Bio 226: Cell and Molecular Biology

1
Game plan We will study effects of elevated CO2
and temperature on flowering time and see where
it takes us. 1. Learn more about how plants
choose when to flower
2

• Game plan
• We will study effects of elevated CO2 and
  temperature on flowering time and see where it
  takes us.
• 1. Learn more about how plants choose when to
  flower
• Environmental influences on flowering

3

• Game plan
• We will study effects of elevated CO2 and
  temperature on flowering time and see where it
  takes us.
• 1. Learn more about how plants choose when to
  flower
• Environmental influences on flowering
• 2. Pick some plants to study

4

• Game plan
• We will study effects of elevated CO2 and
  temperature on flowering time and see where it
  takes us.
• 1. Learn more about how plants choose when to
  flower
• Environmental influences on flowering
• 2. Pick some plants to study
• 3. Get them growing

5

• Game plan
• We will study effects of elevated CO2 and
  temperature on flowering time and see where it
  takes us.
• 1. Learn more about how plants choose when to
  flower
• Environmental influences on flowering
• 2. Pick some plants to study
• 3. Get them growing
• 4. Design some experiments for other things to
  test before they start flowering

6

• Game plan
• Suggestions
• Arabidopsis 2. Fast plant
• 3. Sorghum 4. Brachypodium distachyon
• 5. Amaranthus 6. Quinoa
• 7. Kalanchoe 8. Venus fly traps
• Options
• Pick several plants

7

• Game plan
• Suggestions
• Arabidopsis 2. Fast plant
• 3. Sorghum 4. Brachypodium distachyon
• 5. Amaranthus 6. Quinoa
• 7. Kalanchoe 8. Venus fly traps
• Options
• Pick several plants
• C3, C4, CAM

8

• Game plan
• Suggestions
• Arabidopsis 2. Fast plant
• 3. Sorghum 4. Brachypodium distachyon
• 5. Amaranthus 6. Quinoa
• 7. Kalanchoe 8. Venus fly traps
• Options
• Pick several plants
• C3, C4, CAM
• Long Day, short day, Day neutral

9

• Game plan
• Suggestions
• Arabidopsis 2. Fast plant
• 3. Sorghum 4. Brachypodium distachyon
• 5. Amaranthus 6. Quinoa
• 7. Kalanchoe 8. Venus fly traps
• Options
• Pick several plants
• C3, C4, CAM
• Long Day, short day, Day neutral
• Tropical, temperate, arctic

10

• Game plan
• Suggestions
• Arabidopsis 2. Fast plant
• 3. Sorghum 4. Brachypodium distachyon
• 5. Amaranthus 6. Quinoa
• 7. Kalanchoe 8. Venus fly traps
• Options
• Pick several plants
• C3, C4, CAM
• Long Day, short day, Day neutral
• Tropical, temperate, arctic
• ?????

11

• Game plan
• Suggestions
• Arabidopsis 2. Fast plant
• 3. Sorghum 4. Brachypodium distachyon
• 5. Amaranthus 6. Quinoa
• 7. Kalanchoe 8. Venus fly traps
• Options
• Pick several plants
• C3, C4, CAM
• Long Day, short day, Day neutral
• Tropical, temperate, arctic
• ?????
• Pick one plant
• Study many conditions

12

• Options
• Pick several plants
• C3, C4, CAM
• Long Day, short day, Day neutral
• Tropical, temperate, arctic
• ?????
• Pick one plant
• Study many conditions
• Study many variants/mutants
• ?????

13

• Grading?
• Combination of papers, presentations lab
  reports
• 4 lab reports _at_ 2.5 points each
• 5 assignments _at_ 2 points each
• Presentation on global change and plants 5
  points
• Research proposal 10 points
• Final presentation 15 points
• Poster 10 points
• Draft report 10 points
• Final report 30 points
• Assignment 1
• Pick a plant that might be worth studying
• Try to convince the group in 5-10 minutes why
  yours is best i.e., what is known/what isnt
  known

14

• Plant Growth Development
• Occurs in 3 stages
• Embryogenesis
• From fertilization to seed
• 2. Vegetative growth
• Juvenile stage
• From seed germination to adult
• "phase change" marks transition
• 3. Reproductive development
• Start making flowers, can
• reproduce sexually

15

• Transition to Adult Phase
• Juveniles adults are very different!

16

• Transition to Flowering
• Adults are competent to flower, but need correct
  signals
• Very complex process!
• Can be affected by
• Daylength
• Temperature (especially cold!)
• Water stress
• Nutrition
• Hormones

17

• Early Studies
• Julius Sachs (1865) first proposed florigen
• Garner and Allard (1920) discovered
  photoperiodism
• Maryland Mammoth tobacco flowers in the S but not
  in N
• Knott (1934) day length is perceived by the
  leaves

18

• Early Studies
• Knott (1934) day length is perceived by the
  leaves
• Flowers are formed at SAM!
• Florigen moves from leaves
• to SAM
• Is graft-transmissable!
• Moves in phloem

19

• Complications
• Some plants are qualitative (must have correct
  daylength), others are quantitative (correct days
  speed flowering)
• Four pathways control flowering
• Photoperiod
• PHY only
• PHY CRY
• Vernalization requires cold period
• gibberellin (GA)
• Autonomous

20

• Complications
• Florigen is universal transmitted from LDP to
  SDP and vice-versa via grafts
• Solved by identifying genes that control
  flowering time

21

• Genes controlling flowering
• Florigen is universal transmitted from LDP to
  SDP and vice-versa via grafts
• Solved by identifying genes that control
  flowering time
• CONSTANS (CO) co mutants are day-length
  insensitive flower late

22

• Genes controlling flowering
• Florigen is universal transmitted from LDP to
  SDP and vice-versa via grafts
• Solved by identifying genes that control
  flowering time
• CONSTANS (CO) co mutants are day-length
  insensitive flower late
• CO mRNA is expressed in leaf but not SAM
  increases in LD

23

• Genes controlling flowering
• Florigen is universal transmitted from LDP to
  SDP and vice-versa via grafts
• Solved by identifying genes that control
  flowering time
• CONSTANS (CO) co mutants are day-length
  insensitive flower late
• CO mRNA is expressed in leaf but not SAM
  increases in LD
• CO encodes a ZN-finger transcription factor (TF)
  that induces expression of FLOWERING LOCUS T (FT)

24

• Genes controlling flowering
• Florigen is universal transmitted from LDP to
  SDP and vice-versa via grafts
• Solved by identifying genes that control
  flowering time
• CONSTANS (CO) co mutants are day-length
  insensitive flower late
• CO mRNA is expressed in leaf but not SAM
  increases in LD
• CO encodes a ZN-finger TF that induces expression
  of FLOWERING LOCUS T (FT)
• FLOWERING LOCUS T (FT) a strong promoter of
  flowering

25

• Genes controlling flowering
• Florigen is universal transmitted from LDP to
  SDP and vice-versa via grafts
• Solved by identifying genes that control
  flowering time
• CONSTANS (CO) co mutants are day-length
  insensitive flower late
• CO mRNA is expressed in leaf but not SAM
  increases in LD
• CO encodes a ZN-finger TF that induces expression
  of FLOWERING LOCUS T (FT)
• FLOWERING LOCUS T (FT) a strong promoter of
  flowering encodes a RAF kinase inhibitor protein
  

26

• Genes controlling flowering
• CONSTANS (CO) co mutants are day-length
  insensitive flower late
• FLOWERING LOCUS T (FT) a strong promoter of
  flowering encodes a RAF kinase inhibitor protein
• FLOWERING LOCUS C (FLC) a MADS-box gene
  strongly represses flowering

27

• Genes controlling flowering
• CONSTANS (CO) co mutants are day-length
  insensitive flower late
• FLOWERING LOCUS T (FT) a strong promoter of
  flowering encodes a RAF kinase inhibitor protein
• FLOWERING LOCUS C (FLC) a MADS-box gene
  strongly represses flowering
• Highly expressed in non-vernalized tissues

28

• Genes controlling flowering
• CONSTANS (CO) co mutants are day-length
  insensitive flower late
• FLOWERING LOCUS T (FT) a strong promoter of
  flowering encodes a RAF kinase inhibitor protein
• FLOWERING LOCUS C (FLC) a MADS-box gene
  strongly represses flowering
• Highly expressed in non-vernalized tissues
• Turned off by vernalization due to chromatin mod

29

• Genes controlling flowering
• CONSTANS (CO) co mutants are day-length
  insensitive flower late
• FLOWERING LOCUS T (FT) a strong promoter of
  flowering encodes a RAF kinase inhibitor protein
• FLOWERING LOCUS C (FLC) a MADS-box gene
  strongly represses flowering
• Highly expressed in non-vernalized tissues
• Turned off by vernalization due to chromatin mod
• SUPPRESSOR OF CONSTANS 1 (SOC1) a MADS-BOX TF
  that activates genes for floral development.

30
Transition to flowering Upon induction, CO
activates transcription of FT in leaves FT
protein moves from leaves to shoot apex in phloem!
31
Transition to flowering Upon induction, CO
activates transcription of FT in leaves FT
protein moves from leaves to shoot apex in
phloem! In SAM combines with FD to activate SOC1
AP1
32
Transition to flowering Upon induction, CO
activates transcription of FT FT protein moves
from leaves to shoot apex in phloem! In SAM
combines with FD to activate SOC1 AP1 These
activate LFY Flower genes
33
Transition to flowering Upon induction, CO
activates transcription of FT FT protein moves
from leaves to shoot apex in phloem! In SAM
combines with FD to activate SOC1 AP1 These
activate LFY Flower genes Other signals
converge On SOC1, either Directly or via FLC
34
SDP Rice homolog to CO is Hd1 Inhibits expression
of Hd3a (the FT homolog)
35
SDP Rice homolog to CO is Hd1 Inhibits expression
of Hd3a (the FT homolog) Induced by long days
36
SDP Rice homolog to CO is Hd1 Inhibits expression
of Hd3a (the FT homolog) Induced by long
days Only make Hd3a protein under short days
37

• Transition to flowering
• Eventually start flowering
• Are now adults!
• Time needed varies from days to years.
• Shoot apical meristem now starts making new
  organ flowers, with many new structures cell
  types

38

• WATER
• Plants' most important chemical
• most often limits productivity

39

• WATER
• Plants' most important chemical
• most often limits productivity
• Often gt90 of a plant cells weight

40

• WATER
• Plants' most important chemical
• most often limits productivity
• Often gt90 of a plant cells weight
• Gives cells shape

41

• WATER
• Plants' most important chemical
• most often limits productivity
• Often gt90 of a plant cells weight
• Gives cells shape
• Dissolves many chem

42

• WATER
• Dissolves many chem
• most biochem occurs in water
• Source of e- for PS

43

• WATER
• most biochem occurs in water
• Source of e- for PS
• Constantly lose water due to PS (1000 H2O/CO2)

44

• WATER
• most biochem occurs in water
• Source of e- for PS
• Constantly lose water due to PS
• Water transport is crucial!

45

• WATER
• Water transport is crucial!
• SPAC Soil Plant Air Continuum
• moves from soil-gtplant-gtair

46
WATER Formula H2O Formula weight 18
daltons Structure tetrahedron, bond angle
104.5
47
WATER Structure tetrahedron, bond angle
104.5 polar O is more attractive to electrons
than H ? on H ?- on O
48
Water Polarity is reason for waters properties
water forms H-bonds with polar molecules
49
Water Polarity is reason for waters properties
water forms H-bonds with polar
molecules Hydrophilic polar molecules Hydropho
bic non-polar molecules
50

• Properties of water
• Cohesion water H-bonded to water
• -gt reason for surface tension

51

• Properties of water
• Cohesion water H-bonded to water
• -gt reason for surface tension
• -gt why water can be drawn from roots to leaves

52
Properties of water 1) Cohesion water H-bonded
to water 2) Adhesion water H-bonded to
something else
53

• Properties of water
• 1) Cohesion water H-bonded to water
• 2) Adhesion water H-bonded to something else
• Cohesion and adhesion are crucial for water
  movement in plants!

54

• Properties of water
• 1) Cohesion water H-bonded to water
• 2) Adhesion water H-bonded to something else
• Cohesion and adhesion are crucial for water
  movement in plants!
• Surface tension adhesion in mesophyll creates
  force that draws water through the plant!

55

• Properties of water
• 1) Cohesion water H-bonded to water
• 2) Adhesion water H-bonded to something else
• 3) high specific heat
• absorb heat when break H-bonds cools leaves

56

• Properties of water
• 1) Cohesion water H-bonded to water
• 2) Adhesion water H-bonded to something else
• 3) high specific heat
• absorb heat when break H-bonds
• Release heat when form H-bonds

57
Properties of water 1) Cohesion water H-bonded
to water 2) Adhesion water H-bonded to
something else 3) high specific heat 4) Ice floats
58
Properties of water 1) Cohesion water H-bonded
to water 2) Adhesion water H-bonded to
something else 3) high specific heat 4) Ice
floats 5) Universal solvent
59

• Properties of water
• 1) Cohesion water H-bonded to water
• 2) Adhesion water H-bonded to something else
• 3) high specific heat
• 4) Ice floats
• 5) Universal solvent
• Take up transport
• nutrients dissolved in
• water

60

• Properties of water
• 5) Universal solvent
• Take up transport nutrients dissolved in water
• Transport organics dissolved in water

61
Properties of water 1) Cohesion water H-bonded
to water 2) Adhesion water H-bonded to
something else 3) high specific heat 4) Ice
floats 5) Universal solvent 6) Hydrophobic bonds
62
Properties of water 1) Cohesion water H-bonded
to water 2) Adhesion water H-bonded to
something else 3) high specific heat 4) Ice
floats 5) Universal solvent 6) Hydrophobic
bonds 7) Water ionizes
63
pH H acidity of a solution pH convenient
way to measure acidity pH - log10 H pH 7 is
neutral H OH- -gt at pH 7 H 10-7
moles/l
64
pH Plants vary pH to control many processes!
65

• Water movement
• Diffusion movement of single molecules down ?
  due to random motion until is even
• Driving force?

66

• Water movement
• Diffusion movement of single molecules down ?
  due to random motion until is even
• Driving force lowers free energy
• ?G ?H- T?S

67
Water movement Diffusion movement of single
molecules down ? due to random motion until
is even Bulk Flow movement of groups
of molecules down a pressure gradient
68

• Water movement
• Diffusion movement of single molecules down ?
  due to random motion until is even
• Bulk Flow movement of groups of
• molecules down a pressure gradient
• Independent of ? !

69

• Water movement
• Diffusion movement of single molecules down ?
  due to random motion until is even
• Bulk Flow movement of groups of molecules down a
  pressure gradient
• Independent of ? !
• How water moves through xylem

70

• Water movement
• Diffusion movement of single molecules down
  due to random motion until is even
• Bulk Flow movement of groups of molecules down a
  pressure gradient
• Independent of ? !
• How water moves through xylem
• How water moves through soil and apoplast

71

• Water movement
• Bulk Flow movement of groups of molecules down a
  pressure gradient
• Independent of ? !
• How water moves through xylem
• Main way water moves through soil and apoplast
• Very sensitive to radius of vessel increases as
  r4

72

• Water movement
• Diffusion movement of single molecules down ?
  due to random motion until is even
• Bulk Flow movement of groups of molecules down a
  pressure gradient
• Independent of ? !
• How water moves through xylem
• Main way water moves through soil and apoplast
• Very sensitive to radius of vessel increases as
  r4
• Osmosis depends on bulk flow and diffusion!

73
Water movement Osmosis depends on bulk flow and
diffusion! water crosses membranes but other
solutes do not water tries to even its on
each side
74
Water movement Osmosis depends on bulk flow and
diffusion! water crosses membranes but other
solutes do not water tries to even its on
each side other solutes cant result is net
influx of water
75

• Water movement
• Osmosis depends on bulk flow and diffusion!
• Moves through aquaporins, so rate depends on
  pressure and gradients!

76

• Water movement
• Osmosis depends on bulk flow and diffusion!
• Moves through aquaporins, so rate depends on
  pressure and gradients!
• Driving force water's free energy (J/m3 MPa)

77

• Water potential
• Driving force water's free energy
• water potential Yw
• Important for many aspects of
• plant physiology

78

• Water potential
• Driving force water's free energy water
  potential Yw
• Water moves to lower its potential

79

• Water potential
• Driving force water's free energy water
  potential Yw
• Water moves to lower its potential

80

• Water potential
• Driving force water's free energy water
  potential Yw
• Water moves to lower its potential
• Depends on
• H2O Ys (osmotic potential)

81

• Water potential
• Water moves to lower its potential
• Depends on
• H2O Ys (osmotic potential)
• Pressure Yp
• Turgor pressure inside cells

82

• Water potential
• Water moves to lower its potential
• Depends on
• H2O Ys (osmotic potential)
• Pressure Yp
• Turgor pressure inside cells
• Negative pressure in xylem!

83

• Water potential
• Water moves to lower its potential
• Depends on
• H2O Ys (osmotic potential)
• Pressure Yp
• Gravity Yg
• Yw Ys Yp Yg

84

• Water potential
• Water moves to lower its potential
• Depends on
• H2O Ys (osmotic potential)
• Pressure Yp
• Gravity Yg
• Yw Ys Yp Yg
• Yw of pure water at sea level
• 1 atm 0 MPA

85

• Water potential
• Yw Ys Yp Yg
• Yw of pure water at sea level 1 atm 0 MPA
• Ys (osmotic potential) is always negative

86

• Water potential
• Yw Ys Yp Yg
• Yw of pure water at sea level 1 atm 0 MPA
• Ys (osmotic potential) is always negative
• If increase solutes water will move in

87

• Water potential
• Yw Ys Yp Yg
• Yw of pure water at sea level 1 atm 0 MPA
• Ys (osmotic potential) is always negative
• If increase solutes water will move in
• Yp (pressure potential) can be positive or
  negative

88

• Water potential
• Yw Ys Yp Yg
• Yw of pure water at sea level 1 atm 0 MPA
• Ys (osmotic potential) is always negative
• If increase solutes water will move in
• Yp (pressure potential) can be positive or
  negative
• Usually positive in cells to counteract Ys

89

• Water potential
• Yp (pressure potential) can be positive or
  negative
• Usually positive in cells to counteract Ys
• Helps plants stay same size despite daily
  fluctuations in Yw

90

• Water potential
• Yw Ys Yp Yg
• Yp (pressure potential) can be positive or
  negative
• Usually positive in cells to counteract Ys
• Helps plants stay same size
• despite daily fluctuations in Yw
• Yp in xylem is negative, draws
• water upwards

91

• Water potential
• Yw Ys Yp Yg
• Yp (pressure potential) can be positive or
  negative
• Usually positive in cells to counteract Ys
• Helps plants stay same size
• despite daily fluctuations in Yw
• Yp in xylem is negative, draws
• water upwards
• Yg can usually be ignored, but
• important for tall trees