Exam 2 Flashcards
(202 cards)
1
Q
About how many species of bacteria cause plant diseases?
A
~100
2
Q
Fungi or Bacteria? Smaller order of magnitude Structural features difficult to see Metabolically complex Much less terminology
A
Bacteria
3
Q
Visible mass of single cells
A
Colony
4
Q
3 shapes of bacteria
A
Coccus, rod, curved rod
5
Q
Cocci can be found in which 5 morphological structures?
A
single, pairs (diplococci), chains, tetrads, clusters
6
Q
Rods can be found in which 5 morphological structures?
A
Bacillus (single), flagellated bacilli, chains, palisades, filaments
7
Q
Curved rods can be found in which 3 morphological structures?
A
Single curved rod, spirilla, spirochetes
8
Q
Which morphological shape of bacteria has no cell wall and can have varying shapes?
A
Pleomorphic
9
Q
Which type of bacteria has a cell wall with thin peptidoglycan layer between two membranes?
A
Gram negative
10
Q
Which type of bacteria has a cell wall with a single membrane and a thick peptidoglycan layer?
A
Gram positive
11
Q
Which class of bacteria has a cell membrane but no cell wall?
A
Mollicutes
12
Q
What rigid framework is responsible for cell shape and protects the cell from environmental stress?
A
cell wall
13
Q
What are the 4 steps of gram staining?
A
- Crystal violet
- Iodine
- Wash with alcohol/acetone
- Safranin counterstain
14
Q
What are the 4 steps of the KOH test?
A
- KOH on slide
- Collect bacteria from 24-48 hr colony
- Stir in KOH 5-10 sec
- Lift loop
15
Q
In the KOH test, which type of bacteria has viscous slime?
A
Gram negative
16
Q
Which type of flagellated bacteria have a single tail?
A
Monotrichous
17
Q
Which type of flagellated bacteria have a tail on each end?
A
Amphitrichous
18
Q
Which type of flagellated bacteria have many tails?
A
Lophotrichous
19
Q
Which type of flagellated bacteria have tails all around its perimeter?
A
Peritrichous
20
Q
Which bacterial structure is short and its primary function is attachment?
A
Fimbria
21
Q
Which bacterial structure is longer and has multiple types with varying functions?
A
Pilus
22
Q
Which pilus functions in attachment to surfaces?
A
Type 1
23
Q
Which pilus functions in movement on surfaces (without flagella)?
A
Type IV
24
Q
Which pilus functions in attachment to other bacteria for gene transfer?
A
Conjugation (Sex)
25
Which pilus functions in interaction with the host?
HrP
26
Which type of bacteria requires oxygen?
Obligate anaerobe
27
Which type of bacteria grows with or without oxygen?
Facultative anaerobe
28
Which type of bacteria grows best in low-oxygen conditions?
Microaerophilic
29
Which type of bacteria cannot survive in the presence of oxygen because it is toxic to them?
Strict anaerobe
30
What method do bacteria use to reproduce?
Fission - NO SEXUAL REPRODUCTION
31
Where do bacteria keep "extra" DNA?
plasmids
32
How do bacteria communicate?
Cell signaling - they use receptors to identify what's around them
33
When bacteria swarm/multiply to reach a critical concentration for survival, this is an example of
Density-dependent communication
34
What two things are required for a plant bacterial infection to occur?
Critical mass (quorum) and an opening
35
Bacteria do not have spores like fungi, so their ______ is disseminated.
Entire body
36
A specialized survival structure in bacteria
Endospores
37
Do plant pathogenic bacteria produce endospores?
NO
38
Which 5 places do bacterial plant pathogens survive?
```
In/on host tissues
In/on alternate hosts
In soil
On surfaces
In vector
```
39
What are 5 common disease symptoms of bacteria in plants?
Leaf spots & blights
Wilts
Rots
Galls, phyllody
40
What are 2 examples of bacterial signs?
Slime and ooze
41
Which bacterial plant disease is primarily found in rosaecous hosts, its main symptoms include flagging, shepherd's crook, leaf & twig blight, and cankers on the main stem? Its signs include bacterial ooze from fruit, leaves, and stem cankers and it is one of the oldest known bacterial plant diseases?
Fire Blight - Erwinia amylovora
| Gram Negative
42
What is the primary vector of fire blight?
Insects (bees)
43
Which bacterial plant disease is seedborne with symptoms including angular spots on leaves (initially water-soaked), deformation, necrotic margins, leaf drop, and small blister-like brown warty fruit spots?
Bacterial spot of pepper and tomato - Xanthomonas
44
Which bacterial plant disease has a wide host range and is pectolytic? It rots almost anything except the epidermis and its secondary bacterial colonization leads to a foul odor?
Soft Rots - Pectobacterium, Dickeya
45
Which bacterial plant disease is not harmful to humans, but causes fruit blotches on watermelon?
Watermelon fruit blotch - Acidovorax avenae citrulli
46
Which bacterial plant disease has a wide host range in dicots, is a soil inhabitant and its symptoms include gall formation near the soil line and girdling and plant death?
Crown gall - Agrobacterium tumefaciens
47
Which disease is a pathogen only because of the genes on its plasmid - it is not pathogenic on its own? What is the name of the plasmid?
Agrobacterium tumefaciens; Ti Plasmid
48
Which two plant genes are growth hormones whose overproduction causes galls in Agrobacterium tumefaciens?
Auxin, Cytokinin
49
Which bacterial plant disease is found in citrus plants and its symptoms include raised spots with oily, watersoaked margins and a yellow halo, defoliation, and early fruit drop?
Citrus canker - Xanthomonas citri
50
Citrus canker was introduced the first time in what year? The second time?
1910; 1986
51
The first time citrus canker was introduced, how long did it take to eradicate?
20 years
52
Which bacterial plant disease has a wide host range (solanaceae, banana, geranium, pothos), is a soil inhabitant infecting through the roots and moving upward through the xylem? Its symptoms include wilt and vascular discoloration.
Bacterial wilt - Ralstonia solanacearum
53
Which bacterial plant disease is a fastidious bacteria (picky eater), vector borne, and xylem-limited? Its symptoms include interveinal chlorosis, marginal necrosis, leaf drop, fruit shrivels, and plant death?
Pierce's disease - Xylella fastidiosa
54
Which vector transmits X. fastidiosa?
Sharpshooters
55
Which bacterial plant disease is phloem-limited, vectored by psyllids and symptoms include chlorotic shoots, leaf mottling, small lopsided fruit, and dieback/tree death?
Huanglongbing - Candidatus Liberibacter (HLB, yellow dragon, citrus greening)
56
Disease cycle of HLB
```
Psyllid feeds on infected tissue
Bacteria multiply in psyllid
Psyllid feeds on healthy tissue
Systemic spread in plant
Symptom development
```
57
Which bacterial plant disease is a gram-positive filamentous bacteria whose primary hosts are potato, sweet potato, beets, carrots and radishes? Its symptoms include corky surface lesions and root rot in sweet potatoes.
Common scab, pox - Streptomyces
58
Which mollicute plant disease has a primary host of palms, is phloem-limited and its vector is planthoppers? It is not cold-hardy and has had a recent northward spread.
Palm Lethal Yellowing - Candidatus Phytoplasma palmae
59
Which 9 bacteria are gram negative?
Erwinia, Pantoea, Xylophilus, Acidovorax, Burkholderia, Ralstonia, Pseudomonas, Xanthomonas, Agrobacterium
60
Which 4 bacteria are gram positive?
Clavibacter, bacillus, clostridium, streptomyces
61
Motile by single polar flagellum, no pigment produced on nutrient agar, grows at 40 degrees C. One species, A. citrulli, causes watermelon fruit blotch
Acidovorax
62
Motile by 1-6 peritrichous flagella, when growing on carbohydrate-enriched media, the bacteria produce copious extracellular polysaccharide slime. Colonies are non-pigmented to light beige. Induced plant diseases known as crown gall, hairy root, and cane gall
Agrobacterium
63
Motile with lophotrichous flagella, plant pathogenic bacteria with the exception of one species produce fluorescent pigments
Pseudomonas
64
Motile with polar flagella, no growth at 40 degrees C, forms two colony types on media amended with glucose; one is mucoid and the other is dry
Ralstonia
65
Motile with 1 polar flagellum. When growing on glucose-enriched media, the bacteria produces copious extracellular polysaccharide slime. Colonies are yellow, causes leaf spots and vascular wilts.
Xanthomonas
66
Non-motile bacterium; nutritionally fastidious requiring specialized medium such as glutamine peptone medium (PW); habitat is xylem of plant tissues
Xylella
67
Formerly Erwinia species; motile with peritrichous flagella; produce pectolytic enzymes that degrade pectate resulting in macerated plant tissue
Dickeya and Pectobacterium
68
Motile by peritrichous flagella; are non-pectolytic and the type strain E. amylovora causes fire blight
Erwinia
69
Motile by peritrichous flagella; non-pectolytic, most produce a yellow pigment; Stewart's wilt of corn
Pantoea
70
Straight or slightly curved slender rod; irregular and often club-shaped; obligately aerobic, non-motile, bacterial canker of tomato. Gram +
Clavibacter
71
Vegetative hyphae produce extensive mycelium, aerial mycelium forms chains of spores, produce wide variety of pigments, many produce one or more antibiotics. Potato scab incited by S. scabies is most studied, produces a toxin that is a major virulence factor.
Streptomyces
72
What is a nucleic acid containing genes and a protein coat?
Virus
73
What is a circular dsDNA containing genes and no protein coat?
Plasmid
74
What is a small circular ssRNA with no genes and no protein coat?
Viroid
75
What is a nucleic acid (could have genes, could have protein coat) and requires a host virus?
Satellite
76
4 Examples of Mobile Genetic Elements
Plasmid
Virus
Viroid
Satellite
77
A mobile genetic element may consist of which two things?
Genes and protein coat
78
What 3 things do all mobile genetic elements have in common?
They act as obligate parasites
They replicate independently of the host genome
They can affect the host phenotype
79
What is the size in cubic nanometers of a large virus?
6x10^5
80
What is the size in cubic nanometers of a small virus?
2x10^4
81
Ten million particles of a small virus would occupy only ___% of the cell volume in a typical plant cell.
1%
82
Which 3 scientists refuted spontaneous generation and show that bacteria and fungi can cause disease?
DeBary, Pasteur, & Koch
83
Mayer, Ivanovsky, and Beijerinck described which disease?
Tobacco mosaic disease
84
Which scientist showed that the infective agent could pass through agar and showed through serial dilutions that the agent was reproducing in the plant? He was also the first to use the term VIRUS
Martinus Beijerinck 1898
85
What 6 characteristics are used to classify viruses?
Size, shape, coating type, number of particles, type of nucleic acid, and sequence
86
What are two shapes of viruses?
helical and icosahedral
87
How is the size of a helical-shaped virus described?
Length, width, and flexibility
88
How is the size of an icosahedral-shaped virus described?
Diameter
89
The average size of icosahedral viruses are mostly _____nm but can be up to _____nm in diameter.
20-30; 50-80
90
What part of the virus is the protein coat and is usually made up of identical subunits?
Capsid
91
What part of a virus is formed when the capsid subunits and the genome self-assemble?
Virion
92
What may be composed of one or more virions?
Virus
93
A virus particle; an entire virus particle, consisting of an outer protein shell called a capsid and an inner core of nucleic acid (either RNA or DNA); the mature virus particle with all its structural components intact
Virion
94
4 Steps of TMV Assembly
1. Coat protein units assemble into disk-shaped aggregates
2. Aggregate binds to 'origin-of-assembly' loop in RNA
3. Additional aggregates bind, pulling the RNA strand up through the hole in the center
4. Assembly terminates when the end of the RNA is reached
95
Icoashedral Virus Assembly....
Coat protein subunits with bound nucleic acid self-assemble.
96
Nucleic acid enclosed within the capsid protein
Nucleocapsid
97
Bilayer membrane, derived from the host cell membrane with viral proteins
Envelope
98
Which ssRNA may be directly translated like mRNA?
Positive sense
99
Which ssRNA requires conversion by RNA polymerase prior to translation?
Negative sense
100
Which type of RNA virus cannot function as mRNA but must carry transcription enzymes and synthesize mRNAs?
dsRNA
101
Which DNA virus enters the host nucleus and uses host enzymes for replication and transcription?
dsDNA
102
Which DNA virus must use DNA polymerase to make a double stranded intermediate?
ssDNA
103
What is the average number of genes in a plant virus?
4-12
104
What are the minimum requirements for the structural proteins of a virus?
Capsid or nucelocapsid protein
105
What are the minimum requirements for non-structural proteins of a virus?
Polymerase, movement
106
What are the 4 steps of the virus infection process?
1. Virions enter cell (Penetration)
2. Virions uncoat (release nucleic acid)
3. Replication and translation (Reproduction and infection)
4. Movement (Colonization)
107
What conditions are required for a virion to enter a cell?
Vector or wound
108
How do viruses move through a host from cell to cell?
Altered plasmodesmata - they cannot move through normal plasmodesmata
109
Which proteins allow cell-to-cell movement?
Movement proteins
110
What are the two described methods of cell-to-cell movement through plasmodesmata?
1. Increase size of plasmodesmata, bind to viral RNA and chaperone it through.
2. Form tube through plasmodesmata and virions move through tube structures.
111
What are 4 examples of how viruses can move between hosts?
Mechanical (wounding), vegetative (grafting, vegetative propagation), seed (vertical transmission), and vectors
112
What form of transmission occurs when the sap of the infected plant contacts the wound?
Mechanical
113
Which 3 viruses are spread via mechanical transmission?
Tobacco mosaic virus
Potato virus X
Cucumber mosaic virus
114
What form of transmission occurs from budding, grafting, cutting, tubers, corms, rhizomes, and root grafts?
Vegetative
115
Which virus is spread via vegetative transmission?
Tulip breaking virus
116
Which form of transmission occurs through seeds, includes ~18% of plant viruses but still results in very high disease despite very low transmission?
Seed vertical transmission
117
What is the most common viral transmission route?
Insect vectors
118
5 examples of homoptera
Aphids, whiteflies, leafhoppers, planthoppers, mealy bugs
119
Homoptera are (piercing-sucking/chewing).
Piercing-sucking
120
4 examples of chewing bugs
Psyllids, thrips, beetles, grasshoppers
121
Which insect-virus relationship has an ingestion time of 1-10 minutes, a retention time of 1-10 minutes, and the virus is associated with the stylet of the vector?
Non-circulative, non-persistent
122
Which insect-virus relationship has an ingestion time of greater than or equal to 10 minutes, a retention time of 1-7 days, and the virus transmission is associated with the foregut of the vector?
Non-circulative, semi-persistent
123
Which insect-virus relationship has an ingestion time of greater than or equal to 15 minutes, a retention period of 1 day - life, a latent period of 4-6 hours, and the virus is transported across the insect gut wall into the hemocoel then from the hemocoel to the salivary glands?
Circulative, non-propagative
124
Which insect-virus relationship has an ingestion time of greater than or equal to 15 minutes, a retention period of 1 day - life, a latent period of 4-6 hours and the virus replicates within the insect's cells?
Circulative propagative
125
Which plant-viral interaction shows no viral replication or cell-to-cell movement?
Immunity
126
Which plant-viral interaction shows the virus replicating and moving through the plant?
Symptoms
127
Which plant-viral interaction is when the virus replicates and moves, but has no evident symptoms?
Tolerance
128
Which plant-viral interaction is when the virus replicates, plant produces a hypersensitive response leading to programmed cell death?
Necrosis (HR)
129
Which plant-viral interaction is when the virus replicates and moves, causes symptoms in new leaves, but symptoms disappear over time with further growth?
Recovery
130
A polythetic class of viruses that constitutes a replicating lineage and occupies a particular ecological niche
Virus species
131
What is the current criterion for defining a virus species?
Genome sequencing
132
3 steps for naming a virus
1. Common name of the host species in which it was first discovered
2. Characteristic symptom in that host
3. "Virus"
133
What is the first named virus?
TMV
134
What is the 4th step to naming a virus if a new virus is identifed in the same host with the same symptoms as an existing named virus?
Add discovery location after symptom
135
Approved family, genus, and species names are written in _________.
Italics
136
What has to happen for a virus name to be approved??
Genetic sequence
137
What virus has a wide host range, mostly solanaceous, disseminates easily (exceptionally stable!) enters through wounds, and was the first virus identified and described?
TMV
138
Which virus has symptoms of mosaic, spotting, streaking, stunting, vein-yellowing, malformation, yield reduction, and inclusion bodies?
TMV
139
One virion is the virus, the entire virus is contained in one particle
Monopartite
140
What is the largest plant virus genus? It is monopartite, flexuous, forms cylindrical, pinwheel inclusion bodies, and is aphid-transmitted? It is non-persistent and requires a helper protein
Potyviruses
141
Why do potyviruses field incidences commonly reach 100%?
Because of the effectiveness of aphid transmission
142
What potyvirus has a host range including stone fruits, ornamentals and other wild species? It has a long history in Europe, but was introduced into the US In 1999. Its impact includes yield losses and reduced marketability.
Plum Pox Virus (PPV)
143
How is plum pox virus contained?
Infected trees are removed and destroyed
144
What potyvirus includes hosts of papaya and other cucurbits? Its impacts includes young trees being stunted and not producing fruit and older trees producing small, spotted unpalatable fruit.
Papaya Ring Spot Virus
145
What potyvirus is a thread-like virus whose primary hosts are citrus fruit (oranges, grapefruit, lime and sour orange rootstock)? It is disseminated by aphids (semi-persistent), budding or grafting and impacts fruit quantity and quality ultimately leading to tree decline and death.
Citrus tristeza
146
What is the most effective vector of Citrus Tristeza?
Brown citrus aphid
147
What tospovirus affects more than 500 species of hosts and is disseminated by 9+ species of thrips with an infection rate of 50-90%?
Tomato spotted wilt
148
How do thrips transmit tomato spotted wilt?
Acquired by larvae and transmitted by adults for life
149
Which virus is a geminiviridae whose primary host is legumes? It is disseminated by whiteflies (semi-persistent) and causes up to 100% yield loss due to failure to flower.
Bean Golden Mosaic Virus
150
What are the 3 characteristics in the body plan of a nematode?
Digestive tract with excretory system
Nervous system
Sexual reproductive system
151
Which two things does a nematode NOT have in its body plan?
Circulatory system
| Respiratory system
152
What is the size range of a nematode?
0.3mm-8m
153
What are the 4 lifestyles of nematodes?
Bacterial feeders
Fungal feeders
Predators
Parasites
154
What features allow us to distinguish different species of nematodes?
Size and shape (length/width and dimorphism), cuticle (+/- annulations), mouth parts (stylet), esophagus parts, reproductive parts
155
What must a nematode have in order to be a plant pathogen?
Stylet
156
3 types of stylets
Stomatostylet (dagger)
Odontostylet (sword with hand guard)
Onchiostylet (hook)
157
Which stylet has various lengths, is needle-like, and has 3 knobs at its base?
Stomatostylet
158
Which stylet is spear-like, hollow, has flanges at the base, and consists of a stylet, stylet extension, and a guide ring?
Odontostylet
159
Which stylet is blade-like, solid, curved, with no flanges or knobs? This is the least common type of stylet.
Onchiostylet
160
What is the difference between a 2 part esophagus and a 3 part esophagus?
The 3 part has a median bulb
161
One ovary
monodelphic
162
Two ovaries
didelphic
163
Ovary positions in both directions
amphidelphic
164
Ovary position anterior of vulva
prodelphic
165
Male reproductive parts (2)
spicules and bursa
166
Extra flap of cuticle in male nematodes which may or may not be present.
bursa
167
The first molt of a nematode occurs where?
Inside the egg
168
Which stage of the nematode life cycle is when it hatches and finds a plant fo infect?
2nd stage juvenile
169
What is the dormant survival stage in some nematodes?
Quiescent state
170
Which nematode-plant interaction includes a nematode who lives outside the root and feeds on epidermal cells?
Ectoparasites
171
Which nematode-plant interaction includes a nematode who enters the plant root and feeds from within?
Endoparasites
172
Which nematode-plant interaction includes a nematode whose head is in and tail is out of the root?
Semi-endoparasites
173
Which nematode-plant interaction includes a nematode who moves from cell to cell?
Migratory
174
Which nematode-plant interaction includes a nematode who establishes a feeding site and remains there?
Sedentary
175
When talking about sedentary versus migratory nematodes, we are only talking about _____ _______ because _____ and _____ move.
Adult females; juveniles; males
176
What is the most common type of nematode that feeds primarily on epidermal cells?
Migratory ectoparasite
177
What are 5 examples of migratory ectoparasites?
Sting, dagger, stunt, ring, stubby-root
178
What type of nematode feeds on cortical cells?
Migratory endoparasite
179
What are 3 examples of migratory endoparasites?
Lesion, burrowing, lance
180
What are 3 examples of above-ground migratory endoparasites?
Foliar, wheat gall, stem & bulb
181
What type of migratory endoparasite migrates within the plant stem/trunk, invades larvae of insect vector, and remains dormant until the insect matures and moves to the new host?
Insect-vectored vascular nematodes
182
What type of nematode is the most clearly pathogenic, host specific with complicated host relationships? It is a female establishing a specialized feeding site.
Sedentary endoparasite
183
What are 3 examples of sedentary endoparasites?
Root-knot, cyst, citrus
184
What type of nematode is a female establishing a specialized feeding site, but only part of the body is within the root?
Sedentary semi-endoparasite
185
What are 2 examples of sedentary semi-endoparasites?
Reniform and citrus
186
What type of plant damage to pathogenic nematodes cause
Cell death, lesions, galls, excessive lateral roots
187
The majority of pathogenic nematodes are _____ feeders.
Root
188
What above-ground symptoms appear in plants affected by pathogenic nematodes?
Water and nutrient deficiency, poor stand development
189
What diseases do nematodes serve as a vector for?
Viruses; nepoviruses and tobraviruses
190
Which nematode has over 3000 hosts, distributed worldwide in warm climates and impacts 5% of world production lost every year?
Meloidogyne - Root knot nematode
191
What kind of lifestyle does the root knot (meloidogyne) nematode have?
Sedentary endoparasite
192
What kind of stylet does the meloidogyne (root knot) nematode have?
Stomatostylet
193
Does the meloidogyne (root knot) nematode have a median bulb?
Yes
194
How do we differentiate species of meloidogyne?
Perineal patterns on females
195
What are 2 examples of cyst nematodes?
Heterodera (Soybean cyst) and Globodera (Potato Cyst - Golden)
196
What is the lifestyle of the cyst nematodes?
Sedentary endoparasite
197
What nematode has over 400 host plant species (monocots and dicots), is distributed worldwide in both tropical and temperate climates and is 3rd ranked for crop losses?
Lesion nematodes - Pratylenchus
198
What is the lifestyle of the lesion nematodes (pratylenchus)?
Migratory endoparasite
199
What nematode has over 700 host plant species and has 3 species that are distributed worldwide in both tropical and temperate climates?
Foliar nematodes - Aphelenchoides
200
What is the lifestyle of the foliar nematodes (aphelenchoides)?
Migratory endoparasite
201
What nematode has many hosts and is distributed through sandy soils? It is native to SE USA but has been introduced to Australia, the Caribbean, Bermuda, and California.
Sting nematode (Belonolaimus)
202
What is the lifestyle of the sting nematode (Belonolaimus)?
Migratory ectoparasite
