Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

bot 340 midterm > plant response to pest + pathogen > Flashcards

plant response to pest + pathogen Flashcards

1
Q

examples of pests + pathogen

A

insect herbivores : phloem feeders, cell content feeders, chewing insects

disese-causing organisms: fungi, bacteria, viruses, nematodes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

define constitutive defenses

A

performed mechanisms that are in place prior to attack

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

define induced defenses

A

initiated only after attack is perceived.

  • generalized defense or specialized defense (in response to early ID of specific invader
  • response to insect herbivore + pathogen are different
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is systemic acquired resistance?

A

if plan survives an attack, can develop increased resistance to subsequent attacks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

constitutive and/or induced defense strategies

A 
mechanical barriers
recognition strategies
local + long distance signaling
biochemical defenses
- secondary metabolite arsenal, protein-based defense
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

purpose of mechanical barriers

A

provide first line of defense against insect pests + pathogens
-> surface structures, mineral crystals, thigmonastic leaf movements
thorns, prickles, spines, trichomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are trichomes useful for?

- what are glandular trichomes

A

structural barrriers. deter herbivore attack via physical and/or chemical means

glandular trichomes contain 2-ary metabolites with defensive properties
- burst upon contact

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are mineral crystals

A
  • structural barriers, mechanical obstacle to herbivory.
  • silica crystals AKA phytoliths in epidermal cell wall abrasive + tough = deter insect herbivoes
  • calcium oxalate crystals in vacuole, needle-like and harmful to large herbivores
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

lignin as mechanical barrier

A

in 2-ary CW.

  • can be synthesized as part of induced response by cells with 1-ary CW to seal off and contain pathogens.
  • reduces nutritional quality of plant tissues for many herbivores
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

lipids as mechanical barriers

  • what is cuticle?
  • what is suberin?
A

basis of cutin, wax, suberin = structural barriers to reduce water loss + pathogen invasion
= cuticle is complex mix of cutin, coated by wax.
= suberin is highly hydrophobic, rubbery material. limits apoplastic flow across endodermis. exodermis undearneath epidermis enriched in suberin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

mimosa plant as example of thigmotaxis

A

when touched, turgor changes to move leaf. in mimosa, close leaf.

rapid movements deter feeding insects + grazing herbivores by startling them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

specialized plant metabolites as deterent

– 3 classes of 2-ary metabolites = effects?

A

chemical defense - 2nd line of defense.
- phenolics, terpenoids, alkaloids.
= potent toxins or have medicinal properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are phenolics

A

base structure is phenol. phenylalanine is precursor.

  • phenylpropanoids most abundant phenolic compounds.
  • UV protection, defend against herbivores, floral pigment + scent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is phenylpropanoid p-Coumaric acid

A

precursor for synthesis of flavonoids,, class of phytochemicals.
= protect from UV
= chemical messenger: secrete flavonoids to secrete od factors during nodulation of legumes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are condensed tannins

A

polymers composed of flavonoid units. antimicrobial, feeding repellents, general toxins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

tannins in fruits?

- tannins in agriculture

A

bitter flavour and astringency

  • unripe = higher level of tannin, deters feeders.
  • tannins not in major cereal crops, except tropical cereal sorghum.
  • resistant to grain mold + bird damage. decrease protein digestibility.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what are terpenoids

A

5-C isoprene units assembled/modified numerous ways.

  • isopentenyl diphosphate is precursor for terpene synthesis
  • aromatic qualities
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

monoterpenes,
sesquiterpenes, triterpenes
diterpenes, tetraterpenes

A

C10
C15, C30
C20, C40

diff properties based on this property

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

mono vs sesquiterpenes - characteristic?

A

volatile essential oil.

insect-repellent properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what are alkaloids

A

diverse N-containing compounds synthesized from aa

  • many diff biosynthetic pathways.
  • physiological actions on humans ( drugs, poisons)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

nicotine + caffeine

A

both alkaloids.

  • nicotine; in nightshade family. antiherbivore + stimulant.
  • constitutive and inducible defense

= caffeine, toxic to both pathogens and herbivorse. - prevents premature feeding. toxic/bitter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what are phytoalexins

A

chemically diverse group of 2-ary metabolites with strong antimicrobial activity
- constitutively produced but sometimes induced at site of infection as well

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

where are constitutively produced 2-ary metabolites stored?

A

specialized strucutres

  • glandular trichomes
  • anatomical structures (resin duct, laticifer)
  • sequenstered into vacuoles
24
Q

how are 2-ary metabolites released?

A

upon damage. toxin only active at site of damage

25
Q

secondary metabolites in glandular trichomes

A

terpenoids synthesized or accumulated in trichomes and other specialized cell strucutres

26
Q

conifer resin ducts as storage.

A

contain terpenoids + resins.
release resin at site of herbivory damage.
- secretory cell surround resin duct + release resin into duct.
- repelllent and toxic properties
- physically incapacitates herbivore, sels damage

27
Q

what are lacticifers

A

emulsified milky fluid (latex)
- wounding cases release of latex from laticifers (series of fused cells, or single long cell) that repels/poisins or engulfs herbivore

  • fluid until reaches air, then becomes sticky, rubbery
28
Q

sequestration in vacuoles

A

store as nnontoxic water-soluble sugar conjugates in specialized vacuoles that are spatially separated fro activating enyzymes
- brassica family produce glucosinolates sulfur-containing compound. defensive secondary metabolites

29
Q

how to make glucosinolates

A

glycosylation makes toxin water-soluble = water storage

- naturally found in pungent plants

30
Q

how to sequester glucosinolates

A

hydrolyzing enzyme + glucosinolates stored in diff cells, or in separate compartments in same cell.
myrosinase and glucosinolates mix when tissue damaged by herbivore. glucosinolates broken down to biologically active defense compounds, isothiocyanates and nitriles.
mustard-smelling volatiles compound are effetive deterrents of most generalist insect herbivores.

31
Q

examples of herbivores

A

flea beetle
potato beetle
wheat stem sawfly
grasshopper - can predict crop based on grasshoppers from year prior

32
Q

why inducible preferred over constitutive

A

constitutive is costly - divert metabolites from growth repro to other molecules.
- pes + pathogen adapt to const chemical defenses

= save energy when produce compounds when induced.

33
Q

elicitors

A

specific pathogen molecule (animal) or CW fragments (plants) that bind to plant proteins
- signals for activation of plant defenses against herbivore

34
Q

insect-induced response to ?

A

mechanical wounding, insect saliva elicitors

35
Q

how insect saolica elicitors act as defence?

A

trigger systemic signaling pathways

- initiate defense responsee distant from region of herbivory

36
Q

insect saliva elicitor chemical composition?

A

fatty-acid-based compounds.

  • plant derived, modified by animal digestion.
  • animal derived
37
Q

how elicitors initatie defense signaling

A

poorly understood but probs bind to PM receptors.

species-specific response

38
Q

herbivore damage releases endogenous elicitors

A

Damage associated molecular patterns (DAMPS) - molecule originating from nonpathogenic (nonherbivory) sources that can initiate immune responses
=when molecules of plant are broken down, this acts as a signal itself for immune response initiation

= Jasmonic acid (JA), increases rapidly in response to insect damage: key signalling. have linoleic acid

39
Q

Jasmonic acid - plant hormone

A

increases rapidly in response to insect damage.

  • JA critical for plant responses to to herbivory
  • JA deficient highly susceptible to insect damage
  • JA induces transcription of genes involved in local plant defence
  • JA transported via phloem to induce systemic plant defenses
40
Q

7 steps on induction of systemic defenses via JA signaling

A
  1. wounding - synthesize prosystemin protein
  2. prosystemin cleaved to produce systemin
  3. systemin released into apoplast
  4. systemin binds to pattern recognition receptor on PM of adjacent tissue
  5. systemin receptor activates signaling cascade involving phospholipase A2 (PLA2) + mitogen-activated protein (MAP) = biosynthesis of JA
  6. JA induces local plant defense response (proteins)
  7. . JA transport through phloem to unwounded leaves - signalling to protect with proteinase inhibitor genes.
41
Q

JA = 2-ary metabolite and protein based defenses against insect herbivores

A
  • produce toxic or repellant 2-ary metabolites
  • JA activates synthesis of defensive proteins:
    • enzymes degrade insectexoskeleton
  • -a-amylase inhibitor to stop plant starch breakdown
  • lectin: inhibit nutrient absorption in insect gut
  • proteinase inhibitor: suppress proteinase in insect gut
42
Q

HIPV

A

herbivore-induced plant volatiles

  • includes compounds from all major pathways for 2-ary metabolites + lipid-derived products.
  • systemic defense signal: diffuse to distal regions
  • attract predators/parasites of herbivore
  • repel other herbivores
  • prime defense responses in neighbouring plants prior to attack
43
Q

routes of pathogen entry

A

fungi - penetrate cells (digest cutin, cellulose)
bacteria - penetrate through wounding site
fungi - penetrate plant through stomata, bacteria do too = sotmatal closure to inhibit penetration

44
Q

pathogen attack strategies

A

biotrophs: live with host without causing death. minimal damage as pathogen feeds on host resource.

necrotrophs: cell wall degrading enzymes + toxins = massive tissue maceration + plant death. kill cells + consume contents. trigger JA response
hemibiotrophs: initial biotrophic stage, followed by necrotrophic state

45
Q

effector molecules of pathogens

A
  • aid in colonization of plant host cells

- change plant’s structure, metabolism, hormonal regulation

46
Q

three classes of effectors

A

enzymes: degrade plant cuticle, cell wall
toxins: target specific proteins of plant (fusicoccin activates PM H+-ATPase - acid growth and stomatal opening

growth regulators : gibberellins accelerate shoot growth, bigger plants = disperse fungal spores

47
Q

plant immune response to pathogen

A

active processes that include recognition of active pathogen + defense responses.
- Pattern Recognition Receptors (PRR) set off defense responses when activated by evolutionarily conserved microbe-associated molecular pattern (MAMPs) plants dont ave MAMPs

48
Q

recognition pattern

A

PRR recognize extracellular MAMPs.
- localized basal defense response - inhibit growth and activity of non-adapted pathogen/pests

plants respond to cell damage - DAMPs

49
Q

virulent pathogens + immune response

A

overcome MAMP-triggered immunity.

secrete effectors directly into cytoplasm - avoid detection by PRRs

50
Q

effector-triggered susceptibility

A

pathogen effector suppress plant’s immune response and/or pathogen viability.

  • suppress singalling path
  • suppress MAMPs
  • inhibit stomatal closure = bacterial entry
51
Q

Resistance proteins

A

cytosolic receptors in plant - recognize pathogen-derived effectors in cytosol.

  • resistance by recognizing strain-sepciic effectors
  • bidning effector to receptor = anti-pathogen signaling pathway
  • Re-protein leads to enhanced defense: Effector-triggered immunity
52
Q

Rprotein - effector detection

A

directly

indirectly: R rotein bound to plant protein = target for pathogen effectors. once bind effector R protein activates

53
Q

R protein activation = enhanced defense responses (ETI) - how?

A

hypersensitive cell death response triggered by production of ROS (necrosis + tissue death)

  • production os SA (salicylic acid) = system acquried resistance.
  • biosynthesis of lignins, phytoalexins and hydrolytic enzymes to target pathogen directly
54
Q

plant resistance
- PTI
ETS
ETI

A

PTI triggered by MAMPs (flagellin, chitin) low-level response to suppress without severe action.

pathogen effectors develop + suppress PTI = decrease immunity ETS

host develop effector thats sensitive to pathogen effector = specifically adapted, specific and strong response. ETI. kill tissue surrounding pathogen.

55
Q

eTI recognition of biotrophic pathogen leads to?

A

hypersensitive response: rapid, localized cell death surrounding infected site.

  • effective aagainst biotrophs (deprive nutrient + prevent spread)
  • HR preceded by rapid accumulation of ROS, NO

HR before slower systemic response

56
Q

plant SAR

A

systemic acquired resistance
- increase resistance throughout plant to range of pathogen following infectio by pathogen at one sit.
SAR associated with induction of wide range of pathogenesis-related genes
- activation of SAR requires SA

57
Q

response triggered by biotrophs vs necrotrophs

A

biotrophs: trigger ETI - HSR and SA-mediated SAR

necrotrophs trigger JA- response. (HR would benefit necrotrohphs, JA and SA antagonistic

bot 340 midterm (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions