classification and diagnostic charecterstics of main plant pathogenic fungi

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]

Pytophthora

Classification

Kingdom : Mycota

Division : Eumycota

Subdivision : Mastigomycotina

Class : Oomycetes

Order : Pernosporales

Family : Pythiaceae

Genus : Phytophthora

Phytophthora

• 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


Class : Oomycetes


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


Class : Oomycetes


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





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





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



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



Order : Moniliales


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



Order : Moniliales


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



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


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



Order : Moniliales


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

celled.

Rhizoctonia

Classification:

Kingdom : Mycota

Division : Eumycota



Order : Myceliasterilia

Family : Rhizoctoniaceae

Genus : Rhizoctonia

Rhizoctonia

• The fungus mostly present in the soil as

parasite and cause root rot and damping off

diseases in plants.

• Mycelium is septate, branched, inter or

intercellular.

• No sexual reproductive organs is present.

Scelerotia form which germinate and form

mycelium.

Rhizoctonia

classification and diagnostic charecterstics of main plant pathogenic fungi

Education