Improving WUE

Question 1

What are the three main factors controlling water use efficiency in plants?

Answer 1

• Cuticle (low permeability)
• Boundary layer (thin layer of still air)
• Stomata

Question 2

What is the main balance that stomatal opening controls?

Answer 2

Stomata control the balance between:
- CO2 entering for photosynthesis
- H2O exiting through transpiration

Question 3

How does light, CO2 an water affect stomatal opening?

Answer 3

Low light promotes stomatal opening
Low Co2 promotes stomatal opening
Low water promotes stomatal closure

Question 4

What is the relationship between stomatal density and drought tolerance?

Answer 4

Plants with fewer stomata:
- Have decreased water loss in the lead
- Are more drought tolerant

Question 5

What has research sown about reduced stomatal density in crop plants?

Answer 5

• Barley with lower stomatal density is more drought tolerant with no yield cost
• Rice with lower stomatal density is more drought tolerant with no yield loss

Question 6

What are the grand challenges in improving water use efficiency?

Answer 6

• Evolutionary conservation of metabolic pathways C3/C4
• Evolutionary distinctness of some C3 species (rice)
• Control of leaf structure
• Advances in evolutionary genomics
• Advances in gene editing / transformation
• Understanding of stomatal function
• Evolutionary conservation of stomatal signalling / patterning