Download Topic 19: Plant Responses to Signals

SFR 100 - Lecture #19 : Plant Response to Signals
Topic #19
Plant Response to Signals
(Campbell and Reece 821-849)
I.
II.
Objectives
A.
Review basic requirements for stimulus and response
B.
Learn the basic plant hormones and their functions.
C.
Summarize how plants respond to environmental stimuli.
Flow of information in plants.
A.
Three steps.
B.
Scale of response
1.
Plant
2.
Cell
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SFR 100 - Lecture #19 : Plant Response to Signals
III.
Classes of plant hormones and cell level response.
A.
B.
C.
Overview
1.
Chemical signals that coordinate organism functions
2.
Minute amounts result in major changes
3.
Variability in function.
Auxin.
1.
IAA.
2.
Stimulates cell wall elongation.
3.
Produced in apical buds.
4.
Seeds - involved in germination
5.
Commercial applications.
Cytokinins.
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SFR 100 - Lecture #19 : Plant Response to Signals
D.
Gibberellins.
E.
Abscisic acid (ABA).
F.
1.
Produced in leaves and developing seeds
2.
Associated with dormancy.
3.
Stomata control
Ethylene.
1.
Produced by tissue under stress.
2.
Apoptosis - programmed cell death.
a)
Cells respond to ethylene by
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SFR 100 - Lecture #19 : Plant Response to Signals
IV.
b)
Leaf abscission - many breakdown products reabsorbed.
c)
Fruit ripening.
Plant Hormone Interactions.
A.
Apical dominance.
B.
Shoot and root growth, differentiation .
1.
Shoots.
2.
Roots.
3.
Ratios.
4.
Dormancy.
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SFR 100 - Lecture #19 : Plant Response to Signals
V.
Flowering and photoperiodism.
A.
Phytochrome.
1.
Protein complex with chromophore
2.
Chromophore has two forms.
3.
VI.
a)
Pr
b)
Pfr
Ratio for day and night.
B.
Photoperiodism - flowering dependent on night length.
C.
Appropriate stimulus will result in meristem forming flower parts
Responses to other environmental stimuli
A.
Phototropism.
B.
Gravitropism.
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SFR 100 - Lecture #19 : Plant Response to Signals
VII.
C.
Drought - ABA and guard cells
D.
Damage (including pests)
Key Terms.
flow of information
stimulus
communication
response
hormone
auxin
IAA
indoleacetic acid
cytokinin
gibberellin
abscisic acid
dormancy
ethylene
Apoptosis
abscission layer
apical dominance
Phytochrome
chromophore
Pr
Pfr
photoperiodism
long night plant
short night plant
phototropism
gravitropism
periderm
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