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Plant response to the environment
Unique Mechanisms
•Grow indeterminately
•Endure climate
•Obtain nutrients locally
•Defend self without running away
Plant response to the environment
Environmental trigger: light, gravity, touch
response: movement
Environmental trigger: herbivores
response: communication
Darwin•The Power of Movement in Plants (1881)
•http://javalab.cs.uni-bonn.de/research/darwin/images/darwin.jpg
Why do plants need to move?
gather nutrients
optimize light exposure
Movement responses
Light
courtesy: Roger Hangarter, Plants in Motion
http://plantsinmotion.bio.indiana.edu/plantmotion/starthere.html
QuickTime™ and aSorenson Video decompressorare needed to see this picture.
Plant cells have an array of light receptors
phyphy
sun
plant cell
movementtowards
light
germination
Some plants require light to germinate
CB 39.18
darklight,
then dark
germination!
PHYTOCHROMEPHYTOCHROME
UV BLUE RED FAR-RED
PHYTOCHROME
PFRPR
TRANSLOCATED INTO
NUCLEUS
RED LIGHT
FAR-REDLIGHT
Red light = ON
Far Red light = OFF
phy
phy
pRform
pFRform
Some plants require light to germinate
CB 39.18
phy inactive phy active phy inactive
Sunlight contains both r and fr light
R absorbed
lowR:FRratio
highR:FRratio
Gravity
courtesy: Roger Hangarter, Plants in Motion
http://plantsinmotion.bio.indiana.edu/plantmotion/starthere.html
QuickTime™ and aSorenson Video decompressorare needed to see this picture.
Starch grains detect vector of gravity
Blancaflor and Masson (2003) Plant Physiology 133:1677Kiss (2006) PNAS
103:829
Shoots
Growth occurs on ‘bottom’ side
shoots
Touch
touched not touched
Touch
courtesy: Roger Hangarter, Plants in Motion
FIRE
http://plantsinmotion.bio.indiana.edu/plantmotion/starthere.html
QuickTime™ and aH.263 decompressor
are needed to see this picture.
Touch
courtesy: Roger Hangarter, Plants in Motion
http://plantsinmotion.bio.indiana.edu/plantmotion/starthere.html
Changes in cell size close or open leaves
Interactions
• Light, gravity and touch
Wind
G
Light, gravity and touchLight
perceived by light receptorsblue light - movement towards lightred/far red (phytochromes) - germination
Gravityperceived by falling starch grainscells growth on one side bends shoot up
Touchelectrochemical gradient (like nerves in animals)changes cell size closes/opens leaves
Communication
www.panoptikum.net
Plants know when they are being
chewed on!
Insect saliva •
lets plant know which insect is attacking
Alerts othersJasmonic acid
ProteaseInhibitors
ProteaseInhibitors
http://www.geocities.com/brisbane_parawasps/images/Parasi3.jpg
Calls reinforcements“The enemy of my enemy is a friend of mine!”
SummaryMovement responses
triggers: light, gravity, touch
changes in cell length or cell size
Communication responses
triggers: herbivores
release of volatile chemicals (Jasmonic acid)
