FUNGI
Fungus is a Latin word , which means mushroom . Fungi are achlorophyllous (but carotenoids are normally present ) , heterotrophic thallophytes . Study of mashrooms or study of fungi is called mycology .
Term fungus was used by a group name by Gaspard Bauhin . Father of mycology is Pier Antonio Micheli . He wrote Nova Genera Plantarum . Father of Modern Mycology and Plant pathology is de Bary . Father of Indian Mycology and plant pathology is E. J. Butler . Largest fungus is Bracket fungi and smallest fungus is Yeast . The largest organism is a fungus Amillaria ostoyae spread in area of thousands of acres . Puffball is a fungus . Luminescent fungi parts are pileus in Panus and Pleuronus species .
General characteristics of fungi
1. Plant body is made up of branched filamentous hyphae . Hyphae form mycelium . Mycelium is absent in yeast , Synchytrium .
2. Hyphae are aseptate ( cystopus ) and coenocytic ( in phycomycetes ) or septate ( in ascomycetes , basidiomycetes , deuteromycetes ) .
3. Septa have simple pores . But in basidiomycetes , septa have dolipores . On both sides of dolipore , double membraned cap or parenthosome occurs .
4. Main component of cell wall is chitin ( fungal cellulose ) .
5. Motile cells are absent in the life cycle of higher fungi ( ascomycetes , basidiomycetes , deuteromycetes ) .
6. Modification of fungal mycelium -
Prosenchyma - Hyphae are loosely interwoven , more or less parallel to one another .
Pseudo-parenchyma - closely interwined, running in all directions , hyphae are not distinguishable , resemble parenchyma .
Rhizomorph - a thick strand of underground hyphae resembling a root
Sclerotium - compact globose structure , survive for long periods .
Haustorium - intracellular absorbing structures in obligate parasitic fungi , absent in Synchytrium .
Appressorium - terminal swollen strucutre of infectious hyphae of parasitic fungus .
Stromata - compact structure like mattresses
Hyphal traps - network of hyphal loops , help in capturing nematodes .
7. Fungi may be eucarpic ( only a part of vegetative mycelium frorms reproductive unit ) eg .yeast ,or holocarpic ( whole vegetative cell is transformed into a reproductive unit ) e.g. synchytrium .
8. All fungi are heterotrophs . Some are obligate parasites like Albugo , Puccinia . Synchytrium is an intracellluar parasite .
9. Ascospors ( endogenous origin ) and basidiospores ( exogenous origin ) are sexually produced spores .
10 . Asexual spores are zoospores , chlamydospores , aplanspores , oidia etc .
Sexual reproduction in fungi
There is progressive complexity in vegetative body and a gradual degeneration of sex organs in fungi . Sexual reproduction in fungi involves plasmogamy , karyogamy and meiosis . It takes place by -
1. Planogametic coupulation - It is fusion of two naked motile gametes . It is of 3 types -
a. Isogamy ( morphologically similar but physiologically different gametes ) - Synchytrium
b. Anisogamy ( both morhologically & physiologically idfferent ) - Allomyces
c. Oogamy (motile male gamete & non-motile female gamete ) - It is of 3 types
i. Gametangial contact ( involves fertilization tube ) - Albugo , Aspergillus , Pythium , Phytophthora
ii. Gametangial coupulation - Mucor , Rhizopus
iii. Spermatization ( sex organs absent , spermatia & receptive hyphae ) - Puccinia
iv. Somatogamy ( fusion of two vegetative cells ) - Peziza , Agaricus .
Taxonomic status of fungi
Ainsworth treated fungi as separate kingdom Mycota . Alexopoulus and Mims also included fungi in separate kingdom Myceteae . The classification of fungi is not yet settled . Gwynne-Vaugham and Barnes , Gaumann and Dodge , Tippo , Bessey , Martin , Alexopoulus , Alexopoulus and Mims , Ainsworth etc proposed the classification of fungi . Criteria for classification were thallus organisation , kinds of asexual spores , presence or absence of sexual reproductin , nature of life cycle etc . According to latest classification of Ainworth , Fungi includes -
Kingdom Mycota - It includes 2 divisions .
Division 1 Myxomycota ( slime molds ) - It includes 4 classes .
1. Acrasiomycetes
2. Hydromyxomycetes
3. Myxomycetes
4. Plasmodiophoromycetes
Division 2 Eumycota ( true fungi ) - It includes 5 sub divisions .
Sub division Mastigomycotina -
1. Chytridiomycetes
2. Hypochytridiomycetes
3. Oomycetes
Sub division zygomycotina
1. Zygomycetes ( sometimes called phycomycetes )
2. Trichomycetes
Sub division ascomycotina
1. Hemiascomycetes
2. Loculoascomycetes
3. Plectomycetes
4. Laboulbeniomycetes
5. Pyrenomycetes
6. Discomycetes
Sub division Basidiomycotina
1. Teliomycetes
2. Hymenomycetes
3. Gasteromycetes
Sub division Deuteromycotina
1. Blastomycetes
2. Hyphomycetes
3. Coelomycetes
Heterothallism in fungi
Heterothallism is a condition where two complementary mating types are needed for sexual reproduction . It was discovered by A. F. Blackeslee in mucorales .
It may be of 2 types -
1. Morphological heterothallism - Two mating types are morphologically different . It is also called haplodioecious . Example - Achlya ambisexualis .
2. Physiological heterothallism - Two mating types are morphologically similar but physiologically different . It is also known as haploid incompatibility . It is of 2 types -
A. Two allele heterothallism - Sexual compatibility is governed by a single pair of genetic factors ( A , a ) . Example Mucor mucedo .
B. Multiple allele heterothallism - Sexual compatibility is governed by more than two alleles . It may be of two types -
( a ) Bipolar - Bipolar multiple allele heterothallism is governed by more than two alleles of a single locus ( L1 , L2 , L3 ..... where L1 is compatible two any other allele except L1 ) . It is characteristic feature of basidiomycetes except rusts and smuts .
( b ) Tetrapolar - Tetrapolar multiple allele heterothallism is governed by more than two alleles of two locus ( A1B1 is not compatible to A1B1 , not fully compatible to A1B2 , A2B1 etc but compatible to A2B2 . Example Ustilago maydis .
Homothallic fungi - They have single mating types . They may be primary ( have uninucleate spores ) or secondary ( have binucleate spores with two compatible nuclei ) .
Parasexuality
It was discovered by Pontecorvo and Raper in Aspergillus nidulans . It is common in fungi in which sexual process is absent ( deuteromycetes ) though it also occurs in several fungi with sexual reproduction . Parasexuality is a process in which plasmogamy , karyogamy and meiosis do take place , but not at specific time or specific points in the life cycle of fungus . Meiosis in sexual cycle and mitosis in parasexual cycle are responsible for genetic recombination ( most imp difference ) .
The sequence of steps in this process are -
1. Formation of hetrokaryotic mycelium is the first important & necessary step . Most common method for this is anastomosis ( fusion of two hyphae ) .
2. It results in the formation of heterozygous diploid nucleus ( A and B , AA , BB , AB ) .
3. Mutiplication of this diploid nucleus ( 1: 1000 in comparision of multiplication of haploid nucleus ) .
4. Occasional mitotic crossing over during multiplication of diploid nucleus results in new gene recombinations . It is most important step .
5. These new recombinations of diploid nuclei are sorted out as diploid conidia . These diploid conidia germinate in diploid mycelia .
6. Occasionally some hypha of diploid mycelium form haploid conidia ( haploidization ) .
7. These haploid conidia are sorted out as haploid mycelia .
Parasexuality can be used in developing mycelium strains of desirable characters , in analysis of genetic and physiological processes of perfect and imperfect fungi .
Sex hormones in fungi
Some important sex hormones in fungi ( Allomyces , Achlya , Mucor mucedo etc ) are sirenin , antherdiol and oogoniol , hormone-D , trisporic acid , yeast alpha factors etc .
Economic importance of fungi
Benificial importance
1. Sufu is obtained from Mucor and Antimucor species .
2. Basidiocarps of Agaricus campestris , Morchella esculenta ( guchhi ) are edible fungus .
3. Ergot ( powerful hallucinogenic drug ) is obtained from the sclerotia of Claviceps purpurea .
4. Penicillin , wonder drug was for the first time extracted from sac fungi Penicillium notatum by Alexander Fleming in 1944 . At large scale it is obtained from P. chrysogenum . Griseofulvin is obtained from Penicillium greseofulvum . Fumagillin is obtained from Aspergillus fumigatus . Clavicin is obtained from Aspergillus clavatum . Ergotin is obtained from Claviceps purpurea . Cephalosporin is obtained from Cephalosporium .
5. Yeast cells are best source of vitamin B .
6. Organic acids - Citric acid is produced by fermentation of sugar by Aspergillus niger .
7. In research , Physarum polycephalum is very good study material for DNA synthesis , morphogenesis and mitotic cycle . Neurospora is referred as Drosophila of plant kingdom .
8. In brewery , Saccharomyces cerevisiae is used in the production of alcohol from sugar (glucose) , beer . P. camembertile , P. rocqueforti are used in cheese industry .
9. Enzyme invertase and zymase is produced by Saccharomyces cerevisae . Amylase is obtained from Aspergillus niger .
10. In agriculture ,Trichoderma is used in biological control of diseases .
11. Species like Rhizoctonia , Phoma etc show symbiotic relationship with roots of higher plants . This is called mycorrhiza .
12. Gibberellin is otained from Gibberella fujikuroi .
Harmful importance
1. Aflatoxin , a powerful toxin is produced by Aspergillus .
2. Amanita phlloides is a poisonous fungus .
3. Plant diseases - Early blight of potato -Alternaria solani
Irish famine ( Late blight of potato) - Alternaria solani
Red rot of sugarcane - Colletotrichum fulcatum
Downy mildew of pea - Peronospona pisi
Bengal famine ( brown leaf spot of rice ) - Helminthosporium oryzae
Salmon disease of fishes - Saprolegnia
Panama disease of banana - Fusarium oxysporum
Ergot of rye - Claviceps purpurea
Powdery mildew - Erysiphens
Black wart disease - Sychytrium endobioticum
White rust of crucifer - Albugo candida
Loose smut of barley - Ustilago nuda
Loose smut of wheat - Ustilago tritici
Black rust of wheat - Puccinia graminis tritici
Tikka disease of groundnut - Cercospora personata
Wilt of arhar - Fusarium udum
4. Animal diseases -
Athelete foot - Tinea rubrum
Mucomycosis - Mucor , Rhizopus
Aspergillosis - Asppergillus flavus , A. niger
Bordeaux mixture
It is mixture of copper sulphate and lime . It is used common antifungal . It was prepared by Millardet .
Study material for TGT , PGT , CSIR-NET , Assistant Professor , M Sc entrance , Medical entrance etc
DEUTEROMYCOTINA
SUB DIVISION DEUTEROMYCOTINA
Deuteomycotina are also called fungi imperfecti because it includes those fungi in which only asexual ( inperfect ) stages are known and sexual ( perfect ) stages are not yet recorded . The classification of deuteromycotina is artificial hence the various taxa are known as form-order , form- family , form-genus etc .
FORM CLASS HYPHOMYCETES
Form genus Alternaria ( Form Order Monilliales )
Alternaria species are saprophytic or pathogenic . Alernaria solani causes early blight of potato . Symptoms appear as yellow brown spots ( in the form of concentric rings ) on the leaves . These are known as target board symptoms . Conidiophores may be geniculate ( bent like knee ) and conidia may be muriform ( brick like arrangement ) in shape . Perfect stage of alternaria is Pleospora infectoria .
Form genus Cercospora ( Form Order Monilliales )
They are mostly pathogens . Tikka disease of groudnut is caused by Cercospora personata . Perfect stages of species of Cercospora are included in Mycoshaerella .
Form genus Helmithosporium (Form Order Monilliales )
The conidium germinates characteristically from both the ends .
Form genus Fusarium (Form Order Monilliales )
Most of the species of Fusarium are facultative parasites . Characteristic symptom is wilting of seedlings and plants .
Form genus colletotrichum ( Form Order Melanoconiales )
Colletotrichum is a parasitic fungus causing anthracnose disease in plants . Colletotrichum falcatum is responsible for red rot of sugarcane . Acervuli ( having conidiophores ) and lesions appear on sugarcane stem . The internodes of infected sugarcane plants usually get shrink .
Deuteomycotina are also called fungi imperfecti because it includes those fungi in which only asexual ( inperfect ) stages are known and sexual ( perfect ) stages are not yet recorded . The classification of deuteromycotina is artificial hence the various taxa are known as form-order , form- family , form-genus etc .
FORM CLASS HYPHOMYCETES
Form genus Alternaria ( Form Order Monilliales )
Alternaria species are saprophytic or pathogenic . Alernaria solani causes early blight of potato . Symptoms appear as yellow brown spots ( in the form of concentric rings ) on the leaves . These are known as target board symptoms . Conidiophores may be geniculate ( bent like knee ) and conidia may be muriform ( brick like arrangement ) in shape . Perfect stage of alternaria is Pleospora infectoria .
Form genus Cercospora ( Form Order Monilliales )
They are mostly pathogens . Tikka disease of groudnut is caused by Cercospora personata . Perfect stages of species of Cercospora are included in Mycoshaerella .
Form genus Helmithosporium (Form Order Monilliales )
The conidium germinates characteristically from both the ends .
Form genus Fusarium (Form Order Monilliales )
Most of the species of Fusarium are facultative parasites . Characteristic symptom is wilting of seedlings and plants .
Form genus colletotrichum ( Form Order Melanoconiales )
Colletotrichum is a parasitic fungus causing anthracnose disease in plants . Colletotrichum falcatum is responsible for red rot of sugarcane . Acervuli ( having conidiophores ) and lesions appear on sugarcane stem . The internodes of infected sugarcane plants usually get shrink .
GASTEROMYCETES Lycoperdales
SUB DIVISION BASIDIOMYCOTINA
CLASS GASTEROMYCETES
ORDER LYCOPERDALES
Lycoperdon is commonly known as puff ball . Fruiting bodies basidiocarps are angiocarpous . Basidiospores are discharged in the form of small spore clouds from the fruiting bodies by large rain drops or wind borne debris , hence the name is puff ball .
CLASS GASTEROMYCETES
ORDER LYCOPERDALES
Lycoperdon is commonly known as puff ball . Fruiting bodies basidiocarps are angiocarpous . Basidiospores are discharged in the form of small spore clouds from the fruiting bodies by large rain drops or wind borne debris , hence the name is puff ball .
HYMENOMYCETES Aphyllophorales
SUB DIVISION BASIDIOMYCOTINA
CLASS HYMENOMYCETES
ORDER APHYLLOPHORALES
Members of aphyllophorales are commonly known as pore fungi , bracket fungi , tooth fungi or coral fungi . Basidia are stichobasidia ( nuclear spindle is longitudinal ) . Polyporus is commonly known as bracket fungi . Polyporus occurs as saprophyte on dead wood logs or as a parasite causing serious damage to forest trees . Fruiting bodies basidiocarps are more or less flat , leathery or fan shaped . Basidiocarp is made up of 3 different types of hyphae . Sex organs are absent . Polyporus sulphureus is commonly known as sulpher mashroom .
CLASS HYMENOMYCETES
ORDER APHYLLOPHORALES
Members of aphyllophorales are commonly known as pore fungi , bracket fungi , tooth fungi or coral fungi . Basidia are stichobasidia ( nuclear spindle is longitudinal ) . Polyporus is commonly known as bracket fungi . Polyporus occurs as saprophyte on dead wood logs or as a parasite causing serious damage to forest trees . Fruiting bodies basidiocarps are more or less flat , leathery or fan shaped . Basidiocarp is made up of 3 different types of hyphae . Sex organs are absent . Polyporus sulphureus is commonly known as sulpher mashroom .
HYMENOMYCETES Agaricales
Sub division Basidiomycotina
Class Hymenomycetes
Order Agaricales
Agaricales are also known as gill fungi because of gills (develop on the under surface of fruiting bodies) .
Agaricus ( Family Agaricaceae )
They are saprophytic fungus which grow on dead decaying leaves , wood logs etc in rainy season . They are locally known as kukurmutta / khumb / dhingri . Agaricus bisporus is common species . Primary mycelium is formed by germination of basidiospore . It is branched , septate and monokaryotic . Primary mycelium is short lived . It is of + or - strain . Primary mycelia of two opposite strains fuse to form dikaryotic secondary mcelium . It is perennial and contains dolipore septa ( barrel shaped pore found in basidiomycetes ) . The hyphae of secondary mycelium twist together to form white hyphal cords , called rhizomorphs .
Hyphae grows outward from a center in a circle in soil ( centrifugal growth ) . Fruiting bodies are called basidiocarps . Basidiocarps are commonly known as mashrooms . They grow in successive rings above the soil . These rings are called fairy rings , based on the ancient belief that they marked the path of dancing fairies .
All species of agaricus are not edible .The edible mashrooms are propagated by vegetative means ( small pieces of dikaryotic mycelium ) . Asexual reproduction is uncommon and takes place by chlamydospores . Primary mycelia of two different strains act as male and female sex organs . Somatogamy takes place between primary mycelia of two different strains . It results in diploidization and formation of secondary mycelium . The secondary mycelium later develops fruiting bodies basidiocarps . Fruiting body is made up of tertiary mycelium . Somatogamy involves plasmogamy , karyogamy and meiosis .
Meiosis forms 2 + and 2 - nuclei . One + and one - nuclei are transferred to each daughter cell by the formation of clamp connection . Clamp connections are lateral branches that create bridges for nuclear movement between regions of the hypha that will become separate compartments . Clamp connections are present in dikaryophase but incomplete clamp connections occur in monokaryotic phase .
Basidiocarp is an umbrella shaped structure . It is made up of stipe ( basal part ) and pileus ( apical hemispherical part ) . Velum or inner veil is a membranous structure which joins stipes and pileus . As the pileus expands velum ruptures . Remnants of velum are attached to the stipe in the form of a ring called annulus . Gills hang from the inner surface of pileus . Gills may be of full , half or qurter length . Gill wall is made up of hymenium , sub hymenium and trama . Hymenium is a fertile layer of basidia . Basidia are arranged in palisade like layer . The upper hilar appendics of basidia bear basidiospores. They are sightly oblique at sterigma .
Class Hymenomycetes
Order Agaricales
Agaricales are also known as gill fungi because of gills (develop on the under surface of fruiting bodies) .
Agaricus ( Family Agaricaceae )
They are saprophytic fungus which grow on dead decaying leaves , wood logs etc in rainy season . They are locally known as kukurmutta / khumb / dhingri . Agaricus bisporus is common species . Primary mycelium is formed by germination of basidiospore . It is branched , septate and monokaryotic . Primary mycelium is short lived . It is of + or - strain . Primary mycelia of two opposite strains fuse to form dikaryotic secondary mcelium . It is perennial and contains dolipore septa ( barrel shaped pore found in basidiomycetes ) . The hyphae of secondary mycelium twist together to form white hyphal cords , called rhizomorphs .
Hyphae grows outward from a center in a circle in soil ( centrifugal growth ) . Fruiting bodies are called basidiocarps . Basidiocarps are commonly known as mashrooms . They grow in successive rings above the soil . These rings are called fairy rings , based on the ancient belief that they marked the path of dancing fairies .
All species of agaricus are not edible .The edible mashrooms are propagated by vegetative means ( small pieces of dikaryotic mycelium ) . Asexual reproduction is uncommon and takes place by chlamydospores . Primary mycelia of two different strains act as male and female sex organs . Somatogamy takes place between primary mycelia of two different strains . It results in diploidization and formation of secondary mycelium . The secondary mycelium later develops fruiting bodies basidiocarps . Fruiting body is made up of tertiary mycelium . Somatogamy involves plasmogamy , karyogamy and meiosis .
Meiosis forms 2 + and 2 - nuclei . One + and one - nuclei are transferred to each daughter cell by the formation of clamp connection . Clamp connections are lateral branches that create bridges for nuclear movement between regions of the hypha that will become separate compartments . Clamp connections are present in dikaryophase but incomplete clamp connections occur in monokaryotic phase .
Basidiocarp is an umbrella shaped structure . It is made up of stipe ( basal part ) and pileus ( apical hemispherical part ) . Velum or inner veil is a membranous structure which joins stipes and pileus . As the pileus expands velum ruptures . Remnants of velum are attached to the stipe in the form of a ring called annulus . Gills hang from the inner surface of pileus . Gills may be of full , half or qurter length . Gill wall is made up of hymenium , sub hymenium and trama . Hymenium is a fertile layer of basidia . Basidia are arranged in palisade like layer . The upper hilar appendics of basidia bear basidiospores. They are sightly oblique at sterigma .
TELIOMYCETES Uredinales
Sub division Basidiomycetes
Class Teliomycetes
Order Uridinales
Members of order uridinales are commonly known as rust fungi because of characteristic rust like reddish-brown colour of their spores . They may be autoecious ( complete their life cycle on a single host , example Puccinia butleri ) or heteroecious ( complete their life cycle on two hosts , example Puccinia graminis ) . Rusts may be microcyclic ( only one type of dikaryon spores , example Puccinia malvacearum ) or macrocyclic ( more than one type of dikaryon spores , example Puccinia graminis ) .
Puccinia ( Family Pucciniaceae )
Many species of Puccinia cause rust diseases in cereal crops . Puccinia striiformis is causal organism of Yellow rust of wheat . Puccinia graminis is the causal organism for black rust or stem rust of wheat and other cereal crops . P. graminis is a composite species . It has been divided into 6 strains each having a different cereal host eg. P. graminis tritici ( on wheat ) , P. graminis secalis ( on rye ) . Each strain has several physiological races .
Puccinia shows phenomenon of biological specialization ( specific host is infected by specific pathogen ). It means Puccinia graminis tritici will infect only wheats not any other cereal crops . Symptoms appear on leaves and stem . Spores come out by rupturing epidermis of the tissue .
It is a macrocyclic , heteroecious fungus . Although Puccinia graminis can survive in the absence of alternate host , its life cycle is completed only when both hosts are available .
There are 5 spores fromed in life cycle of puccinia -
On primary host wheat ( Triticum aestivum )
1. Uredospore
2. Teleutospore
3. Baisidiospore
On alternate host Barberry ( Berberis vulgaris )
4. Pycnidiospore
5. Aeciospore
Uredospores - Mycelium produced by germination of aeciospores enters through stomata on wheat plants . They develop uredospores . Uredospores are stalked , unicellular and binucleate . They develop in groups called uredosori . Uredosorus shows reddish brown rust like appearance . They germinate and germ tubes develop in appressorium ( vesicle like structure ) . Intracellular hyphal branches develop from appressorium . Uredospores are capable of reinfcting wheat plants .
Teleutospores - At the end of wheat season uredosori are converted into teleutosori . Teleutosori appear as black raised streaks . Group of cells called telia produces teleutospores . Teleutospores are stalked , bicelluar , each cell with 2 nuclei and black in colour . 2 nuclei fuse to form synkaryon . Teleutspores are incapable of reinfecting wheat plants .
Basidiospores - Teleutospores remain dormant during summer season and basidiospores are not formed until rainy season . In spring season teleutospores germinate to form germ tube of limited growth called promycelium or epibasidium . Diploid nucleus moves in promycelium and undergoes meiosis . It forms 4 haloid basidiospores , two of + strain and two of - strain . Basidiospores survive only for few days and they perish in the absence of alternate host . They are discharged by explosive mechanism and are disseminated by wind .
Pycnidiospores - Basidiospore infects and germinates on upper surface of Barberis leaf . They produce mycelium of + and - strains . They form spermogonia or pycnidia of + and - strains . They are produced in spermogonium . Spermogonium opens on the upper surface of leaf by ostiole . Pycniophores are arranged like a palisade layer on inner surface of spermogonium . Pycniophores abstracts many small uninuclear pycniospores . They are ooze out through ostiole . Each spermogonium has receptive hyphae and spermatium of either both + or both - strains . Receptive hyphae and spermatium of two opposite strains undergo spermatization . Spermatization is a type of sexual reroduction . It results in formation of dikaryotic mycelium . It is also called diploidization .
Aeciospores - When dikaryotic mycelium formed by spermatization reaches on the lower surface of barberry leaf they form aecial cups . Aecial cup has aeciophores which produce binucletate aeciospores . They are dispersed by winds .
Annual recurrence of wheat rust in India
K C Mehta worked on the recurrence of rust in India while he was at Agra . There is no role of Berberis in the recurrence of wheat rust in India . Uredospores present on wheat or collateral hosts in hill areas are responsible for recurrence of the disease .
Difference between rust and smuts
1. Rust may be autoecious or heteroecious but smuts are always autoecious .
2. Rust symptoms appear as coloured pustules while smut symptoms appears as black powdery mass .
Class Teliomycetes
Order Uridinales
Members of order uridinales are commonly known as rust fungi because of characteristic rust like reddish-brown colour of their spores . They may be autoecious ( complete their life cycle on a single host , example Puccinia butleri ) or heteroecious ( complete their life cycle on two hosts , example Puccinia graminis ) . Rusts may be microcyclic ( only one type of dikaryon spores , example Puccinia malvacearum ) or macrocyclic ( more than one type of dikaryon spores , example Puccinia graminis ) .
Puccinia ( Family Pucciniaceae )
Many species of Puccinia cause rust diseases in cereal crops . Puccinia striiformis is causal organism of Yellow rust of wheat . Puccinia graminis is the causal organism for black rust or stem rust of wheat and other cereal crops . P. graminis is a composite species . It has been divided into 6 strains each having a different cereal host eg. P. graminis tritici ( on wheat ) , P. graminis secalis ( on rye ) . Each strain has several physiological races .
Puccinia shows phenomenon of biological specialization ( specific host is infected by specific pathogen ). It means Puccinia graminis tritici will infect only wheats not any other cereal crops . Symptoms appear on leaves and stem . Spores come out by rupturing epidermis of the tissue .
It is a macrocyclic , heteroecious fungus . Although Puccinia graminis can survive in the absence of alternate host , its life cycle is completed only when both hosts are available .
There are 5 spores fromed in life cycle of puccinia -
On primary host wheat ( Triticum aestivum )
1. Uredospore
2. Teleutospore
3. Baisidiospore
On alternate host Barberry ( Berberis vulgaris )
4. Pycnidiospore
5. Aeciospore
Uredospores - Mycelium produced by germination of aeciospores enters through stomata on wheat plants . They develop uredospores . Uredospores are stalked , unicellular and binucleate . They develop in groups called uredosori . Uredosorus shows reddish brown rust like appearance . They germinate and germ tubes develop in appressorium ( vesicle like structure ) . Intracellular hyphal branches develop from appressorium . Uredospores are capable of reinfcting wheat plants .
Teleutospores - At the end of wheat season uredosori are converted into teleutosori . Teleutosori appear as black raised streaks . Group of cells called telia produces teleutospores . Teleutospores are stalked , bicelluar , each cell with 2 nuclei and black in colour . 2 nuclei fuse to form synkaryon . Teleutspores are incapable of reinfecting wheat plants .
Basidiospores - Teleutospores remain dormant during summer season and basidiospores are not formed until rainy season . In spring season teleutospores germinate to form germ tube of limited growth called promycelium or epibasidium . Diploid nucleus moves in promycelium and undergoes meiosis . It forms 4 haloid basidiospores , two of + strain and two of - strain . Basidiospores survive only for few days and they perish in the absence of alternate host . They are discharged by explosive mechanism and are disseminated by wind .
Pycnidiospores - Basidiospore infects and germinates on upper surface of Barberis leaf . They produce mycelium of + and - strains . They form spermogonia or pycnidia of + and - strains . They are produced in spermogonium . Spermogonium opens on the upper surface of leaf by ostiole . Pycniophores are arranged like a palisade layer on inner surface of spermogonium . Pycniophores abstracts many small uninuclear pycniospores . They are ooze out through ostiole . Each spermogonium has receptive hyphae and spermatium of either both + or both - strains . Receptive hyphae and spermatium of two opposite strains undergo spermatization . Spermatization is a type of sexual reroduction . It results in formation of dikaryotic mycelium . It is also called diploidization .
Aeciospores - When dikaryotic mycelium formed by spermatization reaches on the lower surface of barberry leaf they form aecial cups . Aecial cup has aeciophores which produce binucletate aeciospores . They are dispersed by winds .
Annual recurrence of wheat rust in India
K C Mehta worked on the recurrence of rust in India while he was at Agra . There is no role of Berberis in the recurrence of wheat rust in India . Uredospores present on wheat or collateral hosts in hill areas are responsible for recurrence of the disease .
Difference between rust and smuts
1. Rust may be autoecious or heteroecious but smuts are always autoecious .
2. Rust symptoms appear as coloured pustules while smut symptoms appears as black powdery mass .
DISCOMYCETES Pezizales
Sub division Ascomycotina
Class Discomycetes
Order Pezizales
Pezizales are known as cup fungi . All cup fungi show degeneration of sexuality . Asexual repdroduction is uncommon or absent . In Peziza and Morchella sex organs do not develop at all . They reproduce by somatogamy ( between nuclei of two cells ) or by autogamous pairing ( between nuclei of same cell ) . It results in formation of a dikaryon . Dikaryon cell gives rise ascogenous hyphae which ultimately form ascus . Fruiting body in Pezizales is apothecia .
Peziza ( Family Pezizaceae )
Mycelium is branched , septate with uninucleate cells within the sustrarum but apothecia are above the substratum . They are saprophytic fungus and found on rotting logs , bark of trees , humus rich soil etc . Some species are coprophilous . Apothecia has hymenium , sub hymenium and excipulum regions . Excipulum is outermost sterile region . Hymenium is innermost , palisade like layer of asci and paraphysis .
Morchella ( Family Morchellaceae )
Morchella is comonly called true morel , sponge mushroom or guchhi . Common species is Marchella esculenta . It is most highly prized edible fungus . It is a saprophytic fungus . It occurs mainly on humus rich soil , dead leaves and branches . It is a hollow structure made up of pileus and stalk like stipe . Mycelium is branched , septate and multinucleate . Apothecia has hymenium , sub hymenium and trama regions . Hymenium is confined only to the grooves of fertile pileus . Hymenium is innermost , palisade like layer of asci and paraphysis . During dikaryon formation remaining nuclei degenerate .
Class Discomycetes
Order Pezizales
Pezizales are known as cup fungi . All cup fungi show degeneration of sexuality . Asexual repdroduction is uncommon or absent . In Peziza and Morchella sex organs do not develop at all . They reproduce by somatogamy ( between nuclei of two cells ) or by autogamous pairing ( between nuclei of same cell ) . It results in formation of a dikaryon . Dikaryon cell gives rise ascogenous hyphae which ultimately form ascus . Fruiting body in Pezizales is apothecia .
Peziza ( Family Pezizaceae )
Mycelium is branched , septate with uninucleate cells within the sustrarum but apothecia are above the substratum . They are saprophytic fungus and found on rotting logs , bark of trees , humus rich soil etc . Some species are coprophilous . Apothecia has hymenium , sub hymenium and excipulum regions . Excipulum is outermost sterile region . Hymenium is innermost , palisade like layer of asci and paraphysis .
Morchella ( Family Morchellaceae )
Morchella is comonly called true morel , sponge mushroom or guchhi . Common species is Marchella esculenta . It is most highly prized edible fungus . It is a saprophytic fungus . It occurs mainly on humus rich soil , dead leaves and branches . It is a hollow structure made up of pileus and stalk like stipe . Mycelium is branched , septate and multinucleate . Apothecia has hymenium , sub hymenium and trama regions . Hymenium is confined only to the grooves of fertile pileus . Hymenium is innermost , palisade like layer of asci and paraphysis . During dikaryon formation remaining nuclei degenerate .
PYRENOMYCETES Sphaeriales
Sub division Ascomycotina
Class Pyrenomycetes
Order sphaeriales
Most of the members of sphaeriales are saprophytes . Characteristic feature is that either they do not produce antheridia or if at all formed , they are non-functional . The fruiting body is usually flask shaped perithecium .
Family Sodariaceae
Perithecia are usually stomatous .
Neurosora
Sub division - Ascomycotina
Class - Pyrenomycetes
Order - Sphaeriales
Family - Sodariaceae
Neurospora are called drosophila of plant kingdom because it is useful in study mycology , genetics and biochemistry . N. sitophila is commonly known as bakery mold or red bread mold . Mycelium is well branched , multinucleate and septate . Asexual reproduction takes place by two types of conidia - macroconidia and microconidia . Sexual reproduction is normal ascomycotina type . Ascospores are dark and characteristically with ribbed wall .
Claviceps
Sub division - Ascomycotina
Class - Pyrenomycetes
Order - Sphaeriales
Family - Clavicipitaceae
Claviceps infects members of family poaceae , causing ergot disease ( C. purpurea causes ergot of rye ) . The fungus infects mostly the gynoecium of the host plant , which soon turns black due to accumulation of compact masses of fungal hyphae , called sclerotia or ergot grain . Sclerotia of Claviceps are called ergot . Hence they are also known as ergot fungi . Sclerotia of C. purpurea contain a number of toxic alkaloids , such as ergotamine , ergometrin and ergonovin which affects blood vessels and nervous system . Sclerotia of Claviceps are used to hasten or induce uterine contraction during child birth . LSD , a psycotic dug is obtained from C. purpurea .
Other species
Xylaria ( xylariaceae ) are parasites on woody plants causing white rye . Chaetomium thermophile ( melanosporaceae ) is a thermophilic and coprophilous fungus or cellulose degrading fungus . They are found on heaps of dung and compost manure , substances rich in cellulose . Thin long hairs or hairy appendages on the outer surface of perithecium is characteristic feature of chaetomium .
Class Pyrenomycetes
Order sphaeriales
Most of the members of sphaeriales are saprophytes . Characteristic feature is that either they do not produce antheridia or if at all formed , they are non-functional . The fruiting body is usually flask shaped perithecium .
Family Sodariaceae
Perithecia are usually stomatous .
Neurosora
Sub division - Ascomycotina
Class - Pyrenomycetes
Order - Sphaeriales
Family - Sodariaceae
Neurospora are called drosophila of plant kingdom because it is useful in study mycology , genetics and biochemistry . N. sitophila is commonly known as bakery mold or red bread mold . Mycelium is well branched , multinucleate and septate . Asexual reproduction takes place by two types of conidia - macroconidia and microconidia . Sexual reproduction is normal ascomycotina type . Ascospores are dark and characteristically with ribbed wall .
Claviceps
Sub division - Ascomycotina
Class - Pyrenomycetes
Order - Sphaeriales
Family - Clavicipitaceae
Claviceps infects members of family poaceae , causing ergot disease ( C. purpurea causes ergot of rye ) . The fungus infects mostly the gynoecium of the host plant , which soon turns black due to accumulation of compact masses of fungal hyphae , called sclerotia or ergot grain . Sclerotia of Claviceps are called ergot . Hence they are also known as ergot fungi . Sclerotia of C. purpurea contain a number of toxic alkaloids , such as ergotamine , ergometrin and ergonovin which affects blood vessels and nervous system . Sclerotia of Claviceps are used to hasten or induce uterine contraction during child birth . LSD , a psycotic dug is obtained from C. purpurea .
Other species
Xylaria ( xylariaceae ) are parasites on woody plants causing white rye . Chaetomium thermophile ( melanosporaceae ) is a thermophilic and coprophilous fungus or cellulose degrading fungus . They are found on heaps of dung and compost manure , substances rich in cellulose . Thin long hairs or hairy appendages on the outer surface of perithecium is characteristic feature of chaetomium .
PLECTOMYCETES Erysiphales
SUB DIVISION ASCOMYCOTINA
Class Plectomycetes
Order Erysiphales
Fungi of order erysiphales appear as white powdery coating on the surface of host hence they are popularly known as powdery mildews . Mature cleistothecia of erysiphales are characterised by the presence of appendages .
Family erysiphaceae
They are biotrophic parasites ( derive their nutrients from living host cells ) of flowering plants causing the powdery mildews disease . Fruiting bodies are cleistothecium which bears myceloid appendages in erysiphe , circinoid appendages in uncinula . They have conidia in basipetal succession .Uncinula causes powdery mildew of grape - vines . Sphaerotheca fuliginea causes powdery mildew of cucurbits .
Erysiphae
Sub division - Ascomycotina
Class - Plectomycetes
Order - erysiphales
Family - erysiphaceae
Genus - Erysiphe
Mycelium is superficial ( ectoparasite ) , branched and septate . Erysiphe shows branched haustoria . Digitate haustoria is found in erysiphe graminis . Sex organs usually develop in late summer and conidia develop in cool and humid conditions .
Class Plectomycetes
Order Erysiphales
Fungi of order erysiphales appear as white powdery coating on the surface of host hence they are popularly known as powdery mildews . Mature cleistothecia of erysiphales are characterised by the presence of appendages .
They are biotrophic parasites ( derive their nutrients from living host cells ) of flowering plants causing the powdery mildews disease . Fruiting bodies are cleistothecium which bears myceloid appendages in erysiphe , circinoid appendages in uncinula . They have conidia in basipetal succession .Uncinula causes powdery mildew of grape - vines . Sphaerotheca fuliginea causes powdery mildew of cucurbits .
Erysiphae
Sub division - Ascomycotina
Class - Plectomycetes
Order - erysiphales
Family - erysiphaceae
Genus - Erysiphe
Mycelium is superficial ( ectoparasite ) , branched and septate . Erysiphe shows branched haustoria . Digitate haustoria is found in erysiphe graminis . Sex organs usually develop in late summer and conidia develop in cool and humid conditions .
PLECTOMYCETES eurotiales
SUB DIVISION ASCOMYCOTINA
Class plectomycetes
Order Eurotiales
Members of order eurotiales show gradual reduction of sexuality . Conidia give a characteristic tint to the fungus .
Aspergillus ( Eurotium )
Sub division - Ascomycotina
Class - Plectomycetes
Order - Eurotiales
Family - Eurotiaceae ( Aspergillaceae )
Genus - Aspergillus
A. flavus produces aflatoxins which are carcinogenic in nature . It contaminates food stuffs like groundnuts . Citric acid is obtained from fermantation of sugar by aspergillus .Mycelium is profusely branched , septate and multinucleate . Foot cell of somatic hyphae forms erect branch called conidiophore which swells at the tip , accumulates cytoplasm and forms a vesicle . Shape of vesicle differs in different species of aspergillus . Several finger shape projections called phialides or sterigmata develop on vesicle . First layer is primary sterigmata and subsequent layers are secondary and tertiary sterigmata . Conidia develop exogenously in long basipital chains on sterigmata .
Most of the species of aspergillus are homothallic but few are heterothallic . Male sex organ is unicellular antheridia ( Antheridia is not a common feature of all species of aspergillus ) and female sex organ is ascogonium . Ascogonium has terminal receptive region trichogyne and unicellular ascogonium . Fertilization takes place by gametangial contact between antheridia and trichogyne and results in formation of a dikaryon in ascgonium .
Dikaryon develops into a ascogenous hypha by septation .Terminal cell of ascogenous hypha curves to from a hook like structure crozier . The two nuclei of dikaryon in crozier divide to form 4 daughter nuclei . Now septa is formed in crozier in such a way that the basal cell has 1 nuclei , penultimate cell has 2 nuclei and terminal cell has 1 nuclei . Penultimate cell functions as ascus mother cell and elongates to form ascus . 2 nuclei of penultimate cell fuse to form a diploid nucleus which undergoes meiosis followed by mitosis . It results in formation of 8 haploid ascospores . At the same time cells below ascogonium form a layer called peridium . Peridium encloses ascogenous hyphae . It results in fruiting body called ascocarp . The ascocarp is completely closed cleitsothecium .
Sexual stage is called perfect state and sexual stage is called imperfect state . There are different names for these states . Eurotium , Emericella etc are perfect states of aspergillus .
Penicillium
Classification and life cycle are same as of Aspergillus . Penicillium is commonly known as blue or green mold . Latin word Penicillus means artists brush , penicillium shows brush like appearance due to its branched conidiophores .
Penicillin was discovered by Alexander Fleming in 1929 . Wonder drug penicillin is commonly obtained from P. chrysogenum and P. notatum , griseofulvin is obtained from P. greseofulvin . P. rocqueforti and P. camembertile are used in cheese industry .
Mycelium is profusely branched , septate , uni to multinucleate . Branched conidiophores have ramus , metulae , phialides ( sterigmata ) and conidia in a sequence according to type of species . In some species sex organs do not develop at all . Most of the species of Penicillium are homothallic but few are heterothallic . Antheridium coils spirally around the ascogonium . Fertilization takes place by gametangial contact . Ascocarp is cleistothecium type as in aspergillus . Perfect stage of penicillium are Talaromyces , Eupenicillium .
Class plectomycetes
Order Eurotiales
Members of order eurotiales show gradual reduction of sexuality . Conidia give a characteristic tint to the fungus .
Aspergillus ( Eurotium )
Sub division - Ascomycotina
Class - Plectomycetes
Order - Eurotiales
Family - Eurotiaceae ( Aspergillaceae )
Genus - Aspergillus
A. flavus produces aflatoxins which are carcinogenic in nature . It contaminates food stuffs like groundnuts . Citric acid is obtained from fermantation of sugar by aspergillus .Mycelium is profusely branched , septate and multinucleate . Foot cell of somatic hyphae forms erect branch called conidiophore which swells at the tip , accumulates cytoplasm and forms a vesicle . Shape of vesicle differs in different species of aspergillus . Several finger shape projections called phialides or sterigmata develop on vesicle . First layer is primary sterigmata and subsequent layers are secondary and tertiary sterigmata . Conidia develop exogenously in long basipital chains on sterigmata .
Most of the species of aspergillus are homothallic but few are heterothallic . Male sex organ is unicellular antheridia ( Antheridia is not a common feature of all species of aspergillus ) and female sex organ is ascogonium . Ascogonium has terminal receptive region trichogyne and unicellular ascogonium . Fertilization takes place by gametangial contact between antheridia and trichogyne and results in formation of a dikaryon in ascgonium .
Dikaryon develops into a ascogenous hypha by septation .Terminal cell of ascogenous hypha curves to from a hook like structure crozier . The two nuclei of dikaryon in crozier divide to form 4 daughter nuclei . Now septa is formed in crozier in such a way that the basal cell has 1 nuclei , penultimate cell has 2 nuclei and terminal cell has 1 nuclei . Penultimate cell functions as ascus mother cell and elongates to form ascus . 2 nuclei of penultimate cell fuse to form a diploid nucleus which undergoes meiosis followed by mitosis . It results in formation of 8 haploid ascospores . At the same time cells below ascogonium form a layer called peridium . Peridium encloses ascogenous hyphae . It results in fruiting body called ascocarp . The ascocarp is completely closed cleitsothecium .
Sexual stage is called perfect state and sexual stage is called imperfect state . There are different names for these states . Eurotium , Emericella etc are perfect states of aspergillus .
Penicillium
Classification and life cycle are same as of Aspergillus . Penicillium is commonly known as blue or green mold . Latin word Penicillus means artists brush , penicillium shows brush like appearance due to its branched conidiophores .
Penicillin was discovered by Alexander Fleming in 1929 . Wonder drug penicillin is commonly obtained from P. chrysogenum and P. notatum , griseofulvin is obtained from P. greseofulvin . P. rocqueforti and P. camembertile are used in cheese industry .
Mycelium is profusely branched , septate , uni to multinucleate . Branched conidiophores have ramus , metulae , phialides ( sterigmata ) and conidia in a sequence according to type of species . In some species sex organs do not develop at all . Most of the species of Penicillium are homothallic but few are heterothallic . Antheridium coils spirally around the ascogonium . Fertilization takes place by gametangial contact . Ascocarp is cleistothecium type as in aspergillus . Perfect stage of penicillium are Talaromyces , Eupenicillium .
HEMIASCOMYCETES endomycetales
SUB DIVISION ASCOMYCOTINA
They are commonly called sac fungi or bladder fungi . They produce endogenously produced perfect state spores called ascospores . Higher members of ascomycotina show gradual degeneration of sex . Ascomycotina show physiological heterothallism . It is the male gamete of one mating type fertilizes the ascogonium of other mating type. Fruiting bodies are known as ascocarps which may be of following types -
1. Apothecium - It is cup like .example - Peziza
2. Perithecium - It is flask shaped . example - Claviceps .
3. Cleistothecium - It is globose and completely closed . Example - Aspergillus , Penicillium .
Some classes under sub division ascomycotina -
1. Hemiascomycetes
2. Plectomycetes
3. Pyrenomycetes
4. Discomycetes
Class Hemiascomycetes
One of the order of hemiascomycetes -
Endomycetales - yeast
Sachharomyces (Yeast )
Sub division - Ascomycotina
Class - Hemiascomycetes
Order - Endomycetales
Family - Sachharomycetaceae
Genus - Sachharomyces
Yeasts are of considerable importance therefore S. cerevisiae is commonly called bakers yeast or brewer yeast . They are rich source of proteins , vitamin B2 , enzymes invertase and zymase . Yeast is eukaryotic , unicellular and holocarpic ( whole cell transformed in reproductive structure ) . It has a large central vacuole . Cell wall is chiefly composed of chitin , polysachharides glucan , mannan ( cellulose is absent ) .
Vegetative reproduction in yeast takes place by budding , fission and endospores . Budding results in branched or unbranched chains of cells having appearance of pseudomycelium . Sexual reproduction in yeast takes place by gametangial coupulation in which two vegetative cells or two ascosores function as coupulating gametangia and fuse together to form zygote .Zygote develops into ascus which forms 4 / 8 ascospores . Three types of life cycles are recognised in yeasts -
1. Haplobiontic - Haplo phase is long . S. octosporus
2. Diplobiontic - Diplo phase is long . S. ludwigii
3. Haplo-diplobiontic - Both phases are long . S. cerevisiae
They are commonly called sac fungi or bladder fungi . They produce endogenously produced perfect state spores called ascospores . Higher members of ascomycotina show gradual degeneration of sex . Ascomycotina show physiological heterothallism . It is the male gamete of one mating type fertilizes the ascogonium of other mating type. Fruiting bodies are known as ascocarps which may be of following types -
1. Apothecium - It is cup like .example - Peziza
2. Perithecium - It is flask shaped . example - Claviceps .
3. Cleistothecium - It is globose and completely closed . Example - Aspergillus , Penicillium .
Some classes under sub division ascomycotina -
1. Hemiascomycetes
2. Plectomycetes
3. Pyrenomycetes
4. Discomycetes
Class Hemiascomycetes
One of the order of hemiascomycetes -
Endomycetales - yeast
Sachharomyces (Yeast )
Sub division - Ascomycotina
Class - Hemiascomycetes
Order - Endomycetales
Family - Sachharomycetaceae
Genus - Sachharomyces
Yeasts are of considerable importance therefore S. cerevisiae is commonly called bakers yeast or brewer yeast . They are rich source of proteins , vitamin B2 , enzymes invertase and zymase . Yeast is eukaryotic , unicellular and holocarpic ( whole cell transformed in reproductive structure ) . It has a large central vacuole . Cell wall is chiefly composed of chitin , polysachharides glucan , mannan ( cellulose is absent ) .
Vegetative reproduction in yeast takes place by budding , fission and endospores . Budding results in branched or unbranched chains of cells having appearance of pseudomycelium . Sexual reproduction in yeast takes place by gametangial coupulation in which two vegetative cells or two ascosores function as coupulating gametangia and fuse together to form zygote .Zygote develops into ascus which forms 4 / 8 ascospores . Three types of life cycles are recognised in yeasts -
1. Haplobiontic - Haplo phase is long . S. octosporus
2. Diplobiontic - Diplo phase is long . S. ludwigii
3. Haplo-diplobiontic - Both phases are long . S. cerevisiae
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