Postharvest Biology and Technology of Fruits, Vegetables, and Flowers

POSTHARVEST ENHANCEMENT OF PHENOLIC PHYTOCHEMICALS IN APPLES 343
Cytosol
NADP
NADP
NADP
NADPH
Pentose phosphate pathway
Glucose
Glucose
G-6-P dehydrogenase
6-Phosphogluconolactone
6-Phosphogluconolactone
dehydrogenase
Ribulose-5-P
Glycolysis
Glucose-6-P
Fructose-6-P
Ribose-5-P
Erythrose-4-P
Phosphoenol
pyruvate
Shikimate pathway
Pyruvate
3-Dioxyarabino heptulosonate 7-P
)
TCA
Shikimate
Chorismate
Tyr Phe Trp
Cinnamate
Phenolic
Lignin
Phenylpropanoid pathway
Fig. 16.1
Biosynthesis of phenolic phytochemicals.
phenolic phytochemicals (Mann, 1978; Chugh and Sawhney, 1999; Shetty et al., 2003;
Shetty and Wahlqvist, 2004; Vattem et al., 2005; Fig. 16.2).
These phenolic phytochemicals have been shown to have a wide array of functions in
plants. In plants biotic and abiotic stress has been shown to stimulate secondary metabolite
synthesis that results in the production of phenolics (Dixon et al., 1994; Dixon and Paiva,
1995). Ozone exposure has been shown to increase transcript levels of enzymes involved in
the phenolic synthesis and lignin pathways (Brooker and Miller, 1998). Studies have linked