** Images and lecture material were not entirely created by J. ** Images and lecture material were not entirely created by J. Bond. Some of this material was created by others.**Bond. Some of this material was created by others.**

Rhizopus sp. on peach

Rhizopus sp. on sunflower

Plant Pathology – G.N. Agrios

TRUE FUNGI

ASCOMYCETES - called the sac fungi because sexual spores (ascospores) are produced in a sac (ascus).

This is the largest group of fungi (35k +)with the most economically important members.

ASCOMYCETESCharacteristics :1. Most are facultative parasites - they can survive in

soil or plant debris, often for several years. A few are obligate parasites.

2. They produce a cellular hyphae (i.e., with distinct cell cross walls).

3. They produce a stroma - a mass of hyphae in which fruiting bodies are produced.

4. Sexual spores = ascospores. They are produced in groups of 8, which are enclosed in a single ascus (asci).

5. Ascospores in asci are produced in an ascocarp.There are several basic types of ascocarps, but each

fungus produces only one type:

Plant Pathology – G.N. Agrios

Ascocarps

a. Naked - asci are produced exposed on a plant surface, i.e., not in an ascocarp.

Ex: Taphrina deformans - peach leaf curlEx: Saccharomyces spp. - the yeasts

Naked - asci

Ascocarpsa. Naked - asci are produced exposed on a plant surface, i.e., not in an

ascocarp.

b. Cleistothecia - asci are produced in a completely closed spherical structure.

Ex: Sphaerotheca pannosa - powdery mildew of roseEx: Erysiphe graminis - powdery mildew of wheat

Plant Pathology – G.N. AgriosPlant Pathology – G.N. Agrios

Cleistothecia

APS Slide Collection

APS Slide CollectionAPS Slide Collection

APS Slide Collection

Ascocarpsa. Naked - asci are produced exposed on a plant surface, i.e., not in an

ascocarp.b. Cleistothecia - asci are produced in a completely closed spherical structure.

c. Perithecia - asci are produced in a nearly-completely closed structure with a single opening and a distinct wall. Perithecia can be round or some version of flask-shaped.

Ex: Claviceps purpurea - ergot of grains

Ex: Ophiostoma ulmi - Dutch elm disease

Ex: Cryphonectria parasitica - chestnut blight

Plant Pathology – G.N. Agrios

Perithecia

APS Slide Collection

APS Slide Collection

Ascocarpsa. Naked - asci are produced exposed on a plant surface, i.e., not in an

ascocarp.b. Cleistothecia - asci are produced in a completely closed spherical

structure.c. Perithecia - asci are produced in a nearly-completely closed structure

with a single opening and a distinct wall. Perithecia can be round or some version of flask-shaped.

d. Apothecia - asci are produced in an open cup- or saucer-shaped structure.

Ex: Monilina fructicola – brown rot of stone fruitsEx: Sclerotinia sclerotiorum - white mold of bean

Plant Pathology – G.N. Agrios

Apothecia

APS Slide Collection

APS Slide Collection

Ascocarpsa. Naked - asci are produced exposed on a plant surfaceb. Cleistothecia - asci are produced in a completely closed spherical

structure.c. Perithecia - asci are produced in a nearly-completely closed

structure with a single opening. Perithecia can be round or some version of flask-shaped.

d. Apothecia - asci are produced in an open cup- or saucer-shaped structure.

e. Pseudothecia (aka ascostroma) - asci are produced in cavities without a distinct wall within a stroma of mycelium within host tissues.

Ex: Venturia inaequalis - apple scabEx: Guignardia bidwellii - black rot of grape

Plant Pathology – G.N. AgriosPlant Pathology – G.N. Agrios

PseudotheciaAPS Slide Collection

APS Slide Collection

Ascocarpsa. Naked - asci are produced exposed on a plant surfaceb. Cleistothecia - asci are produced in a completely

closed spherical structure.c. Perithecia - asci are produced in a nearly-

completely closed structure with a distinct wall with a single opening. Perithecia can be round or some version of flask-shaped.

d. Apothecia - asci are produced in an open cup- or saucer-shaped structure.

e. Pseudothecia (aka ascostroma) - asci are produced in cavities without a distinct wall within a stroma of mycelium produced within host tissues.

Teleomorph vs AnamorphTeleomorph vs AnamorphThe The teleomorph teleomorph

(perfect stage)(perfect stage) is is the sexual stagethe sexual stage

The The anamorphanamorph (imperfect (imperfect stage)stage) is the is the asexual stageasexual stage

NectriaNectria - peritheciaperithecia FusariumFusarium - conidiaconidia

APS Slide CollectionAPS Slide Collection