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Flowering Time Flower Meristem Identity Flower Organ Identity Fruit Development FT APETALA1, LEAFY, CAULIFLOWER, (TERMINAL FLOWER) A, B, C, D FRUITFULL,

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Flowering Time

Flower Meristem Identity

Flower Organ Identity

Fruit Development

FT

APETALA1, LEAFY, CAULIFLOWER, (TERMINAL FLOWER)

A, B, C, D

FRUITFULL, SHATTERPROOFINDEHISCENT

B

A C C A

B

carp

el

pet

al

pet

al

stam

en

stam

en

sep

al

sep

al

1 12 23 34

normal flower

sep

al

sep

al

pet

al

pet

alst

amen

stam

en

carp

elBB

A C C A

What gene prevents the B gene from beingactive in the center of flowers?

In SUPERMAN mutants (SUP), the B activityexpands into the center of the flower and convertsthe two carpels into two stamens.

A C C A

B B

stam

en

stam

en

sep

al

sep

al

pet

al

pet

al

stam

en

Superman mutant

The SUPERMAN gene normally functions toprevent B gene activity in the center of flowers

A C C A

B B

stam

en

stam

en

sep

al

sep

al

pet

al

pet

al

stam

en

normal BC mutant ??se

pal

sep

al

pet

al

pet

alst

amen

stam

en

carp

el

BB

A C C A

A A A A

normal BC mutantse

pal

sep

al

pet

al

pet

alst

amen

stam

en

carp

el

BB

A C C A

A A A A

sep

al

sep

al

sep

al

sep

alse

pal

sep

al

*

BC double mutant

all organsare sepals

sep

al

sep

al

pet

al

pet

alst

amen

stam

en

carp

elBB

A C C A

What happens if the A, B and C genes are allinactivated in the ABC triple mutant?

normal ABC mutant ??se

pal

sep

al

pet

al

pet

alst

amen

stam

en

carp

el

BB

A C C A

ABC mutant

leaf

leaf

leaf

leaf

leaf

leaf*

normalse

pal

sep

al

pet

al

pet

alst

amen

stam

en

carp

el

BB

A C C A

“ABC” triple mutant

all organsare leaves

Goethe believed that floral organs are derived from leaves

Goethe, 1790

• All flower organs are converted into leaves in the abc triple mutant.

• The ABC genes are necessary to convert leaves into each of the flower organs.

• The A and B genes are necessary for petal development.

• What would happen if the A and B genes were mis-expressed in leaves? Are the A and B genes sufficient to convert normal leaves into petals?

leaf petal?A+B

“D” mutant

all organsare sepals

A B

C D

D Activity is required forpetal, stamen and carpel development

• The D gene is expressed in cells that will form petals, stamens and carpels.

• The D gene is required for the activity of the B and C genes.

sep

al

stam

en

pet

al

carp

el

pet

al

stam

en

sep

al

B

A C C A

B

D D

normal D mutantse

pal

sep

al

pet

al

pet

alst

amen

stam

en

carp

el

BB

A C C A

A A A A

sep

al

sep

al

sep

al

sep

alse

pal

sep

al*

DD

• The A, B and D genes are necessary for petal development.

• What would happen if the A, B and D genes were mis-expressed in leaves? Are the A, B and D genes sufficient to convert normal leaves into petals?

Regulatory regionPetals, stamens and carpels

D GENECoding Region

leavesAdd Leaf regulatory region:

Remove regulatory region:

leaf petalA+B+D

?

leaf petalA+B+D

A = sepals

A + B + D = petals

C + D = carpels

B + C + D = stamens

The ABCD genes act alone, or incombination, to specify the fourtypes of flower organs

The ABCD genes are sufficient to convert leaves into flower organs

The ABCD model is applicable to allflowering plants

The C gene is active in cells that will form stamens and carpels

petal

sepalcarpel

leaf

sepalstamen

What would happen if the C gene was mis-expressedin cells that would normally form sepals?

petal

sepalcarpel

leaf

sepalstamen

B

normal

stam

en

stam

en

carp

el

sep

al

sep

al

B

A C C A

pet

al

pet

al

Regulatory regionstamens and carpels

C GENECoding Region

sepalsAdd sepal regulatory region:

Remove regulatory region:

Flowering Time

Flower Meristem Identity

Flower Organ Identity

Fruit Development

FT

APETALA1, LEAFY, CAULIFLOWER, (TERMINAL FLOWER)

A, B, C, D

FRUITFULL, SHATTERPROOFINDEHISCENT