lecture 10 Flashcards

1
Q

what are elicitors?

A

distinctive molecules in pathogens that trigger plant defenses

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2
Q

what are Avr (arirulence) genes?

A

genes that code for elicitors

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3
Q

what are r (resistance) genes?

A

plant genes that confer resistance to specific pathogens

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4
Q

how to elicitors do what they do?

A

they bind with membrane receptor proteins encoded by R resistance genes (gene for gene)

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5
Q

what does the binding of elicitors do?

A

it sets in motion a signal transduction pathway leading to two main inducible responses

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6
Q

what are the two main inducible responses

A

local responses and systemic responses

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7
Q

what are the induced defenses

A

elicitors, avr genes, and r genes

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8
Q

what are examples of local responses (3 things)

A
  1. phytoalexins 2.pathogenesis 3.physical isolation
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9
Q

what are phytoalexins

A

antibiotics toxic to bacteria and fungi produced by dying cells surrounding infection

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10
Q

what are pathogenesis related proteins

A

some are enzymes that break down cell ways of pathogens

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11
Q

what is physical isolation in plants

A

infected regions die and plasmodesmata are plugged

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12
Q

what are examples of systemic responses (4 things)

A
  1. general increase in resistance of entire plant 2. salicylic acid 3. jasmonate 4.methyl salicylate
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13
Q

what does salicylic acid do

A

it initiates responses to pathogens that depend on living plant tissues and leads to systemic acquired resistance (SAR)

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14
Q

what does jasmonate do

A

it initiates responses to microorganisms that kill plant cells and feed on their remains as well as insects

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15
Q

what does methyl salicylate do

A

is volatile and can signal remote parts of plant or other species that attack

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16
Q

plant responses to environment cues that influence growth are regulated by

A

hormones and photoreceptors

17
Q

what are plant hormones

A

chemical signals that act at very low concentrations at sites often far from where theyre produced

18
Q

what are photoreceptors

A

pigments associated with proteins that absorb light

19
Q

what is auxin

A

controls the direction and arrangement of apical growth, gravitropism, phototropism, and apical dominance, causes cells to elongate by cell wall acidification

20
Q

what is negative gravitropism

A

the auxin travels to the bottom causing the shoot to grow UPWARDS

21
Q

what is positive gravitropism

A

the auxin travels to the top side causing the shoot to grow DOWNWARDS

22
Q

what is apical dominance

A

apical buds inhibit growth of axillary buds, the terminal bud produces auxin and prevents lateral buds from growing

23
Q

what is ethylene gas

A

it promotes leaf abscission (falling) and senescence (part of plant die) and SPEES RIPENING OF FRUIT , presence of ethylene gas causes more ethylene gas to be made, and apical hook

24
Q

what are phytochromes

A

photoreceptors that mediate effects of red and far red light

25
how can effects of red light be reverse
by exposure of far red light
26
how many isoforms does phytochromes exist in
2
27
the ratio of red and far red light determines what
seed germination, flowering, shoot development
28
what is the usual ratio of red light/far red light during day
1.2:1 having far red light predominate
29
what is the usual ratio of red light/far red light during the night
0.13:1 having red light predominate
30
how does phytochrome effect the plant
by stimulating gene transcription
31
what is a photoperiod
some plants only flower when days reach a specific length
32
what do long day plants like
they like short nights as they flower on long days (summer)
33
what do short day plants like
they like long nights and flower on short days (winter)
34
poinsettia are what time of photoperiod plant
short day plant