# ABC model of flower development

ABC model of flower development is a scientific model of the process by which flowering plants produce a pattern of gene expression in meristems that leads to the appearance of an organ oriented towards sexual reproduction, a flower.

## Quotes

* The ABC model was popularized in a review in Nature published later in 1991 by the senior author and Enrico Coen, whose group had been making parallel new findings of similar homeotic mutants in snapdragon. [...] The ABC model is still widely used as a framework for understanding floral development today.
** John L. Bowman, David R. Smyth and Elliot M. Meyerowitz, "The ABC model of flower development: then and now", Development (2012)
* Two general conclusions can be reached from the comparison of flower development genes in two distantly related species. The first is that the basic mechanisms that define organ identity in developing flowers appear to be the same in both species. Genes exist whose mutants have similar phenotypes and similar interactions, and a single model can explain the action of these genes in both species.
** Enrico S. Coen and Elliot M. Meyerowitz, "The war of the whorls: genetic interactions controlling flower development", Nature (1991)
* Perhaps it was Goethe's breadth of mind, his desire to understand the underlying unity of nature without too much concern for experimental details, that led him to this remarkable insight. [...] His clear appreciation of the significance of abnormalities was certainly ahead of its time. Goethe's perspective only came to experimental fruition in the twentieth century, as mutations affecting development stated to be investigated in detail. The unraveling of the abc model is a good example of how the outlook underwent a change.
** Enrico Coen, The Art of Genes: How Organisms Make Themselves (1999)
* ...we may equally well say that a stamen is a contracted petal, as that a petal is a stamen in a state of expansion; or that a sepal is a contracted stem leaf approaching a certain stage of refinement, as that a stem leaf is a sepal expanded by the influx of cruder saps.
** J.W. von Goethe (1790), Versuch die Metamorphose der Pflanzen zu erklaren. Gotha, Ettlinger; paragraph 120.
* Much of our fascination with the data of evo-devo arises from the sheer novelty of discovery in biological domains that had been previously and totally inaccessible. These empirical gems also illustrate, even in these early days, the integrating power of scientific conclusions to translate a previous descriptive chaos into explanatory sensibility. As an example, consider the name given to the truly elegant theory of floral genesis, as developed by students of Arabidopsis, the "Drosophila" of angiosperm biology—the ABC Model (Coen and Meyerowitz, 1991; Weigel and Meyerowitz, 1994; Jurgens, 1997; Busch, Bomblies, and Weigel, 1999; Wagner, Sablowski, and Meyerowitz, 1999). In this elegantly simple model (see Fig. 10-12), based on genes with homeotic effects upon serially repeated structures arranged in systematic order (with repetition in concentric whorls rather than linearly along a body axis), A genes operating alone determine the form of the outermost whorl of leaf-like sepals; A plus B genes regulate petals in the next whorl within; B plus C genes mark the male stamens, while C genes working alone determine the most interior female carpels. Moreover, leafy, a "higher control" gene previously recognized as an initiator or suppressor of floral growth and placement in general (Weigel and Nilsson, 1995), apparently also regulates the more specific operation of the ABC series. (Busch et al., 1999, demonstrate that a protein produced by leafy bonds directly to a particular DNA segment of a C gene responsible for the generation of carpels.)
** Stephen Jay Gould, The Structure Of Evolutionary Theory (2002), Chapter 10: The Integration of Constraint and Adaptation (Structure and Function) in Ontogeny and Phylogeny: Historical Constraints and the Evolution of Development