Plant Pathology - Fungi

Morphology

what something looks like

Cladogram

where fungi fit

More closely related to animals than plants

Fungi are heterotrophic

organisms that obtain their food by absorbing nutrients from their environment rather than producing it through photosynthesis.

Reproduction through…

spores

Filamentous body

formed by hyphae to create mycelium

Plant are primary producers, fungi are…

decomposers

What are fungi cell walls made of?

cell walls made of chitin

what fungi type does not have chitin cell walls?

oomycetes

how do fungi store energy?

Store energy as glycogen (vs. starch)

Do fungi cells have cell walls (vs. animal cells)?

Yes

Can fungi move independently?

no

Do fungi have sensory organs?

No, but they can sense and react

Are fungi eukaryotic?

Yes - so are plants, and animals

What are saprophytic fungi?

• Feed on dead organic matter 

• Show up after initial invasion is done, after more sophisticated invasion has taken place by another pathogen 

• Many can cause plant diseases

Can fungi cells contain one or more nuclei?

Yes

Where does fungal growth occur?

At hyphal tip - radial expansion

Where would you take a sample from to grow more fungi?

The hyphal tip or edge of the fungal growth

Chytridiomycota

Chytra: “little pot” pot-like sporangium, true fungi

Sporangium

the fruiting body, container that holds asexual spores - will only ever hold asexual spores!

Flagellum

the tail

Zoospores

swimming spores

Zygomycota

Zygon: “yolk”, big sexual spores like an egg yolk, true fungi

Zygospore

sexual spore

Sporangiospores

asexual spores

fusion of gametangia: male + female makes…

thick-walled resting spores

Ascomycota

• Askos: “sac”

• Ascus: sac-like structures

• True fungi

Ascospores

Sexual spores created inside sac-like structures

Basidiomycota

Basidium: “little pedestal”, true fungi

think mushrooms that are produced on a stem-like structure

Oomycota

fungi-like organism, not true fungi

what is one pathogen that is an oomycete?

phytopthora

Myxomycota

fungi-like organism, not a true fungi

Reproductive units of fungi

Conidia

Asexual spores not produced in any container. Loose. Ex. green mold on fruit.

What is the structure that supports conidia spores?

Conidiophores - Stem at the bottom that produces the chain of spores. Structure that holds spores together.

Are asexual spores genetically identical to parents?

yes

Are fungi with asexual spores easier to manage?

Yes - less genetic diversity, mutation, and adaptation to management techniques

What type of spore is a combination of male and female parents?

Sexual spore

Where are sexual spores produced?

Within or on fruiting bodies

Are fungi with sexual spores harder or easier to manage?

Harder - higher genetic diversity and adaptation

What are plant symptoms caused by pathogenic fungi?

• Leaf spots: localized, irregular, not vein-limited 

• Wilts: invasion of xylem vessels

• Cankers: necrotic lesions of phloem and vascular cambium 

• Root rots: destruction of root function

• Damping-off: rapid collapse of young seedlings

• Blights: rapid browning and death of aerial tissues

What is a biotroph?

An organism that needs a living host to survive

Septate hyphae

Hyphae that connect to another using a septum and bridge connection to expand

Are zygomycota saprophytic?

Most of them are, yes - feed on dead organic matter in their environment

Are zygomycota septate or non-septate?

Non-septate

Do zygomycota produce asexual or sexual spores?

Both

What do oomycetes make their cell walls out of?

Cellulose (vs. chitin for true fungi)

Are oomycetes septate or non-septate?

Septate

What is the disease triangle?

Host + Environment + Pathogen

What is a fungicide mode of action?

How, when, and where a fungicide disrupts the fungal life cycle. MOAs should be rotated in use to avoid pathogen resistance and increase management efficacy.

Which fungus causes rust and smut of wheat?

Basidiomycota

Basidium

The stem-like structure that holds basidiospores

Are Basidiomycota easy or difficult to manage?

Difficult - they have many host plants, can produce up to 5 different spore types, high genetic diversity,

Ascomycota

The largest family of pathogenic fungi

Which fungus causes downy mildews and white rusts?

Oomycota

What are common signs of pathogenic fungi in plants?

• Mycellium

• fruiting bodies