in which large number of asexual spores called “CONIDIA are formed, each on germination giving rise to new mycelium is known as CONIDIAL REPRODUCTION.
EXPLANATION
CONIDIA
Conidia are non-motile, asexual spores which may be produced in very large number & can survive for weeks, causing rapid colonization on new food.
CONIDIOPHORES
Conidia are not developed inside the sporangium but they are usually cut off at the end of modified hyphae called CONIDIOPHORES, commonly in chains or clusters.
EXAMPLE
Asexual reproduction by conidia formation is very common in ASCOMYCETES.
3.BASIDIOMYCOTA
INTRODUCTION
The basidiomycetes, third division of fungi have about 16,000 named species. More is known about some members of this group than about any other fungi.
CHARACTERISTIC FEATURE
Basidiomycetes are named for their characteristic sexual reproductive structures, the BASIDIUM, which is club shaped like as ascus.
LIFE CYCLE OF BASIDIOMYCOTA
In life cycle of Basidiomycota, reproduction is usually sexual. Asexual reproduction is not very important.
(A) SEXUAL REPRODUCTION IN BASIDIOMYCOTA
The life cycle of basidiomycetes begin with the production of hyphae which may be of two types.
1- Homokaryotic hyphae giving rise to primary mycelium.
2- Heterokaryotic hyphae giving rise to secondary mycelium.
PRIMARY OR MONOKARYOTIC MYCELIUM
Homokaryotic or monokaryotic hyphae lack septa at first. Eventually, However, septa are formed between nuclei of these hyphae. A basidiomycete mycelium made up of monokaryotic hyphae is called PRIMARY MYCELIUM.
SECONDARY OR DIKARYOTIC MYCELIUM
Mycelium of basidiomycetes, with two nuclei, representing the two different mating types b/w each pair of septa, is called SECONDARY OR DIKARYOTIC MYCELIUM. Most of the mycelium of basidiomycetes that occur in nature is dikaryotic & often only dikaryotic mycelium is able to form basidiocarps.
FORMATION OF BASIDIOCARP OR FRUITING BODY
Dikaryotic mycelium is responsible for the formation of FRUITING BODY in Basidiomycetes called as BASIDIOCARP, made up of tightly interwoven dikaryotic hyphae.
FORMATION OF BASIDIUM
Basidium is characteristic reproductive structure of Basidiomycetes, which is club shaped & formed with in the Basidiocarp. This produces slender projection at the end called as STERIGMATA, in this way.
SYNGAMY & ZYGOT FORMATION
Nuclear fusion or syangamy occurs in Basidium, giving rise to diploid zygote, the only diploid cell of the life cycle.
MEIOSIS & BASIDIOSPORE FORMATION
Meiosis occurs immediately after the formation of zygot, resulting in the formation of four haploid nuclei, which are incorporated in Basidiospores. In most member of this division basidiospores are borne at the sterignata
DISPERSION AND GERMINATION
Same as in Ascomycetes
(B) ASEXUAL REPRODUCTION IN IN BASIDIOMYCOTA
In contrast to their effective sexual reproduction, asexual reproduction is rare in most basidiomycetes.
EXAMPLES OF BASIDIOMYCETES
INTRODUCTION
“The fungi that are classified is this group, are simply those in which the sexual reproductive stages have not been observed. In other words, most of the Fungi Imperfecti are as ascomycota that have lost the ability to reproduce sexually. There are some 17000 described species of this group.”
CHARACTERISTIC FEATURE
Sexual reproduction is absent among Fungi Imperfecti
LIFE CYCLE OF DEUTEROMYCOTA
Although in life cycle of deuteromycetes or Fungi Imperfecti, true sexual reproduction is absent, but there is certain type of GENETIC RECOMBINATION which seems to be responsible for some of the production of new pathogenic strains of wheat rust.
GENETIC RECOMBINATION IN FUNGI IMPERFECTI PARASEXUALITY
In parasexuality, exchange of portions of chromosomes between the genetically distinct nuclei with in a common hyphae takes place. This is the special type of genetic recombination occurs in fungi Imperfecti.
EXAMPLES OF FUNGI IMPERFECTI
Among the economically important genera of Fungi Imperfecti are
1-PENICILLIUM
2- ASPERGILLUS
3- Most of the fungi that cause skin diseases in humans, including athlete’s foot & ring worm are also fungi imperfecti.
ECONOMIC IMPORTANCE OF FUNGI
Fungi play a vast role in economic field they show both harmful & useful activities to human beings.
USEFUL FUNGI
Following are some of the beneficial effects of fungi.
FOOD
Many kinds of edible fungi are in the form of mushrooms, are a source of nourishing & delicious food dishes. But not all the mushrooms are edible. Some of them are poisonous & called as toad stools or death stool. Yeast, another kind of fungi, are utilized in baking industry.
MEDICINES
Nearly two dozens antibiotics have been isolated from different types of fungi & bacteria, like
Many kinds of Yeast are used in the production of bakery & brewery products. Some species of genus PENICILLIUM give characteristic flavors & aromas to the cheese.
FERMENTATION
Species of Aspergillus, are used for fermenting soya sauce & soya paste. Citric Acid is produced commercially with members of this genus under highly acidic condition.
SOIL FERTILITY
Fungi maintain the soil fertility by decomposing the dead organic matter e.g Mycorhizal fungi.
PRODUCTION OF ORGANIC COMPOUNDS
May species of fungi are used in the production of organic compound such as vitamins, proteins & fats. Saccharomyces, synthesizes a range of vitamin B group.
HARMFUL FUNGI
Following are some of the harmful effects of fungi,
FOOD SPOILAGE
Saprophytic fungi cause tremendous amounts of spoilage of food stuff. 15-20% of worlds fruit is lost each year due to fungal attack.
SPOILAGE OF WOOD & LEATHER ARTICLES
Many fungi spoil leather goods, woods, wool, books, timber, cotton & etc. WOOD-ROTTING FUNGI destroy not only living trees but also structural timber. BRACKET/SHELF FUNGI cause lot of damage to store cut lumber as well as stands of timber of living trees.
TOXINS
Many fungi are poisonous . AMANITA VERNA is a mushroom, which produces deadly poisonous substance known as AMANITIN, which causes serious problems in respiratory system & blood circulatory system.
FOOD POISONING
Some fungi during decomposing food release certain poisonous substances collectively known as MYCOTOXINS. Mycotoxins are the major source of food poisoning.
DISEASES
Fungi cause a number of diseases in plants as well as in human beings.
PLANT DISEASES CAUSED BY FUNGI
Fungi destroy many agricultural crops, fruits, ornamentals & other kinds of plants because they produce several enzymes that can breakdown cellulose, Lignin and even cutin. Following are some of the serious plant disease caused by Fungi.
RUST & SMUT DISEASES
Rust & smut diseases are serious diseases of WHEAT, RICE, CORN &other cerial crops. They cause extensive damage.
POTATO BLIGHT
A serious disease of potato caused by a fungus known as PHYTOPTHORA INFESTANS. Other plant disease are.
Following are some of the fungal diseases in man.
SKIN DISEASES
RING WORM & ATHELETE’S FOOT are superficial fungal infection caused by certain Fungi Inperfecti
ORAL THRUSH
CANIDIA ALBICANS, a yeast causes oral & Vaginal thrush.
ASPERGILLOSIS
Aspergillosis is the disease of ear & lungs caused by ASPERGILLUS. It occurs only in person with defective immune system such as AIDS & cause death.
CANCER
Some strains of ASPERGILLUS FLAVUS produce one of the most carcinogenic ( cancer causing ) mycotoxins called AFLATOXINS.
ERGOTISM
Ergotism is caused by eating bread made from PUROLE ERGOT- Contaminated flour. The poisonous material in the ergot causes nervous spasm, convulsions, psychotic delusion & even gangrene.
HISTOPLASMOSIS
Histoplasmosis is a serious disease of lungs caused by inhaling spores of a fungus, which is common in soil contaminated with bird’s feces.
“Fungi are a group of unicellular to multicellular, thalloid, heterotrophic, eukaryotic living organisms having a body called MYCELLIUM, made up of HYPHAE which are non-chlorophyllous & have cell wall (made up of chitin). Reproduction is usually ASEXUAL by means of spores”.
FUNGI ARE NEITHER COMPLETELY PLANTS NOR ANIMALS
Previously fungi were regarded as plants as they resemble the plants in many characteristics. But in addition fungi have many qualities just like the animals. So they are regarded in the midway between plants and animals.
PLANT LIKE CHARACTERISTICS OF FUNGI
Fungi resemble the plants in
- Having Cell Wall
- Lacking Centrioles
- Being non-motile
But Fungi also resemble with animals as they are
- Heterotrophic
- Lack cellulose in their cell wall
- Presence of chitin
Fungi are neither completely plants nor animals.
CONFIRMATION
Detail studies also confirm that Fungi are different from all other organisms.
NUCLEAR MITOSIS
They have a characteristic mitosis called Nuclear-mitosis, during which nuclear membrane does not break & spindle is formed with in the nucleus.
SOME REPRESENTATIVES OF KINGDOM FUNGI
Some imp. Examples are as follows:-
- YEAST
- MUSHROOMS
- PENICILLIUM
- MOLD
- MUCOR
- RHIZOPUS
MYCELIUM
The complete multicellular body of fungus is called MYCELIUM, which is composed of white fluffy mass of branched hyphae.
HYPHAE
A few of true fungi are unicellular (such as yeast) but most have multicellular body (mycelium) consisting of long, slender, branched, tubular, thread like filaments called as Hyphae which spread extensively over the surface of substrate.
HYPHAE
TYPES OF HYPHAE
Hyphae can be divided in to two types:
1. Septate or Multicellular Hyphae
2. Non-septate or multinuclear or coenocytic hyphae.
1.SEPTATE HYPHAE
DEFINITION
“Those hyphae which are separated by cross-walls called “septa” into individual cells containing one or more nuclei , are called “Septate Hyphae”
EXAMPLE: Mushrooms
2. NON-SEPTATE HYPHAE
DEFINITION
Those hyphae, which lack septa & are not divided into individual cells, instead these are in the form of long, multinucleated large cells are called Non-septate or Coenocytic Hyphae.
EXAMPLE Mucor & Rhizopus
CELL WALL OF HYPHAE
CHITIN is the chief component present in the cell wall of most fungi, Because it is more resistant to decay than are the Cellulose & lignin which make up plant cell wall.
CYTOPLASM OF HYPHAE
In septate Hyphae —– Cytoplasm flows through the pores of septa from cell to cell, carrying the materials to growing tips & enabling the hyphae to grow rapidly, under favorable conditions. In non-septate hyphae —— cytoplasm moves effectively, distributing the materials throughout.
NUCLEI OF HYPHAE
All fungal nuclei are HAPLOID except for transient diploid zygote that forms during sexual reproduction.
MAIN FUNCTION OF HYPHAE
Extensive spreading system of Hyphae provides enormous surface area for absorption.
NUTRITION IN FUNGI
ABSORPTIVE HETEROTROPHS
All fungi lack chlorophyll & are heterotrophs ( obtain carbon & energy from organic matter, They obtain their food by direct absorption from immediate environment & are thus “ABSORPTIVE HETEROTROPHS”.
DIFFERENT MODES OF HETEROTROPHIC NUTRITION IN FUNGI
Being Heterotrophic, fungi can exist as
1- Saprotrophs or saprobes ( Decomposers )
2- Parasites
3- Predators
4- Mutualists
1. SAPROBIC OR SAPROTROPHIC FUNGI ( DECOMPOSERS)
Saprobic fungi along with bacteria, are the major decomposers of biosphere, contributing to the recycling of the elements (C,N,P,O,H & etc) used by living things.
DEFINITION
“Those fungi which obtain their food (energy, carbon & nitrogen), directly by digesting the dead organic matter are called “SAPROBIC FUNGI” OR “DECOMPOSERS”
MECHANISM OF ABSORBING FOOD (DEVELOPMENT OF RHIZOIDS)
These fungi anchor to the substrate by modified hyphae, the RHIZOID, which provide enormous surface area for absorptive mode of nutrition.
SECRETION OF DIGESTIVE JUICES
Saprobic fungi secrete digestive juices, which digest organic matter & the organic molecules thus produced are absorbed, back into the fungus.
2. PARASITIC FUNGI
DEFINITION
Those fungi which absorb nutrients directly from living host cytoplasm are called PARASITIC FUNGI.
MECHANISM
For obtaining, their food requirements, these fungi develop specialized hyphal tips called as HAUSTORIA which penetrate the host tissues for absorbing nutrients.
TYPES OR PARASITIC FUNGI
Parasitic fungi may be of two types
A. OBLIGATE PARASITES
B. FACULTATIVE PARASITES.
(A) OBLIGATE PARASITES
DEFINITION
Those parasitic fungi which can grow only in their living host & cannot be grown on available defined growth culture medium, are called “ Obligate Parasites”.
EXAMPLES
Many mildews
Most of Rust species.
(B) FACULTATIVE PARASITES
DEFINITION
“Those parasitic fungi which can grow parasitically on their host as well as by themselves on artificial growth media, are called “ Facultative Parasites”.
3. PREDATORY FUNGI
DEFINITION
“Those fungi which obtain their food by killing other living organisms are called PREDATORY FUNGUS
EXAMPLES
1. Oyster Mushrooms ( Pleurotus astreatus ).
2. Some species of Arthrobotrys.
MECHANISM OF OBTAINING FOOD
1. IN OYSTER MUSHROOMS
Oyster mushroom is a carnivorous fungus. It Paralyses the nematodes (that feed on this fungus), penetrate them & absorb their nutritional contents, primarily to fulfill nitrogen requirements. It fulfill it glucose requirements by breaking the woods.
2. IN ARTHROBOTRYS
Constrictor ring development
Some species of Arthrobotrys trap soil nemotodes by forming CONSTRICTING RING, their hyphae invading & digesting the unlucky victim.
4. MUTUALISTIC FUNGI
DEFINITION
“Those fungi which form such symbiotic associations with other living organisms in which both partners of association get benefit from each other are called MUTUALISTIC FUNGI & Such association are called as “MUTUALISTIC SYMBIOTIC ASSOCIATIONS”
TWO MUTUALISTIC SYMBIOTIC ASSOCIATIONS FORMED BY FUNGI
Fungi form two key mutualistic symbiotic associations. These are:
1. LICHENS
2.MYCORRHIZAE
1. LICHENS
SYMBIOTIC PARTNERS IN LICHENS
Lichens are mutualistc & have symbiotic associations b/w certain fungi (mostly Ascomycetes) & imperfect fungi & few Basidiomycetes (about 20 out of 15000 species of lichens) & certain photoautotroph either green algae or cynobacterium or sometimes both.
MUTUAL BENEFIT
In lichens, fungi protect the algal partner from strong light & desiccation & itself gets food through the courtesy of alga.
AREAS WHERE LICHENS GROW
Lichens can grow at such places such as bare rocks & etc, where neither of the components alone can grow.
ECOLOGICAL IMPORTANCE OF LICHENS
From ecological point of view, lichens are very important because they serve as BIO INDICATORS of AIR POLLUTION.
2. MYCORRHIZAE
SYMBIOTIC PARTNERS
Mycorrhizae are mutualistic association b/w certain fungi & roots of vascular plants (about 95% of all kinds of vascular plants).
MUTUAL BENEFIT
The fungal hyphae dramatically increase the amount of soil contact & total surface area for absorption & help in direct absorption of nutrients from soil. The plant on the other hand, supplies organic carbon to fungal hyphae.
TYPES OF MYCORRHIZAE
There are two main types of mycorrhizae.
1. Endomycorrhizae
2. Ectomycorrhizae
1. ENDOMYCORRHIZAE
In Endomycorrhizae, the fungal hyphae penetrate the outer cells of plant root, forming coils, swellings & minute branches, & also extend out into surrounding soil.
2.ECTOMYCORRHIZAE
In Ectomycorshizae the hyphae surround & extend between the cell but don’t penetrate the cell walls of roots.
EXAMPLE
Mutualistic association between fungi & pines & firs
REPRODUCTION IN FUNGI
Two kinds of reproduction are usually found in Fungi
1. ASEXUAL REPRODUCTION
2. SEXUAL REPRODUCTION
Except In perfect Fungi in which sexual reproduction has not been observed.
1. ASEXUAL REPRODUCTION
DEFINITIION
The most common means of reproduction in fungi which does not involve sexes, reduction division & fertilization is called A SEXUAL REPRODUCTION
DIFFERENT MODES OF ASEXUAL REPRODUCTION
In fungi , asexual reproduction take place by following ways:
1- SPORE FORMATION
2- CONIDIA FORMATION
3- FRAGMENTATION
4- BUDDING.
1- SPORE FORMATION
INTRODUCTION
It is the most common type of asexual reproduction in fungi in which large no of spores are developed with in the sporangia. Each spore on generation produces another mycelium.
EXPLANATION OF THE PROCESS
SPORES
Spores may be produced by sexual or asexual process, are haploid, thick walled, non-motile & not needing water for their dispersal, They are very small & produced in very large no. with in the SPORANGIUM.
SPORANGIUM
Spores are produced inside the reproductive structures called SPORANGIA, which develop as swellings at the tips of SPORANGIOPHORES.
SEPARATION OF SPORANGIUM FROM HYPHAE
After the formation of spores, sporangium becomes separated from hypae by a complete septa.
BREAKAGE OF SPORANGIAL WALL
On maturity of the spores, the outer wall of sporangium breaks down & spores are dispersed.
DISPERSION OF SPORES
Spores are usually dispersed by air currents to great distances & cause wide distribution of many kinds of fungi. They may also be dispersed by small animals & insects & by rain splashes.
GERMINATION OF SPORES
In a favorable condition, on a proper substrate, the spore germinates giving rise to new fungal hyphae.
2.CONIDIA FORMATION
INTRODUCTION
The type of asexual reproduction in fungi in which large number of asexual spores called “CONIDIA are formed, each on germination giving rise to new mycelium is known as CONIDIAL REPRODUCTION.
EXPLANATION
CONIDIA
Conidia are non-motile, asexual spores which may be produced in very large number & can survive for weeks, causing rapid colonization on new food.
CONIDIOPHORES
Conidia are not developed inside the sporangium but they are usually cut off at the end of modified hyphae called CONIDIOPHORES, commonly in chains or clusters.
EXAMPLE
Asexual reproduction by conidia formation is very common in ASCOMYCETES.
3.FRAGMENTATION
It is the type of asexual reproduction in which mycelium of some fungal hyphae breaks into pieces or fragments. Each fragment develops into a new mycelium.
4. BUDDING
INTRODUCTION
Budding is an asymmetric asexual division in which tiny outgrowth or bud is produced which may separate & grow by simple relatively equal cell division into new mycelium.
EXAMPLE
Unicellular yeasts reproduce by budding
SEXUAL REPRODUCTION
INTRODUCTION
Details of sexual reproduction very in different groups of fungi on the basis of which fungi can be divided into four major phyla, However the fusion of haploid nuclei & meiosis are common to all.
EXPLANATION
Sexual reproduction in fungi takes place through several stages, which are as follows.
PLASMOGAMY
When fungi reproduce sexually, hyphae of two genetically different but compatible mating types come together & their cytoplasm fuse. This process is called PLASMOGAMY, This step is common in all types of fungi.
IN ZYGOMYCOTA
In Zygomycota after Plasmogamy following steps occur.
KARYOGAMY
In zygomycetes, Plasmogamy is followed by fusion of nuclei, called as KARYOGAMY
ZYGOT FOMATION & MEIOSIS
In ZYGOMYCETES, fusion of nuclei, leads directly to the formation of zygot, which divides by meiosis when it germinates.
IN ASCOMYCOTA AND BASIDIOMYCOTA
In these groups of fungi, following steps after plasmogamy.
FORMATION OF DIKARYOTIC NYPHAE
In these groups, the two genetic types of haploid nuclei from two individuals my coexist & divide in the same hyphae for most of the life of fungus. Such as fungal hyphae is called DIKARYOTIC OR HETEROKARYOTIC HYPHA/CELL.
FORMATION OF FRUITING BODIES
Extensive growth of dikaryotic hyphae may lead to the formation of massive structures of interwoven hyphae called as Fruiting Bodies, such as
- Basidia/ Basidiocarps
- Asci/ Ascocarps
Fusion of two haploid nuclei occurs with in the fruiting bodies forming a zygote, This is called as SYNGAMY, followed immediately by meiosis.
FORMATION OF HAPLOID SEXUAL SPORES
Each zygote divides immediately by meiosis to form four haploid spores, which when release are dispersed, some of them giving rise to new hyphae.
CLASSIFICATION OF FUNGI
There are four major divisions of fungi, which are divided on the basis of their sexual reproduction.
1- ZYGOMYCOTA
2- ASCOMYCOTA
3- BASIDIOMYCOTA
4- DEUTEROMYCOTA
1- ZYGOMYCOTA
INTRODUCTION
Zygomycota are by far the smallest of four groups of fungi, with only about 600 named species. This group includes more frequently bread molds as well as a variety of other microscopic fungi found on decaying organic material.
CHARACTERISTIC FEATURE
The group is named after a characteristic feature of the life cycle of its member, the production of temporalily dormant structures called ZYGOSPORES.
The zygomycetes lack septa in their hyphae i.e coenocytic hyphae, except when they form sporangia or gametangia.
LIFE CYCLE OF ZYGOMYCOTA
In the life cycle of zygomycota, two types of reproduction occurs:
A- SEXUAL REPRODUCTION IN ZYGOMYCOTA
B- ASEXUAL REPRODUCTION IN ZYGOMYCOTA
(A) SEXUAL REPRODUCTION IN ZYGOMYCOTA
Sexual reproduction takes place by fusion of GAMETANGIA in following steps:
FORMATION OF PROGAMETANGIUM
When two hyphae came in contact with each other, each of them gives a lateral progametangium, facing each other.
DIFFERENTIATION OF PROGAMETANGIA INTO GAMETANGIA & SUSPENSORS
Later on, each of the progametangium differentiates into two parts
- Apical swollen part called GAMETANGIUM, containing numerous nuclei
- Basal hollow part called SUSPENSOR.
The gametangia may be formed on hyphae of different mating types or on a single hyphae. If different mating types are involved, fusion between pairs of haploid nuclei occurs immediately.
ZYGOT FORMATION
Fusion of haploid nuclei results in formation of diploid zygote nuclei, Except for the zygote nuclei, all nuclei of zygomycota are haploid.
ZYGOSPORE FORMATION
After the formation of diploid zygote nuclei, the fused portion of hyphae develops into ZYGOSPORES.
GERMINATION OF ZYGOSPORE
Under favorable condition zygospore germinates & giving rise to new mycelium. Meiosis occurs during germination.
(B) ASEXUAL REPRODUCTION IN ZYGOMYCOTA (BY SPORE FORMATION )
Asexual reproduction occurs much more frequently than sexual reproduction in the zygomycetes.
EXPLANATION
As previously discussed in spore formation
EXAMPLES OF ZYGOMYCETES
1- MUCOR
2- RHIZOPUS STOLONIPER
2-ASCOMYCOTA
INTRODUCTION
The second division of fungi, the ASCOMYCOTA is a very large group of about 30,000 named species with many more being discovered each year.
CHARACTERISTIC FEATURE
The ascomycota are named for their characteristic reproductive structure, the microscopic, club shaped ASCUS.
TYPE OF HYPHAE
The hyphae of ascomycetes are divided by septa i.e septate hyphae, but the septa are perforated & the cytoplasm flows along the length of each hyphae. The septa that cut off the asci & conidia are initially perforated like all other septa, but later they often become blocked.
LIFE CYCLE OF ASCOMYCOTA
In life cycle of ascomycota, Both sexual & asexual reproduction occurs.
(A) SEXUAL REPRODUCTION IN ASCOMYCOTA
Sexual reproduction occurs through following steps.
1-FORMATION OF MALE GAMETANGIUM OR ANTHERIDIUM
The hyphae of ascomycetes may be either homokaryotic & heterokaryotic. The cells of these hyphae usually contain from several to many nuclei. These cells form Antheridium or male gametangium.
2-FEMALE GAMETANGIUM OR ASCOGONIUM
The gametangium which develop beak like out growth called as TRICHOGYNE, is called female gametangium or Ascogonium.
3-FUSION OF MALE & FEMALE GAMETANGIUM
When antheridium is formed , it fuses with trichogyne of an adjacent ascogonium. Fusion of cytoplasm or plasmogamy occurs.
4-PAIRING OF NUCLEI
After plasmogamy, nuclei from antheridium then migrate through the trichogyne into the ascogonium, & pair with nuclei of opposite mating types.
5-FORMATION OF DIKARYOTIC HYPHAE & DIKARYOTICY
Dikarytic hyphae then arise from the area of fusion. Throughout such hyphae, nuclei that represent the two different original mating types occur ( DIKARYOTICY ) Such hyphae are also called as HETEROKARYOTIC HYPHAE.
6-FORMATION OF ASCOCARPS OR FRUITING BODIES
Excessive growth of monokaryotic or dikaryotic hyphae results in formation of massive structures of tightly interwoven hyphae, called as FRUITING BODIES OF ASCOCARPS, which corresponds to the visible portions of a morel or cup fungus.
7- ASCI FORMATION
Asci are special reproductive structures which are formed on special fertile layers of dikaryotic hyphae with in the Ascocarps.
8- SEPARATION OF ASCI
-+The asci are cut off by the formation of septa at the tips of heterokaryotic hyphae.
9- SYNGAMY
There are two haploid nuclei with in each ascus one of each of which belongs to different mating type. Fusion of these two nuclei occurs within each ascus called as SYNGAMY.
10-ZYGOT FORMATION
Syngamy results in zygote formation, which divides immediately by meiosis, forming four haploid daughter cells.
11- FORMATION OF ASCOSPORES
Four haploid daughter nuclei, usually divide again by mitosis , producing 8 haploid nuclei that become walled & called ASCOSPORES.
12-BURSTING OF ASCUS
In most Ascomycetes, the ascus becomes highly turgid at maturity and ultimately bursts, often at a perforated area, which may be pore or slit or lid
13- DESPERSION & GERMINATION OF ASCOSPORES
After bursting, the ascospores may be thrown as far as 30 cm. Under favorable circumstances they germinate giving new hyphae.
TYPES OF ASCOCARPS IN ASCOMYCETES
According to their shape, Ascocarps are of following three types:
1- OPOTHECIUM
The ascocarps of cup fungi & the morels are open, with the asci lining the open cups called OPOTHECIUM.
2- CLEISTOTHECIUM
Some ascocarps are closed & called as ‘CLESTOTHECIUM’
3- PERITHECIUM
Some ascocarps have small opening at the apex called as PERITHECIUM. Ascocarps of NEUROSPORA are of this type.
(B) ASEXUAL REPRODUCTION IN ASCOMYCOTA (BY CONDIA FORMATION)
INTRODUCTION
The type of asexual reproduction in fungi in which large number of asexual spores called “CONIDIA are formed, each on germination giving rise to new mycelium is known as CONIDIAL REPRODUCTION.
EXPLANATION
CONIDIA
Conidia are non-motile, asexual spores which may be produced in very large number & can survive for weeks, causing rapid colonization on new food.
CONIDIOPHORES
Conidia are not developed inside the sporangium but they are usually cut off at the end of modified hyphae called CONIDIOPHORES, commonly in chains or clusters.
EXAMPLE
Asexual reproduction by conidia formation is very common in ASCOMYCETES.
3.BASIDIOMYCOTA
INTRODUCTION
The basidiomycetes, third division of fungi have about 16,000 named species. More is known about some members of this group than about any other fungi.
CHARACTERISTIC FEATURE
Basidiomycetes are named for their characteristic sexual reproductive structures, the BASIDIUM, which is club shaped like as ascus.
LIFE CYCLE OF BASIDIOMYCOTA
In life cycle of Basidiomycota, reproduction is usually sexual. Asexual reproduction is not very important.
(A) SEXUAL REPRODUCTION IN BASIDIOMYCOTA
The life cycle of basidiomycetes begin with the production of hyphae which may be of two types.
1- Homokaryotic hyphae giving rise to primary mycelium.
2- Heterokaryotic hyphae giving rise to secondary mycelium.
PRIMARY OR MONOKARYOTIC MYCELIUM
Homokaryotic or monokaryotic hyphae lack septa at first. Eventually, However, septa are formed between nuclei of these hyphae. A basidiomycete mycelium made up of monokaryotic hyphae is called PRIMARY MYCELIUM.
SECONDARY OR DIKARYOTIC MYCELIUM
Mycelium of basidiomycetes, with two nuclei, representing the two different mating types b/w each pair of septa, is called SECONDARY OR DIKARYOTIC MYCELIUM. Most of the mycelium of basidiomycetes that occur in nature is dikaryotic & often only dikaryotic mycelium is able to form basidiocarps.
FORMATION OF BASIDIOCARP OR FRUITING BODY
Dikaryotic mycelium is responsible for the formation of FRUITING BODY in Basidiomycetes called as BASIDIOCARP, made up of tightly interwoven dikaryotic hyphae.
FORMATION OF BASIDIUM
Basidium is characteristic reproductive structure of Basidiomycetes, which is club shaped & formed with in the Basidiocarp. This produces slender projection at the end called as STERIGMATA, in this way.
SYNGAMY & ZYGOT FORMATION
Nuclear fusion or syangamy occurs in Basidium, giving rise to diploid zygote, the only diploid cell of the life cycle.
MEIOSIS & BASIDIOSPORE FORMATION
Meiosis occurs immediately after the formation of zygot, resulting in the formation of four haploid nuclei, which are incorporated in Basidiospores. In most member of this division basidiospores are borne at the sterignata
DISPERSION AND GERMINATION
Same as in Ascomycetes
(B) ASEXUAL REPRODUCTION IN IN BASIDIOMYCOTA
In contrast to their effective sexual reproduction, asexual reproduction is rare in most basidiomycetes.
EXAMPLES OF BASIDIOMYCETES
- MUSHROOMS
- TOAD STOOLS
- PUFF BALLS
- JELLY FUNGI
- SHELF FUNGI
- PLANT PATHOGENS CALLED RUSTS & SMUTS,
INTRODUCTION
“The fungi that are classified is this group, are simply those in which the sexual reproductive stages have not been observed. In other words, most of the Fungi Imperfecti are as ascomycota that have lost the ability to reproduce sexually. There are some 17000 described species of this group.”
CHARACTERISTIC FEATURE
Sexual reproduction is absent among Fungi Imperfecti
LIFE CYCLE OF DEUTEROMYCOTA
Although in life cycle of deuteromycetes or Fungi Imperfecti, true sexual reproduction is absent, but there is certain type of GENETIC RECOMBINATION which seems to be responsible for some of the production of new pathogenic strains of wheat rust.
GENETIC RECOMBINATION IN FUNGI IMPERFECTI PARASEXUALITY
In parasexuality, exchange of portions of chromosomes between the genetically distinct nuclei with in a common hyphae takes place. This is the special type of genetic recombination occurs in fungi Imperfecti.
EXAMPLES OF FUNGI IMPERFECTI
Among the economically important genera of Fungi Imperfecti are
1-PENICILLIUM
2- ASPERGILLUS
3- Most of the fungi that cause skin diseases in humans, including athlete’s foot & ring worm are also fungi imperfecti.
ECONOMIC IMPORTANCE OF FUNGI
Fungi play a vast role in economic field they show both harmful & useful activities to human beings.
USEFUL FUNGI
Following are some of the beneficial effects of fungi.
FOOD
Many kinds of edible fungi are in the form of mushrooms, are a source of nourishing & delicious food dishes. But not all the mushrooms are edible. Some of them are poisonous & called as toad stools or death stool. Yeast, another kind of fungi, are utilized in baking industry.
MEDICINES
Nearly two dozens antibiotics have been isolated from different types of fungi & bacteria, like
- Penicilliun from penecillium notatum
- Neomycin
- Chloromycetin
- Tetramycin & etc.
Many kinds of Yeast are used in the production of bakery & brewery products. Some species of genus PENICILLIUM give characteristic flavors & aromas to the cheese.
FERMENTATION
Species of Aspergillus, are used for fermenting soya sauce & soya paste. Citric Acid is produced commercially with members of this genus under highly acidic condition.
SOIL FERTILITY
Fungi maintain the soil fertility by decomposing the dead organic matter e.g Mycorhizal fungi.
PRODUCTION OF ORGANIC COMPOUNDS
May species of fungi are used in the production of organic compound such as vitamins, proteins & fats. Saccharomyces, synthesizes a range of vitamin B group.
HARMFUL FUNGI
Following are some of the harmful effects of fungi,
FOOD SPOILAGE
Saprophytic fungi cause tremendous amounts of spoilage of food stuff. 15-20% of worlds fruit is lost each year due to fungal attack.
SPOILAGE OF WOOD & LEATHER ARTICLES
Many fungi spoil leather goods, woods, wool, books, timber, cotton & etc. WOOD-ROTTING FUNGI destroy not only living trees but also structural timber. BRACKET/SHELF FUNGI cause lot of damage to store cut lumber as well as stands of timber of living trees.
TOXINS
Many fungi are poisonous . AMANITA VERNA is a mushroom, which produces deadly poisonous substance known as AMANITIN, which causes serious problems in respiratory system & blood circulatory system.
FOOD POISONING
Some fungi during decomposing food release certain poisonous substances collectively known as MYCOTOXINS. Mycotoxins are the major source of food poisoning.
DISEASES
Fungi cause a number of diseases in plants as well as in human beings.
PLANT DISEASES CAUSED BY FUNGI
Fungi destroy many agricultural crops, fruits, ornamentals & other kinds of plants because they produce several enzymes that can breakdown cellulose, Lignin and even cutin. Following are some of the serious plant disease caused by Fungi.
RUST & SMUT DISEASES
Rust & smut diseases are serious diseases of WHEAT, RICE, CORN &other cerial crops. They cause extensive damage.
POTATO BLIGHT
A serious disease of potato caused by a fungus known as PHYTOPTHORA INFESTANS. Other plant disease are.
- Powdery mildews ( on grapes, rose, wheat & etc).
- Ergot of rye
- Red rot of sugar cane
- Potato will
- Cotton root rot
- Apple scab
- Brown rot of peaches, plums, apricots & cherries.
Following are some of the fungal diseases in man.
SKIN DISEASES
RING WORM & ATHELETE’S FOOT are superficial fungal infection caused by certain Fungi Inperfecti
ORAL THRUSH
CANIDIA ALBICANS, a yeast causes oral & Vaginal thrush.
ASPERGILLOSIS
Aspergillosis is the disease of ear & lungs caused by ASPERGILLUS. It occurs only in person with defective immune system such as AIDS & cause death.
CANCER
Some strains of ASPERGILLUS FLAVUS produce one of the most carcinogenic ( cancer causing ) mycotoxins called AFLATOXINS.
ERGOTISM
Ergotism is caused by eating bread made from PUROLE ERGOT- Contaminated flour. The poisonous material in the ergot causes nervous spasm, convulsions, psychotic delusion & even gangrene.
HISTOPLASMOSIS
Histoplasmosis is a serious disease of lungs caused by inhaling spores of a fungus, which is common in soil contaminated with bird’s feces.
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