How Romanesco cauliflower forms its spiraling fractals

Scientists were able to duplicate the pattern by modifying just three genes in a typical lab plant. 

The fractal display of Romanesco cauliflower (pictured) is one of nature's most beautiful.  FLICKR/AURELIEN GUICHARD (CC BY-SA 2.0)
The fractal display of Romanesco cauliflower (pictured) is one of nature's most beautiful.  FLICKR/AURELIEN GUICHARD (CC BY-SA 2.0)

The swirling green cones that make up a Romanesco cauliflower head also form a fractal design, which repeats itself on numerous scales. Researchers announce in Science on July 9 that the genes that underpin this remarkable structure have been found, and the fractal pattern has been duplicated in a common lab plant, Arabidopsis thaliana.

"Romanesco is one of nature's most visible fractal designs," says Christophe Godin, a computer scientist at the National Institute for Research in Digital Science and Technology at ENS de Lyon in France. "Why is that?" says the narrator. Scientists have been unable to find a solution for a long time.

An Arabidopsis variety could create miniature cauliflower-like structures, according to Godin and his colleagues. As a result, the researchers used computer simulations and lab experiments to modify the genes of A. thaliana. The researchers were able to streamline their trials and extract the basic fractal-spawning mechanism by working with the well-studied plant (SN: 6/15/21).

The researchers produced a Romanesco-like head-on A. thaliana by modifying three genes. Two of the genetic tinkerings slowed flower growth and sparked an out-of-control shoot growth. According to plant biologist François Party of the CNRS in Paris, the plant grows a shoot in place of a flower, and on that shoot, it grows another shoot, and so on. "It's a chain reaction," says the narrator.

The researchers then changed another gene, allowing spiraling conical fractals to form by increasing the growth area at the end of each shoot. "You don't have to make a lot of genetic changes to get this shape to appear," Party explains. "The next stage for the researchers will be to control these genes in cauliflower," he says.

E. Azpeitia, et alCauliflower fractal forms arise from perturbations of floral gene networksScience. Vol. 373, July 9, 2021, p. 192. DOI: 10.1126/science.abg5999.


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