Recent research has shed light on the genetic origins of domesticated plants, particularly focusing on cauliflower (Brassica oleracea) and its fractal cousin, romanesco. During domestication, humans selected plants best suited to their needs, leading to significant genetic modifications.
Cauliflower and romanesco exhibit strikingly different appearances, with romanesco characterized by its fractal structure made of spirals of conical florets. This study, published in the journal Science, explores how accumulated genetic changes over centuries have led to such complex forms.
Using Arabidopsis thaliana, a well-studied relative of cabbage, researchers discovered that two specific genetic mutations can transform flowers into small cabbages. This suggests that a limited number of mutations are essential for converting ancestral plant structures into edible forms.
The growth of plants is influenced by a competition between 'stem' and 'flower' genes within buds. The study employed a combination of biological experimentation, mathematical modeling, and 3D simulations to isolate the genetic mechanisms responsible for cauliflower's structure.
In normal plants, a gene termed the 'floral architect' activates in flower buds, calling upon additional floral genes to prevent stem gene interference. However, in Arabidopsis cauliflower, the required floral genes are inactive due to mutations, allowing stem genes to dominate.
This leads to a chain reaction where modified stem buds produce new flower buds that revert to stem buds, creating a compounding effect of stems. The research indicates that both cauliflower and romanesco share similar genetic mechanisms, although romanesco's growth rate and structure result in its distinct fractal appearance.
The findings have significant implications for both research and agriculture. Identifying the mutations responsible for these unique shapes may facilitate the domestication of wild green cabbages with agricultural benefits, such as disease resistance and temperature tolerance. This approach, termed 'de novo domestication,' aims to replicate the lengthy domestication process through modern genome editing techniques.
Christophe Godin serves as a research director at Inria, while Francois Parcy leads the 'Flower Development Regulators' team at Inrae.