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Plant Path_Test 2

Arkansas Tech - Plant Pathology

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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