basidiomycete plant pathogens

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Basidiomycete Plant Pathogens Rust s! Smut s & Bunt s! Wood & Root Rots! Rots & Damping- Off!

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Basidiomycete Plant Pathogens. Wood & Root Rots!. Rusts!. Smuts & Bunts!. Rots & Damping-Off!. Review: Pathogen Characteristics. Oospore. Asco -spore. Basidio -spore. no. Oomycota. yes. Ascomycota. yes. Basidiomycota. Basidiomycota. Mushrooms Agaricus Lentinula (shitake) - PowerPoint PPT Presentation

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Page 1: Basidiomycete  Plant Pathogens

Basidiomycete Plant Pathogens

Rusts!

Smuts &

Bunts!

Wood & Root Rots!

Rots & Damping-Off!

Page 2: Basidiomycete  Plant Pathogens

Review: Pathogen Characteristics

Somatic ploidy

2n

n

n+n

Chitin wallMotile

zoospores

yes

no

no

Septate hyphae

no

yes

yes

Sexual spore

noOomycota

Ascomycota

Basidiomycota

yes

yes

Oospore

Asco-spore

Basidio-spore

Page 3: Basidiomycete  Plant Pathogens

Basidiomycota Mushrooms

Agaricus Lentinula (shitake) Aminita (destroying angel)

Mycorrhizal fungi – forest ecosystems Wood decay fungi Pathogens on major crops:

Rusts of grains, soybean, coffee, ornamentals Smuts of small grains and corn

Page 4: Basidiomycete  Plant Pathogens

Basidio Sexual Reproduction

Sexual reproduction structure:

Basidium - “club”

Basidiospores (1n)

4 per basidium

www.apsnet.org

n

Page 5: Basidiomycete  Plant Pathogens

Basidiomycota

•HymenomycetesMushroo

ms

•UrediniomycetesRusts

•UstilaginomycetesSmuts

Tom Volk

apsnet.org

Page 6: Basidiomycete  Plant Pathogens

Uredinales - Rusts Puccinia – grass and cereal rusts Phakopsora – Soybean Rust Gymnosporangium – Cedar-Apple Rust Hemileia – Coffee Rust Cronartium – White Pine Blister Rust Uromyces – carnation and bean rusts Phregmidium – Orange rust of blackberry

Page 7: Basidiomycete  Plant Pathogens

Wheat RustPuccinia graminis

Urediospores erupting from uredinia on wheat stem.

a.k.a. Stem Rust, Black Rust

USDA, ARS

Page 8: Basidiomycete  Plant Pathogens

Rusts in History Described in Bible and Broadway:

Famine in Joseph and Amazing Technicolor Dreamcoat story

In writings of Theophrastus (“Father of Botany”)

Robigus – Roman rust god Honored by Robigalia – sacrificed

reddish-colored animals

Page 9: Basidiomycete  Plant Pathogens

Puccinia graminis Obligate biotroph – no saprophytic stage.

Heteroecious – 2 hosts required for lifecycle: Grass species (monocot) Barberry (dicot)

Polycyclic pathogen Aerial urediospores spread 100s of miles.

Page 10: Basidiomycete  Plant Pathogens

Lifecycle of Puccinia graminis

Basidiospores

Spermatia and receptive hyphae

Urediospore

Teliospore

AeciosporeBarberry

Wheat

1

5

4

3

2

Page 11: Basidiomycete  Plant Pathogens

Barberry Barberry infected by Basidiospore (n) in

spring (primary inoculum)

Overwinters as Teliospore (n+n)

in crop debris

Wheat

Page 12: Basidiomycete  Plant Pathogens

Dikaryotic hyphae (n+n)

form on Barberry.

Direct penetration of barberry leaf

Page 13: Basidiomycete  Plant Pathogens

Puccinia graminis

Spermagonia (upper) and aecia (lower) on leaf of barberry seen in cross section by light

microscopy

Aecia form from (n+n) hyphae created by fusion of receptive hyphae with spermatia of

opposite mating type

Aeciospores (n+n) on underside of barberry leaf.

Infect only wheat plants

Spermacia (n-) and (n+) Receptive Hyphae on upper barberry leaf surface

Page 14: Basidiomycete  Plant Pathogens

Puccinia graminis infection of barberry showing aecia on lower leaf surface

Page 15: Basidiomycete  Plant Pathogens

Aeciospores (n+n) wind blown to wheat host plants and infect leaves by

penetrating stomates.

Urediospores ( n+n) erupt from upper leaf surface.

Repeating stage.

Aeciospores(n+n)

Stomate

Page 16: Basidiomycete  Plant Pathogens

Puccinia graminis uredia erupting from upper

epidermis of wheat leaf.

Urediospores

Page 17: Basidiomycete  Plant Pathogens

Barberry

Wheat

Teliosporesn+n

Urediosporesn+n

Wheat hosts senesce and dry at end of season

In Teliosporen+n 2n 4 (1n)Meiosis occurs

Page 18: Basidiomycete  Plant Pathogens

Puccinia graminis Teliospore produced at end of season when

grain plants begin to senesce and dry down

Uredia shift production to thick-walled dark colored 2-celled Teliospores (n+n)

that overwinter in debris

Rusty Urediospores

Dark Teliospores

Page 19: Basidiomycete  Plant Pathogens

Life cycle of Puccinia graminis

Basidiospores

Spermatia and receptive hyphae

UrediosporeTeliospore

AeciosporeBarberry

WheatA

MACROCYCLIC RUST

Page 20: Basidiomycete  Plant Pathogens

Control of Wheat Rust Resistant varieties

Fungicides Many applications required = $$$ Scouting and Forecasting

Barberry Eradication

Page 21: Basidiomycete  Plant Pathogens
Page 22: Basidiomycete  Plant Pathogens

Spread of P. graminis in 1923

E.C.Stakeman and J.G.Harrar. 1957

Page 23: Basidiomycete  Plant Pathogens

Rusts are very specific Formae speciales (f.sp.) – “special forms”

Puccinia graminis f.sp. tritici - wheat Puccinia graminis f.sp. secalis – barley

Pathogen recognizes host morphology – only then will it penetrate and infect. Guard cells of stomata Leaf topography

Page 24: Basidiomycete  Plant Pathogens

Stomate architecture influences penetration.

Wynn, W. 1976. Phytopathology 66: 136-146Urediospores Bean rust fungus - Uromyces phaseoli

Page 25: Basidiomycete  Plant Pathogens

Bean rust fungus (Uromyces phaseoli) penetrating stomate in bean leaf host.

guard cells

stomate

urediospore

appressorium

Host Specificity

Page 26: Basidiomycete  Plant Pathogens

Rust does not recognize non-host stomata:

No penetration, no infection

Page 27: Basidiomycete  Plant Pathogens

Host topography affects appressorium formation

Allen et al., Phytopathology, 1991

Uromyces

Puccinia

Polystyrene membranes with

6.7um ridges

thigmotropism

Page 28: Basidiomycete  Plant Pathogens

P. graminis as biological weapon

Rapidly spreading (aerial), polycyclic pathogen capable of destroying an economically important crop.

Potential use in bio-terrorism/warfare: Rust pandemic would have negative economic, food

security and psychological effects.

Has been weaponized in the past by USSR and US Army Biological Weapons lab at Fort Detrick, MD.

1970 – USSR & USA signed Biological Weapons Treaty banning development and testing of biological warfare weapons.

Page 29: Basidiomycete  Plant Pathogens

USDA-ARS Foreign Disease Containment GreenhouseFort Detrick, Frederick, MD

Page 30: Basidiomycete  Plant Pathogens

“New” race of P. graminis:

UG99 Uganda, 1999

Defeats more of the known resistance genes than any other known strain. Could infect 90% of world’s wheat varieties.

$26.8 million grant from the Bill & Melinda Gates Foundation.