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L3 Plant Sciences > Week 14 L6: Abiotic Environment - Water Stress > Flashcards

Week 14 L6: Abiotic Environment - Water Stress Flashcards

1
Q

What is the abiotic environment?

A

everything that isnt another organism e.g. soil, light levels

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2
Q

What do plants needs to live?

A

light water CO2

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3
Q

Does the amount of CO2 in the atmosphere vary?

A

no- constant, plant doesnt have to adapt

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4
Q

When does CO2 levels change?

A

e.g. volcano

CO2 enriched

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5
Q

What light changes does a plant have to adapt to?

A

quality, quantity and direction

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6
Q

What water changes does a plant have to adapt to?

A

availability, air vs soil, transpiration

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7
Q

What are the different water conditions?

A

drought salinity cold

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8
Q

What traits are being looked at with water and agricultural improvement?

A

survival traits and yield traits

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9
Q

What does modern thinking focus on in regards to plant breeding?

A

yield traits

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10
Q

What is water use efficiency?

A

least volume of water for largest amount of food is what you want.
How much biomass/crop you make per unit volume fo water.

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11
Q

What does constitutive mean abilities?

A

traits there all the time = constant

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12
Q

What are examples of constitutive abilities?

A 
Hairy leaves
C4 or CAM photosynthesis
Waxy cuticle
Folded leaves
Photosynthetic stems with loss of leaves
Swollen stems or leaves
Thermonasty
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13
Q

What are examples of adaptive abilities?

A 
Stomatal closure
C4 or CAM photosynthesis
Compatible solute production
Heat shock protein production
LEA protein production
Detoxification/Sequestration
Pigment production
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14
Q

How would you describe the constituitive abilities of plants?

A

mostly developmental

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15
Q

How would you describe the adaptive abilities?

A

mostly by gene induction

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16
Q

How quick can adaptive abilities occur?

A

minutes, hours and sometimes days

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17
Q

When will water stress of a plant occur?

A

Common effect of salt, drought and freezing stresses

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18
Q

What is the classic plant stress hormone?

A

ABA

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19
Q

How would you describe the constitutive abilities of plants?

A

mostly developmental

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20
Q

What is the classic plant stress hormone?

A

ABA

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21
Q

How do plants know if a stress is going to occur?

A

Given sufficient warning plants can at least partially adapt to these conditions
predict stress by other factors.
Plant might not encounter the stress, they can detect other signals that equate to that stress coming along.

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22
Q

What abilities do plants have to adapt to stress?

A

predict ability and memory ability

23
Q

What are biochemical drought adaptaion mechnaims in plants?

A
  • Compatible solutes - osmolytes
  • Protein folding and stabilising 0 prevent denaturation and aggregation
  • Membrane stabilising - prevent phase transitions and lysis
24
Q

What are the physiological adaptations in plants?

A

stomatal closure

25
Q

What are stomata?

A

Stomata are pores on the leaf surface that allow transpiration (water loss) and gas exchange (CO2 in).

26
Q

What can happen to mangrove trees in a high salinity water?

A

water is pulled out of them due to salt in water.
Water potential outside the plant is lower than inside.
Just because its wet, doesn’t mean water is available.

27
Q

What is the constitutive ability of a plant?

A

responses that allows a plant to cope with low water availability.
They are developmental, evolved and they do them all the time because they are always living in those kinds of conditions.

28
Q

What kind of plants have adaptive ability?

A

crop plants, have to adapt to where they are grown

29
Q

When is salinity a particular issue to plants?

A

In irrigated land

30
Q

What can irrigation do to the soil?

A

water from irrigation, evaporates and leaves behind last deposits. Leading to highly saline soil.
Despite being miles away from any seawater

31
Q

How can the cold impact plants?

A

Climate change is increasing occurrence of unpredictable cold and freezing weather.

32
Q

What are yield traits?

A

maintaining growth and yield

33
Q

How are the water stresses of drought, salt and freezing common?

A

They all reduce the water uptake of the plant

34
Q

What does turgor mean?

A

Pressure exerted by fluid in a cell that presses the cell membrane against the cell wall. Turgor is what makes living plant tissue rigid. Loss of turgor, resulting from the loss of water from plant cells, causes flowers and leaves to wilt.

35
Q

What changes in the plant due to reduced external water potential?

A

Loss of turgor
Membrane damage
Protein denaturation
Increase in ABA synthesis but also ABA independent pathways

36
Q

What is the difference between cytoplasm and cell wall in a water-deprived and a plant in plentiful water?

A

The plant in an environment with enough water. The cytoplasm has no gaps between it and the cell wall.

Drought conditions, lose turgor and become flaccid. there is a gap between the plasma membrane and the cell wall.

Lead to ABA synthesis

37
Q

What are examples of biochemical drought adaptation mechanisms? ABA responses?

A
  • Compatible solutes osmolytes (and antifreeze)
  • Protein folding and stabilizing – prevent denaturation and aggregation
  • Membrane stabalizing - Prevent phase transitions and lysis.
38
Q

How does the compatible solutes help with drought adaptation?

A

help balance the water potential on the inside to the outside to help water stay in the cell.

39
Q

What are the compatible solutes which help with drought adaptation?

A

proline
sugars
quaternary ammonium compounds

40
Q

How does protein folding and stabilising help with drought adaptation?

A

prevent denaturation and aggregation

41
Q

What substances are involved in protein folding and stabilisation?

A

Induction of heat shock proteins
Induction of LEA proteins
Polyols
Proline

42
Q

What is the purpose of polyols and proline in protein folding and stabilisation?

A

They substitute for water in terms of hydrogen bonding.

43
Q

How does the membrane stabilising help in drought adaptation?

A

prevent phase transitions and lysis

44
Q

How does the plant stabilise its membrane?

A

Increase phospholipids and reduce ceramides

Induction of LEA proteins.

45
Q

How does changes in temperature alter the membrane?

A

the membrane fluidity changes according to temperature.

If fluidity is reduced too much it ruptures and buckles.

46
Q

How does the plant maintain fluidity of the membrane?

A

As things get hot, increase amount of saturated lipids. A temps gets cold, increase amount of unsaturated lipids.

47
Q

What is the purpose of LEA proteins?

A

Late embryogenesis abundant (LEA) proteins are mainly low molecular weight (10-30 kDa) proteins, which are involved in protecting higher plants from damage caused by environmental stresses, especially drought (dehydration).

Hugh amino acid composition that leads to high hydrophilicity and heat stability in membrane and mannitol, ie membrane stability.

48
Q

What can LEA proteins be classed as?

A

hydrophilins

49
Q

What is mannitol and what can help stabilise it?

A

an osmotic or metabolic store. powerful quencher of reactive oxygen species (ROS). … Mannitol is essential in pathogenesis to balance cell reinforcements produced by both plants and animals.

LEA proteins help stabilise.

50
Q

What can happens within minutes of the plant ABA levels increasing?

A

stomata closure

51
Q

Why would the stomata close in a water stress situation?

A

Stomata are pores on the leaf surface that allow transpiration (water loss) and gas exchange (CO2 in).

52
Q

What are the guard cells?

A

pairs of epidermal cells that control gas diffusion by regulating the opening and closure of stomatal pores.

53
Q

What is a stoma and what is it surrounded by?

A

pore on the surface of the leaves and other aerial parts. surrounded by a pair of guard cells.

54
Q

What moves in and out of the stoma?

A

uptake of CO2 for photosynthesis and the loss of water vapour from the transpiration stream.

L3 Plant Sciences (17 decks)

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