Researchers from the Plant Molecular and Cellular Biology Institute, mixed centre of the UPV and CSIC, have taken part in an international study that unveils the mystery of the striking fractal structure and pyramid shape of this cauliflower of Italian origin.
The mystery of the peculiar shape of the Roman cauliflower has been solved by a team of international scientists including members from the Plant Molecular and Cellular Biology Institute (IBMCP, in Spanish), mixed centre of the Universitat Politècnica de València and the Spanish National Research Council (CSIC, in Spanish). The study, published in Science, was led by the National Centre for Scientific Research of France (CNRS, in French) and the French National Computing and Automation Research Institute (INRIA).
In the study, the researchers combined in vivo experiments with 3D computational models that reproduced the development of the plant’s inflorescence. Their goal was to discover the molecular bases of the growth of cauliflower in general, and Roman cauliflower in particular. They verified that both are in reality a proliferation of buds (meristems) programmed to become flowers but which never reach their goal; what they do is become stems that, in turn, continue trying to produce flowers. The cauliflower is born from the repetition of this process, which causes a sequence of stems upon stems.
Thus, the atypical shape of Romanesco is explained by the progressively faster production of stems that fail to become flowers, whereas this rate of production is constant in other types of cauliflower. As a result, the inflorescence of Roman cauliflower acquires a pyramid structure comprised by smaller pyramids, causing its fractal appearance.
“The meristems of the cauliflower fail to achieve their goal of becoming flowers, but they ‘remind us’ that they did temporarily acquire a floral state. The additional mutations that affect the growth and activity of the meristems are the ones that cause the characteristic fractal forms of Romanesco,” say IBMCP researchers Francisco Madueño, Antonio Serrano and Carlos Giménez.
Contribution of the IBMCP
The work of the IBMCP researchers in this study focused on characterising the network of genes that determines whether a flower or a stem is produced, and whose activity is therefore altered in the meristems of cauliflower and Romanesco. Specifically, they observed how TFL1, an essential gene for the formation of stems, is activated by genes that promote the formation of flowers, a result which is initially contradictory, but which is key to understand the development of plant inflorescence and, specifically, the formation of fascinating structures such as the fractal forms of Romanesco.
Cauliflower fractal forms arise from perturbations of floral gene networks. Eugenio Azpeitia, Gabrielle Tichtinsky, Marie Le Masson, Antonio Serrano-Mislata, Jérémy Lucas, Veronica Gregis, Carlos Gimenez, Nathanaël Prunet, Etienne Farcot, Martin M.Kater, Desmond Bradley, Francisco Madueño, Christophe Godin and Francois Parcy. Science, 9 July 2021. DOI : 10.1126/science.abg5999