Test 2 (study guide) Flashcards
4 main groups of plant pathogenic fungi.
Ascomycota
Basidiomycota
Chytridiomycota
Ztgomycota
Three main groups of fungus-like organisms that cause plant disease.
Oomycota
Myxomycota
Plasmodiophoromyctoa
What is a sclerotium
The hard dark resting body of a certain fungi consisting of a mass of hyphal threads, capable of remaining dormant for long periods.
Ascomycetes:
Sexual-
Asexual-
Ascospores
Conidia
How do ascomycetes overwinter?
As sclerotia
Name two diseases caused by Ascomycetes.
Powerdy mildew
Sudden death syndrome of soybeans
Dollar spot of turf
What is the normal chromosome content of basidiomycetes during most of their life cycle?
Dikarotic hyphe(two haploid nuclei)
What are clamp connections and what group and the unique to?
Structure formed by growing hypal cells of certain fungi.
Basidiomycetes
Basidiomycetes:
Sexual-
Asexual-
Basidiospores
Teliospores
Smut fungi is a ______
rust fungi is a _______
facilatie saprophyte
obligate parasite
What are two diseases caused by Basidiomycetes?
Common smut of corn
stem rust of barley
cedar apple rust
What type of spores are produced by the chytridiomycetes?
Zoospores
What type of mycelia are produced by the zygomycetes?
Nonseptate mycelia
Zygomycetes:
Sexual spores-
Asexual spores-
Zygospores
Sporangiospores
What is the name of the fruiting body in zygomycetes that produces the asexual spores?
Sporangia
What are not in the fungi kingdom?
Oomycetes
What type of hypae are produced by oomycetes?
nonseptate hyphae
What is the chromosome content for most of the oomycetes lifecycle?
Diploid
Oomycetes:
Sexual-
Asexual-
oospores
zoospores
In oomycetes what fruiting body produces these spores?
sporangium
Name two plant diseases caused by oomycetes?
Pythium root rot
Phytophtora root rot
What is plasmodium?
A mass of cytoplasm containing many nuclei but no cell wall.
what fungus groups produce plasmodium?
myxomycetes
Plasmodiophoromycetes
What type of spores produce myxomycetes and plasmodiophoromycetes?
Zoospores
How can fungal disease be managed?
Avoidance- choose planting sites w/ no infection.
Exclusion- use pathogen free seed
Eradication- crop rotation
Protection- Apply fungicides
How do prokaryotic cells differ from eukaryotic cells?
Prokaryotic are single celled microragnisms with no membrane bound oragnelles.
Eukaryotic are multicellular with membrane bound oragnelles
what are the 3 shapes of bacterial cells with cell walls?
Round- coccal
Rod-shaped(bacilliform)
spiral-shaped
What are mollicutes?
No cell walls, only cell membranes
what are Phytoplasms?
pleomorphic or variably shaped
Spiroplasmas
usually helicle
What are actinobacterium (actinomycetes) and why are they important?
bacteria that produce long branched filaments and live in the soil. They make antibiotics.
How do bacteria reproduce?
Binary fission
what is fastidious bacteria?
Cultured only on complex, specialized media; phytoplasmas and spiroplasmas.
What is gram-positive mean?
bacteria with thick cell walls that stain purple with gram stain.
What is gram-negative?
thin cell walls and do not retain purple dye
how are bacteria disseminated?
Water, insects and animals.
How do bacteria enter plants? where do they live?
through stomata wounds and hydathode. Live on ouside of plant ,in spaces, or in cell.
How are bacteria identified?
size, shape,chemical composition, pathogenicity, enzymatic action.
Name 3 genera of bactera that cause plant disease?
Agrobacterium
Erwinia
Xyella
What are two signs of bacteria in a plant?
Bacterial ooze
Bacterial streaming
what are types of symptoms caused by bacteria
Leaf spots and blights soft rots water-soaking wilts galls scabs and cankers
What are types of bacterial diseases are there?
soft rots leaf spots fire blight in apple scorch crown gall on apple scab in potato
How are bacterial diseases managed?
Exclusion- plant bacteria free seed
Eradication- crop rotation to non host plant
protection- apply copper based chemicals.
What are the two parts of a virus particle?
Core of infectious nucleic acid surrounded by a protein coat.
What are the 2 main shapes of viruses?
Elongate- rods
Roughly spherical- iscohedral( more than 20 sides)
Cylindrical
whats a viron?
individual virus particles, cannot be seen with light microscope.
What is a capsid?
protein coat composed of repeating sub units.
What types of nucleic acid are found in viruses?
ribonucleic acid(RNA) and Deoxyribonucleic acid(DNA)
What does multipartite genomes mean?
genes are located on more than one peice
define Multiparticulate?
more than one particle
How do viruses get the materials needed for replication?
from the host cell
needs: amino acids, nucleotides, enzymes, cellular structure, and energy from host.
What are symptoms of viruses?
Dwarfing or stunting mosiaic or mottles ring spots chlorosis leaf rolling flowerbreak
How do viruses survive outside of hosts?
Some can survive on tools, in soils, or in plant debris
How are viruses transmitted between plants? (4)
vectors,
mechanical transmission,
infected pollen,
infected seed
What organisms are vectors of viruses?
insects-mites
nematodes
fungi and fungus like organisms
What is meant by nonpersistent transmission?
virus can be acquired and transmited by an insect in seconds.
persistent or circulative transmission-
insect must feed for minutes to hours to acquire virus
persistent propagative transmission-
virus also replicates in the cells of the insect vector.
How are viral diseases diagnosed?
purification and electron microscopy and serology
What does ELISA stand for?
enzyme linked immunosorbent assy
PCR
Polymerase chain reaction
How are viruses named?
Generally based on primary symptoms and first host plant in which they are studied.
How are virus diseases managed?
Avoidance- plant susceptible crop at different times
Exclusion- quarantine, inspection certification
Eradication- herbicides to destroy host weed.
Protection- insecticides or oils
What is cross-protection?
infect plant with a mild strain of virus to prevent infection by more severe strain.
What are viroids?
Small infectious, single-stranded , circular RNA’s
How are viroids different from viruses?
No protein coat, encode no proteins.
How are viroids transmitted?
By contaminated tools and equpit,
vegatative propagation,
seeds and pollen.
What are nematodes?
nonsegmented roundworms. Animal kingdom
What percentage of nematodes are plant parasites?
10%
How many juvenile stages are there for nematodes?
4
Do nematodes molt between stages?
yes
Where does first molt occur for nematodes?
What stage emerges from egg?
What is often the only infective stage?
First molt occurs in the egg.
juvenile 1
The J2 stage.
What does parthenogenetic mean?
Egg develops
How big are nematodes?
how are they generally shaped?
300 to 1000um
eel-shaped round in cross section
What is a stylet?
Used to puncture plant cells
Define ectoparasite-
feed from outside the plant.
Define endoparasite-
invades roots and feed within host tissue
Define Sedentart-
remains on same
Define Migratory-
Moves from place to place
What are above ground symptoms of nematodes?
Stunting
Yellowing(chlorosis)
Wilting
Abnormal growth
What are below ground symptoms of nematodes?
reduced/necrotic root system
Abnormal growth
Root- knot nematodes
Meloidogyne spp. Sedentary endoparasites
Cyst Nematodes
Heterodera spp, Globodera spp, Sedentary endoparasites
Lesion nematodes
Pratylenchus spp, Migratory endoparasites
What are giant cells?
induce permanent feeding sites called giant cells within galls( plant cell nucleus divides but cell division does not occur)
What are syncytia?
formed by dissolution of cell walls.
How are nematodes dispersed?
Short distances through soil by themselves
anything that moves soil
some by insects
How do nematodes survive unfavorable conditions?
Eggs- stored energy
Juviniles- have fat reserves
Cryptobiosis- dormancy of nematodes
Cryptobiosis-
Dormancy of nematodes
Nema wool-
nematodes accumulate in masses
What is a disease complex?
A disease caused by interaction of 2 or more species or types of pathogens.
What is an elutraitor?
extracting nematodes from the soil
How do you manage nematodes?
Avoidance- fert. and water plan.
Exclusion- quarantines
Eradication- Biological control- parasites or predators
Protection- Genetic resistance.
Scientific name for Soybean cyst nematode?
Heterodera glycines
What plants host SCN
soybeans, legumes, vegetables,weeds, and ornamentals
Symptoms of SCN
Yellowing or browning
Stunting
reduced nodulation
affected plants in oval or irregular shaped patches in field.
Shape are female nematodes?
Lemon shaped
What is a cyst, why are some pale yellow while other are brownish.
Cyst is a female nematode, and they get darker with age.
How many generations of SCN can there be in one growing season?
3-6
How can SCN be managed?
Resistant cultivars Crop rotation Other cultural practices Nematicides of fumigants Biological control
