Transgenic Ornamental Crops - Transgenic Horticultural Crops: Challenges and Opportunities - page 59

OH

CoAS

+ 3 Malonyl-CoA

O

p -Coumaroyl CoA

CHS

HO OH

OH

Chalcones

OH O

Tetrahydroxychalcone

CHI

OH OH

3'

4' OH

OH OH

B

8

HO O HO 7 O 5'

Flavanones

HO O

OH

A C

6

F3'5'H

F3'H

5

OH OH O

O OH O

Naringenin

Pentahydroxy avanone Eriodictyol

F3H F3H

F3H

OH OH

OH OH

OH

HO O HO HO O

O

Dihydro avonols

OH

OH OH OH

F3'5'H F3'H

OH O OH O

OH O

Dihydromyricetin Dihydrokaempferol Dihydroquercetin

DFR DFR DFR

DFR

OH

OH OH

Leucoanthocyanidins

OH OH

OH
OH

OH

HO O HO O HO O

HO O

OH OH OH

OH OH OH

OH OH OH

OH OH

Leucodelphinidin Leucopelargonidin Leucocyanidin Luteoforol

LDOX/ANS LDOX/ANS LDOX/ANS

OH OH OH

OH
OH

OH OH

OH

HO HO O HO O HO O

O

Anthocyanidins

OH OH OH

OH OH OH OH

Delphinidin Pelargonidin Cyanidin Luteolinidin

FIGURE 3.1 Key. steps. of. anthocyanin. pigment. biosynthesis. in. plants.. CHS,. chalcone.
synthase;. CHI,. chalcone. isomerase;. F3′5′H,. lavanone. 3′5′-hydroxylase;. F3′H,. lavanone.
3′-hydroxylase;. F3H,. lavanone. 3-hydroxylase;. DFR,. dihydrolavonol. 4-reductase;. LDOX/
ANS,.leucoanthocyanidin.dioxygenase/anthocyanidin.synthase..(Reprinted.from.Grotewold,.E.,.
Annu. Rev. Plant Biol .,.57,.761,.2006..With.permission..©.2006.by.Annual.Reviews.www.
annualreviews.org)

to the formation.of.this.type.of.complex.is.of.interest.for.engineering.blue.color.in.
lowers.but.has.yet.to.be.elucidated.
A.novel.orange.color.was.irst.introduced.into. Petunia .by.incorporating.a.maize.
DFR .gene.into.the.genome.of.a.variety.lacking.F3′H.and.F3′5′H.activity. 19 .The.back-
ground. chosen. for. introducing. the. maize. DFR . was. important. as. petunias. lacking.
F3′H.and.F3′5′H.activity.accumulate.the.dihydrolavonol.dihydrokaempferol.since.the.
Petunia .DFR.does.not.accept.dihydrokaempferol.as.a.substrate.for.leucoanthocyanidin.
synthesis..The.maize.DFR,.which.uses.the.substrate.dihydrokaempferol,.opened.up.a.