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Low temperature stress

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Chilling & freezing stress Chilling Chilling injury occurs at temperatures lower than normal growth temperatures, but not freezing temperatures temps around 10C ... – PowerPoint PPT presentation

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Title: Low temperature stress


1
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2
Chilling freezing stress
  • Chilling
  • Chilling injury occurs at temperatures lower than
    normal growth temperatures, but not freezing
    temperatures
  • temps around 10C
  • usually occurs in plants adapted to warm climates
  • The main damage caused by chilling is to the
    membranes
  • leakage of ions out of the cell
  • inefficient functioning of photosynthetic or
    respiratory ATP synthesis
  • leaf lesions, wilting

3
Freezing
  • Freezing damage occurs primarily due to the
    formation of ice crystals, which damage cell
    structure
  • ice usually forms first in the cell walls and
    intercellular spaces
  • damage occurs when ice crystals grow and
    puncture into the cytoplasm

4
Physiology of low Temp.
  • Chill-sensitive plants have a higher proportion
    of saturated fatty acids
  • 1-saturated lipids solidify at higher
    temperatures
  • 2-membranes change from fluid to gel as temps
    drop, lose function
  • Plants can become acclimated by slow exposure to
    colder temps, so
  • increase the proportion of unsaturated fats in
    the membranes

5
Physics of ice formation
  • In plants, the temperature of water will drop
    below its freezing temperature and will still
    remain liquid supercooling
  • for the transition to solid phase to take place,
    need ice nucleation points
  • when becoming solid, ice gives off heat, so the
    temperature rises
  • when all of the water in the cell wall has
    frozen, then the temperature begins to drop again

6
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7
Avoidance through supercooling
  • Many plants can avoid freezing injury, because
    they allow deep supercooling
  • the liquid in the intercellular space never
    makes the transition to solid phase, so ice
    crystals don't form
  • some can supercool down to -35C
  • at -40C, ice crystal formation begins
    spontaneously
  • occurs in hardwoods and some fruit trees

8
Plants that live in environments colder than -40C
usually don't supercool
  • ice crystal formation begins at -3 or -5C in the
    cell walls
  • over time, water is pulled from the cytoplasm and
    accumulates on the growing ice crystals (if temps
    drop slowly)
  • these plants must have sufficient intercellular
    space for ice crystals to grow
  • this results in greater concentration of solutes
    in the cytoplasm (dehydration)
  • these plants must also tolerate dehydration,
    similar effect during drought

9
Bacteria and ice formation
  • Some bacteria can promote ice crystal formation
    at warm temps (-3 or -5C)
  • formation of ice crystals at warmer temps can be
    damaging to the plants
  • can isolate mutant bacteria that do not promote
    ice formation, these can be sprayed on sensitive
    plants to protect them from frost damage
    (strawberry)
  • Acclimation to cold involves the expression of
    some different genes
  • isoforms of enzymes that are active at lower
    temps )antifreeze protein(

10
According to lindow (1984) report, effective
bacteria for cold injury
  • I ce nucleation active bacteria
  • Pseudomonas syringae
  • P. fluorescens
  • Ervinia herbicola
  • E. Stewartii
  • Therefore, using bactericides inhibit freezing

11
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12
Cold Tolerance
  • It is plain for all to see that some plants are
    able to survive low temperatures whereas others
    are not. While it is not know precisely what is
    required for cold tolerance, it is known that
    plants respond to low temperatures in a number of
    ways.
  • These responses include synthesizing a large
    number of proteins that are not expressed under
    normal conditions. The functions of these
    cold-induced proteins are also not well understood

13
Protein synthesize
  • organisms typically do not waste their resources
    making proteins that do not serve an important
    and useful function. In this case, you might
    guess that the function of cold-induced proteins
    would be to help the plant survive low
    temperature conditions

14
How can this set of proteins be activated in
transgenic plants?
  • The approach to this question has been to
    identify what activates all the genes that are
    expressed when it gets cold. The activator is a
    protein that switches on transcription of
    cold-induced genes, referred to as a
    transcription activator. The diagram below
    illustrates how this activator functions.
  • Low temperatures --gt Activator is induced --gt
    Cold-induced genes are expressed
  • ?? ???? ?? ???? ??? ?? ????? ?????? ???? ?????
    ???? (???????) ??? ???? ???? ?? ?? ? ??????
    ?????? ?? ?? ???? ?????? ?? ???? ?? ?????.

15
Calcium level and cold stress
  • Some plants can adapt to chilling and
    dehydration,
  • and some can actually develop a tolerance to
    freezing.
  • Low temperature stress appears to be signaled by
    an increase in cellular levels of calcium.
  • Sustained exposure to cold stress can cause
    chronic calcium elevation, resulting in
    organismal death.
  • Thus, calcium levels must be carefully
    controlled.

16
Calcium Cont.
  • a connection between stress induced and
  • increases in cellular calcium and the similar
    induction of calcium-binding proteins, suggesting
    a physiological role for these proteins in cold-
    and dehydration-stress management.

17
calcium-binding proteins are requisite for plants
to respond to dehydration and cold-stress
  • Testing whether these calcium-binding proteins
    are requisite for plants to respond to
    dehydration and cold-stress.
  • The identification of the location of these
    proteins within the cell and the mechanisms by
    which their calcium-binding properties may be
    regulated will help us to understand the
    biochemical mechanisms that underlie plant
    responses to stress. Through this increased
    understanding we will be better able to manage
    plants in variable and adverse environments.

18
  • Whats relation between photoperiod acclimation
    and tolerance?
  • How long will be hardiness?

19
  • freezing tolerance is not affected by the
    photoperiod but acclimation is mainly triggered
    by low nonfreezing temperatures.
  • Cold acclimation is a rather rapid process in
    many herbaceous species. Upon return to normal
    growth temp. freezing tolerance is rapidly lost.

20
  • Except low temp. which kinds of other factors may
    be tolerated plant?
  • Whats physiol. And Bioch. Changes after
    acclimation?

21
  • In addition to low non-freezing temperatures,
    cold acclimation can be
  • triggered by exposing the plants to moderate
    water stress or exogenously applied abscisic acid
    (ABA).
  • Cold acclimation is associated with several
  • physiological and biochemical alterations in the
    plants.The best-characterized changes include
  • alterations in gene expression, changes in
    hormone levels, increases in soluble sugars,
    amino acids and organic acids, accumulation of
    osmoprotectants and protective proteins as well
    as modification of membrane lipid
  • composition

22
  • Which evidences show the role of ABA in
    acclimation?
  • Whats primary sensor to cold stress?

23
  • Several lines of evidence indicate the role of
    ABA-controlled processes in cold acclimation
  • (i) Exogenous application of ABA at normal
    growth temperature leads to increased freezing
    tolerance
  • (ii) There is a transient increase in endogenous
    ABA at the onset of acclimation
  • (iii) Several low temperature induced genes are
    also responsive to ABA

24
Primary signal to low temperature
  • primary signal might be the change in membrane
    fluidity, which is one of the most rapid effects
    of temperature on the plasma membrane.
  • Reduction of membrane fluidity would lead to gene
    activation, are not understood.
  • a clear correlation between temperature and
    calcium influx to the cells has been
    demonstrated.
  • temperature modulated Ca channel could indeed be
    involved in the temperature sensing.

25
  • ????? ?? ?? ???? ??? ????? ????? ?? ?????
  • ???? ????? ??? ?? ?? ???? ?????
  • ?? ??? ???? ??? ???? ?? ???? ? ????? ????? ????
    ??????? ??????????? ?????

26
  • ????? ?? ???????? ????? ????? ???? ??
  • ?? ?? ???. ??? ?? ???? ?? ??? sym ? ?op
    ??? ?? ?? ????? ????? ???? ?? ? ???????? ???? ??
    ???? ? ?? ???? ???? ?? ???? ???????? ?? ???.
    ???? ?? ??? ??? ??? ??? ?? ?? ?? ???? ?? ???
    ???????? ?? ?? ??? ? ??????? ??? ????? ?? ??
    ???? ???? ???.

27
  • ????? ??? ??
  • ?? ??? ?????? ??? ????? ????????? ?? ???? ???.
    ??? ??? ????????? ???? ???. ???? ?? ??? ???
    ????? ???? (????????) ???? ?????? ???? ????? ??
    ??? ?? ???????? ?? ????? ????????? ?? ????
    ???? ???? ???? ??? ?????? ??? ??? ???? ????
    ???? ???? ???? ????? ???? ?? ??? ???? ?? ??? ?
    ??? Leakage ?? ???? ? ?????? ?? ??? ???? ??
    ??? ?? ????

28
  • Acclimation ? ??????? ?????
  • ????? ??
  • ???? ?? ? ?????????? ????? ????? ?? ?????
    Acclimation
  • ???? ?? ????
  • ??????????
  • ????? ?????????? ?????? ???? ?? ????. ?????
    ?????? ???? ?? ????.

29
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30
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31
  • ???????
  • ????????? ??????? ?? ??? ????? ?? ????? ??
    ???.??????? ???? ?? ??????? ??? ????? (????
    ????? ??) ?? ?????? ???? ?? Acclimation ?????
    ??? ???.
  • ??????
  • ???? ?????? ? ???? ??? ??? ????? ?????? ?? ????
    ? ??? ??????? ????? ?? ?????? ?????? ?? ??????.

32
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33
  • ABA
  • ABA ??????? ????? ??? ???? ????? ??? ??? ?????
    ?????? ????? ???? ??????? ??? ????? ???????
    ??????? ????? ? ??????? ?? ?????? ????
  • ABA ?? ????? ????? ?????? ?? ?????? ?? ????
    ???? ???. ?????? ABA ?????? ?? ????? ?????
    ?????? ??? ?? ?? ????? ?? ???? ??????? ?????
    ?? ????.

34
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35
  • ???????? ????? ? ?????????
  • ??? ??????? ? ????? ?? ?? ?????? ?? ???? ??????
    ???? ????
  • ?? ?? ??????? ????? ?????? ???? ???? ?? ???
  • ???? ABA / GA
  • ????? ?????? ?? ????? ?? ?????
  • ????? ???? ????? ??? ? ????? ????? ?? ???
  • ?????? ?? ???? ?? ???? ?? ???.
  • ????????? ?? ???? ???????? ??? ?? ?? ????? ?????
    ???? ???. ? ?????? ????? ABA ??? ????? ?? ????.

36
  • ??????? ????????? ???? ?? ??????? ?? ???? ?????

37
???????? ????????? ???? ?? ???????
  • ?????? ABA ? NADPH
  • ?? ?? ????? ???? ??????? ?? ???????? ????????
    ???
  • ?? ?????? ABA ?????? ????? ??????? (Rubisco)
    ???? ?? ???? ? ???? ????? ?? ???? ?? ???.

38
  • ????? PEP ?????????? ?????? ?? ???? PEPC
  • 3Co2 ? 6PGA PEP Co2 ? OAA (MA)

  • PEPC ???? ???? ?? ??? ???? ????? ??? ?????? C4
    ?????? ?? ???? ?? ????? ???? PEPC ????? ??? ???.
    MA ?? ???????? ????? ????? ?? ???.
  • ATP ?? ???? ????? ?? ???? ???? ?? ??? ?? ????
    ???? ? ?? ????? ??????? ????? ?? ????.

39
  • ????????? ???
  • ???? ????????? ??? ?? ??? ???? ???
  • 1- ATP ???? ??? 2- NADPH ?? ?? ?????????
    ??? ???? ???.
  • ???? ????? ?? ???? ???? ???? ????????
  • NADPH / NADP ???? ?? ????? ??? ?? ????.
  • PEP ?? ???? ? ????? NADPH ????? ?? ??? ????????
    ???? ????? MA ?? NADPH ???? ???.
  • ??? ????? ???? ??? ?????? ?? ???? ????? ??
    ????.
  • ?? ??? ?? ????? ???? ????? NADPH ?? ?????
    ?????? ??? ??? ???? ?????? ?? ???? ????? ???.

40
  • ?????? ??????? ????? ??? ??????
  • ???? ?? ????.
  • ??????? ??? ???????? ?? ????? ??? ?? ????? ????
    ???? ???? ??? ?? ???? ATP ? NADPH ?????? ??
    ????.
  • NADPH ????? ???????? ??? ????????? ?? ???? ??
    ??? ? ???? ?? ??? ?? ??????? ?? ?? ??? SH
    ???? ????? ???? ??????? ??? SH ?? ?? ??? ?????
    ??? ?????? ?? ???? ????? ????? ??.

41
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42
  • ???? ??? ????? ???? ?? ??????? ?? ??? ?????

43
  • ???? ??? ????? ???????
  • 1- ???? ??? ??? ??? ??????
  • Black heart
  • ?? ???? ???? ????? ?? ???? ???? ??? ??? 2 ??
    ???? ??? ????? ???. ???? ???? ?? ????
  • ?? ??? ???? ???? ???? ?? ?? ????.
  • ???? ???? ???? ???? ???? ???? ???? ????? ????
    ?? ?? ???? ????? ?? ???
  • ????? ???? ???? ??? ???? ??? ?? ???????? ????
    ????? ???? ???? ??????? ? ?? ???? ??????? ???
    ???? ???? ?? ???.

44
  • ????? ??????
  • ?? ?????? ?? ?????? ?? ????? ? ?? ???? ???? ???
    ?? ??? ????? ??? ?? ??? ? ??????? ???? ??????
    ????? ?? ????.
  • ?? ???? ???? ????? ???? ???? ?? ???? ??????
    ???? ????? ??? ??? ??? ???? ?? ??? ?? ??? (
    ?????? injury South west)
  • ?? ??? ????? ??????? ???? ????? ?? ?? ????
    ??????? ??? ???? ????? ????? ???? ?????? ?????
    ?? ??? (????? ?? ?? ???? verification )

45
  • ?????
  • ???? ???? ??? ????
  • ???? ????? ???? ???? ???? ????
  • ???????? ??? ????
  • ?????? ??????? ?????? ?????? ????? ??? Winter
    Burn
  • ???? ???? ????? ???? ??? ?? ??? ??????? ???? ??
    ??? ? ?? ???? ???? ????? ??????.
  • ?????? ????? ?? ??? ??? ????? ??? ??? ?? ?
    ????
  • ???? ?? ?? ???.
  • ??? ??????
  • ?????? ?? ?? ??? ?? ?? ???? ???? ?? ????? ??
    ???
  • ?? ?????? ?? ???? ??? ?? ???
  • ????? ???? ???? ????? ??? ?? ???? ?? ??? ?
  • ???? ?? ?? ?? ???.

46
  • ??????? ?? ???? ??? ??? Soil hearing
  • ?? ??????? ???? ???? ????? (????)? ???? ??? ??
    ?? ???
  • ?? ????? ???? ???? ???? ? ????? ????? ?? ??? ???
    ?????? ???? ?? ???? ? ???? ?? ??? ?? ????. ???
    ????? ??? ??? ?? ?? ????.
  • ??? ??? ??? ?? ??? ????? ???? ?? ???? ???? ????
    ?? ??????? ??? ???? ????? ?? ???? ?????? ?? ??
    ???? ? ??? ??? ?? ???? ??? ?? ???.

47
  • ????? ????
  • ?? ??????? ?? ???? ????? ?? ??? ??????? ???? ?
    ?? ??? ? ????? ????? ???? ???? ?? ???. ?? ??????
    ??? ????? ??? ??? ???????? ????.
  • ???????? ????? ?? ??????
  • Winter kill of dormant ?? ???? ?????? ?????
    ?????? ??????? ??? ???? ????? ??? ????? ?? ??
    ??? ??? ?? ????? ??? ??? ??? ? ?????? ??? ??
    ??? ??? ??? ????? ???? ???? ?? ????.

48
  • ??? ??????? ??????? ????
  • Shoot die back
  • ???? ??? ?????? ???? ?? ??? ????? ????? ?? ????
    ? ???? ????
  • ??? ???? ????? ? ????? ????? ????? ??????? ????
    ?????? ?? ????? ?? ??? ? ????? ?????? ?? ?????
    ??? ????? ??? ?????? ????? ???? ?? ???? ?? ??
    ????? ????.
  • ???????? ??? ??? ?? ????? ???????

49
  • ????? ??? ??? ???? ?? ?? ??????
  • Water Sauked
  • ??? ??? ? ???? ?? ?? ???? ??? ???? ?? ?? ???
  • ?? ???? ????? ????? ?? ?? ?? ??? ?? ??? ??????
    ????? ? ??? ????? ????? ?? ?? ??? ?????? ???? ??
    ???? ? ????? ??? ?? ???.
  • ?? ????? ????? ?? ???? ??? ????? ? ???????? ????
    ????
  • ??? ??? ?????
  • ??????? ?? ?? ????? ?? ???? ???? ?? ????? ????
    ??? ????? ???? ?? ??? ???? ?? ??? ????? ?????
    ??? ?? ???
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