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Flowering Time
FT
Flower Meristem Identity
APETALA1, LEAFY, CAULIFLOWER,
(TERMINAL FLOWER)
Flower Organ Identity
A, B, C
Fruit Development
FRUITFULL, SHATTERPROOF
INDEHISCENT
4
3 2 1
carpel
stamen
C
sepal
C
petal
A
stamen
1 2 3
petal
sepal
B
B
A
normal flower
What gene prevents the B gene from being
active in the center of flowers?
B
C
carpel
C
sepal
petal
stamen
A
A
stamen
petal
sepal
B
In SUPERMAN mutants (SUP), the B activity
expands into the center of the flower and converts
the two carpels into two stamens.
B
C
C
A
stamen
stamen
stamen
petal
sepal
sepal
petal
A
B
Superman mutant
The SUPERMAN gene normally functions to
prevent B gene activity in the center of flowers
B
C
C
A
stamen
stamen
stamen
petal
sepal
sepal
petal
A
B
C
stamen
petal
sepal
A
carpel
sepal
petal
stamen
normal
B
C
BC mutant ??
B
A
A
A
A
A
C
A
A
A
*
sepal
sepal
sepal
B
sepal
sepal
sepal
C
stamen
petal
sepal
A
carpel
sepal
petal
stamen
normal
BC mutant
B
A
A
BC double
mutant
all organs
are sepals
What happens if the A, B and C genes are all
inactivated in the ABC triple mutant?
B
C
carpel
C
sepal
petal
stamen
A
A
stamen
petal
sepal
B
B
C
C
stamen
petal
sepal
A
carpel
sepal
petal
stamen
normal
ABC mutant ??
B
A
C
C
*
leaf
leaf
leaf
A
leaf
leaf
leaf
B
stamen
petal
sepal
sepal
petal
stamen
carpel
normal
ABC mutant
B
A
“ABC” triple
mutant
all organs
are leaves
Goethe believed that floral organs are derived from leaves
Goethe, 1790
petal
stamen
sepal
carpel
sepal
leaf
The C gene is active in cells that
will form stamens and carpels
petal
stamen
sepal
carpel
sepal
leaf
What would happen if the C gene was mis-expressed
in cells that would normally form sepals?
C
stamen
petal
sepal
A
carpel
sepal
petal
stamen
normal
B
B
C
A
Regulatory region
stamens and carpels
Remove regulatory region:
Add sepal regulatory region:
sepals
C GENE
Coding Region
Flowering Time
FT
Flower Meristem Identity
APETALA1, LEAFY, CAULIFLOWER,
(TERMINAL FLOWER)
Flower Organ Identity
A, B, C
Fruit Development
FRUITFULL, SHATTERPROOF
INDEHISCENT