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Plant Phys > Abiotic Interactions > Flashcards

Abiotic Interactions Flashcards

1
Q

Main examples of primary abiotic affects on plant growth

A

light, water, CO2, O2, soil nutrient content and availability, temperature and toxins

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2
Q

Define ideal plant growth conditions

A

conditions that allow the plant to achieve maximum growth and reproduction potential measured by components of total biomass

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3
Q

Define stress

A

any environmental condition, abiotic or biotic, that prevent the plant from achieving full genetic potential (growth and reproduction)

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4
Q

explain competition within plants/plant processes when under optimal growing conditions vs. when under stress conditions

A

optimal = minimal competition because can grow and reproduce where see fit
stress = competition present between reproduction and growth, where plants will likely use energy to reproduce even if not at full size

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5
Q

Define annual vs. perennial plants

A

annual = plants that complete a life cycle in a single season
perennial = plants that have multiple seasons to produce seeds

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6
Q

How would annual vs. perennial plants use their energy differently for growing and reproducing

A

annual plants would adjust to focus on reproducing as many viable seeds as possible
whereas perennial plants would adjust to ensure optimal storage of resources and enable surviving to the next season

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7
Q

Define acclimation

A

improvement of a response with repeated exposure to a stress that is a non-permanent change that is epigenetic instead of genetically passed down

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8
Q

Define adaptations

A

changes in a population over many generations due to natural selection that are heritable changes

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9
Q

How does the stress, temperature, affect plants

A

increase temperature increases fluidity (and vise versa)
and fluidity disrupts the coupling between protein complexes resulting in reactive oxygen species that can cause cell damage

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10
Q

What is plants most limiting resource, explain

A

water
97% lost to transpiration
1% used for metabolic processes (photosynthesis)

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11
Q

Define water deficit

A

caused by intermittent to continuous periods without precipitation

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12
Q

Define drought

A

term for a period of insufficient precipitation resulting in plant water deficit

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13
Q

How does the stress, water deficit, affect plants

A

cell dehydration occurs and affect basic physiological processes (Ex. cell turgor)
also induces ABA accumulation which promotes stomatal closure, reducing water loss and gas exchange and inhibiting photosynthesis

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14
Q

Define osmotic stress

A

due to salinity and results in water deficit symptoms

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15
Q

Define cytotoxicity

A

toxic to living cells that results from accumulation of toxic ions interfering with nutrient uptake

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16
Q

Define halophytes vs. glycophytes

A

halophytes = salt tolerant plants with genetic adaptations to saline conditions
glycophytes = plants not adapted to saline conditions that show growth inhibition and leaf discolouration

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17
Q

How does the stress, salinity, affect plants

A

cytosolic Na increases and ions become cytotoxic and can cause protein degradation and membrane destabilization in the plant

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18
Q

Explain the effects of salinity occurring in 2 phases

A

fast response = reduction in shoot growth, leaf expansion, and inhibition of lateral bud form
slow response = accumulation of toxic Na in leaves and inhibits photosynthetic and biosynthetic processes.

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19
Q

What do extreme temperatures do to the plant

A

melt or harden RNA and DNA secondary structures which can cause protein buildup and degradation

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20
Q

explain the effects of freezing temperature causing ice crystals

A

ice crystals can be lethal and likely form in apoplast because they have a higher freezing point.
ice crystals in apoplast decrease water potential causing the cell to become more negative and unfrozen water moves from the cell and causes plasma membrane to contract and pull away from the wall
plasma may become damaged and symplast loses 90% of osmotic active water

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21
Q

how does the stress, flooding, affect plants

A

oxygen decreases in the roots because air in the soil is replaced by water.
causes less energy production and slowing of many processes resulting in acidification of cytosol and toxicity from ethanol accumulation.

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22
Q

why should you not rapidly increase oxygen levels after flooding

A

because ROS will increase and can cause damage to plant root cells

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23
Q

Define anaerobic stress and results

A

the absence of oxygen that can cause cell death within hours-days depending on the degree of genetic adaptation of the species

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24
Q

Define light stress

A

occurs when high light intensity overwhelms capacity of photosynthetic machinery

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25
Q

What do plants do to increase light capture

A
  1. add more light harvesting chlorophyll units to PSII
  2. increase number of PSII relative to PSI to enhance light capture and energy transfer
26
Q

How does the stress, high light, affect plants

A

overwhelms ability to convert energy into sugars and can results in producing ROS and causing cell damage

27
Q

How does excess UV radiation affect plants

A

disrupts photosynthesis, damages DNA, and induces formation of ROS

28
Q

How does the stress, heavy metals, affect plants

A

uptake and disrupt photosynthesis, mineral utilization, and enzymatic functions

29
Q

heavy metals can mimic _____

A

essential metal ions

30
Q

explain aluminum as an essential metal

A

it is a major component in soils but becomes toxic in acidic solutions and can cause stunted growth

31
Q

essential nutrients can be…

A

toxic and cause stress in excess

32
Q

explain the acclimation of a single stress vs. a combination of stresses

A

they can be different!

33
Q

Explain the difference in acclimation of heat on it’s own vs. heat and drought

A

heat = increase plant stomatal conductance so leaves lose heat by open stomata and heat
vs.
heat and drought = stomata are closed to reduce lose of water and cause leaf temperature to increase

34
Q

explain the results of heavy metal or salinity with heat

A

enhanced transpiration (to cool down) could result in enhanced uptake of Na or heavy metals

35
Q

Examples of benefits of combinations

A

drought and ozone, ozone and UV, high CO2 and drought

36
Q

What is cross-protection

A

sequential exposure to different abiotic stresses that results in accumulation of the same general response proteins and metabolites and they persist after the stress conditions has reduced

37
Q

stress can cause signaling pathways to (sensing)

A

damage if not adapted, receptor activation to either phosphorylation or secondary messengers

38
Q

what developmental program is activated in response to stress

A

phenotypic plasticity

39
Q

What are the 5 main ways leaves show phenotypic plasticity to stresses

A
  1. leaf structure
  2. orientation
  3. rolling
  4. trichomes
  5. waxy cuticles
40
Q

Explain how leaf structure/area changes in response to stress

A

flat for optimal surface for production of photosynthates and increase in surface area for evaporation and absorption

41
Q

Explain how orientation (and rolling) changes in response to stresses

A

parallel or perpendicular to sun to reduce damage
also rolling and wilting of the leaves changes interception of radiation and reduces damage

42
Q

Explain how trichomes change in response to stress/display phenotypic plasticity

A

hair-like epidermal cells, can be densely packed and reflect radiation and reduce evaporation to keep leaves cooler
however disadvantage is in pubescent leaves they reflect needed light for photosynthesis

43
Q

Explain how the cuticle responds to stress/ displays phenotypic plasticity

A

consists of a multi-layer of waxes and hydrocarbons on the epidermis that reflects light, restricts diffusion of gases and water, and deters pathogens

44
Q

Specifically, ____ structures are sensitive to stresses such as

A

protein structures
temperature, pH, light, etc.

45
Q

Define molecular chaperone proteins

A

proteins that physically interact with other proteins to facilitate protein folding, reduce misfolding, and stabilize tertiary structures

46
Q

Define heat shock proteins

A

a unique chaperone protein type that synthesizes in response to many stresses.
ex. to heat stress, they improve thermal tolerance that would otherwise be lethal

47
Q

Define late embryogenesis abundant (LEAs)

A

proteins that accumulate with response to dehydration during later stages of seed maturation.

48
Q

Define hydrophilins

A

a group of proteins with strong affinity for water and have molecular shielding which reduce aggregation of sensitive proteins

49
Q

Define dehydrins

A

proteins that accumulate due to stress, serve as molecular shielding and cryoprotectants

50
Q

____ and ____ can send distress signals to the _____ to influence stress responses

A

chloroplast and mitochondria
nucleus

51
Q

What is the response of ABA hormone

A

most rapid response in drought conditions that controls stomatal closure and guard cell turgor

52
Q

when water is limited, ____ reduces before the _____ is affected

A

leaf expansion
photosynthetic activity

53
Q

What regulates the shoot:roots ratio and how does it change with stress

A

ABA controls it
it increase with roots growing at the expense of leaves

54
Q

Define osmotic adjustment

A

capacity for plants to accumulate solutes and use them to lower water potential during osmotic stress

55
Q

what are the two main ways of osmotic adjustment

A

one with vacuole and one with cytosol

56
Q

Explain the uptake of ions during osmotic adjustment

A

plants take up ions from soil mainly into vacuole, then other solutes accumulate in cytosol to maintain equilibrium between 2 compartments

57
Q

Define compatible solutes

A

organic compounds that are osmotically active in the cell but do not destabilize membranes or interfere with enzyme functions like ions do

58
Q

Define aerenchyma

A

tissue formed by root cells separated by prominent air-filled spaces in plants well adapted to wetland conditions

59
Q

What happens in the response to ROS accumulation during many stresses

A

they are detoxified by specialized enzymes and antioxidants (accept electrons from ROS and neutralize them) by ROS scavenging processes

60
Q

What are the 2 main ways to cope with toxic metals and metalloid ions and explain each

A
  1. exclusion = ability of plants to block uptake of toxic ions preventing reaching toxic levels which involves the activation of plasma membrane and ion transport proteins
  2. internal tolerance = biochemical adaptations that enable plants to tolerate, chelate, or compartmentalize with elevated concentrations of potential toxic ions
    (hyperaccumulation = internal tolerance to toxic ions, but rare)
61
Q

Define/explain supercooling

A

occurs during rapid freezing in protoplast when water remains liquid below its theoretical freezing point

62
Q

Define antifreeze proteins

A

specialized proteins that limit growth of ice crystals by binding to them to slow their growth

Plant Phys (15 decks)

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