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200 Cards in this Set
- Front
- Back
Aphanomyces cochliodes taxonomy
|
Stramenopila
Heterokontophyta Peronosporomycetes Saprolegniales Saprolegniaceae |
|
Aphanomyces euteiches taxonomy
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Stramenopila
Heterokontophyta Peronosporomycetes Saprolegniales Saprolegniaceae |
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Pythium ultimum taxonomy
|
Stramenopila
Heterokontophyta Peronosporomycetes Pythiales Pythiaceae |
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Plasmopara spp taxonomy
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Stramenopila
Heterokontophyta Peronosporomycetes Peronosporales Peronosporaceae |
|
Peronospora spp taxonomy
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Stramenopila
Heterokontophyta Peronosporomycetes Peronosporales Peronosporaceae |
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Phytophthora ramorum taxonomy
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Stramenopila
Heterokontophyta Peronosporomycetes Peronosporales Peronosporaceae |
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Phytophthora nicotianae taxonomy
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Stramenopila
Heterokontophyta Peronosporomycetes Peronosporales Peronosporaceae |
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Phytophthora cinnamomi taxonomy
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Stramenopila
Heterokontophyta Peronosporomycetes Peronosporales Peronosporaceae |
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Phytophthora infestans taxonomy
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Stramenopila
Heterokontophyta Peronosporomycetes Peronosporales Peronosporaceae |
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Albugo candida taxonomy
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Stramenopila
Heterokontophyta Peronosporomycetes Peronosporales Albuginaceae |
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Labyrinthula spp taxonomy
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Stramenopila
Heterokontophyta Labyrinthulomycetes Labyrinthulales Labyrinthulaceae |
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Polymyxa betae taxonomy
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Rhizaria
Cercozoa Plasmodiophorea Plasmodiophorida Plasmodiophoridae |
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Spongospora subterranea taxonomy
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Rhizaria
Cercozoa Phytomyxea Plasmodiophorales Plasmodiophoraceae |
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Plasmodiophora brassicae taxonomy
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Rhizaria
Cercozoa Phytomyxea Plasmodiophorales Plasmodiophoraceae |
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Synchytrium endobioticum taxonomy
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Eumycota
Chytridiomycota Chytridiomycetes Chytridiales Synchytriaceae |
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Olpidium brassicae taxonomy
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Eumycota
Chytridiomycota Chytridiomycetes Chytridiales Olpidiaceae |
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Physoderma maydis taxonomy
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Eumycota
Blastocladiomycota Blastocladiomycetes Blastocladiales Physodermataceae |
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Physoderma maydis
Host and Disease |
Corn
Physoderma Brown Spot |
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Olpidium brassicae
Host and Disease |
Multiple Herbaceous
Lettuce Big Vein (Olpidium + LBVaV) |
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Synchytrium endobioticum
Host and Disease |
Potatoes
Potato Wart |
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Plasmodiophora brassicae
Host and Disease |
Brassica
Club Root of Crucifers |
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Spongospora subterranea
Host and Disease |
Potatoes
Powdery Scab |
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Polymyxa betae
Host and Disease |
Beets
Rhizomania (Polymyxa + BNYVV) |
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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 |
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Aphanomyces cochliodes
Host and Disease |
Sugar beets
Black Root |
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Why chytrids and chytrid-like organisms are significant in agriculture
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Plant pathogens
Virus vectors |
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Chytrid (and chytrid-like) fungi characteristics
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Water or soil niches
Survive in soil or plant tissue as resting spores Obligate parasites |
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Chytrid-like genera
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Plasmodiophora
Spongospora Polymyxa |
|
Key genera of chytrids
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Synchytrium
Physoderma (Blastcladiomycota) Olpidium |
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Characteristic of Synchytrium life cycle
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Forms a prosorus, sorus, and then sporangia within the sorus
|
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Characteristic of Olpidium life cycle
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Forms a multi-nucleate protoplast, then sporangium with binucleate zoospores
|
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Characteristic of Plasmodiophora
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Forms primary plasmodium with secondary zoospores that fuse to form dikaryotic amoeba to develop into multi-nucleate secondary plasmodium and sporangium
|
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Key distinction between chytrids and chytrid-like fungi
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Chytrids have uni-flagellate zoospores
Chytrid-like have bi-flagellate whiplash zoospores |
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Polymyxa characteristics
|
Non-pathogenic obligate parasite of cereal grasses
Vectors soil-borne viruses of cereals, peanut, and beet |
|
Taxonomic classification criteria
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Morphology
Physiology Phylogenetics (evolutionary relationships) |
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Functional (biological) classification criteria
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Life style (biotroph, hemi-biotroph, necrotroph)
Localization on host (foliar, root, vascular) Growing system (greenhouse, row crop, forest) Crop |
|
Characteristics of eumycota
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Eukaryotes
Heterotrophic, absorptive nutrition Filamentous or single-celled Produce spores Chitin in cell walls Mitochondria with plate-like cristae Glycogen as primary storage product |
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Three kingdoms of fungi and fungi-like organisms
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Eumycota (Fungi)
Rhizaria Chromista |
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Chytridiomycota characteristics
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Coenocytic hyphae
Rhizoids Motile spores (uni-flagellate) Chitinaceaous cell walls Meiosis occurs in resting sporangium Forms resting sporangia in plant tissue (FPPs) |
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Defines the division of eumycota into the four phyla
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Reproductive modes
|
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Phylum that comprises the majority of FPPs
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Ascomycota
|
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Phylum that comprises many significant plant pathogens and wood decay fungi
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Basidiomycota
|
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Phylum that comprises very few plant pathogens but post-harvest decay fungi
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Zygomycota
|
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Zygomycota characteristics
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Aseptate hyphae
Rhizoids sometimes Sporangia Non-motile spores |
|
The number of products that come from meiosis
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Four
|
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Ascomycota characteristics
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Septate hyphae
Asexual spores in various non-sporangial bodies Sexual spores in sacs |
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Basidiomycota characteristics
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Septate hyphae
Asexual spores in various non-sporangial bodies Clamp connections sometimes Dolipore septa sometimes Sexual spores on basidium |
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Fungus-like organisms
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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
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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
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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
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Uni-flagellate zoospores
|
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Chytridiomycetes
Zygomycetes |
Rhizoids
|
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Phylum suffix
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-mycota
|
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Class suffix
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-mycetes
|
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Order suffix
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-ales
|
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Family suffix
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-aceae
|
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Superkingdom clade of oomycetes
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Chromalveolate
|
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Kingdom of oomycetes
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Stramenopila
Chromista |
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Phylum of oomycetes
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Heterokontophyta
Oomycota Heterokonta |
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Aliases of oomycetes
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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 |
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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 |
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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 |
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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 |
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Sporangium definition
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Asexual vegetative fruiting structure
|
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Cyst definition
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Thick-walled resting spore
|
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Chlamydospore definition
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Asexual vegetative spores
|
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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 |
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Phytophthora germination characteristic
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Direct germination
Sporangia release zoospores |
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Why SBI fungicides don't work on oomycetes
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SBI fungicides inhibit sterol biosynthesis
Ergosterol is the dominant sterol in most asco and basidio fungal cell membranes... but not in oomycete cell membranes! |
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Six infamous oomycete genera
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Phytophthora
Pythium Aphanomycetes Peronospora Plasmopara Albugo |
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Why Phytophthora discoveries have doubled in the last ten years
|
Molecular resolution
Active searching to find them due to regulatory mandates |
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Discovered Phytophthora infestans and Sclerotinia sclerotiorum
|
Antoine deBary
|
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How Phytophthora infestans is spread globally
|
Planting materials
|
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Origin of Phytophthora infestans
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Andes in South America
|
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How Phytophthora infestans is regionally spread
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Airborne sporangia
|
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How Phytophthora cinnamomi is spread globally
|
Planting materials
|
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Origin of Phytophthora cinnamomi
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SE Asia
|
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How Phytophthora cinnamomi is regionally spread
|
Flooding and water flow
|
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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 |
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Which orders are the downy mildews placed
|
Peronosporales (dicot hosts)
Sclerosporales (monocot hosts) |
|
Basipetal definition
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Formed at the base
|
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Key characteristic of Albugo
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Sporangia formed in basipetal succession giving them the rust-like "powdery" appearance
|
|
Fungus definition (biological)
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Eukaryotic, heterotrophic organism devoid of chlorophyll that obtains its nutrients by absorption and reproduces by spores
|
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Fungus definition (phylogenetic)
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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
|
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How oomycetes are related to fungi
|
Biologically: they are same
Phylogenetically: distinct |
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Disease definition
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Detrimental change in normal structure and/or function of host cells/tissue caused by continuous interaction with pathogenic agent or abiotic factor
|
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Symptom definition
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Observable/measurable internal/external alterations/reactions of the host as a result of disease
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Pathogenicity definition
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Ability to cause disease (qualitative)
|
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Virulence definition
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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 |
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How a pathogen enters the host
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Host recognition (physical, chemical cues)
Penetration (appressoria, simple modified hyphae, multi-hyphal complexes) |
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How a pathogen colonizes the host
|
Avoids host defenses (modify cell walls, subvert activation of host defenses)
Interfaces with host cells (biotrophic vs necrotrophic) |
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Biotroph definition
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Acquires nutrients from living cells
|
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Necrotroph definition
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Acquires nutrients from cells it has KILLED
|
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Hemi-biotroph definition
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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 |
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Haustorium definition
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Specialized feeding structure produced by biotrophic and some hemi-biotrophic FPPs
E.g. rusts, powdery mildews, downy mildews |
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How a haustorium is formed
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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 |
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How FPPs reach new hosts
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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 |
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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 |
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Pathogenicity factor definition
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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 |
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Host-specific toxin definition
|
Toxin that is toxic only to that host
E.g. ToxA of Stagonospora and Pyrenophora |
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Importance of toxins to FPPs
|
Host-specific colonization and symptom development
|
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Toxin definition
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Small molecular weight secondary metabolites
|
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The significance of receptors to FPPs
|
Perceives and responds to environment
|
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How ToxA of Stagonospora is also in Pyrenophora
|
Likely due to horizontal gene transfer
ToxA is direct gene product that host selective |
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Importance of interfering molecules to FPPs
|
Detoxification of host plant saponins, phytoalexins, and phytoanticipans
|
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Phytoalexin definition
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Isoflavanoid with anti-microbial properties produced in response to pathogen attack
|
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The significance of transporters to FPPs
|
Export pathogenicity/virulence molecules into host
Export host defense molecules out Import nutrients |
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Phylum in which Glomales (AM fungi) are found
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Glomeromycota
|
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Phylum in which Endogonales are found
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Zygomycota
|
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Commensualism definition
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Association where one partner benefits but the other does not
|
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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
|
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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
|