Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2024 Nov 5;151(21):dev203027. doi: 10.1242/dev.203027

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© 2024. Published by The Company of Biologists Ltd

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.

PMC Copyright notice

Fig. 3. — Variation in flower organ number and identity is related to floral display complexity. (A-E) Schematics of the ABC model that underpins the formation of floral organs in selected species, showing the final floral architecture and the underlying genes contributing to organ identity. The identity of floral organs is controlled by combinatorial action of the ABC genes. Colours of the boxes indicate the class of genes (A, green; B, purple; C, orange; E, blue). The organ identities defined by these gene combinations are shown at the bottom of the schematics (c, carpel; it, inner tepal; la, labellum; le, lemma; lo, lodicule; ot, outer tepal; p, petal; pa, palea; s, sepal; sd, staminode; st, stamen). (A) The canonical ABC model was first described in Arabidopsis. Different combinations of A, B, C and E gene expression promote the formation of sepals, petals, stamens and carpels. For example, regions where the B, C and E class genes are expressed form stamens, and regions where the A and E class genes are expressed form sepals. AG, AGAMOUS; AP1/2/3, APETALA 1/2/3; PI, PISTILLATA; SEP1/2/3/4, SEPALLATA 1/2/3/4. (B) In female Silene latifolia flowers (left), repression of B function expression in whorl 3 underpins the loss of stamens. In male S. latifolia flowers (right), extension of B function expression into whorl 4 explains the loss of carpels. SLM1/2/3/4/5, SILENE LATIFOLIA MADS 1/2/3/4/5; SEP, SEPALLATA. (C) Extensive duplication within B class genes is thought to explain the diversity of tepal morphology in orchids, which form inner and outer tepals, such as those of Phalaenopsis spp. AP3-1/3-2/3-3/3-4, APETALA3-1/3-2/3-3/3-4; OMADS4/6/8/10/11, ORCHID MADS 4/6/8/10/11. (D) Rice florets exhibit ABC model expression patterns that are very similar to the canonical ones, but changes in the targets of A and B function genes lead to the novel morphologies of the lemma, palea and lodicule. OM2/3/4/14/15/16/58, ORYZA SATIVA MADS 2/3/4/14/15/16/58; SEP, SEPALLATA. (E) In Aquilegia flowers, the duplication and diversification of the B function genes enables the development of a staminode (sterile stamens) whorl in addition to the usual four whorls. AG1, AGAMOUS 1; AP3-1/3-2/3-3, APETALA 3-1/3-2/3-3; FUL-like, FRUITFUL-like; PI, PISTILLATA; SEP, SEPALLATA.