Test #2 Flashcards
How are chytrid zoospores dispersed
They use their whiplash flagella to swim like sperm
Chemotaxis
to ascend a chemical gradient
Mucor spore dispersal
Spores are coated in a sticky slime that helps them attach to the fur of small animals who then carry them elsewhere
Rhizopus spore dispersal
Spores are spread by the wind
Pilobus spore dispersal
Spores are shot out like a water cannon. The sporangium is phototropic and angles itself towards sunlight, building up pressure in the subsporangial vesicle until it shoots off and disperses the spores.
Why do Coprophilious fungi need to shoot their spores long distances
They rely on being eaten by animals and most animals do not eat where they shit
Operates like a trap-door, shooting spores out
Unitunicate-operculate
Operates like a sphincter, squeezing spores out
Unitunicate-inoperculate
Operates like a jack-in-the-box
Bitunicate asci
A closed ascoma that is dispersed by animal vectors
Cleistothecial and prototunicate
How spores in Ophistoma are dispersed
Spores are in a perithecial ascoma that has a long neck full of mucilage that expands when it gets wet and moves up the neck, taking the ascospores with it. The spores are then dispersed by beetles.
Basidiospore dispersal
Forcefully shot downwards with a “water catapult”.
Why is the umbrella shape of a typical mushroom important
it directs the spores downwards and protects the hymenium from getting saturated with water
A mass of dry basidiospores (7 million) inside of a puffball fungus
Gleba
Puffball fungus spore dispersal
A raindrop or something else causes the spore to dimple, forcing a small puff of air mixed with spores out of the opening in the top of the structure.
The fleshy outer shell of an earthstar
Peridium
How earthstar spores are dispersed
by wind and rain
The normal spore count per cubic meter
10^6
An acute response to high concentrations of fungal spores, found in many harvesters and threshers
Farmer’s lung
The fungus commonly referred to as “black mold”
Stachybotrys chartarum
What percentage of crops fail to yield due to fungal disease
12.5%
Three parameters that dictate the likelihood of an infection
The presence of a susceptible host, a favorable environment, and the presence of a pathogen
Derive energy from living cells and do not kill their plant rapidly
Biotrophs
Derive energy from killed cells; invade and kill the plant rapidly, then live on the remains
Necrotrophs
Initial period of biotrophy, followed by necrotrophy
Hemibiotrophs
What happens to most of the spores that germinate
They die shortly after germination
How a penetration peg is able to break through the plant cell wall
With help from lytic enzymes
The origin and role of the haustorial membrane
host-derived and keeps the fungus cytoplasm separate from the plant cytoplasm
Two ways that a necrotroph kills its host cells
Secretes metabolites that kill the host cell directly or secretes oxalate that can trigger programmed cell death
Types of necrotic lesions
Antracnose, blight, canker, scab, leaf spot
Chestnut blight (Cryphonectria) exhibits
Necrosis
Example of Permanent wilting
Ophiostoma (Dutch elm disease)
Hypertrophy
Excessive growth due to release of growth hormones (Ustilago maydis)
Leaf abscission
Loss of leaves via release of hormones (Hemileia)
Etoliation
Excessive growth in length, seen in foolish seedling disease
Prevention of reproduction
replacement of reproductive structure with fungus, as seen in Ergot
Causes rice blast fungus, is the most economically important plant disease in the world
Magnaporthe grisea (ascomycete)
What type of conidia does Magnaporthe grisea create
Thallic, solitary conidia
A badidiomycete referred to as “honey fungus” that is spread via root to root contact
Armillaria ostoyae
An Ascomycete teleomorph that causes barley powdery mildew
Blumeria graminis
The type of spore that causes secondary inocula in Blumeria graminis
Conidiospore
Which spore overwinters with Blumeria graminis
Ascospore
Why does Ustilago maydis cause hypertrophy in corn
because it’s yeast form makes auxin
The ascomycete teleomorph that causes Dutch Elm disease
Ophiostoma novo-ulmi
The Basidiomycete that causes black stem rust
Puccinia graminis
What connects the barberry bush to Puccinia graminis
The teliospores land on the barberry leaves and do their sexual phase, then send out aeciospores to infect cereal crops
Sexual spores found on the barberry leaf, found inside spermagonia
spermatia
A cup-like hyphal structure found on the underside of barberry leaves that are infected
Aecium
Four different types of spores made by Puccinia graminus
Aeciospore, uridiniospores, teliospores, basidiospores
The spore responsible for the primary inoculum of the primary host in Puccinia graminus
Aeciospores
Spores responsible for secondary inoculation of the host in Puccinia graminus
Urediniospores
The type of spore responsible for overwintering in Puccinia graminus
Teliospores
The “Puccinia Pathway”
The spread of Puccinia graminus via the wind from Canada to Mexico
The basidiomycete responsible for coffee leaf rust
Hemileia vastatrix
The type of spores that spread Hemileia vastatrix
Uridiniospores
The Ascomycete responsible for chestnut blight
Cryphonectria parasitica
How does Cryphonectria parasitica infect it’s host
through wounds in the bark
What kind of necrosis does Cyrphonectria parasitica exhibit
a canker
A pocket where the formation of asexual spores (conidia) occurs
Pycnidium
Why do shrub-like trees regrow after a chestnut tree has died from necrosis
because it does not infect the roots
First generation fungicides
Inorganic fungicides, also called protectants; Sulfur salts
Problems associated with 1st generation fungicides
Phototoxic, washed off in the rain, need to be constantly reapplied
Second Generation Fungicides
Organic fungicides (also called protectants), contain thiocarbamates
Disrupt the basic metabolic process, so fungi do not develop resistance easily
Thiocarbamates
Major problem with thiocarbamates
break down into ethylene thiourea, a carcinogen and teratogen
Third Generation Fungicides
Systemic fungicides; contain Benzimidazoles
Where do systemic fungicides accumulate in the plant
in the apoplast
Which direction do systemic fungicides move in the plant
Up through the xylem
How do Benzimidazoles work
they interfere with microtubule assembly, blocking mitosis and hyphal growth
Which phyla are relatively resistant to benzimidazoles
Basidiomycetes
Problems associated with benzimidazoles
Resistance due to mutation of the B-microtubulin gene where the fungicide binds; Exposure during pregnancy causes children to be born without eyes
How have fungi developed resistance to benzimidazoles
by altering the binding site, so the fungicide loses affinity
How do azole fungicides work
They inhibit cytochrome p-450, which is involved in demythylating sterols and the fungi is not able to produce a functional membrane
Three ways that fungi have developed resistance to azole systemic fungicides
Exclude the uptake of azoles, develop altered membrane with reduced ergosterol content, and mutating the fungicide binding site
Why did fungus develop a resistance to systemic fungicides so easily
because they target one specific site within the fungus, which was easy to change
Pasteurization of soil
Raising the soil to 65-70 degrees for 30 minutes
To introduce or favor a natural predator, parasite, or competitor of the organism to be controlled
Biocontrol
Advantages of using Biocontrol
High reproductive capacity, short generation time, usually highly specific host range, saprophytic or resting stage when host isn’t available
Problems with using Biocontrol
May only damage host, may only reduce target, is relatively slow
Muscardine disease
fungal infection of insects; often causes summit disease
The Ascomycete anamorph that causes muscardine disease in silk worms
Beauveria bassiana
A “self-quarantine” or psychosis behavior that causes the infected insect to crawl to a high area where they then die
Summit disease
Zombie ants
ants infected with Cordyceps bassiana
The structure that comes out of a zombie ant’s head
vegetable caterpillar
The fungus that protects chrysanthemums
Lecanicillim lecanii
Insects that are controlled by Lecanicillium lecanii
Aphids and white flies
The Zygomycete that causes “fly fungus”
Entomophthora muscae
The white structure surrounding a fly killed by Entomophthora muscae
Mitosporangia
What was introduced to Australia to control spotted alfalfa aphids
Entomophthora
The Basidiomycete used to control rush skeleton weed in Australia
Puccinia chondrillina
Why can’t Puccinia chondrillina be mass produced as a biocontrol
because it is obligately biotropic
The Ascomycete used to control northern joint vetch and dodder
Colletotrichum gloeosporioides
Problems with commercializing fungal biocides
Lack of continued commercial backing, high cost of production, introduction of newer herbicidal chemistries, resistance biotype, limited market
The Basidiomycete that causes stem blight in peanuts
Sclerotium rolfsi
Brown balls containing hyphen threads
Sclerotium
The fungus that controls Sclerotium rolfsi
Trichoderma harzianum
The problem found with using Trichoderma
Farmers spray with fungicides to kill Cercospora and end up killing the Trichospora, too.
The fungus that causes dry bubble in other mushrooms
Lecanicillium fungicola
What is used to control Lecanicillium fungicola
Trichoderma
Has Trichoderma been commercially successful?
Yes, it is available in stores
