19. Phytohormones - Others

Question 1

4 main effects of phytohormones:

Answer 1

effect on vegetative growth
reproductive development
abiotic stress
biotic stress

Question 2

cytokinins:

Answer 2

regulation of auxin, cell division, nutrient allocation, root nodules

Question 3

1950s: Folk Skoog

Answer 3

discovered cytokinins while creating synthetic cmpds to increase plant growth

Question 4

comparison of CK and auxin on growth in experiments

Answer 4

plants with only CK –> lots of leaf development, no roots
Plants with only auxin –> lots of root development, no leaves

Question 5

while auxin ___ root brancing, CK __ root branching

Answer 5

promotes ; inhibits

Question 6

while auxin ___ shoot branching, CK ___ shoot brancing

Answer 6

inhibits ; promotes

Question 7

cytokinins are derived from:

Answer 7

adenine

Question 8

main gibberellin

Answer 8

gibberellic acid (GA)

Question 9

effects of GA

Answer 9

growth, flowering, fruit growth, seed germination, stem elongation

Question 10

bakanae disease/foolish seedling disease

Answer 10

too much GA causes too much stem elongation, plant becomes too long and falls over

Question 11

GA’s role in green revolution

Answer 11

GA inhibitors were used
prevent stem elongation: creates sturdier plants that put more energy into fruits/leaves/seeds
prevent seed formation: create seedless fruits

semidwarf varieties
huge fruits

Question 12

what phytohormone was used to create semidwarf varieties?

Answer 12

GA

Question 13

what phytohormone is important for phototropism?

Answer 13

auxin

Question 14

what phytohormone is important for gravitropism?

Answer 14

auxin

Question 15

what phytohormone (or deliberate lack of) is important for creating seedless fruits?

Answer 15

GA

Question 16

what is the only gaseous phytohormone?

Answer 16

ethylene

Question 17

ethylene is important for:

Answer 17

fruit ripening, senescence, organ expansion

Question 18

ethylene is synthesized from:

Answer 18

methionine

Question 19

1901: dimitry Neljubow

Answer 19

growing pea seedlings in the dark and found very strange growth patterns, realized it was from ethylene produced by gas burning lamps in the house

Question 20

1934: Game

Answer 20

purified ethylene, realized it was endogenous

Question 21

endogenous means:

Answer 21

plants make it within themselves

Question 22

what constitutes fruit ripening?

Answer 22

fruit softening, flavor and color development

Question 23

leaf senescence

Answer 23

when leaves fall off plants
olden days peoples houseplants would senesce very quickly because of ethylene produced by lamps

Question 24

what phytohormone shortens longevity of cut flowers and fruits?

Answer 24

ethylene

Question 25

abscisic acid mainly acts on plants:

Answer 25

abiotic stress responses

Question 26

when would abscisic acid be most prevalent?

Answer 26

during drought

Question 27

abscisic acid affects:

Answer 27

dormancy, germination, stomatal aperature

Question 28

during drought, abscisic acid causes:

Answer 28

guard cells to close and prevent stomatal opening to conserve water

Question 29

2 main phytohormones for dealing with biotic stress:

Answer 29

jasmonates and salicylates

Question 30

salicylates protect against ___ organisms

Answer 30

biotrophic

Question 31

jasmonates protect against ____ organisms

Answer 31

necrotrophic

Question 32

biotrophic organisms

Answer 32

derive nutrients and energy from living cells

Question 33

necrotrophic cells

Answer 33

derive energy and nutrients from dead cells

Question 34

2 types of responses to biotic defenses:

Answer 34

constitutive and induced

Question 35

constitutive defenses

Answer 35

produced all the time

Question 36

induced defenses

Answer 36

triggered by presence of pathogen, detected via hormone signalling

Question 37

how do salicylates act?

Answer 37

when a pathogen binds to the cell membrane, causes infected plant cells to release antimicrobial molecules and then die
dying cells release salicylic acid which produces more antimicrobial molecules preventing infection

Question 38

how do jasmonates act?

Answer 38

induce production of volatiles
can induce production of protease inhibitors that reduce protein digestion in the insect

Question 39

what is the purpose of anti-herbivory volatiles?

Answer 39

they prime other tissues to ready defenses, can attract predatory insects to come and eat the herbivorous insect

they can also warn other plants of the attack so that they prime tissues for attack

Question 40

what phytohormone is responsible for producing anti-herbivory volatiles?

Answer 40

jasmonates

Question 41

production of anti-herbivory volatiles are triggered by:

Answer 41

wound induced insect oral secretions

Question 42

insect saliva:

Answer 42

triggers production of volatiles (jasmonates)

can also have an enzyme that closes stomates and inhibits volatile release

Question 43

what phytohormone is antimicrobial?

Answer 43

salicylates

Question 44

auxin is derived from:

Answer 44

tryptophan

Question 45

what phytohormone is especially important for stem elongation?

Answer 45

gibberellic acid