1. We will study effects of stresses on plants and see where it leads us
Course Plan
We will study effects of stresses on plants and see where it leads us
Phytoremediation
Plant products
Biofuels
Effects of seed spacing on seed germination
Effects of nutrient deprivation
Effects of stresses
Climate/CO2 change
Non-coding RNAs
Biotechnology
Plant movements: flytraps, mimosa, soybeans
Carnivorous plants
Stress responses/stress avoidance
Plant signaling (including neurobiology)
Flowering?
Hormones?
Plant pathology?
Plant tropisms and nastic movements
Root growth responses
Metal toxicity?
Circadian rhythms?
Effects of magnetic fields?
Effects of different colors of light on plant growth?

2. We will study effects of stresses on plants and see where it leads us
Learn about plant stress
Pick some stresses to study
Decide which plants to study and how to assay the stress effects
What to measure?
Biomass
Yield
Proteins, pigments
Secondary products
Responses to stimuli
Solar tracking
Leaf closing
Tropisms
Flowering

3. Plant Stress
Won Senator Proxmire’s “Golden Fleece” award for wasteful government spending
Water?
Nutrients?
Environment?
Temp?
pCO2?
Pollution?
Ozone, other gases?
Herbicides, eg Round-Up, Atrazine?
Light?
Insects and other herbivores?
Pathogens = bacteria, viruses, fungi

4. Mineral Nutrition
Studied by soil-free culture in nutrient solutions:

5. Mineral Nutrition
Soil-free culture
Sand culture
Hydroponics: immerse roots in nutrient solution
Slanted film maintains [nutrients] & O2
Aeroponics sprays nutrient solution on roots

6. Mineral Nutrition
Macronutrients
CHOPKNS
CHOPNS make biopolymers

7. Mineral Nutrition
Macronutrients
CHOPNS make biopolymers
N deficiency
mobile in plant, so old leaves go yellow first

8. Mineral Nutrition
P deficiency
mobile in plant, so shows first in old leaves which turn dark green or purple

9. Mineral Nutrition
S deficiency
mobile in plant, so shows first in old leaves which turn yellow

10. Mineral Nutrition
K deficiency
mobile in plant, so shows first in old leaves which go yellow at edges.

11. Mineral Nutrition
Ca deficiency
immobile in plant, so shows first in young leaves which show blotches of necrotic tissue
Crucial role in water-
splitting!

12. Mineral Nutrition
Fe deficiency
immobile in plant, so shows first in young leaves which turn yellow while veins stay green

13. Mineral Nutrition
Mg deficieincy
mobile in plant, so shows first in old leaves which brown off at edges

14. Mineral Nutrition
Mg deficieincy
mobile in plant, so shows first in old leaves which brown off at edges
One/ chlorophyll and also cofactor for many enzymes

15. Mineral Nutrition
Micronutrients: BNaCl
B: cell elongation. NA metabolism
immobile in plant, so shows first in young leaves

16. Mineral Nutrition
Micronutrients: BNaCl
B: cell elongation. NA metabolism
Na: PEP regeneration in C4, K substitute
mobile in plant, so shows first in old leaves

17. Mineral Nutrition
Micronutrients: BNaCl
B: cell elongation. NA metabolism
Na: PEP regenerationin C4, K substitute
Cl: water-splitting, osmotic balance
mobile in plant, so shows first in old leaves

18. 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

19. Mineral Nutrition
Micronutrients: BNaCl others include Cu, Zn, Mn
Mn: cofactor for many enzymes, especially water splitting enzyme
Immobile in plants so shows first in young leaves

20. Mineral Nutrition
Commercial fertilizers mainly supply NPK

21. 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%)

22. Nutrient excesses
More infrequent since plants control nutrient uptake

23. Nutrient excesses
More infrequent since plants control nutrient uptake
Na stress: frequently occurs in areas that have been irrigated or are near oceans

24. Effects of excess Sodium
Reduced turgor due to lower Ys
Reduced growth rate
Plasmolysis

25. Effects of excess Sodium
Reduced turgor due to lower Ys
Enzyme inhibition
[Na] > 100 mM inhibit enzymes of all spp
Even spp that live in 5 M NaCl

26. Effects of excess Sodium
Reduced turgor due to lower Ys
Enzyme inhibition
Accumulation in old leaves to
toxic levels

27. Mechanisms of Sodium Tolerance
Exclusion
negative correlation with HKT1 (unloads Na from xylem)and salt tolerance in Arabidopsis
Accumulation of Na+ in leaf promotes Na tolerance!

28. Mechanisms of Sodium Tolerance
Exclusion
Compartmentalization in vacuoles
Some plants make salt glands
that excrete salt

29. Mechanisms of Sodium Tolerance
Exclusion
Compartmentalization in vacuoles
Osmotic tolerance
Mechs not fully understood; sometimes involve accumulation of organics such as trehalose in vacuole
Reason weak HKT1
promotes Na tolerance?

30. Mineral Nutrition
Soil nutrients
Amounts & availability vary
PSU extension Text

31. Mineral Nutrition
Soil nutrients
Amounts & availability vary
Many are immobile, eg P, Fe

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

33. 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

34. Mineral Nutrition
Immobile nutrients must be “mined”
Root hairs get close
Mycorrhizae get closer

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

36. Mineral Nutrition
Solubility varies w pH
5.5 is best compromise

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

38. Mineral Nutrition
Nutrients in soil
Plants alter roots to aid uptake
Also use symbionts
Mycorrhizal fungi help: especially with P

39. Mineral Nutrition
Also use symbionts
Mycorrhizal fungi help: especially with P
P travels poorly: fungal hyphae are longer & thinner

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

41. 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

42. 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

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

44. 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

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

46. 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

47. 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

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

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

50. 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

51. Rhizosphere
N-fixing bacteria supply N to many plant spp
Most live in root nodules & are fed & protected from O2 by plant

52. Nutrient uptake
Most nutrients are dissolved in water

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

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

55. Selective 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

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

57. Nutrient uptake
Then must cross plasma membrane
Gases, small uncharged & non-polar molecules diffuse
down their ∆ [ ]
Important for CO2, auxin & NH3 transport

58. Nutrient uptake
Then must cross plasma membrane
Gases, small uncharged & non-polar molecules diffuse
down their ∆ [ ]
Polar chems must go through proteins!

59. Selective Transport
1) Channels
integral membrane proteins with pore that specific ions diffuse through

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

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

62. 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

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

64. Channels
driving force : electrochemical D
“non-saturable”

65. Channels
driving force : electrochemical D
“non-saturable”
regulate by opening & closing

66. Channels
regulate by opening & closing
ligand-gated channels open/close when bind specific chemicals

67. Channels
ligand-gated channels open/close when bind specific chemicals
Stress-activated channels open/close in response to mechanical stimulation

68. Channels
Stress-activated channels open/close in response to mechanical stimulation
voltage-gated channels open/close in response to changes in electrical potential

69. Channels
Old model: S4 slides up/down
Paddle model: S4 rotates

70. Channels
Old model: S4 slides up/down
Paddle model: S4 rotates
3 states
Closed
Open
Inactivated

71. Selective Transport
1) Channels
2) Facilitated Diffusion (carriers)
Carrier binds molecule

72. Selective Transport
Facilitated Diffusion (carriers)
Carrier binds molecule
carries it through membrane
& releases it inside

73. Selective Transport
Facilitated Diffusion (carriers)
Carrier binds molecule
carries it through membrane
& releases it inside
driving force = ∆ [ ]

74. Selective Transport
Facilitated Diffusion (carriers)
Carrier binds molecule
carries it through membrane
& releases it inside
driving force = ∆ [ ]
Important for sugar
transport

75. Selective Transport
Facilitated Diffusion (carriers)
Characteristics
1) saturable
2) specific
3) passive: transports
down ∆ []

76. Selective Transport
1) Channels
2) Facilitated Diffusion (carriers)
Passive transport should equalize [ ]
Nothing in a plant cell is at equilibrium!

77. Selective Transport
Passive transport should equalize [ ]
Nothing in a plant cell is at equilibrium!
Solution: use energy to transport specific ions against their ∆ [ ]

78. Active Transport
Integral membrane proteins
use energy to transport specific ions against their ∆ [ ]
allow cells to concentrate some chemicals, exclude others

79. Active Transport
Characteristics
1) saturable
ions/s
molecules/s

80. Active Transport
Characteristics
1) saturable
2) specific

81. Active Transport
Characteristics
1) saturable
2) specific
3) active: transport up ∆ [ ] (or ∆ Em)

82. 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

83. 4 classes of Active transport ATPase proteins
1) P-type ATPases (P = “phosphorylation”)
2) V-type ATPases (V = “vacuole”)
H+ pump in vacuoles

84. 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”) a.k.a. ATP synthases
mitochondrial ATP synthase
chloroplast ATP synthase

85. 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

86. 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

87. Secondary active transport
Uses ∆ [ ] created by active transport to pump something else across a membrane against its ∆ [ ]

88. Secondary active transport
Uses ∆ [ ] created by active transport to pump something else across a membrane against its ∆ [ ]
Symport: both substances pumped same way

89. 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

90. 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

91. Nutrient uptake
Gases enter/exit by diffusion down their ∆ [ ]

92. Nutrient uptake
Gases enter/exit by diffusion down their ∆ [ ]
Ions vary dramatically!

93. Nutrient uptake
Gases enter/exit by diffusion down their ∆ [ ]
Ions vary dramatically!
H+ is actively pumped out of cell by P-type H+ -ATPase

94. 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!

95. 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)!

96. 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

97. Nutrient uptake
K+ diffuses through channels down ∆Em
Also taken up by transporters

98. Nutrient uptake
K+ diffuses through channels down ∆Em
Also taken up by transporters
some also transport Na+

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

100. 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

101. 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

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

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

104. Nutrient uptake
Ca2+ is expelled by P-type ATPases in PM
pumped into vacuole & ER by H+ antiport & P-type
enters cytosol via gated channels

105. Nutrient uptake
PO43-, SO42-, Cl- & NO3-
enter by H+ symport

106. Nutrient uptake
PO43-, SO42-, Cl- & NO3- enter by H+ symport
also have anion transporters of ABC type

107. Nutrient uptake
PO43-, SO42-, Cl- & NO3- enter by H+ symport
also have anion transporters of ABC type
and anion channels

108. Nutrient uptake
PO43-, SO42-, Cl- & NO3- enter by H+ symport
also have anion transporters of ABC type
and anion channels
Plants take up N many ways

109. Nutrient uptake
Plants take up N many ways: NO3- & NH4+ are main forms

110. Nutrient uptake
Plants take up N many other ways
NO3- also by channels
NH3 by diffusion
NH4+ by carriers

111. Nutrient uptake
Plants take up N many other ways
NO3- by channels
NH3 by diffusion
NH4+ by carriers
NH4+ by channels

112. Nutrient uptake
Plants take up N many other ways
3 families of H+ symporters take up amino acids

113. Nutrient uptake
Plants take up N many other ways
3 families of H+ symporters take up amino acids
Also have many peptide transporters
some take up di- & tri-
peptides by H+ symport

114. Nutrient uptake
Plants take up N many other ways
3 families of H+ symporters take up amino acids
Also have many peptide transporters
some take up di- & tri-
peptides by H+ symport
others take up tetra- &
penta-peptides by H+ symport

115. Nutrient uptake
Plants take up N many other ways
3 families of H+ symporters take up amino acids
Also have many peptide transporters
some take up di- & tri-
peptides by H+ symport
others take up tetra- &
penta-peptides by H+ symport
Also have ABC transporters
that import peptides

116. Nutrient uptake
Plants take up N many other ways
3 families of H+ symporters take up amino acids
Also have many peptide transporters
some take up di- & tri-
peptides by H+ symport
others take up tetra- &
penta-peptides by H+ symport
Also have ABC transporters
that import peptides
N is vital!
NO3- & NH4+ are main forms

117. Nutrient uptake
Metals are taken up by ZIP proteins & by ABC transporters
same protein may import Fe, Zn & Mn!

118. Nutrient uptake
Much is coupled to
pH gradient

119. Nutrient transport in roots
Move from soil to endodermis in apoplast

120. Nutrient transport in roots
Move from soil to endodermis in apoplast
Move from endodermis to xylem in symplast

121. Nutrient transport in roots
Move from endodermis to xylem in symplast
Transported into xylem by H+ antiporters

122. Nutrient transport in roots
Move from endodermis to xylem in symplast
Transported into xylem by H+ antiporters, channels

123. Nutrient transport in roots
Transported into xylem by H+ antiporters, channels,pumps

124. Nutrient transport in roots
Transported into xylem by H+ antiporters, channels,pumps
Lowers xylem water
potential -> root pressure

125. Transport to shoot
Nutrients move up
plant in xylem sap

126. Nutrient transport in leaves
Xylem sap moves through apoplast
Leaf cells take up what
they want