Bio%20226:%20Cell%20and%20Molecular%20Biology

1

• Course Plan
• We will study effects of soil and stresses on
  plant secondary products and see where it leads
  us
• Learn more about plant secondary products
• Why do they make them?
• When do they make them?
• Where do they make them?

2

• Pick some plants to study
• Capsicum (Chiles) capsaicin
• Nicotiana (Tobacco) nicotine
• Onions (Allium cepa)? syn-Propanethial-S-oxide
• Garlic (Allium sativum)? Alliin
• Radishes (Raphanus sativus) glucosinolates
• Mustard (Brassica juncea) glucosinolates
• Basil (Ocimum basilicum) eugenol (and others)
• Cilantro (Coriandrum sativum) lots of
  candidates!
• Peppermint (Mentha piperita) menthol many
• Catnip (Nepeta cataria) nepetalactone
• Dill dillapiole
• Purslane (Portulaca oleracea) omega-3 fatty
  acids
• Brassica rapa glucosinolates

3

• Plant Stress
• Won Senator Proxmires Golden Fleece award for
  wasteful government spending
• Water?
• Nutrients?
• Environment?
• Temp?
• Pollution?
• Ozone, other gases?
• Herbicides, eg Round-Up, Atrazine?
• Insects and other herbivores?
• Pathogens bacteria, viruses, fungi

4
Plant Stress Next assignment presenting a plant
stressor, what is known about it, and why it
might affect plant 2 compounds in an 10 minute
presentation? Alternative presenting another
good plant/stressor response to study and why we
should choose it over the ones already presented.
5

• Mineral Nutrition
• Macronutrients CHOPKNSCaFeMgBNaCl
• Ca signaling, middle lamella, cofactor
• Fe cofactor
• Mg cofactor
• mobile in plant, so shows first in old leaves

6

• Mineral Nutrition
• Micronutrients BNaCl others include Cu, Zn, Mn
• B cell elongation. NA metabolism
• Na PEP regeneration, K substitute
• Cl water-splitting, osmotic balance
• Cu cofactor
• immobile in plant, so shows first in young leaves

7

• Plant food
• 2.6 ammoniacal nitrogen
• 4.4 nitrate nitrogen
• 9 phosphorus
• 5 potassium
• calcium (2)
• magnesium (0.5)
• sulfur (0.05)
• boron (0.02)
• chlorine (0.1)
• cobalt (0.0015)
• copper (0.05)
• iron (0.1)
• manganese (0.05)
• molybdenum (0.0009)
• nickel (0.0001)
• sodium (0.10)
• zinc (0.05)

8

• Mineral Nutrition
• Soil nutrients
• Amounts availability vary
• PSU extension Text

9

• Mineral Nutrition
• Soil nutrients
• Amounts availability vary
• Many are immobile, eg P, Fe

10

• Mineral Nutrition
• Soil nutrients
• Amounts availability vary
• Many are immobile, eg P, Fe
• Mobile nutrients come with soil H2O

11

• Mineral Nutrition
• Soil nutrients
• Amounts availability vary
• Many are immobile, eg P, Fe
• Mobile nutrients come with soil H2O
• Immobiles must be mined
• Root hairs get close

12

• Mineral Nutrition
• Immobile nutrients must be mined
• Root hairs get close
• Mycorrhizae get closer

13

• Mineral Nutrition
• Immobile nutrients must be mined
• Root hairs get close
• Mycorrhizae get closer
• Solubility varies w pH

14

• Mineral Nutrition
• Solubility varies w pH
• 5.5 is best compromise

15

• Mineral Nutrition
• Solubility varies w pH
• 5.5 is best compromise
• Plants alter pH _at_ roots to
• aid uptake

16

• Mineral Nutrition
• Nutrients in soil
• Plants alter pH _at_ roots to aid uptake
• Also use symbionts
• Mycorrhizal fungi help especially with P

17

• Mineral Nutrition
• Also use symbionts
• Mycorrhizal fungi help especially with P
• P travels poorly fungal hyphae are longer
  thinner

18

• Mineral Nutrition
• Also use symbionts
• Mycorrhizal fungi help especially with P
• P travels poorly fungal hyphae are longer
  thinner
• Fungi give plants nutrients

19

• Mineral Nutrition
• Also use symbionts
• Mycorrhizal fungi help especially with P
• P travels poorly fungal hyphae are longer
  thinner
• Fungi give plants nutrients
• Plants feed them sugar

20

• Mineral Nutrition
• Also use symbionts
• Mycorrhizal fungi help especially with P
• P travels poorly fungal hyphae are longer
  thinner
• Fungi give plants nutrients
• Plants feed them sugar
• Ectomycorrhizae surround root only trees, esp.
  conifers

21

• Mineral Nutrition
• Ectomycorrhizae surround root only trees, esp.
  conifers
• release nutrients into apoplast to be taken up
  by roots

22

• Mineral Nutrition
• Ectomycorrhizae surround root trees
• release nutrients into apoplast to be taken up by
  roots
• Endomycorrhizae invade root cells
  Vesicular/Arbuscular
• Most angiosperms, especially in nutrient-poor
  soils

23

• Mineral Nutrition
• Endomycorrhizae invade root cells
  Vesicular/Arbuscular
• Most angiosperms, especially in nutrient-poor
  soils
• May deliver nutrients into symplast

24

• Rhizosphere
• Endomycorrhizae invade root cells
  Vesicular/Arbuscular
• Most angiosperms, especially in nutrient-poor
  soils
• May deliver nutrients into symplast
• Or may release them when arbuscule dies

25

• Rhizosphere
• Endomycorrhizae invade root cells
  Vesicular/Arbuscular
• Most angiosperms, especially in nutrient-poor
  soils
• Deliver nutrients into symplast or release them
  when arbuscule dies
• Also find bacteria, actinomycetes, protozoa
  associated with root surface rhizosphere

26

• Rhizosphere
• Also find bacteria, actinomycetes, protozoa
  associated with root surface rhizosphere
• Plants feed them lots of C!

27

• Rhizosphere
• Also find bacteria, actinomycetes, protozoa
  associated with root surface rhizosphere
• Plants feed them lots of C!
• They help make nutrients available

28

• Rhizosphere
• Also find bacteria, actinomycetes, protozoa
  associated with root surface rhizosphere
• Plants feed them lots of C!
• They help make nutrients available
• N-fixing bacteria supply N to many plant spp

29
N assimilation by N fixers Exclusively performed
by prokaryotes Dramatically improve the growth of
many plants
30
N assimilation by N fixers Exclusively done by
prokaryotes Most are free-living in soil or
water
31
N assimilation by N fixers Exclusively done by
prokaryotes Most are free-living in soil or
water Some form symbioses with plants
32
N assimilation by N fixers Exclusively done by
prokaryotes Most are free-living in soil or
water Some form symbioses with plants Legumes are
best-known, but many others including
mosses, ferns, lichens
33
N assimilation by N fixers Exclusively done by
prokaryotes Most are free-living in soil or
water Some form symbioses with plants Legumes are
best-known, but many others including
mosses, ferns, lichens Also have associations
where N-fixers form films on leaves or roots and
are fed by plant
34
N assimilation by N fixers Exclusively done by
prokaryotes Also have associations where
N-fixers form films on leaves or roots and are
fed by plant All must form O2-free environment
for nitrogenase
35
N assimilation by N fixers All must form O2-free
environment for nitrogenase O2 binds
inactivates electron -transfer sites
36
N assimilation by N fixers O2 binds inactivates
electron -transfer sites Heterocysts lack PSII,
have other mechs to lower O2
37
N assimilation by N fixers Heterocysts lack PSII,
have other mechs to lower O2 Nodules have
special structure leghemoglobin to protect from
O2
38
Nodule formation Nodules have special structure
leghemoglobin to protect from O2 Bacteria induce
the plant to form nodules
39

• Nodule formation
• Bacteria induce the plant to form nodules
• Root hairs secrete chemicals that attract
  N-fixers

40

• Nodule formation
• Bacteria induce the plant to form nodules
• Root hairs secrete chemicals that attract
  N-fixers
• Bacteria secrete Nod factors that induce root
  hair to coil up. Nod factors determine
  species-specificity

41

• Nodule formation
• Root hairs secrete chemicals that attract
  N-fixers
• Bacteria secrete Nod factors that induce root
  hair to coil up. Nod factors determine
  species-specificity
• Nod factors induce degradation of root cell wall

42

• Nodule formation
• Nod factors induce degradation of root cell wall
• Plant forms "infection thread"internal protusion
  of plasma membrane that grows into cell
• When reaches end of cell bacteria are released
  into apoplast and repeat the process on inner
  cells

43

• Nodule formation
• When reaches end of cell bacteria are released
  into apoplast and repeat the process on inner
  cells
• Cortical cells near xylem form a nodule
  primordium

44

• Nodule formation
• When reaches end of cell bacteria are released
  into apoplast and repeat the process on inner
  cells
• Cortical cells near xylem form a nodule
  primordium
• When bacteria reach these cells the infection
  thread breaks off, forming vesicles with bacteria
  inside

45

• Nodule formation
• When bacteria reach these cells the infection
  thread breaks off, forming vesicles with bacteria
  inside
• Vesicles fuse, form the peribacteroid membrane
  and bacteria differentiate into bacteroids.

46

• Nodule formation
• Vesicles fuse, form the peribacteroid membrane
  and bacteria differentiate into bacteroids.
• Plant cells differentiate into nodules

47

• Nodule formation
• Vesicles fuse, form the peribacteroid membrane
  and bacteria differentiate into bacteroids.
• Plant cells differentiate into nodules have
  layer of cells to exclude O2 vasculature
• to exchange nutrients

48

• Nodule formation
• Plant cells differentiate into nodules have
  layer of cells to exclude O2 vasculature to
  exchange nutrients
• Complex process that is difficult to engineer 21
  non-legume plant genera have N-fixers

49
Nitrogen fixation N2 8H 8e- 16 ATP ? 2NH3
H2 16ADP 16 Pi Catalysed by nitrogenase, a
very complex enzyme!
50
Nitrogen fixation N2 8H 8e- 16 ATP ? 2NH3
H2 16ADP 16 Pi Catalysed by nitrogenase, a
very complex enzyme! Also catalyzes many other
reactions Usually assayed by acetylene reduction
51
Nitrogen fixation N2 8H 8e- 16 ATP ? 2NH3
H2 16ADP 16 Pi Usually assayed by acetylene
reduction Sequentially adds 2 H per cycle until
reach NH3
52
Nitrogen fixation Sequentially adds 2 H per cycle
until reach NH3 May then be exported to cytosol
assimilated by GS/GOGAT or assimilated inside
bacteroid
53
Nitrogen fixation Sequentially adds 2 H per cycle
until reach NH3 May then be exported to cytosol
assimilated by GS/GOGAT or assimilated inside
bacteroid Are then converted to amides or
ureides exported to rest of plant in the xylem!
54

• Nutrient uptake
• Most nutrients are dissolved in water

55

• Nutrient uptake
• Most nutrients are dissolved in water
• Enter root through apoplast until hit endodermis

56

• Nutrient uptake
• Most nutrients are dissolved in water
• Enter root through apoplast until hit endodermis
• Then must cross plasma membrane

57
Crossing membranes A) Diffusion through bilayer
B) Difusion through protein pore C)
Facilitated diffusion D) Active transport E) Bulk
transport 1) Exocytosis 2) Endocytosis
Selective
Active
58

• Nutrient uptake
• Then must cross plasma membrane
• Gases, small uncharged non-polar molecules
  diffuse

59

• Nutrient uptake
• Then must cross plasma membrane
• Gases, small uncharged non-polar molecules
  diffuse
• down their ?
• Important for CO2, auxin NH3 transport

60

• Nutrient uptake
• Then must cross plasma membrane
• Gases, small uncharged non-polar molecules
  diffuse
• down their ?
• Polar chems must go through proteins!

61
Selective Transport 1) Channels integral membrane
proteins with pore that specific ions diffuse
through
62

• Selective Transport
• 1) Channels
• integral membrane proteins with pore that
  specific ions diffuse through
• depends on size
• charge

63

• Channels
• integral membrane proteins with pore
• that specific ions diffuse through
• depends on size charge
• O in selectivity filter bind
• ion (replace H2O)

64

• Channels
• integral membrane proteins with pore
• that specific ions diffuse through
• depends on size charge
• O in selectivity filter bind
• ion (replace H2O)
• only right one fits

65

• Channels
• O in selectivity filter bind
• ion (replace H2O)
• only right one fits
• driving force?
• electrochemical D

66
Channels driving force electrochemical
D non-saturable
67
Channels driving force electrochemical
D non-saturable regulate by opening closing
68
Channels regulate by opening closing ligand-gate
d channels open/close when bind specific chemicals
69
Channels ligand-gated channels open/close when
bind specific chemicals Stress-activated channels
open/close in response to mechanical stimulation
70
Channels Stress-activated channels open/close in
response to mechanical stimulation voltage-gated
channels open/close in response to changes in
electrical potential
71

• Channels
• Old model S4 slides up/down
• Paddle model S4 rotates

72

• Channels
• Old model S4 slides up/down
• Paddle model S4 rotates
• 3 states
• Closed
• Open
• Inactivated

73
Selective Transport 1) Channels 2) Facilitated
Diffusion (carriers) Carrier binds molecule
74
Selective Transport Facilitated Diffusion
(carriers) Carrier binds molecule carries it
through membrane releases it inside
75
Selective Transport Facilitated Diffusion
(carriers) Carrier binds molecule carries it
through membrane releases it inside driving
force ?
76
Selective Transport Facilitated Diffusion
(carriers) Carrier binds molecule carries it
through membrane releases it inside driving
force ? Important for sugar transport
77
Selective Transport Facilitated Diffusion
(carriers) Characteristics 1) saturable 2)
specific 3) passive transports down ?
78
Selective Transport 1) Channels 2) Facilitated
Diffusion (carriers) Passive transport should
equalize Nothing in a plant cell is at
equilibrium!
79
Selective Transport Passive transport should
equalize Nothing in a plant cell is at
equilibrium! Solution use energy to transport
specific ions against their ?
80

• Active Transport
• Integral membrane proteins
• use energy to transport specific ions against
  their ?
• allow cells to concentrate some chemicals,
  exclude others

81
Active Transport Characteristics 1) saturable
102-104 molecules/s
105-106 ions/s
82
Active Transport Characteristics 1) saturable 2)
specific
83
Active Transport Characteristics 1) saturable 2)
specific 3) active transport up ? (or ? Em)
84

• 4 classes of Active transport ATPase proteins
• 1) P-type ATPases (P phosphorylation)
• Na/K pump
• Ca pump in ER PM
• H pump in PM
• pumps H out of cell

85

• 4 classes of Active transport ATPase proteins
• 1) P-type ATPases (P phosphorylation)
• 2) V-type ATPases (V vacuole)
• H pump in vacuoles

86

• 4 classes of Active transport ATPase proteins
• 1) P-type ATPases (P phosphorylation)
• 2) V-type ATPases (Vvacuole)
• 3) F-type ATPases (F factor) a.k.a. ATP
  synthases
• mitochondrial ATP synthase
• chloroplast ATP synthase

87

• 4 classes of Active transport ATPase proteins
• 1) P-type ATPases (P phosphorylation)
• 2) V-type ATPases (V vacuole)
• 3) F-type ATPases (F factor)
• 4) ABC ATPases (ABC ATP Binding Cassette)
• multidrug resistance proteins

88

• 4 classes of Active transport ATPase proteins
• 1) P-type ATPases (P phosphorylation)
• 2) V-type ATPases (V vacuole)
• 3) F-type ATPases (F factor)
• 4) ABC ATPases (ABC ATP Binding Cassette)
• multidrug resistance proteins
• pump hydrophobic drugs out of cells
• very broad specificity

89
Secondary active transport Uses ? created by
active transport to pump something else across a
membrane against its ?
90
Secondary active transport Uses ? created by
active transport to pump something else across a
membrane against its ? Symport both
substances pumped same way
91
Secondary active transport Uses ? created by
active transport to pump something else across a
membrane against its ? Symport both
substances pumped same way Antiport substances
pumped opposite ways
92
Secondary active transport Uses ? created by
active transport to pump something else across a
membrane against its ? Symport both
substances pumped same way Antiport substances
pumped opposite ways
93
Nutrient uptake Gases enter/exit by diffusion
down their ?
94
Nutrient uptake Gases enter/exit by diffusion
down their ? Ions vary dramatically!
95
Nutrient uptake Gases enter/exit by diffusion
down their ? Ions vary dramatically! H is
actively pumped out of cell by P-type H -ATPase
96
Nutrient uptake Gases enter/exit by diffusion
down their ? Ions vary dramatically! H is
actively pumped out of cell by P-type H
-ATPase and into vacuole by V-type!
97

• Nutrient uptake
• H is actively pumped out of cell by P-type H
  -ATPase
• and into vacuole by V-type!
• Main way plants make membrane potential (?Em)!

98

• Nutrient uptake
• H is actively pumped out of cell by P-type H
  -ATPase
• and into vacuole by V-type!
• Main way plants make membrane potential (?Em)!
• K diffuses through channels down ?Em

99

• Nutrient uptake
• K diffuses through channels down ?Em
• Also taken up by transporters

100

• Nutrient uptake
• K diffuses through channels down ?Em
• Also taken up by transporters
• some also transport Na

101

• Nutrient uptake
• K diffuses through channels down ?Em
• Also taken up by transporters
• some also transport Na
• why Na slows
• K uptake?

102

• Nutrient uptake
• K diffuses through channels down ?Em
• Also taken up by transporters
• some also transport Na
• why Na slows
• K uptake?
• Na is also expelled
• by H antiport

103

• Nutrient uptake
• K diffuses through channels down ?Em
• Also taken up by transporters
• some also transport Na
• why Na slows
• K uptake?
• Na is also expelled
• by H antiport
• Enters through channels

104

• Nutrient uptake
• Na is also expelled
• by H antiport
• Enters through channels
• Ca2 is expelled by P-type
• ATPases in PM

105

• Nutrient uptake
• Na is also expelled
• by H antiport
• Enters through channels
• Ca2 is expelled by P-type
• ATPases in PM
• pumped into vacuole
• by H antiport

106

• Nutrient uptake
• Na is also expelled
• by H antiport
• Enters through channels
• Ca2 is expelled by P-type
• ATPases in PM
• pumped into vacuole
• by H antiport
• enters cytosol via channels
• PO4, SO4, Cl NO3
• enter by H symport

107

• Nutrient uptake
• PO4, SO4, Cl NO3
• enter by H symport
• also have anion channels of ABC type