L4- Grand challenges water use

Question 1

what is structure of leaf

Answer 1

top you have cutical- low permability
boundary layer- thin layer of still air
stomata- open/close
stomatal opening controls balance
co2 in for photosynthesis, h2o out for transpiration

Question 2

what are stomata

Answer 2

openings in leaf
when gaurd cells are flaccid the stomatal pore is cosed, to open stomata H+ is forced from the gaurd cells, leads to K+ uptake into the gaurd cells via activation of K+ channels, this lowers water potential so that water flows from epidermal cells into the gaurd

light-
low light promotes stomatal opening
-blue light more effective then red light

CO2
-low co2 promotes opening

water stress
-low water promotes stomatal closure

Question 3

how can you improve water-use efficiency

Answer 3

water loss modulated by
- stomatal open/closed, number (density) of stomata

gene and signals control stomatal differentiation
-transcription factor provides cell identity/differentiation
-peptide signals provide local communication (EPF1, EPF2) via specific receptors (TMM)

seen via infared thermal imaging

Question 4

what is effect of stomatal density

Answer 4

plants with fewer stomata are more drought tolerant, but if ur strategy for life is to grow more and outcompete neighbours then more stomata beneficial

decreased stomatal density leads to decreased water loss, however less CO2 fixation (trade off)

But overall water-use efficiency increases

Question 5

what is water-use efficiency in barley

Answer 5

barley with a lower stomatal density is more drought tolerant, with NO yield loss

rice with a lower stomatal density is more drought tolerant, with NO yield loss

Question 6

can you target individual stomata

Answer 6

polymer in cell wall called pectin, this exists in methylated and de methylated form, if you demthylate this it allows CA2+= this makes cell wall much stronger/stiffer, this could make opening and closing more rapid and so more efficient