Light regulation of growth

1

• Light regulation of growth
• Plants sense
• Light quantity
• Light quality (colors)
• Light duration
• Direction it comes from

2

• Types of Phytochrome Responses
• Two categories based on speed
• 3 classes based on fluence (amount of light
  needed)

3

• Circadian rhythms
• Many plant responses show circadian rhythms
• Once entrained, continue in constant dark, or
  light!
• Gives plant headstart on photosynthesis, other
  processes that need gene expression

4
Circadian rhythms Light TOC1 activate LHY
CCA1 at dawn LHY CCA1 repress TOC1 in day, so
they decline too At night TOC1 is activated (not
enough LHY CCA1) Phytochrome entrains the clock
So does blue light
5

• Blue Light Responses
• Circadian Rhythms

6

• Blue Light Responses
• Circadian Rhythms
• Solar tracking

7
Blue Light Responses Circadian Rhythms Solar
tracking Phototropism
8
Blue Light Responses Circadian Rhythms Solar
tracking Phototropism Inhibiting stem elongation
9
Blue Light Responses Circadian Rhythms Solar
tracking Phototropism Inhibiting stem
elongation Chloroplast movement
10
Blue Light Responses Circadian Rhythms Solar
tracking Phototropism Inhibiting stem
elongation Chloroplast movement Stomatal opening
11
Blue Light Responses Circadian Rhythms Solar
tracking Phototropism Inhibiting stem
elongation Chloroplast movement Stomatal
opening Gene expression
12
Blue Light Responses Circadian Rhythms Solar
tracking Phototropism Inhibiting stem
elongation Chloroplast movement Stomatal
opening Gene expression Flowering in Arabidopsis
13
Blue Light Responses Circadian Rhythms Solar
tracking Phototropism Inhibiting stem
elongation Chloroplast movement Stomatal
opening Gene expression Flowering in
Arabidopsis Responses vary in their fluence
requirements
14
Blue Light Responses Circadian Rhythms Solar
tracking Phototropism Inhibiting stem
elongation Chloroplast movement Stomatal
opening Gene expression Flowering in
Arabidopsis Responses vary in their fluence
requirements lag times
15
Blue Light Responses Responses vary in their
fluence requirements lag time Stomatal opening
is reversible by green light others arent
16
Blue Light Responses Responses vary in their
fluence requirements lag time Stomatal opening
is reversible by green light others
arent Multiple blue receptors with different
functions!
17
Blue Light Responses Responses vary in their
fluence requirements lag time Stomatal opening
is reversible by green light others
arent Multiple blue receptors with different
functions! Identified by mutants
18
Blue Light Responses Responses vary in their
fluence requirements lag time Stomatal opening
is reversible by green light others
arent Multiple blue receptors with different
functions! Identified by mutants, then clone the
gene and identify the protein
19
Blue Light Responses Responses vary in their
fluence requirements lag time Stomatal opening
is reversible by green light others
arent Multiple blue receptors with different
functions! Identified by mutants, then clone the
gene and identify the protein Cryptochromes
repress hypocotyl elongation
20
Blue Light Responses Cryptochromes repress
hypocotyl elongation Stimulate flowering
21
Blue Light Responses Cryptochromes repress
hypocotyl elongation Stimulate flowering Set the
circadian clock (in humans, too!)
22
Blue Light Responses Cryptochromes repress
hypocotyl elongation Stimulate flowering Set the
circadian clock (in humans, too!) Stimulate
anthocyanin synthesis
23
Blue Light Responses Cryptochromes repress
hypocotyl elongation Stimulate flowering Set the
circadian clock (in humans, too!) Stimulate
anthocyanin synthesis 3 CRY genes
24
Blue Light Responses 3 CRY genes All have same
basic structure Photolyase-like domain binds FAD
and a pterin (MTHF) that absorbs blue transfers
energy to FAD in photolyase (an enzyme that uses
light energy to repair pyr dimers)
25
Blue Light Responses 3 CRY genes All have same
basic structure Photolyase-like domain binds FAD
and a pterin (MTHF) that absorbs blue transfers
energy to FAD in photolyase (an enzyme that uses
light energy to repair pyr dimers) DAS binds COP1
has nuclear localization signals
26
Blue Light Responses 3 CRY genes All have same
basic structure Photolyase-like domain binds FAD
and a pterin (MTHF) that absorbs blue transfers
energy to FAD in photolyase (an enzyme that uses
light energy to repair pyr dimers) DAS binds COP1
has nuclear localization signals CRY1 CRY2
kinase proteins after absorbing blue
27
Blue Light Responses 3 CRY genes CRY1 CRY2
kinase proteins after absorbing blue CRY3 repairs
mt cp DNA!
28

• Blue Light Responses
• 3 CRY genes
• CRY1 regulates blue effects on growth
  light-stable
• Triggers rapid changes in PM potential growth

29

• Blue Light Responses
• 3 CRY genes
• CRY1 regulates blue effects on growth
  light-stable
• Triggers rapid changes in PM potential growth
• Opens anion channels in PM

30

• Blue Light Responses
• 3 CRY genes
• CRY1 regulates blue effects on growth
  light-stable
• Triggers rapid changes in PM potential growth
• Opens anion channels in PM
• Stimulates anthocyanin synthesis

31

• Blue Light Responses
• 3 CRY genes
• CRY1 regulates blue effects on growth
  light-stable
• Triggers rapid changes in PM potential growth
• Opens anion channels in PM
• Stimulates anthocyanin synthesis
• Entrains the circadian clock

32

• Blue Light Responses
• 3 CRY genes
• CRY1 regulates blue effects on growth
  light-stable
• Triggers rapid changes in PM potential growth
• Opens anion channels in PM
• Stimulates anthocyanin synthesis
• Entrains the circadian clock
• Also accumulates in nucleus interacts with PHY
  COP1 to regulate photomorphogenesis, probably
  by kinasing substrates

33

• Blue Light Responses
• 3 CRY genes
• CRY1 regulates blue effects on growth
  light-stable
• Triggers rapid changes in PM potential growth
• Opens anion channels in PM
• Stimulates anthocyanin synthesis
• Entrains the circadian clock
• Also accumulates in nucleus interacts with PHY
  COP1 to regulate photomorphogenesis, probably
  by kinasing substrates
• 2. CRY2 controls flowering

34

• Blue Light Responses
• 3 CRY genes
• CRY1 regulates blue effects on growth
  light-stable
• 2. CRY2 controls flowering little effect on
  other processes
• Light-labile

35

• Blue Light Responses
• 3 CRY genes
• CRY1 regulates blue effects on growth
  light-stable
• 2. CRY2 controls flowering little effect on
  other processes
• Light-labile
• 3. CRY3 enters cp mito, where binds repairs
  DNA!

36

• Blue Light Responses
• 3 CRY genes
• CRY1 regulates blue effects on growth
• 2. CRY2 controls flowering little effect on
  other processes
• CRY3 enters cp mito, where binds repairs DNA!
• Cryptochromes are not
• involved in phototropism or
• stomatal opening!

37

• Blue Light Responses
• Cryptochromes are not involved in phototropism or
• stomatal opening!
• Phototropins are!

38

• Blue Light Responses
• Phototropins are involved in phototropism
  stomatal opening!
• Many names (nph, phot, rpt) since found by
  several different mutant screens

39

• Phototropins
• Many names (nph, phot, rpt) since found by
  several different mutant screens
• Mediate blue light-induced growth enhancements

40

• Phototropins
• Many names (nph, phot, rpt) since found by
  several different mutant screens
• Mediate blue light-induced growth enhancement
  blue light-dependent activation of the plasma
  membrane H-ATPase in guard cells

41

• Phototropins
• Many names (nph, phot, rpt) since found by
  several different mutant screens
• Mediate blue light-induced growth enhancement
  blue light-dependent activation of the plasma
  membrane H-ATPase in guard cells
• Contain light-activated serine-threonine kinase
  domain and LOV1 (light-O2-voltage) and LOV2
  repeats

42

• Phototropins
• Many names (nph, phot, rpt) since found by
  several different mutant screens
• Mediate blue light-induced growth enhancement
  blue light-dependent activation of the plasma
  membrane H-ATPase in guard cells
• Contain light-activated serine-threonine kinase
  domain and LOV1 (light-O2-voltage) and LOV2
  repeats
• LOV1 LOV2 bind FlavinMonoNucleotide cofactors

43

• Phototropins
• Many names (nph, phot, rpt) since found by
  several different mutant screens
• Mediate blue light-induced growth enhancement
  blue light-dependent activation of the plasma
  membrane H-ATPase in guard cells
• Contain light-activated serine-threonine kinase
  domain and LOV1 (light-O2-voltage) and LOV2
  repeats
• LOV1 LOV2 bind FlavinMonoNucleotide cofactors
• After absorbing blue rapidly autophosphorylate
  kinase other proteins

44

• Phototropins
• After absorbing blue rapidly autophosphorylate
  kinase other proteins
• 1 result phototropism
• due to uneven auxin
• transport

45

• Phototropins
• After absorbing blue rapidly autophosphorylate
  kinase other proteins
• 1 result phototropism
• due to uneven auxin
• transport
• Send more to side away
• from light!

46

• Phototropins
• After absorbing blue rapidly autophosphorylate
  kinase other proteins
• 1 result phototropism
• due to uneven auxin
• transport
• Send more to side away
• from light!
• Phot 1 mediates LF

47

• Phototropins
• After absorbing blue rapidly autophosphorylate
  kinase other proteins
• 1 result phototropism
• due to uneven auxin
• transport
• Send more to side away
• from light!
• PHOT 1 mediates LF
• PHOT2 mediates HIR

48

• Phototropins
• 2nd result stomatal opening via stimulation of
  guard cell PM proton pump
• Also requires photosynthesis by guard cells!

49

• Phototropins
• 2nd result stomatal opening via stimulation of
  guard cell PM proton pump
• Also requires photosynthesis by guard cells
  signaling from xanthophylls

50

• Phototropins
• 2nd result stomatal opening via stimulation of
  guard cell PM proton pump
• Also requires photosynthesis by guard cells
  signaling from xanthophylls
• npq mutants dont
• make zeaxanthin
• lack specific blue
• response

51

• Phototropins
• 2nd result stomatal opening via stimulation of
  guard cell PM proton pump
• Also requires photosynthesis by guard cells
  signaling from xanthophylls
• npq mutants dont
• make zeaxanthin
• lack specific blue
• response
• Basic idea open when pump in K

52

• Phototropins
• 2nd result stomatal opening via stimulation of
  guard cell PM proton pump
• Also requires photosynthesis by guard cells
  signaling from xanthophylls
• npq mutants dont
• make zeaxanthin
• lack specific blue
• response
• Basic idea open when pump in K
• Close when pump out K

53

• Phototropins
• Basic idea open when pump in K
• Close when pump out K
• Control is hideously complicated!

54

• Phototropins
• Basic idea open when pump in K
• Close when pump out K
• Control is hideously complicated!
• Mainly controlled by blue light

55

• Phototropins
• Basic idea open when pump in K
• Close when pump out K
• Control is hideously complicated!
• Mainly controlled by blue light, but red also
  plays role

56

• Phototropins
• Basic idea open when pump in K
• Close when pump out K
• Control is hideously complicated!
• Mainly controlled by blue light,
• but red also plays role
• Light intensity is also important

57

• Phototropins
• Mainly controlled by blue light, but red also
  plays role
• Light intensity is also important due to effect
  on
• photosynthate in guard cells

58

• Phototropins
• Mainly controlled by blue light, but red also
  plays role
• Light intensity is also important due to effect
  on
• photosynthate in guard cells
• PHOT1 2 also help

59

• Phototropins
• Mainly controlled by blue light, but red also
  plays role
• Light intensity is also important due to effect
  on
• photosynthate in guard cells
• PHOT1 2 also help
• Main GC blue
• receptor is zeaxanthin!

60

• Phototropins
• Mainly controlled by blue light, but red also
  plays role
• Light intensity is also important due to effect
  on
• photosynthate in guard cells
• PHOT1 2 also help
• Main GC blue
• receptor is zeaxanthin!
• Reason for green reversal

61

• Phototropins
• Mainly controlled by blue light, but red also
  plays role
• Light intensity is also important due to effect
  on
• photosynthate in guard cells
• PHOT1 2 also help
• Main GC blue
• receptor is zeaxanthin!
• Reason for green reversal
• water stress overrides light!

62

• Phototropins
• water stress overrides light roots make Abscisic
  Acid closes stomates blocks opening regardless
  of other signals!

63
Plant Growth Size shape depends on cell
cell size Decide when,where and which way to
divide
64

• Plant Growth
• Size shape depends on cell cell size
• Decide which way to divide which way to
  elongate
• Periclinal perpendicular to surface

65

• Plant Growth
• Size shape depends on cell cell size
• Decide which way to divide which way to
  elongate
• Periclinal perpendicular to surface get
  longer

66

• Plant Growth
• Size shape depends on cell cell size
• Decide which way to divide which way to
  elongate
• Periclinal perpendicular to surface get
  longer
• Anticlinal parallel to surface

67

• Plant Growth
• Size shape depends on cell cell size
• Decide which way to divide which way to
  elongate
• Periclinal perpendicular to surface get
  longer
• Anticlinal parallel to surface add more layers

68

• Plant Growth
• Decide which way to divide which way to
  elongate
• Periclinal perpendicular to surface get
  longer
• Anticlinal parallel to surface add more layers
• Now must decide which way to elongate

69

• Plant Growth
• Decide which way to divide which way to
  elongate
• Periclinal perpendicular to surface get
  longer
• Anticlinal parallel to surface add more layers
• Now must decide which way to elongate which
  walls to stretch

70

• Plant Cell Walls and Growth
• Carbohydrate barrier
• surrounding cell
• Protects gives cell shape

71

• Plant Cell Walls and Growth
• Carbohydrate barrier
• surrounding cell
• Protects gives cell shape
• 1 wall made first
• mainly cellulose
• Can stretch!

72

• Plant Cell Walls and Growth
• Carbohydrate barrier
• surrounding cell
• Protects gives cell shape
• 1 wall made first
• mainly cellulose
• Can stretch!
• 2 wall made after growth
• stops
• Lignins make it tough

73

• Plant Cell Walls and Growth
• 1 wall made first
• mainly cellulose
• Can stretch! Control elongation by controlling
  orientation of cell wall fibers as wall is made

74

• Plant Cell Walls and Growth
• 1 wall made first
• mainly cellulose
• Can stretch! Control elongation by controlling
  orientation of cell wall fibers as wall is made
• 1 walls 25 cellulose, 25 hemicellulose, 35
  pectin, 5 protein (but highly variable)

75

• Plant Cell Walls and Growth
• 1 walls 25 cellulose, 25 hemicellulose, 35
  pectin, 5 protein (but highly variable)
• Cellulose ordered chains made of glucose linked
  b 1-4

76

• Plant Cell Walls and Growth
• 1 walls 25 cellulose, 25 hemicellulose, 35
  pectin, 5 protein (but highly variable)
• Cellulose ordered chains made of glucose linked
  b 1-4
• Cross-link with neighbors to form strong, stable
  fibers