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200 Cards in this Set

  • Front
  • Back
Aphanomyces cochliodes taxonomy
Stramenopila
Heterokontophyta
Peronosporomycetes
Saprolegniales
Saprolegniaceae
Aphanomyces euteiches taxonomy
Stramenopila
Heterokontophyta
Peronosporomycetes
Saprolegniales
Saprolegniaceae
Pythium ultimum taxonomy
Stramenopila
Heterokontophyta
Peronosporomycetes
Pythiales
Pythiaceae
Plasmopara spp taxonomy
Stramenopila
Heterokontophyta
Peronosporomycetes
Peronosporales
Peronosporaceae
Peronospora spp taxonomy
Stramenopila
Heterokontophyta
Peronosporomycetes
Peronosporales
Peronosporaceae
Phytophthora ramorum taxonomy
Stramenopila
Heterokontophyta
Peronosporomycetes
Peronosporales
Peronosporaceae
Phytophthora nicotianae taxonomy
Stramenopila
Heterokontophyta
Peronosporomycetes
Peronosporales
Peronosporaceae
Phytophthora cinnamomi taxonomy
Stramenopila
Heterokontophyta
Peronosporomycetes
Peronosporales
Peronosporaceae
Phytophthora infestans taxonomy
Stramenopila
Heterokontophyta
Peronosporomycetes
Peronosporales
Peronosporaceae
Albugo candida taxonomy
Stramenopila
Heterokontophyta
Peronosporomycetes
Peronosporales
Albuginaceae
Labyrinthula spp taxonomy
Stramenopila
Heterokontophyta
Labyrinthulomycetes
Labyrinthulales
Labyrinthulaceae
Polymyxa betae taxonomy
Rhizaria
Cercozoa
Plasmodiophorea
Plasmodiophorida
Plasmodiophoridae
Spongospora subterranea taxonomy
Rhizaria
Cercozoa
Phytomyxea
Plasmodiophorales
Plasmodiophoraceae
Plasmodiophora brassicae taxonomy
Rhizaria
Cercozoa
Phytomyxea
Plasmodiophorales
Plasmodiophoraceae
Synchytrium endobioticum taxonomy
Eumycota
Chytridiomycota
Chytridiomycetes
Chytridiales
Synchytriaceae
Olpidium brassicae taxonomy
Eumycota
Chytridiomycota
Chytridiomycetes
Chytridiales
Olpidiaceae
Physoderma maydis taxonomy
Eumycota
Blastocladiomycota
Blastocladiomycetes
Blastocladiales
Physodermataceae
Physoderma maydis
Host and Disease
Corn
Physoderma Brown Spot
Olpidium brassicae
Host and Disease
Multiple Herbaceous
Lettuce Big Vein (Olpidium + LBVaV)
Synchytrium endobioticum
Host and Disease
Potatoes
Potato Wart
Plasmodiophora brassicae
Host and Disease
Brassica
Club Root of Crucifers
Spongospora subterranea
Host and Disease
Potatoes
Powdery Scab
Polymyxa betae
Host and Disease
Beets
Rhizomania (Polymyxa + BNYVV)
Labyrinthula spp
Host and Disease
Marine Grasses, Turfgrass
Eelgrass Wasting Disease
Albugo candida
Host and Disease
Brassica
White Rust
Phytophthora infestans
Host and Disease
Solanaceous
Late Blight
Phytophthora cinnamomi
Host and Disease
Woody
Phytophthora Dieback
Phytophthora nicotianae
Host and Disease
>72 Genera (Herbaceous, Woody)
Phytophthora Rot
Phytophthora ramorum
Host and Disease
Tanoak (Woody)
Sudden Oak Death
Peronospora spp
Host and Disease
~75 Species (Herbaceous Dicot Host Specific)
Downy Mildew
Plasmopara spp
Host and Disease
~75 Species (Herbaceous Dicot Host Specific)
Downy Mildew
Pythium ultimum
Host and Disease
Mono-/Dicot, Woody, Herbaceous
Pythium Blight/r.r./Damping Off
Aphanomyces euteiches
Host and Disease
Legumes
Legume Root Rot
Aphanomyces cochliodes
Host and Disease
Sugar beets
Black Root
Why chytrids and chytrid-like organisms are significant in agriculture
Plant pathogens
Virus vectors
Chytrid (and chytrid-like) fungi characteristics
Water or soil niches
Survive in soil or plant tissue as resting spores
Obligate parasites
Chytrid-like genera
Plasmodiophora
Spongospora
Polymyxa
Key genera of chytrids
Synchytrium
Physoderma
(Blastcladiomycota)
Olpidium
Characteristic of Synchytrium life cycle
Forms a prosorus, sorus, and then sporangia within the sorus
Characteristic of Olpidium life cycle
Forms a multi-nucleate protoplast, then sporangium with binucleate zoospores
Characteristic of Plasmodiophora
Forms primary plasmodium with secondary zoospores that fuse to form dikaryotic amoeba to develop into multi-nucleate secondary plasmodium and sporangium
Key distinction between chytrids and chytrid-like fungi
Chytrids have uni-flagellate zoospores
Chytrid-like have bi-flagellate whiplash zoospores
Polymyxa characteristics
Non-pathogenic obligate parasite of cereal grasses
Vectors soil-borne viruses of cereals, peanut, and beet
Taxonomic classification criteria
Morphology
Physiology
Phylogenetics (evolutionary relationships)
Functional (biological) classification criteria
Life style (biotroph, hemi-biotroph, necrotroph)
Localization on host (foliar, root, vascular)
Growing system (greenhouse, row crop, forest)
Crop
Characteristics of eumycota
Eukaryotes
Heterotrophic, absorptive nutrition
Filamentous or single-celled
Produce spores
Chitin in cell walls
Mitochondria with plate-like cristae
Glycogen as primary storage product
Three kingdoms of fungi and fungi-like organisms
Eumycota (Fungi)
Rhizaria
Chromista
Chytridiomycota characteristics
Coenocytic hyphae
Rhizoids
Motile spores (uni-flagellate)
Chitinaceaous cell walls
Meiosis occurs in resting sporangium
Forms resting sporangia in plant tissue (FPPs)
Defines the division of eumycota into the four phyla
Reproductive modes
Phylum that comprises the majority of FPPs
Ascomycota
Phylum that comprises many significant plant pathogens and wood decay fungi
Basidiomycota
Phylum that comprises very few plant pathogens but post-harvest decay fungi
Zygomycota
Zygomycota characteristics
Aseptate hyphae
Rhizoids sometimes
Sporangia
Non-motile spores
The number of products that come from meiosis
Four
Ascomycota characteristics
Septate hyphae
Asexual spores in various non-sporangial bodies
Sexual spores in sacs
Basidiomycota characteristics
Septate hyphae
Asexual spores in various non-sporangial bodies
Clamp connections sometimes
Dolipore septa sometimes
Sexual spores on basidium
Fungus-like organisms
Plasmodiophorids
Labyrinthulids
Oomycetes
Deuteromycota
"fungi imperfecti" = no known sexual state
Most are ascomycetes
Some basidiomycetes
Characteristics of Plasmodiophorids
Cyst = dormant resting stage
Amoeboid
Multinucleate plasmodium
Zoospores with two whiplash flagella
Characteristics of Labyrinthulids
Spindle-shaped cells within an ectoplasmic net of filaments
Zoospores with tinsel and whiplash flagella
Purpose of whiplash and tinsel flagella
Whiplash = orientation
Tinsel = locomotion
Characteristics of oomycetes
Coenocytic hyphae
Asexual spores in sporangia
Zoospores with tinsel and whiplash flagella
Oomycetes
Chytridiomycetes
Zygomycetes
Non-septate hyphae
Asexual spores in sporangium
Oomycetes
Chytridiomycetes
Motile spores
Chytridiomycetes
Uni-flagellate zoospores
Chytridiomycetes
Zygomycetes
Rhizoids
Phylum suffix
-mycota
Class suffix
-mycetes
Order suffix
-ales
Family suffix
-aceae
Superkingdom clade of oomycetes
Chromalveolate
Kingdom of oomycetes
Stramenopila
Chromista
Phylum of oomycetes
Heterokontophyta
Oomycota
Heterokonta
Aliases of oomycetes
Water molds, stramenopiles
Nearest taxonomic groups for oomycetes and fungi
Oomycetes: diatoms + brown algae
Fungi: animals
Difference between oomycetes and fungi
Hyphal architecture
Oomycetes: Coenocytic tubular hyphae
Fungi: Coenocytic or septate hyphae
Difference between oomycetes and fungi
Ploidy of thallus
Oomycetes: Diploid
Fungi: Haploid or dikaryotic mostly
Difference between oomycetes and fungi
Genome size
Oomycetes: Bigger (50-250 Mb)
Fungi: Smaller (10-40 Mb)
Difference between oomycetes and fungi
Cell wall components
Oomycetes: cellulose
Fungi: chitin
Difference between oomycetes and fungi
Pigmentation
Oomycetes: non pigmented
Fungi: pigmentation common
Difference between oomycetes and fungi
Toxins
Oomycetes: none
Fungi: various
Difference between oomycetes and fungi
Mating hormones
Oomycetes: Non-peptide
Fungi: Small peptides
Difference between oomycetes and fungi
Asexual spore type
Oomycetes: undesiccated, unicellular sporangia
Fungi: Desiccated single or multi-cellular conidia
Difference between oomycetes and fungi
Motility of spores
Oomycetes: motile bi-flagellated zoospores
Fungi: non-motile except in chytrids
Difference between oomycetes and fungi
Sexual spores
Oomycetes: oospores
Fungi: Various
Difference between oomycetes and fungi
Major energy reserves
Oomycetes: mycolaminarin and lipid
Fungi: glycogen, trehalose, sugar alcohols, lipids
Sporangium definition
Asexual vegetative fruiting structure
Cyst definition
Thick-walled resting spore
Chlamydospore definition
Asexual vegetative spores
How to deal with oomycete FPPs
Treat with cellulose and their cell walls will degrade
Pythium germination characteristic
Indirect germination
Sporangia releases zoospores, which encyst, then germinate
Phytophthora germination characteristic
Direct germination
Sporangia release zoospores
Why SBI fungicides don't work on oomycetes
SBI fungicides inhibit sterol biosynthesis
Ergosterol is the dominant sterol in most asco and basidio fungal cell membranes...
but not in oomycete cell membranes!
Six infamous oomycete genera
Phytophthora
Pythium
Aphanomycetes
Peronospora
Plasmopara
Albugo
Why Phytophthora discoveries have doubled in the last ten years
Molecular resolution
Active searching to find them due to regulatory mandates
Discovered Phytophthora infestans and Sclerotinia sclerotiorum
Antoine deBary
How Phytophthora infestans is spread globally
Planting materials
Origin of Phytophthora infestans
Andes in South America
How Phytophthora infestans is regionally spread
Airborne sporangia
How Phytophthora cinnamomi is spread globally
Planting materials
Origin of Phytophthora cinnamomi
SE Asia
How Phytophthora cinnamomi is regionally spread
Flooding and water flow
Primary difference between Pythium and Phytophthora
Pythium sporangia release immature zoospores into a membranous vesicle, zoospores mature in vesicle, vesicle bursts
Phytophthora sporangia directly release mature zoospores
Of Pythium and Phytophthora, the better saprotrophs and pathogens
Pythium: better saprotroph
Phytophthora: better pathogen
Key characteristic of downy mildew
Right-angle dichotomous branching of hyphae
Easily dislodged (airborne) sporangia
Obligate pathogens
Which orders are the downy mildews placed
Peronosporales (dicot hosts)
Sclerosporales (monocot hosts)
Basipetal definition
Formed at the base
Key characteristic of Albugo
Sporangia formed in basipetal succession giving them the rust-like "powdery" appearance
Fungus definition (biological)
Eukaryotic, heterotrophic organism devoid of chlorophyll that obtains its nutrients by absorption and reproduces by spores
Fungus definition (phylogenetic)
Monophyletic group of the Opisthokonts distinct from the closest living relatives (animals and slime molds) having a single basal flagellum on reproductive cells or non-motile spores with flat mitochondrial cristae
How oomycetes are related to fungi
Biologically: they are same
Phylogenetically: distinct
Disease definition
Detrimental change in normal structure and/or function of host cells/tissue caused by continuous interaction with pathogenic agent or abiotic factor
Symptom definition
Observable/measurable internal/external alterations/reactions of the host as a result of disease
Pathogenicity definition
Ability to cause disease (qualitative)
Virulence definition
Relative amount of disease caused by a pathogen (quantitative)
Makes a fungus pathogenic
Fight for nutrients/resources
Exchange of genetic components (e.g. Fusarium oxysporum)
Difference between pathogen and saprophyte
Substrate
Saprotroph: Competes for substrate
Pathogen: Accesses substrate
Difference between pathogen and saprophyte
Survival
Saprotroph: Must survive environmental variability
Pathogen: Must survive between hosts
Difference between pathogen and saprophyte
Food
Saprotroph: Food variability
Pathogen: Host recognition
Difference between pathogen and saprophyte
Cortex
Saprotroph: Does NOT enter cortex
Pathogen: Enters cortex
How a pathogen enters the host
Host recognition (physical, chemical cues)
Penetration (appressoria, simple modified hyphae, multi-hyphal complexes)
How a pathogen colonizes the host
Avoids host defenses (modify cell walls, subvert activation of host defenses)
Interfaces with host cells (biotrophic vs necrotrophic)
Biotroph definition
Acquires nutrients from living cells
Necrotroph definition
Acquires nutrients from cells it has KILLED
Hemi-biotroph definition
Middle of the pathogen spectrum
Can be biotroph (earlier stages) and can transition to necrotroph (later stages)
Developmental structures only seen on FPPs
Appressoria
Haustoria
Penetration pegs
Haustorium definition
Specialized feeding structure produced by biotrophic and some hemi-biotrophic FPPs
E.g. rusts, powdery mildews, downy mildews
How a haustorium is formed
Invagination of host membrane forming extrahaustorial matrix between haustorium and host membrane
How a haustorium is similar to arbuscules
They are sites of nutrient and signal exchange
They do not blast past the host membrane but form complexes with it
How FPPs reach new hosts
Must disperse (wind, rain, vectors,)
Must survive between hosts (dormancy, opportunists)
How opportunistic pathogens differ from obligate pathogens
Competition
Opportunistic: Competes well off host (dead tissue of other hosts)
Obligate: Cannot complete life cycle off host
How opportunistic pathogens differ from obligate pathogens
Specialization
Opportunistic: Not highly specialized
Obligate: Highly specialized for pathogenicity
How opportunistic pathogens differ from obligate pathogens
Rank
Opportunistic: Secondary "weak" pathogens
Obligate: Primary pathogens
How opportunistic pathogens differ from obligate pathogens
Life style
Opportunistic: Necrotrophic
Obligate: Biotrophic
Five types of pathogenicity factors
Metabolites (toxins)
Proteins (defense interference)
Enzymes (enter/colonize host)
Transporters (toxins out, nutrients in)
Sensors/receptors
Pathogenicity factor definition
Gene products required for pathogenicity on a given host
What studies have shown in enzymatic activity between non-pathogens and pathogens
Not a heckuva lot of difference
What studies have shown in FPP enzyme mutants
And what results mean
No notable difference between mutants and WT until regulators (kinases) are disrupted, which influence several enzymes
Large amount of redundancy of enzymes/genes
Activities in culture are not the same in plant
Host-specific toxin definition
Toxin that is toxic only to that host
E.g. ToxA of Stagonospora and Pyrenophora
Importance of toxins to FPPs
Host-specific colonization and symptom development
Toxin definition
Small molecular weight secondary metabolites
The significance of receptors to FPPs
Perceives and responds to environment
How ToxA of Stagonospora is also in Pyrenophora
Likely due to horizontal gene transfer
ToxA is direct gene product that host selective
Importance of interfering molecules to FPPs
Detoxification of host plant saponins, phytoalexins, and phytoanticipans
Phytoalexin definition
Isoflavanoid with anti-microbial properties produced in response to pathogen attack
The significance of transporters to FPPs
Export pathogenicity/virulence molecules into host
Export host defense molecules out
Import nutrients
Phylum in which Glomales (AM fungi) are found
Glomeromycota
Phylum in which Endogonales are found
Zygomycota
Commensualism definition
Association where one partner benefits but the other does not
Two types of mycorrhizae
Endomycorrhizae (Glomales, Endogonales)
Ectomycorrhizae (Ascomycetes, Basidiomycetes)
The function of vesicles for AM fungi
Fungal storage
Structures seen with EM fungi
Hartig net (micro-scale): hyphae between plant cells
Mantle (macro-scale): hyphal mass surrounding root surface
Difference between endophytes and epiphytes
Endophytes: IN the leaves, mostly ascomyctes
Epiphytes: ON the leaves
Percentage of plant disease that are fungal diseases
85%
Difference between saprophyte and necrotroph
Saprotroph: utilizes dead cells when found
Necrotroph: utilizes dead cells it has KILLED
Appressorium definition
Hardened melanized germ tube tip that adheres tightly to host tissue and penetrates the host
Fungal disease symptoms
Leaf spots
Blights
Root rots
Crown and stem rots
Wilts
Damping off
Fungal life cycles
Foliar
Soilborne
Watermolds
When a pathogen is a pathogen
Associations are context dependent!
Depends on nutrient availability, season, host, stage in the interaction pathway
Where in the host do you find vesicles and arbuscules of AM fungi?
Arbuscules: root cortex
Vesicles: root epidermis
How selective media is helpful in diagnosis
Narrows the field of fungal recovery but is NOT completely discriminatory
Why having a pure fungal culture is important
Can conduct Koch's postulates
Can conduct inhibition assays
Can conduct bioassays
Why many non-target fungi appear despite surface sterilization
Endophytic lifestyle of many non-pathogenic fungi
How pH is useful in isolating fungi from plant material
Fungi like low pH while bacteria do not
Note: Too low of pH causes media to not solidify
The discriminatory ability of selective media relative to time
The longer the cultures are allowed to grow, the less selective the medium appears
Examples of non-selective media
Water agar
PDA
V8 agar
Oatmeal agar
Examples of selective media
APDA (for fungi)
PARP+H (for oomycetes)
Media used to differentiate between oomycetes and zygomycetes
PARP (for oomycetes)
Media used for maintenance of oomycetes
Both: PARP
Pythium: PART
Phytophthora: PA or PARPH-V8
To store oomycetes for a long time
Hemp seeds
To store zygomycetes for a long time
Silica gel
Media used for maintenance of zygomycetes
APDA
For storing heavily sporulating cultures
Spore suspension in skim milk is added to sterile silica gel crystals
Silica gel
DOES NOT WORK WELL WITH OOMYCETES
For storing Rhizoctonia and limited other types of fungi
Mycelial or spore suspension added to sterilized soil or sand, incubated at room temperature, and then stored in refrigeration
Sterile soil/sand
Effective long-duration storage for a wide range of organisms but is expensive in terms of time, money, resources, and worries
Discs or spore suspension added to a cryoprotectant like glycerol and cooled at a controlled rate to -90C then stored in liquid nitrogen vapor or in -80C freezer
CryoStorage
Storage method where fungal cultures on agar slants are covered with sterile mineral oil or liquid paraffin and stored at room temperature for up to several years
Oil Overlay
Storage method where sterile filter paper squares or disks are placed on the surface of growing medium and inoculated with fungal plug or spores. When papers are colonized, they are removed from media surface and allowed to air dry in sterile Petri dish then stored in sterile envelopes at -20C, 4C, or 22C
Paper disks
Storage method where discs cut from actively growing cultures are transferred to sterile distilled water and stored either at refrigerator or room temperature for two or more years
Sterile water
Storage method where fungi are allowed to colonize a sterilized plant substrate like wood, cereal grains, or straw
Colonized substrate may be desiccated before storing at either 4C or -20C
Sterile plant materials
Storage method effective only for cultures producing copious small spores (< 10 micrometers)
Spore suspension in protectant (skim milk or bovine serum) is transferred to a lyophilazation tube and frozen at 040 to 050C, then dried under vacuum and sealed
Lyophilization
Purpose of maintaining fungal cultures
Reference strains
Fungal identification
Bioassays
Inhibition assays
Characterization (pathogenicity, host range)
Taxonomic, genetic, physiological characterization
Considerations when storing fungi
Length of storage
Cost
Characteristics of fungi
Needed equipment
How to differentiate Pythium from Phytophthora based on zoosporangium shape
Globose is rare among Phytophthora
Ovoid and limoniform can be both
Filamentous, swollen, lobed sporangia is Pythium only
Papillate and semi-papillate only in Phytophthora
How to differentiate Pythium from Phytophthora based on zoosporangium position
Terminal is typical for Phytophthora
Intercalary is rare for Phytophthora
Internal proliferation is common for Phytophthora
How to differentiate Pythium from Phytophthora based on zoospore release
Immature spores released into vesicle in Pythium
Mature spores released from sporangium in Phytophthora
How to differentiate Pythium from Phytophthora based on zoosporangium caducity
Caducous (deciduous) sporangia typical for Phytophthora
Persistant sporangia for Pythium (empties stay on)
How to differentiate Pythium from Phytophthora based on hyphae
Hyphal swellings common with Phytophthora
Hyphal swellings rare with Pythium
Hyphae are long and flexuous with Pythium
Hyphae are meandering and branched in Phytophthora
How to differentiate Pythium from Phytophthora based on oospores
Pigmented oospores are common with Phytophthora
Ornamentation is rare in Phytophthora
Ornamentation is common among Pythium
How to differentiate Pythium from Phytophthora based on antheridium attachment
Amphigynous attachment is common in Phytophthora
and rare in Pythium
.
Paragynous is common to both
.
Paragynous with antheridium attached to basal end of oogonium is common to Phytophthora
.
Paragynous with antheridium attached to distal end of oogonium is common to Pythium
.
Multiple antheridia attached to oogonium is common in Pythium
Hyphal knots surrounding the antheridium is common in Phytophthora.
Types of zoosporangium shapes
Globose
Limoniform
Ellipsoid
Fusiform
Reniform
Pyriform
Obpyriform
Ovoid
Obovoid
Obturbinate
Intercalary
Intercalary swelling
Lobed, branched
Lobed, unbranched
Types of chlamydospores
Terminal
Intercalary
Catenulate
Types of sporangia proliferation and papilla
Internal and extended proliferation
Internal and nested proliferation
External proliferation (at base)

Non-papillate
Semi-papillate
Papillate
How to determine chlamydospore from lobed hyphae
A distinct wall closes off the chlamydospore from the rest of the hyphae
Why sporangia are called conidia in downy mildews
Sporangium is a sac producing spores inside of it
If the sporangium does not produce spores, directly germinates, and is blown by the wind, it's functionally a conidium
Difference between homothallic and heterothallic
Homothallic: self-fertile
Heterothallic: requires two mating types
How to distinguish between downy mildew genera
Branched, stalked conidiophores are distinct to genera
Plasmopara distinguishing characteristics
Short branches and sub-branches
Blunted sterigmata
Peronospora distinguishing characteristics
Longer bifurcated branches and tips
Pointed sterigmata
Bremia distinguishing characteristics
Longer branches
Swelling at tips producing sterigmata
Sclerospora distinguishing characteristics
Short, stubby, blunted branches