The ABC model of floral development, formulated by George Haughn and Chris Somerville in 1988, explains the genetic basis for the formation of flower whorls—sepal, petal, stamens, and carpel—in Arabidopsis thaliana. It posits that three genes, A, B, and C, govern the transition from vegetative shoot to floral meristem, with A and C being equally dominant and B expressed in conjunction with them. Mutations in these genes affect the expression of various floral parts, highlighting their roles in floral development.

1. ABC Model of Floral Development
CSIR NET/GSET
Tushar Dedhiya

2. Firstly formulated by George Haughn and chris
somerville in 1988.
Experimental material was
Arabidopsis thaliana.
ABC Model of Floral Development

3. The four whorls are
Sepal, petal, stamens
and carpel.
Abc model of floral development explain the
genetics behind the formation of different
whorls in a flower.
ABC Model of Floral Development

4. Floral Development
• As we know that flower is modified shoot.
• ABC model says that the four whorls are
controlled by 3 genes that is A, B and C.
• this 3 gene are responsible for conversation of
vegetative shoot to floral meristem.

5. 1) A and C genes are equally dominant.
2) B genes are always express in association with A and
C
Remember :

6. Wild type/ Normal condition

7. Mutation in A genes :
C alone B + C B + C C alon

8. Mutation in B genes :
A
alone
A alone C alone C alone

9. Mutation in C genes :
A alone A + B A + B A alone

10. Thank you......😊