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Bio 2D03 > Lecture 8 > Flashcards

Lecture 8 Flashcards

1
Q

what % of crops is lost to insects and diseases every year

A

40%

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2
Q

disease triangle

A

level of disease or resistance observed depends on: pathogen genotype–environment–plant genotype

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3
Q

pathogen (disease triangle)

A

has virulence factors to infect a particular species

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4
Q

plant (disease triangle)

A

must be susceptible when the pathogen tries to infect

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5
Q

environmental conditions

A

must favour disease development

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6
Q

specialist pest

A

microbe or insect that feeds on one or a few plant species/organs

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7
Q

generalist pest

A

microbe or insect that feeds on many plant species/organs

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8
Q

entry of pathogen into plants

A

direct penetration
penetration through natural openings
penetration through wounds

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9
Q

entry of viruses into plants

A

via insects, insects interact with plant by eating it or other interactions and provide a vector of penetration

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10
Q

what must a successful plant pathogen have:

A

ability to obtain nutrients, grow, and reproduce in the plant environment

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11
Q

Disease cycle

A

Inoculation
Penetration
Infection (creating a favourable environment, obtaining nutrients and reproducing)

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12
Q

Erwinia soft rot

A

common among vegetables because environmental conditions require cold and humid conditions common in a refrigerator

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13
Q

Necrotrophs

A

kill plant cells and live on dead plant tissue

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14
Q

biotrophs

A

invade and grow in living plant tissues manipulate plant metabolism

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15
Q

hemibiotrophs

A

begin infection as biotrophs then switch to necrotorophy later in infection to spread to next plant

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16
Q

constitutive plant defence

A

performed defences

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17
Q

constitutive pathogen defence

A

cell walls

cuticles

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18
Q

constitutive herbivore defence

A 
glucosinolates in mustard
nicotine in tobacco
cannabinoids in cannabis
caffeine in coffee
vanilla in vanilla orchid
opium in opium poppy
taxol in pacific yew
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19
Q

Induced pathogen defence

A

prevent pathogen entry via closing of stomata
production of ROS as an antimicrobial
pathogenesis related proteins
phytoalexin production
cell wall strengthening at infection site

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20
Q

Phytoalexins

A

antibiotic-like antimicrobial compounds

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21
Q

pathogen-related PR proteins

A

antimicrobial agent ex: chitin’s degrades chitin in fungal cell walls, glucanase degrades fungal cell walls, lysozyme punch holes in bacterial cell walls

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22
Q

induced cell wall strengthening

A

at infection site, addition of calls, lignin, hydroxy-rich glycoproteins all strengthen the wall to stop entry of pathogens or stop the secretion of effectors into the plant

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23
Q

Induced Responses vs herbivours

A

anti herbivore compounds and proteins in organs

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24
Q

local defence

A

recognition of danger signals

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25
Q

R gene-mediated resistance

A

local defence against biographic pathogens using effector triggered immunity

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26
Q

Basal Resistance

A

local defence vs biographic pathogens using PAMP triggered immunity

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27
Q

age related resistance

A

a form of local defence against biographic pathogens

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28
Q

PAMP-triggered immunity

A

local defence vs neurotrophic pathogens and insects

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29
Q

systemic immunity

A

via inter organ communication

systemic acquired resistance vs biographic pathogens

systemic wound response vs neurotrophic pathogens and insects

30
Q

Explain what is meant by the “Arms Race”

A

most plants are resistant to most pathogens unless the pathogen has evolved a way to get around the plant defence. plants and pathogens are in an evolutionary arms race

31
Q

PAMP

A

pathogen associated molecular patterns

32
Q

MAMP

A

microbe associated molecular patterns

33
Q

Basal Resistance

A

PAMP triggered immunity

Plant Pattern Recognition Receptors (PRR) recognize PAMPs like flagellin triggering a signalling pathway

34
Q

PAMP signalling pathway

A

ROS and Ca2+ signalling, Kinases and transcription factors, stomatal closure, cell wall strengthening, production of antimicrobials

35
Q

R Gene Mediated Resistance

A

effector triggered immunity (ETI)
plant resistance genes encode membrane bound or cytoplasmic R Receptor proteins which recognize pathogen virulence/effector proteins causing a hypersensitive response

36
Q

Overview of R gene-mediated Resistance/ETI

A

plant has functional basal resistance that pathogen effector suppresses

r-receptor recognizes pathogen virulence protein/effector

HR Hypersensitive Response occurs

37
Q

HR

A

Hypersensitive response: rapid necrosis at infection site, form of programmed cell death, pathogen numbers reduced due to loss of life host cells and very dry conditions in HR lesion

not effective vs necrotrophs

38
Q

ETI/R-gene signalling pathway

A

ROS and Ca act as signalling molecules

antimicrobial agents accumulate

cell wall strengthened

HR cell death

39
Q

Resistance

A

receptors perceive pathogens, signalling initiates fast and successful deployment of defence

40
Q

Susceptibility

A

pathogen employs virulence effectors &/ toxins to suppress plant defence leading to pathogen success and disease

41
Q

Pst

A

Pseudomonas syringas pv tomato

needs water on the leaves, needs stomata to open so bacteria can enter. inoculation forces bacteria to enter

42
Q

Bacterial pathogens secrete toxins and effector proteins into the plant during infection to:

A

suppress plant resistance response

manipulate plant to promote growth and development of pathogen

43
Q

Successful basal resistance to bacteria

A

begins with perception of bacteria with PAMP receptors–initiates signal cascade–closure of stomata

44
Q

Pseudomonas

A

inhibit plant response using coronation causing stomata to reopen

45
Q

Coronatine

A

toxin which is used by pseudomonas to re-open plant stomata; pseudomonas Cor- mutants are unable to reopen the stomata even if they successfully inoculate the plant;

46
Q

T3SS

A

Type 3 Secretion System: used by pathogens to secrete effectors into plant cells creating a favourable environment

47
Q

pathogen effectors:

A

pathogens secrete effectors to create a favourable environment

48
Q

SWEET

A

gene encoding sugar transporters on plasma membranes

49
Q

RIN4

A

positive regulator of Basal R/PAMP triggered immunity

50
Q

AvrRpm1 & AvrRps2

A

pathogen effectors that disrupt RIN4 function

51
Q

AvrRpm1

A

phosphorylates RIN4

52
Q

AvrRpt2

A

degrades RIN4

53
Q

RPM1

A

R-receptor that recognizes phosphorylated RIN4 and activates R gene-mediated Resistance or ETI

54
Q

RPS2

A

R-receptor that recognizes RIN4 degradation and activates R gene-mediated Resistance or ETI

55
Q

RPM1 and RPS2 analogy

A

backup generator, recognizes that defence has been deactivated and it reactivated. its a backup security mechanism

56
Q

Indirect interaction of R and AVR/Effector

A

RPM1 and RPS2 indirectly recognize avrRPM1 and avrRPT2 by recognizing the phosphorylation or degradation of RIN4 respectively and activating plant defence

57
Q

fungus plant interaction

A

Blumeria fungal pathogen of barley, arabidopsis is resistant because of PTI which stops penetration builds new cell wall material and ROS which inhibit hyphen entry and fungal growth. Visualized using ROS stain showing attempted penetration sites

58
Q

DAMP

A

damage associated molecular patterns

59
Q

Plant Defence Syndrome:

A

plants perceive a pathogen and do all actions (cell wall strengthening, closing stomata, antimicrobial ROS, signalling ROS, pathogenesis related proteins) which might help them if another pathogen comes along

60
Q

why might inoculation of a plant with one pathogen help it defend against another pathogen?

A

the plant will experience the plant defence syndrome which will initiate all defence mechanisms making it prepared for the second pathogen and allowing it to defend itself more effectively and quicker

61
Q

systemic resistance

A

similar to immunization; initial infection or attack leads to production of long distance signals which move to distant leaves priming them to respond in resistance manner for when the pathogen or insect moves to a new leaf

62
Q

SAR

A

Systemic Acquired Resistance; infect/immunize plant with bacteria to protect against viruses, fungi and other bacteria

63
Q

Systemic Wound Response

A

insect chews on a lower leaf, phloem mobile signal causes upper leaves to express defence related genes increasing ethylene and producing anti-feeding proteins

64
Q

plant to plant communication

A

plants alert surrounding plants about pathogen attack by producing volatile methyl salicylic acid during SAR

65
Q

plant calls for help from community

A

insect and plant produce volatile compounds during insect feeding attracting predators of attacking insect; tobacco horn worm is attacked by wasp which lays its pupae on the worm which will feed on the worm saving the plant

66
Q

Rhizobia bacteria and legumes

A

bacteria fix nitrogen into NH3

plant provides nodule environment and carbon source

67
Q

Mycorrhizal fungi

A

colonize 80% of plants studied; fungal hyphae grow in soil providing plant nutrients, plant provides carbon source, fungal hyphae expand ability of plant to explore soil for nutrients good for farmers because they need less fertilizer

68
Q

Ectomycorrhizae

A

fungus surrounds root as a sheath; interacts with woody plant roots and forms toadstools that produce fungal spores; interacts with 10% of plants

69
Q

Endomycorrhizae

A

fungus grows inside roots and forms transfer structure called abuscule; grow around cortical cells without penetrating them; plant provides carbon, fungus provides phosphate to plant cortical cell

70
Q

does arabidopsis interact with rhizobia or mycorrhizae?

A

no

Bio 2D03 (10 decks)

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