Homeotic Mutations in Fruit Flies and Hibiscus
The two pairs of wings fruit fly results from a bithorax mutation in the third thoracic segment. Normally, fruit flies have one pair of wings from the second thoracic segment and one pair of halteres from the third.
In fruitflies, the second thoracic segment develops into wings, while the third segment develops into halteres.
In contrast, the ultrabithorax mutation causes the third thoracic segment to transform into the second thoracic segment, resulting in two pairs of wings, similar to butterflies!?
Congratulations, Sailakshmi, @~M S Sailekshmi for bringing your 
Hibiscus from the garden to the discussion!
Is it a mutant?
What differences we are seeing here?
In the Hibiscus, we have sepal, petal, stamen, and carpel. In this one, we can see sepal, petal, petal, stamen, and carpel.
In hibiscus, flowers typically consist of sepals, petals, stamens, and carpels. However, double-layered hibiscus has been observed in Sailakshmi’s Homelab, indicating that if the expression of AGAMOUS orthologous genes is down-regulated, it will result in the transformation of stamens and carpels into petaloid structures.
Reference:
Homeosis phenomenon found in the double flower type I and II, where the reduction number of stamen has a
correlation with the additional number of petals, could be explained as an addition of one whorl occurs in parallel to
the deletion of the other [10]. The results showed that the structure of the stamen-petal intermediate closer to the
position of the stamen circle, while the petaloid structure formed in a position that is closer to the corolla circle. This
phenomenon does not only occur in the double and crested H. rosa-sinensis flowers, but also observed in Potentilla
fructicosa [11]. Irish (2000) *argues that the formation of stamen-petal intermediate structures is due to non-
expression of some of the AGAMOUS orthologous genes [12]. If the AGAMOUS orthologous genes expression is
down-regulated, it will have an effect of changing the stamen and carpel into petaloid structure
ABC model of flower development
Class A genes :
APETALA1(AP1)
APETALA2 (AP2)
Class B genes :
APETALA3(AP3)
PISTIL-LATA (PI)
Class C genes :
AGAMOUS (AG)
Sepal = AP1+AP2 (class A genes )
Petal=AP1+AP2+AP3+PI (class A+Class B genes )
Stamen=AP3+PI+AG ( Class B+Class c)
Carpel=AG ( class C genes )
A) Ubx is responsible for all of the differences between the second (T2) and third (T3) thoracic segments. Ubx loss-of-function mutations transform halteres (green box, center panel) into wings (left panel); Ubx gain-of-function in T2 transforms the wings into halteres (right panel). B) In this study, tissue-specific chromatin immunoprecipitation was performed with pure populations of haltere or T3 leg imaginal discs, both of which express Ubx in all cells (green) and express Hth (red) in the subset of cells that will give rise to proximal appendages and body wall.https://www.researchgate.net/figure/A-Ubx-is-responsible-for-all-of-the-differences-between-the_fig1_51042428
