Agriculture Reference
In-Depth Information
Chloroplast/Cytosol
Mitochondria
Glucose
proline
−
e
PDH
(Proline dehydrogenase)
Proline
Glucos-6-P
G6PDH
(Glucose-6-phosphate
dehydrogenase)
+
NADP
P-5-C
NADP H
e
−
6-Phospho-glucose--lactone
P-5-C
6-Phosphogluconate
dehydrogenase
+
NADP
NADPH
Glutamate
Sugar
phosphates for
anabolic
reactions
Glutamate
Ribulos-5-P
Alternative oxidative
phosphorylation under
oxidation stress with
phenolic antioxidants
Erythrose
-4-P
Indole
Chorismate
Shikimate
Pathway
Ribos-5-P
Phenylalanine
(Phosphoribosyl
pyrophosphate)
Tryptophan
IAA
PRP
B.
Cinnamate
Inner
membrane
space
Inner
membrane
Mitochondrial
matrix
Purine
Phenolics
Phenylpropanoid
pathway
Adenine
Proline
(Replacing NADH)
H
+
induced
prolin-linked
pentose
phosphate
pathway
e
−
DNA/RNA, ATP
Guanine
Reactive
oxygen
O
2
Phenolic
Antioxidant
2H
+
e
−
2H
+
Cytokinin
2H
+
e
−
1
/
2
O
2
OH
-
OH
-
OH
H
+
H
+
H
+
pH gradient
electrochemical
gradient
GST/PO/SOD
with phenolics initiate
antioxidant response and
scavenge free radicals with
NADPH from proline-linked
pentose phosphate pathway
-
H
2
O
Proton/hydride ions
(hyperacidification)
2H
+
ATPase
3AT P
H
+
H
+
2H
+
2H
+
Organelle
nuclear
vacuole and
cytosolic reactions
H
+
Reactions of phenolic
Radical on the membrane
-Signaling
-Transport mobilization
-C-transport stimulation
-Transport inhibition, etc.
Receptor
−
O
Phenolic radical reactions on
the membrane and cell wall can
involve peroxidase-induced
polymerization
Phenolic
radical
H
+
H
+
−
COO
H
+
Fig. 16.6
Proline-linked pentose phosphate pathways for phenolic synthesis and efficient antioxidant response
(Shetty and Wahlqvist, 2004).
P5C and linking the electron transport chain (ETC) in the mitochondria with oxygen as
the terminal electron acceptor. P5C is then hydrolyzed nonenzymatically and oxidized to
glutamate by the NAD-dependent P5C dehydrogenase. Following oxidative deamination by
glutamate dehydrogenase, it flows into the TCA cycle through
-ketoglutarate to generate
NADH for oxidative phosphorylation or recycled back into the cytosol (Hare and Cress,
1997; Shetty and Wahlqvist, 2004; Krishnan and Becker, 2006; Fig. 16.6).
α
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