Quiz 4 Botany

Front 1

Name all five classes of plant hormones

Back 1

Auxin, Ethylene, Cytokinins, Abscisic acid, Gibberellins

Front 2

Give three processes that hormones mediate

Back 2

1. Control the expression of specific genes
 Genes coding for enzymes
2. Regulate growth via cell division/elongation
3.Regulate cellular physiology

Front 3

True or false auxin is found in all plants, fungi and some bacteria

Back 3

TRUE!!

Front 4

Where is Auxin Synthesized?

Back 4

shoot apical meristem, young leaves, seeds

Front 5

How is auxin transported?

Back 5

from tip to shoot

Front 6

What did darwin discover about Auxin?

Back 6

Discovered that a hormone produced in tips caused stems to curve toward the light

Front 7

What did frits went discover?

Back 7

 Hormone stimulates cell elongation on the dark side of the stem
 This is only one of auxin’s effects

Front 8

Name all five of Auxin's effects

Back 8

1.stimulates cell elongation on the dark side of the stem
2. Differentiation of vascular tissue
3.Apical Dominance
4. Formation of lateral and adventitious roots
5. Fruit Development
6. Synthetic Auxin

Front 9

Synthetic Auxin

Back 9

 2,4-D a
 Herbacide
 Accumulation leads to death
 Broad-leaved, not grass
 2,4,5-T
 2,4,5-Trichlorophenoxyacetic
acid
 Agent Orange
 Leukemia, Cancer, Death

Front 10

Cytokinins

Back 10

 Resembles adenine
 Zeatin most common
 Synthesized in root tip
 Found in meristematic regions of roots
and stems
 Also dividing regions of fruits, seeds

Front 11

What did Johannes van Overbeek discover?

Back 11

Cytokinins;1941
 Coconut milk
 Accelerated tissue growth

Front 12

what did Folke Skoog & Carlos O. Miller discover?

Back 12

Cytokinins; 1950'a
 Ticotianna tabacum
 Adding coconut milk to medium stimulated cells to divide
 Isolated growth factor in DNA preparation
 Called it kinetin and the group cytokinins
 Miller isolated a natural cytokinin from Zea mays = zeatin

Front 13

Name all the effect of cytokinins

Back 13

1. Promotes cell division
2. Delay of senescence (chlorophyl loss delayed)

Front 14

Ethylene; what is it? wheres it produced?

Back 14

simple hydrocarbon gas
Derived from amino acid Methionine
Produced in all organs of angiosperms
Affects development of tissues – fruit, leaves, meristems

Front 15

History of Ethylene

Back 15

 1800s used for street lights
 Dimitry Nejubov
 1910
 Ethylene the active component affecting plants

Front 16

Ethylene effects(#1 in detail)

Back 16

1. Inhibit or Promote cell expansion
 Decreases longitudinal growth of stem
 Increases radial expansion
 In aquatic species, increases stem internodal elongation

Front 17

Ethylene effects (#2 Fruit Ripening in detail)

Back 17

2.Fruit Ripening
 Promotes breakdown of chlorophyll
 Promotes pectin digestion for cell wall breakdown
 “Ripening on demand”

Front 18

Ethylene effects (#3 abscission promotion detail)

Back 18

3. Abscission promotion
 Stimulates enzymes to breakdown cell walls
 Degrades pectin
 Wounding effect

Front 19

Abscisic Acid..what's it all about?

Back 19

Abscisic Acid (ABA) = Thought to affect abscission (but no!)
Synthesized in mature leaves and roots & developing embryos of seeds

Front 20

Abscisic acid history!

Back 20

 Paul F. Wareing
 1949
 Ash buds
 Growth inhibitor = Dormin
 Frederick T. Addicott
 1960s
 Abscisin in leaves and fruits
 Dormin & Abscisin the same

Front 21

Abscisic acid effects (#1)

Back 21

1. Prevents seed germination
 Stimulates seed storage proteins
 Keeps seeds from premature germination
 Breaking dormancy correlated to declining ABA

Front 22

Abscisic Acid Effects(#2 Stomatal Closure)

Back 22

2. Stomatal closure
 Response to water stress
 Root to shoot signal
 Afterwards, ABA broken down

Front 23

Gibberellins (GA)...

Back 23

125+ denoted by # Found in plants, fungi, and bacteria ~10 per species
Synthesized in apical buds, young leaves, developing seeds

Front 24

Gibberellins (GA)...HISTORY

Back 24

 E. Kurosawa
 Oryza – Rice
 1926
 “Foolish Seedling Disease”
 Something in fungi Gibberella fujikuroi
 T. Yabuta & J. MacMillan
 1934
 Substance named Gibberellin
 J. MacMillan
 1956
 Phaseolus – Bean
 First isolation in plant

Front 25

GA effects

Back 25

1. Extensive growth in stems
2. Breaks seed dormancy
3. Seed germination of cereal grasses
4. Causes Bolting
5. Fruit Production (commercial use)

Front 26

GA effects (#1) Extensive growth in stems

Back 26

1. Extensive growth in stems
 Cell division & Elongation of internodes
 Dwarf mutants return to normal

Front 27

GA effects (#2) Breaks seed dormancy

Back 27

2. Breaks seed dormancy
 Substitutes for cold or light requirement
 Stimulates elongation of radicle
 Commercial use for germination uniformity

Front 28

GA effect (#3) Seed germination of cereal grasses

Back 28

3. Seed germination of cereal grasses
 Barley and Grasses (monocots)
 Stimulates Alpha-amylase for starch break-down
 Aleurone layer

Front 29

GA effect (#4) Causes Bolting

Back 29

4. Causes Bolting
 Brassicaceae – cabbage, brocolli
 Many biannuals
 Grow rosettes before flowering
 Cold or Long Days stimulate bolting
 Cell division & Elongation of internodes

Front 30

GA effects (#5) F_ _ _ _ P_ _ _ _ _ _ _ _ _

Back 30

5. Fruit Production (commercial use)
 Unfertilized carpels to produce parthenocarpic fruits
 Works when auxin fails
 Seedless grapes treated = 3x the size!

Front 31

(What) Control the expression of specific genes

Back 31

 GA activating gene for alpha-amylase  Ethylene for enzyme for abscission

Front 32

(what) Regulate growth via cell division/elongation

Back 32

 Auxin and ethylene for cell elongation  Cytokinins and cell division
 GA for bolting via cell division and cell elongation

Front 33

What Regulate cellular physiology

Back 33

 ABA and stomata
 Strigolactones?

Front 34

New group of hormones discovered in 2008

Back 34

Strigolactones

Front 35

Strigolactones

Back 35

 Derived from carotenoids – pigment in plants
 Named after Striga – a parasitic plant

Front 36

Strigolactones- History

Back 36

 Discovered in 2008
 Pea plants

Front 37

Strigolactones affects(there are two)

Back 37

1. Inhibits shoot branching
2. INcreases capabilities to form relationships with their environments

Front 38

Strigolactone affect # 1

Back 38

1. Inhibits shoot branching Commercial use for cut flowers

Front 39

Strigolactone affect #2

Back 39

2. Increases capabilities to form relationships with their environments
 Stimulates association with symbiotic mycorrhizal fungi
 Triggers germination of parasitic plant seeds
 Striga

Front 40

Auxin Effect #2 Differentiation of vascular tissue

Back 40

 Cells become vascular tissue cells
 Seen in wounds that sever / remove vascular bundles in stem

Front 41

Auxin Effect # 3 Apical Dominance

Back 41

Apical bud inhibits lateral bud growth

Front 42

Auxin Effect # 4 Formation of lateral and adventitious roots

Back 42

 Stimulates pericycle cells to divide  Found in “rootone”

Front 43

Auxin Effect # 5 Fruit Development

Back 43

 Seeds release auxin while maturing
 Hormone influences the development of fruit
 Parthenocarpic fruits with auxin application
 Greek parthenos meaning maiden, virgin
 Seedless fruits

Front 44

Synthetic auxin...talk to me

Back 44

 2,4-D
 2,4-dichlorophenoxyacetic acid
 Herbacide
 Accumulation leads to death
 Broad-leaved, not grass
 2,4,5-T
 2,4,5-Trichlorophenoxyacetic acid
 Agent Orange
 Leukemia, Cancer, Death

Front 45

Auxin and abscission

Back 45

auxin inhibits abscission