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

2. 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

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

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

5. N assimilation by non-N fixers
Nitrate reductase in cytoplasm reduces
NO3- to NO2-
NO3- + NADPH = NO2- + NADP+
large enzyme with FAD & Mo cofactors

6. 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)!

7. Nutrient uptake
Much is coupled to
pH gradient

8. 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

9. 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

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

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

12. 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

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

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

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

16. Nutrient assimilation
Assimilating N and S is
very expensive!
Reducing NO3- to NH4+
costs 8 e- (1 NADPH +
6 Fd)

17. Nutrient assimilation
Assimilating N and S is
very expensive!
Reducing NO3- to NH4+
costs 8 e- (1 NADPH +
6 Fd)
Assimilating NH4+ into
amino acids also costs
ATP + e-

18. Nutrient assimilation
Assimilating N and S is very expensive!
Reducing NO3- to NH4+ costs 8 e- (1 NADPH + 6 Fd)
Assimilating NH4+ into amino acids also costs ATP + e-
Nitrogen fixation costs 16 ATP + 8 e-

19. Nutrient assimilation
Assimilating N and S is very expensive!
Reducing NO3- to NH4+ costs 8 e- (1 NADPH + 6 Fd)
Assimilating NH4+ into amino acids also costs ATP + e-
Nitrogen fixation costs 16 ATP + 8 e-
SO42- reduction to S2- costs 8 e- + 2ATP

20. Nutrient assimilation
Assimilating N and S is very expensive!
Reducing NO3- to NH4+ costs 8 e- (1 NADPH + 6 Fd)
Assimilating NH4+ into amino acids also costs ATP + e-
Nitrogen fixation costs 16 ATP + 8 e-
SO42- reduction to S2- costs 8 e- + 2ATP
S2- assimilation into Cysteine costs 2 more e-
Most explosives are based on N or S!

21. Nutrient assimilation
Most explosives are based on N or S!
Most nutrient assimilation occurs in source leaves!

22. N cycle
Must convert N2 to a form that can be assimilated
N2 -> NO3- occurs in atmosphere: lightning (8%) & Photochemistry (2%) of annual total fixed
Remaining 90% comes from biological fixation to NH4+

23. N cycle
Soil bacteria denitrify NO3- & NH4+ back to N2
Plants must act fast!
Take up NO3- & NH4+ but generally prefer NO3-
Main form available due to bacteria

24. N assimilation by non-N fixers
Nitrate reductase in cytoplasm reduces
NO3- to NO2-
NO3- + NADPH = NO2- + NADP+
large enzyme with FAD & Mo cofactors

25. N assimilation by non-N fixers
Nitrate reductase in cytoplasm reduces
NO3- to NO2-
NO3- + NADPH = NO2- + NADP+
large enzyme with FAD & Mo cofactors
NO2- is imported to plastids & reduced
to NH4+ by nitrite reductase

26. N assimilation by non-N fixers
Nitrate reductase in cytoplasm reduces
NO3- to NO2-
NO3- + NADPH = NO2- + NADP+
large enzyme with FAD & Mo cofactors
NO2- is imported to plastids & reduced
to NH4+ by nitrite reductase

27. N assimilation by non-N fixers
NO2- is imported to plastids & reduced
to NH4+ by nitrite reductase
NO Fdred + 8 H+ = NH Fdox + 2 H2O
0.2% of NO2- is released as N2O : another reason rape & corn biofuels increase global warming

28. N assimilation by non-N fixers
NO2- is imported to plastids & reduced
to NH4+ by nitrite reductase
NO Fdred + 8 H+ = NH Fdox + 2 H2O
0.2% of NO2- is released as N2O : another reason rape & corn biofuels increase global warming
Regulated at NO3- reductase; always << NO2- reductase
NO2- is toxic!

29. N assimilation by non-N fixers
Regulated at NO3- reductase; always << NO2- reductase
NO2- is toxic!
NR induced by light & nitrate

30. N assimilation by non-N fixers
Regulated at NO3- reductase; always << NO2- reductase
NO2- is toxic!
NR induced by light & nitrate

31. N assimilation by non-N fixers
Regulated at NO3- reductase; always << NO2- reductase
NO2- is toxic!
NR induced by light & nitrate
Regulated by kinase in dark, dephosphorylation in day

32. NH4 assimilation
GS -> GOGAT
Glutamate + NH4+ + ATP <=> Glutamine + ADP +Pi

33. GS -> GOGAT
Glutamate + NH4+ + ATP <=> Glutamine + ADP +Pi
Glutamine + a-ketoglutarate + NADH/2 Fdred <=>
2 Glutamate + NAD+/ 2 Fdox

34. GS -> GOGAT
Glutamate + NH4+ + ATP <=> Glutamine + ADP +Pi
Glutamine + a-ketoglutarate + NADH/2 Fdred <=>
2 Glutamate + NAD+/ 2 Fdox

35. GS -> GOGAT
Glutamate + NH4+ + ATP <=> Glutamine + ADP +Pi
Glutamine + a-ketoglutarate + NADH/2 Fdred <=>
2 Glutamate + NAD+/ 2 Fdox
3. Fd GOGAT lives in source cp

36. GS -> GOGAT
Fd GOGAT lives in source cp
NADH GOGAT lives in sinks

37. GS -> GOGAT
Glutamate + NH4+ + ATP <=> Glutamine + ADP +Pi
Glutamine + a-ketoglutarate + NADH/2 Fdred <=>
2 Glutamate + NAD+/ 2 Fdox
3. Use glutamate to make other a.a. by transamination

38. GS -> GOGAT
Glutamate + NH4+ + ATP <=> Glutamine + ADP +Pi
Glutamine + a-ketoglutarate + NADH/2 Fdred <=>
2 Glutamate + NAD+/ 2 Fdox
3. Use glutamate to make other a.a. by transamination

39. GS -> GOGAT
3. Use glutamate to make other a.a. by transamination
Glutamate, aspartate & alanine can be converted to the other a.a.

40. N assimilation by N fixers
Exclusively performed by prokaryotes
Dramatically improve the growth of many plants

41. N assimilation by N fixers
Exclusively done by prokaryotes
Most are free-living in soil or water

42. N assimilation by N fixers
Exclusively done by prokaryotes
Most are free-living in soil or water
Some form symbioses with plants

43. 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

44. 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

45. 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

46. N assimilation by N fixers
All must form O2-free
environment for nitrogenase
O2 binds & inactivates e-transfer
sites

47. N assimilation by N fixers
O2 binds & inactivates e-transfer
sites
Heterocysts lack PSII, have
other mechs to lower pO2

48. N assimilation by N fixers
Heterocysts lack PSII, have
other mechs to lower O2
Nodules have special
structure + leghemoglobin
to protect from O2

49. Nodule formation
Nodules have special structure + leghemoglobin to protect from O2
Bacteria induce the plant to form nodules

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

51. 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 coiling
Nod factors determine species-specificity

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

53. 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

54. 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

55. 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

56. 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.

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

58. 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

59. 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

60. N2 + 8H+ + 8e− + 16 ATP → 2NH3 + H2 + 16ADP + 16 Pi
Nitrogen fixation
N2 + 8H+ + 8e− + 16 ATP → 2NH3 + H2 + 16ADP + 16 Pi
Catalysed by nitrogenase, a very complex enzyme!

61. N2 + 8H+ + 8e− + 16 ATP → 2NH3 + H2 + 16ADP + 16 Pi
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

62. N2 + 8H+ + 8e− + 16 ATP → 2NH3 + H2 + 16ADP + 16 Pi
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

63. 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

64. 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!

65. S assimilation
SO42- comes from weathering or from rain: now an important source! Main thing that makes rain acid!

66. S assimilation
SO42- comes from weathering or from rain: now an important source!
Main cause of rain acid!

67. S assimilation
S is used in cysteine & methionine

68. S assimilation
S is used in cysteine & methionine
Also used in CoA, S-adenosylmethionine

69. S assimilation
S is used in cysteine & methionine
Also used in CoA, S-adenosylmethionine
Also used in sulphoquinovosyl-diacylglycerol

70. S assimilation
S is used in cysteine & methionine
Also used in CoA, S-adenosylmethionine
Also used in sulphoquinovosyl-diacylglycerol

71. S assimilation
S is used in cysteine & methionine
Also used in CoA, S-adenosylmethionine
Also used in sulphoquinovosyl-diacylglycerol
And in many storage compounds: eg allicin (garlic)

72. S assimilation
SO42- comes from weathering or from rain: now an important source! Main thing that makes rain acid!
Some bacteria use SO42- as e- acceptor -> H2S

73. S assimilation
SO42- comes from weathering or from rain: now an important source! Main thing that makes rain acid!
Some bacteria use SO42- as e- acceptor -> H2S
Some photosynthetic bacteria use reduced S as e- donor!

74. S assimilation
SO42- comes from weathering or from rain: now an important source! Main thing that makes rain acid!
Some bacteria use SO42- as e- acceptor -> H2S
Some photosynthetic bacteria use reduced S as e- donor!

75. S assimilation
SO42- comes from weathering or from rain: now an important source! Main thing that makes rain acid!
Some bacteria use SO42- as e- acceptor -> H2S
Some photosynthetic bacteria use reduced S as e- donor!
Now that acid rain has declined in N. Europe Brassica & wheat need S in many places

76. S assimilation
SO4 2- is taken up by roots &
transported to leaves in xylem
Most is reduced in cp

77. S assimilation
SO4 2- is taken up by roots &
transported to leaves in xylem
Most is reduced in cp
1. add SO4 2- to ATP -> APS

78. S assimilation
add SO4 2- to ATP -> APS
Transfer S to Glutathione -> S-sulfoglutathione

79. S assimilation
add SO4 2- to ATP -> APS
Transfer S to Glutathione -> S-sulfoglutathione
S-sulfoglutathione + GSH -> SO32- + GSSG

80. S assimilation
add SO4 2- to ATP -> APS
Transfer S to Glutathione -> S-sulfoglutathione
S-sulfoglutathione + GSH -> SO32- + GSSG
Sulfite + 6 Fd -> Sulfide

81. S assimilation
add SO4 2- to ATP -> APS
Transfer S to Glutathione -> S-sulfoglutathione
S-sulfoglutathione + GSH -> SO32- + GSSG
Sulfite + 6 Fd -> Sulfide
Sulfide + O-acetylserine -> cysteine + acetate
O-acetylserine was made from serine + acetyl-CoA

82. S assimilation
Most cysteine is converted to
glutathione or methionine

83. S assimilation
Most cysteine is converted to
glutathione or methionine
Glutathione is main form
exported

84. S assimilation
Most cysteine is converted to
glutathione or methionine
Glutathione is main form
exported
Also used to make many other
S-compounds

85. S assimilation
Most cysteine is converted to
glutathione or methionine
Glutathione is main form
exported
Also used to make many other
S-compounds
Methionine also has many uses
besides protein synthesis

86. S assimilation
Most cysteine is converted to glutathione or methionine
Cys + homoserine -> cystathione

87. S assimilation
Most cysteine is converted to glutathione or methionine
Cys + homoserine -> cystathione
Cystathione -> homocysteine + Pyruvate + NH4+

88. S assimilation
Most cysteine is converted to glutathione or methionine
Cys + homoserine -> cystathione
Cystathione -> homocysteine + Pyruvate + NH4+
Homocysteine + CH2=THF -> Met + THF
80% of met is converted to S-adenosylmethionine & used for biosyntheses

89. S assimilation
Most cysteine is converted to glutathione or methionine
Glutathione is made enzymatically!
Glutamate + Cysteine -> g-glutamyl cysteine

90. S assimilation
Glutathione (GluCysGly) is made enzymatically!
Glutamate + Cysteine -> g-glutamyl cysteine
g-glutamyl cysteine + glycine -> glutathionine

91. S assimilation
Glutathione (GluCysGly) is made enzymatically!
Glutamate + Cysteine -> g-glutamyl cysteine
g-glutamyl cysteine + glycine -> glutathionine
Glutathione is precursor for many chemicals, eg phytochelatins

92. S assimilation
Glutathione (GluCysGly) is made enzymatically!
Glutamate + Cysteine -> g-glutamyl cysteine
g-glutamyl cysteine + glycine -> glutathionine
Glutathione is precursor for many chemicals, eg phytochelatins
SAM & glutathione are also precursors for many cell wall components