Signal transduction

Why do plants sense signals

- they cant move so its important for them to resposd to all signals

• n  Hormones,
• n  Light
• n  Drought, flooding
• n  Temp
• n  Signalling molecules

PLant recieves many signals - respond by changing plant growth and metabolism e.g. increasd root density - fit for survival.

Cellular level signalling

signalling at cell level translates to tissues and organs - respond via ion flux, gene expression cytoskeleton etc. changes

Long Distance Signal Transduction

signal recieved from one part to another part of plant. eg.

- -- length of photoperiod --

for when tuber will form - plant percieves amount of light and adjust if tubors form in roots.

Agriculturally - want to develop potato variety in part of worlw diff daylengths understanding plant responses can manipulate tubor growth to be better in diff environments

--Systemic defence to herbivores --

Plant sense mechanical stuimulus of insect chewing sends a long distance signal ton toher leaves.

- up regulates defense response so non damaged leaves have increased resitance to herbivory

 Short Distance Signal Trsnduction -1

some plants have root nodules  hat contain bacteria so that they can fix nitrogen to provid eplant with nutrition. 

Beneficial soil bacteria release small peptides called NOD FACTORS

• - This is sensed by root hairs which allows bacterial interaction
• - Allows bacterial entry into root hair
• - Leads to changes in cell division and structure

Short Distance Signal Transduction - 2

e.g.hydropatterning in roots 

-  growing roots show that epidermal cells sense water and induce root hair formation in the direction of water

- if water is all around roots grow in all diff directions

- if water grows straight down 

Different responses to same signal

--Different parts respond different to same signal

Gravity:

shoows are negative to grvitropism and grow up

roots are positive to gravitropism and grow down

Siganlling Mechanisms

Threee steps:

1. Signal PERCIEVED by receptor

2. singla TRANSDUCED via signalling cascade

- protein conformation chainge, change in receptor activity, induces secondary messengers

3. singla trandsuctions leads to CELLULAR RESPONSE

- changes gene transcription, turgor , cytoskeleton etc

PERCIEVED, TRANSDUCED, RESPONDS ;)

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