Classification and Main Diagnostic Characteristics of Important Fungi DR. RAJBIR SINGH Assistant Professor Department of Plant Pathology Gochar Mahavidyalaya (Post Graduate College) Rampur Maiharan, Saharanpur (UP), India Affiliated to: CCS University, Meerut (UP), India Email: [email protected]
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Classification and diagnostic charecterstics of main plant pathogenic fungi
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• Thallus is mycelial type and mycelium is branched, non-septate and
hyaline.
• The hyphae are localised in both intracellular and inter-cellular
position.
• Haustorium is present.
• Asexual reproduction by zoospores which are produced in sporangia.
• The superficial somatic hyphae produce abundant sporangiophores.
• Sporangiophore is sympodially branched at maturity and produces
sporangia laterally. It is very little differentiated from the somatic
hyphae.
• Sporangium is thin-walled, lemon-shaped with an apical papilla.
• Sexual reproduction by oospore.
• Oospore is thick-walled, spherical and develops singly in each
oogonium. It is formed by the union of antheridium and oogonium
arranged in amphigynous manner.
Sporangia of Phytophthora
Pernospora
Classification
Kingdom : Mycota
Division : Eumycota
Subdivision : Mastigomycotina
Class : Oomycetes
Order : Pernosporales
Family : Pernoporaceae
Genus : Pernospora
Pernospora
• Mycelium is coenocytic, branched and intercellular.
• The haustoria are present which are short and knob-like orfilamentous and branched.
• Sporangiophore is dichotomously branched and projected fromthe host-tissue, mostly through stomata covering the greenishpart of the host with a dense white growth, called “downymildew”.
• Sporagium are borne singly at the acute, more or less reflexedtips of the branched sporangiophores.
• Each sporangium appears elliptical to globose, blunt, withoutany apical papilla. They are hyaline or light-coloured.
• Oospore is thick-walled and somewhat spherical. It is formed bythe union of antheridium and oogonium. Each oogonium hasone oospore with periplasm
• Gametangia morphologically distinguishable as male and femalegametangia.
Sclerospora
Classification:
Kingdom : Mycota
Division : Eumycota
Subdivision : Mastigomycotina
Class : Oomycetes
Order : Pernosporales
Family : Pernosporaceae
Genus : Sclerospora
Sclerospora
• Mycelium is eucarpic, filamentous, coenocytic endoparasitic , branched.
• The hyphae are intercellular and freely branched.
• Cell wall is made of cellulose and food is stored in the form of glycogen.
• Haustoria is present which are digitate button shaped in the stem cells but
are simple branched finger shaped occupying a major portion of the cell
cavity of the leaf.
• Asexual reproduction by sporangia and conidia.
• sporangium is hyaline, round or elliptical slightly papillate at the apex andmeasure 13-34 x 12-23 µ in size.
• The sporangiophores emerge out of the stomata of the infected leaves. Eachsporangiophore is a stout broad hypha unbranched in the lower part but givingout a few (2-6) thick short branches, di—or trichotomously, at the upper part.It is 100 µ length and 10-15 µ in width.
• Conidiophores are less branched.
• Conidium size is 13 × 12µm.
• Sexual reproduction by oospore.
Ustilago
Classification:
Kingdom : Mycota
Division : Eumycota
Subdivision : Basidiomycotina
Class : Teliomycetes
Order : Ustilaginales
Family : Ustilaginaceae
Genus : Ustilago
Ustilago
• Mycelium is septate, branched, inter to intracellular,
monokaryotic an dikaryotic
• Basidiocarp is absent.
• Basidium is septate
• Chlamydospore originate from mycelium present in
host tissues
• Chlamydospores are sessile, shperical and black in
color.
• Chlamydospres are not stick in pairs.
• Articulation on the surface of spore is present.
• In later stage spores seems as black dust.
Smut Spores of Ustilago
Sphacelotheca
Classification:
Kingdom : Mycota
Division : Eumycota
Subdivision : Basidiomycotina
Class : Teliomycetes
Order : Ustilaginales
Family : Ustilaginaceae
Genus : Sphacelotheca
Sphacelotheca
• Mycelium is septate.
• Clamp connection in mycelium present.
• Basidiocarp is absent.
• Sexual reproduction by basidiospres which are 4 innumber.
• Basidium is septate.
• Chlamydospore originate from mycelium present inhost tissues
• Chlamydospores are sessile and black in colour.
• Diameter of smut spore is 5-9µ.
• No articulation on the outer surface of spores.
Smut Spores
Tolyposporium
Classification:
Kingdom : Mycota
Division : Eumycota
Subdivision : Basidiomycotina
Class : Teliomycetes
Order : Ustilaginales
Family : Ustilaginaceae
Genus : Tolyposporium
Tolyposporium
• Mycelium is septate and branhed.
• Smut spore originate from mycelium present inhost tissues.
• Infected grains by this genus converted in sourus.
• Sourus is generally 3-4mm × 2-3mm in size.
• Smut spores are egg shaped, rough wall and lightbrown in color.
• Diameter of smut spore is 8-12µ.
• Smut spores are in the form of spare balls whichare transmitted by air.
• Basidiocarp absent.
• Basidium form exogenously on mycelium.
Melampsora
Classification:
Kingdom : Mycota
Division : Eumycota
Subdivision : Basidiomycotina
Class : Teliomycetes
Order : Uredinales
Family : Melampsoraceae
Genus : Melampsora
Melampsora
• Fungus is obligate parasite and cause macro cyclic and
autocious rust.
• Mycelium is dicaryotic and intercellular.
• No basidiocarp.
• Urediospores are small and orange in color.
• Urediospores are spiny, round shaped and size -15-25µ ×
13-17µ.
• Teliospores form on lower side of epidermis.
• Teliospores are cylindrical, unicellular and size – 46-48µ ×
8-20µ.
Alternaria
Classification:
Kingdom : Mycota
Division : Eumycota
Subdivision : Deuteromycotina
Class : Hyphomycetes
Order : Moniliales
Family : Dematiaceae
Genus : Alternaria
Alternaria
• Mycelium is short, septate and branched. The hypal cells are
multinucleate.
• There is no sexual reproduction; only asexual mode of
reproduction by conidia is noted.
• Some short and dark-coloured somatic hyphae behave as
conidiophores.
• Conidia are produced at the tips of conidiophores in chains or
singly.
• Conidia are large, elliptical to ovoid, dark coloured, several
celled and beaked.
• The number of cells varies from 8-14 or even more. The septa
dividing the spore into cells are both transverse and vertical.
• Conidia are measuring 20 – 100 µm in length (average 40 µm)
and 5-16 µm in breadth (average 12 µm).
Helminthosporium
Classification:
Kingdom : Mycota
Division : Eumycota
Subdivision : Deuteromycotina
Class : Hyphomycetes
Order : Moniliales
Family : Dematiaceae
Genus : Helminthosporium
Helminthosporium
• Mycelium is septate, branched and multinucleate.
• Sex organs and sexual reproduction absent
• It reproduces primarily by conidia borne onconidiophores.
• Conidiophore- is dark-coloured, erect, branched andseptate. conidiophores are not united together to formsporodochia, synnemata, accrvulus or pycnidium.
• Conidiophores are grey to olive colored which form inthe group of 3-5.
• Conidia are long, slender, three to 3-7 celled, taperingupward, hyaline to dark colored and straight orslightly curved. Conidia are measuring 15 – 30 µm inlength and 4 – 10 µm in breadth.
• Germ tube form from end cells of conidia.
Pyricularia
Classification:
Kingdom : Mycota
Division : Eumycota
Subdivision : Deuteromycotina
Class : Hyphomycetes
Order : Moniliales
Family : Dematiaceae
Genus : Pyricularia
Pyricularia
• Mycelium is branched, septate with multinucleatecells.
• Width of mycelium is 1.5- 6µm.
• There is complete absence of sex organs and sexualreproduction. They produce conidia as a means ofasexual reproduction.
• Conidiophores are hyaline, mostly free, branched,long, slender and septate. Conidial scars are presenton the conidiophores.
• Conidium is pyriform to ellipsoidal, 2-3 celled,hyaline and developed either laterally or terminallyon the conidiophores.
• Conidia not borne within a pycnidium or acervulus.
• Size of conidium is 19.2 - 27.3 × 8.1 – 10.3µm.
• Chlamydospores can be produced on medium.
Fusarium
Classification:
Kingdom : Mycota
Division : Eumycota
Subdivision : Deuteromycotina
Class : Hyphomycetes
Order : Moniliales
Family : Tuberculariaceae
Genus : Fusarium
Fusarium
• Mycelium is septate, branched, transparent
and restricted to vascular tissues of host.
• Sex organs and sexual reproduction absent.
• Two types of conidia (Micro and Macro
conidia) are produce on conidiophores.
• Micro conidia are 5-15 × 2-4µm in size.
• Macro conidia are 15 -20 × 3-5µm in size.
• Chlamydospores are produce inside tissues
and arranged in a chain.
Micro conidia Macro conidia
ChalamydosporeChalamydospores
Colletotrichum
Classification:
Kingdom : Mycota
Division : Eumycota
Subdivision : Deuteromycotina
Class : Coelomycetes
Order : Melanconiales
Family : Melanconiaceae
Genus : Colletotrichum
Colletotrichum
• Mycelium is septate, branched, dense, inter or intracellular and colored.
• Asexual reproduction by conidia.
• Conidia form in Acervulus on conidiophores. Conidiophores are non septate.
• Acervulus are dark color. Setae are present.
• Conidia are single cell, long or sickle shaped.
Cercospora
Classification:
Kingdom : Mycota
Division : Eumycota
Subdivision : Deuteromycotina
Class : Hyphomycetes
Order : Moniliales
Family : Dematiaceae
Genus : Cercospora
Cercospora
• Mycelium is multicellular, branched and septete.
• Mycelium form stromata under the epidermis of host leaves.
• No sexual reproduction.
• Asexual reproduction by conidia.
• No Pycnidia or Acervulus.
• Conidia form on conidiophores.
• Mycelium, conidiophore and conidia are black in color.
• Conidiophores come out from the host groups.
• Conidiophores are geniculate and branched.
• Conidia are curved. Base of conidia are round shaped and top
is acute.
• Conidia are generally 4-5 celled but some time may be 12-15