Chapter 39 Plant Responses To Stimuli

Front 1

how do plants respond to stimuli

Back 1

- signal transduction pathways (kinases turning on, phosphotases turning off)
- respond to internal and external signaling
- control and coordination

Front 2

plant hormones help control:

Back 2

- growth
- development
- responses to stimuli

Front 3

auxin

Back 3

- plant hormone
- produced in: shoot apical meristems, young leaves.
- cell elongation in young stems (low concentrations)
- apical dominance (retards lateral growth)
- phototropism and gravitropism
- increases activity of proton pump, movement of water.

Front 4

cytokinins

Back 4

- produced in the roots
- regulate cell division in shoots and roots
- modifies apical dominance
- anti-aging effects on cells.
- help regulate apical dominance with auxin (auxin suppresses it)

Front 5

gibberellins

Back 5

- produced in: apical bud and root meristems, young leaves, developing seeds
- stem elongation
- fruit growth
- seed germination

Front 6

how gibberellins help seed germination

Back 6

1. imbibition
2. embryo produces gibberellins
3. gibberellins send signal to aleurone
4. aleurone secretes alpha amylase and other enzymes
5. sugars and other nutrients are consumed.

Front 7

aleurone

Back 7

cell layer that surrounds endosperm

Front 8

abscisic acid (ABA)

Back 8

- produced in: all cells may produce it, moves in xylem and phloem
- drought tolerance (causes stomata to close)
- promotes dormancy

Front 9

ethylene

Back 9

- produced: all over
- high concentrations cause leaf abscission, fruit ripening, and wounding.
- leaf abscission
- fruit ripening
- triple response

Front 10

plant response to light

Back 10

- photomorphogenesis - effects of light on plant morphology
- phototropism - growth toward light

Front 11

how is like detected in plants

Back 11

photoreceptors!
- blue light
- red light (phytochromes)

Front 12

phytochromes

Back 12

- detect red light (light) and far red light (shade)
- ratio of red and far red allows plants to detect: the quality of light, days, seasons
- photoperiodism

Front 13

long-night plants

Back 13

- have longer dark cycle.
- if not, then they won't bloom.
- dark cycle must be uninterrupted. - flash of far red causes blooming. red flash stops blooming

Front 14

short-night plants

Back 14

- longer day cycle.
- if not, then won't bloom.
- dark cycle can be interrupted with a flash (will bloom)

Front 15

florigen

Back 15

- flowering hormone.
- detect light to bloom/not bloom

Front 16

gravitropism

Back 16

- statoliths: filled with starch grains (heavier). respond to gravity. direct root downward.

Front 17

thigmotripism

Back 17

- protection from predators
- water control - become turgid and flaccid
-

Front 18

plant response to environmental stress

Back 18

- drought: reduce transpiration. increase production of abscisic acid (helps keep stomata closed)
- flood: stomata remain open. air tubes get wider to allow removal of water.

Front 19

how to plants protect themselves against attacks by herbivores and pathogens

Back 19

- non-specific recognition - outer membrane (epidermis and periderm)
- specific recognition - gene for gene recognition

Front 20

specific recognition of plant predators

Back 20

- specific gene product of pathogen
- activates signal transduction pathways
- activates specific R gene (hypersensitive response)
- R protein travels throughout activation other signal transduction pathways
- product leads to systemic aquired resistance.