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Plant Path_Test 2
Arkansas Tech - Plant Pathology
| Question | Answer |
|---|---|
| When was the first plant mycoplasma discovered? | 1960s |
| Do mycoplasmas have a cell wall? | YES |
| Who cultured a mycoplasma in 1898 for the first time? | Rocard & Roux |
| Name two examples of mycoplasmas: | Tomato Big Bud Aster Yellow |
| Who treated Aster Yellow with tetracycline in 1967? | Doi & Ishii |
| When they are young, mycoplasmas resemble a ______________. | fungus |
| Mycoplasmas don't have a true cell membrane. It is actually a _____________. | 3-layered membrane |
| pleomorphic | assumes many different shapes (mycoplasma cells are pleomorphic) |
| Mycoplasmas stain what color? | Red (gram -) |
| What do mycoplasmas look like in culture? | a fried egg |
| How are mycoplasmas transmitted in the field? | leaf-hoppers |
| Do antibiotics work on mycoplasmas? | yes - but only during treatment |
| L-phase is a variant of what? | bacteria |
| Some bacteria can shift to the L-phase when they are exposed to ____________. | UV light |
| What microbe was first observed in L-phase? | Streptobacillus moniliformis |
| Why won't penicilan work on a bacteria in L-phase? | It doesn't have a cell wall. |
| When were Rickettsia microorganisms discovered? | 1950s |
| How do Rickettsia stain? | Red (Gram -) |
| Name two Rickettsial diseases | Pierce's Disease of grape Phony Peach (look great then crash) |
| Can Rickettsia be treated with penicillan? | YES |
| What type of cell wall do Rickettsia have? | a wavy cell wall |
| Describe Rickettsia | obligate parasite (must have a living host) |
| Do Spiroplasmas have a cell wall? | NO |
| Give an example of a Spiroplasma | Spiroplasma citri (Citris Stubburn) |
| Describe what a Spiroplasma looks like. | coiled organism pogo stick-like spring |
| Name the most economically important disease. | Fungi |
| Most fungi are _________________. | saprophytic (loves dead things) |
| How many fungal species cause plant diseases? | 8,000 |
| Name the 4 main classes of fungi | Class Phycomycetes Class Ascomycetes Class Basidiomycetes Class Deuteromycetes |
| Name some beneficial things fungi do: | break down dead material into fertile soil; used as medicine (penicillin); some are edible (mushrooms); fermentation (bread, wine, cheese, beer) |
| Most fungi will produce threads called __________. | filaments |
| thallus | simple plant body that does not have stems, roots or leaves; is the vegetative body of a fungus |
| hypha(e) | single thread of filament of a fungus thallus |
| septa | are cross-walls in hypha |
| septated hypha | hypha w/ cross-walls |
| non-septated hyphae | no cross-walls ("coenocytic") |
| a filament is the same thing as a __________ | hypha |
| describe a fungal cell: | a hypha segment bound on each side by a septa |
| How many nuclei does a fungal cell have? | can be uninucleate, binucleate, or multinucleate |
| mycelium | a mass of hyphae (but you can see the seperate hypha) |
| Rhizomorph | a thick interwoven strand of hyphae (like a mop); can't distinguish the individual hyphae |
| describe Rhizomorph dormancy | can go dormant when conditions are bad then resume growth when conditions are better |
| How do fungi reproduce sexually? | by a spore - a propogative unit that functions as a seed, but differs in that it does not contain a pre-formed embryo |
| How do fungi reproduce asexually? | by a spore inside the hyphae |
| chlamydospore | a spore inside the hyphae |
| Where was Dutch Elm Disease first discovered? | in Holland in early 1900 |
| What is Dutch Elm Disease? | a fungus |
| Ceratocystis ulmi | Dutch Elm Disease |
| How did Dutch Elm Disease get to the U.S.? | first came to Cincinnati & Cleveland areas in 1930s in a horticulture trade show |
| Where is Dutch Elm Disease in the U.S. now? | all 50 states |
| What class is Dutch Elm Disease? | Class Ascomycetes |
| Name the Dutch Elm Disease's sexual fruiting structure: | perithecium |
| How can a healthy Elm tree get DED? | 1. a natural root graft 2. Bark Elm Beetle |
| Describe how the Bark Elm Beetle spreads DED: | beetle overwinters in vascular system of a diseased elm; female will lay eggs in xylem; eggs hatch and larvae will pupate and fly out, carrying fungus and feed on healthy trees |
| Name DED's internal symptoms: | 1. beetle gallery 2. brown xylem ring |
| Name DED's external symptoms: | 1. die-back at top 2. yellowing, sparse folliage |
| Name ways to control DED: | 1. cut & burn the tree 2. get a resistant cultivar ("American Liberty") 3. chemical barrier in the Chinese Elm |
| substrate | object on which a fungus grows and gets food |
| most primitive fungus | Class Phycomycetes |
| How many fungi are in class Ascomycetes? | 15,000 |
| Describe the hyphae in class Phycomycetes. | coenocytic - hyphae have no cross-walls |
| hastoria | needle-like structure that enters leaf and then opens up to start feeding |
| zygospore | sexual reproductive structure for class Phycomycetes |
| conidiospore | asexual reproductive structure for class Phycomycetes |
| water molds and pond scum in this class | Phycomycetes |
| How many fungi are in class Phycomycetes? | 1400 |
| Describe the hyphae in class Ascomycetes | hyphae are septated |
| "sac" fungi | class Ascomycetes |
| ascus | sexual fruiting structure in class Ascomycetes |
| describe what an ascus looks like | hotdog bun with 8 sexual ascospores inside |
| stroma | a mass of hyphae with ascospores emerging |
| conidiospores on conidiophores | asexual reproductive structures in class Ascomycetes |
| Name 5 main asexual fruiting structures in class Ascomycetes | 1. free conidiospores/conidiophores 2. synemma 3. acervulus 4. sporodochium 5. pycnidium |
| synemma | dense group of compact conidiospores/conidiophores |
| acervulus | depressed structure, lined w/ conidiospores and conidiophores |
| an example of a fungus with an acervulus | Venturia inaequalis (Apple Scab) |
| sporodochium | cushion-like mass bearing asexual conidiospores/conidiophores (looks like a short synemma) |
| pycnidium | flask-like structure lined w/ asexual conidiospores/conidiophores |
| Name the two sexual subclasses in class Ascomycetes | Subclass Hemiascomycetes Subclass Euascomycetes |
| ostiole | opening of the flask-shaped pycnidium |
| Describe subclass Hemiascomycetes | 1.oddball 2.sexual ascospores inside an "invisible" ascus (hotdog bun) 3. ascospores are stacked up |
| give an example of subclass Hemiascomycetes | Taphrina deformans "Peach leaf curl" |
| name the three groups/series in subclass Euascomycetes | 1. Series Pyrenomycetes 2. Series Plectomycetes 3. Series Discomycetes |
| perithecium | flask-shaped structure filled w/ sexual ascospores in series Pyrenomycetes |
| give an example of something with a perithecium | Venturia inaequalis Apple Scab |
| cleistothecium | a closed structure filled with sexual ascospores |
| an example of something with a cleistothecium | Erisiphe graminis Powdery mildew |
| apothecium | depressed area with upright ascospores |
| an example of something with an apothecium | Sclerotinia fructicola Brown Rot (of stone fruit) |
| Name 2 subclasses of class Basidiomycetes | 1. subclass Heterobasidiomycetes 2. subclass Homobasidiomycetes |
| describe class Basidiomycetes | septated hyphae; has sexual fruiting structure called a Basidium |
| describe the basidium in subclass Heterobasidiomycetes | basidium will be divided into cells or deeply fingered |
| sterigma | little launching pad that the sexual basidiospore is attached to (on a basidium) |
| Name 2 orders under subclass Heterobasidiomycetes | 1. order Uredinales 2. order Ustilaginales |
| Rust fungi | order Uredinales ex: Puccinia Gymnosporangium |
| Smut fungi | order Ustilaginales ex: Tilletia |
| mushrooms and puffballs | subclass Homobasidiomycetes |
| describe the basidium in subclass Homobasidiomycetes | it is 1 cell (not divided) |
| Name 2 orders under subclass Homobasidiomycetes | 1. order Polyporales 2. order Agaricales |
| gill fungi | order Agaricales |
| describe a rust | obligate parasites can produce 5 different spore forms |
| macrocyclic | rust producing all 5 spores |
| microcyclic | rust producing less than all 5 types of spores |
| stroma | mass of hyphae in ascomycetes |
| sorus | mass of hyphae in basidiomycetes |
| rust that needs only 1 host plant | autoecious rust |
| rust that needs 2 host plants | heteroecious rust |
| describe smuts | fungus; saprophyte (love dead stuff); most are host-specific AND plant-part specific |
| classify smuts | class Basidiomycetes subclass Heterosidiomycetes order Ustilaginales |
| rusts and smuts are found in what class? | class Basidiomycetes |
| teliospores | asexual spores in smuts ......... |
| smut symptoms can be _____________ | localized OR systemic |
| give an example of a smut | Tilletia |
| Class of Fungi Imperfecti? | Class Deuteromycetes |
| 2nd class organisms | Fungi Imperfecti Class Deuteromycetes |
| why is Class Deuteromycetes called 2nd class organisms? | have no sexual stage |
| leaf-spotting fungus | Class Deuteromycetes |
| Name the 4 form-orders of class Deuteromycetes | 1. Form-order Sphaeropsidales 2. Form-order Melanconiales 3. Form-order Moniliales 4. Form-order Mycelia Sterilia |
| when was the electron microscope invented? | 1933 |
| What is the asexual structure in form-order Sphaeropsidales? | pycnidium |
| Phoma Septoria Diplodia | Form-order Sphaeropsidales |
| What asexual structure is found in form-order Melanconiales? | acervulus |
| Colletotrichum | an example of form-order Melanconiales |
| the wilts | found in form-order Moniliales |
| What asexual fruiting structure is found in form-order Moniliales? | free, synemma and sporodochium |
| sclerotium | mass of hyphae; found in form-order Mycelia Sterilia |
| define "virus" | poison (Latin) |
| first person to transmit a virus | Mayer; Tobacco Mosaic Virus |
| first thing identified from a virus | Tulip Color Break |
| who found Tulip Color Break? | Clusius; 1576 |
| Who was the first person to crystallize a virus? | Stanley; 1935 |
| Describe a virus | ultra-microscopic inner-core is nucleic acid outer shell is protein obligate parasite will enter a plant passively |
| Describe 3 virus shapes: | 1. rigid rod 2. flexous rod 3. icosahedron (20-sided) |
| Describe virus symptoms | 1.local (like ring spot) 2. systemic (gets in xylem & phloem - yellowing or stunting) |
| masked symptom - virus | plant is infected, has no symptoms until a variable like temperature is changed. Then symptom shows up. |
| symptomless carrier - virus | plant never shows any symptoms, but is a carrier and can transmit the virus |
| Name all virus symptoms | yellowing, stunting, mosaic/molting, ringspot, leaf-curling, excessive branching; vein-clearing, enations |
| enations | little bumps, caused by virus |
| synergism in viruses | Virus A + Virus B = Virus C w/ new symptoms |
| cross-protection | plant makes antibodies in response to exposure to avirulent strain; will protect against virulent strain |
| Describe virus infection process: | virus is passive until enters host; protein coat will unravel; nucleic acid is the infectious part; nucleic acid will take over activity of host plant nucleus; cell makes more virus particles |
Created by:
jlewter
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