Roses, carnations and petunias: their “petalosity” is due to a hyperactive gene

12 February 2020

A study by the Department of Agricultural and Environmental Sciences of the University of Milan, the Institute of Agricultural Biology and Biotechnology of the National Research Council (Cnr-Ibba) and PTP Science Park (Lodi, Italy), published in the Journal of Experimental Botany, identifies regulatory gene mutations that cause the multiplication of petals in some popular flower varieties.

We are perhaps used to thinking that it is normal that roses, carnations and some petunias have many petals, but a research just published in the Journal of Experimental Botany has revealed that their “petalosity” is due to very similar natural genetic mutations. The all-Italian discovery is the result of a collaboration between the University of Milan, where it was coordinated by Laura Rossini, professor of Agricultural Genetics at the Department of Agricultural and Environmental Sciences, the Institute of Agricultural Biology and Biotechnology of the National Research Council (Cnr-Ibba), with the first author Stefano Gattolin, and PTP Science Park.

Beside laboratory experiments, some analyses were also carried out using a computer, thanks to online databases containing the entire genomic sequence of the DNA of different plants. For carnation, for example, genomic information is available online for the famous “Francesco” variety, created in the second half of the last century by the renowned Italian hybridizer Giacomo Nobbio. Researchers have shown that particular mutations in a key flower development gene alter its regulation, so as to make it “work” longer and cause the formation of an abundance of petals compared to the five petals which would be normal in carnation and other species. This information is of great interest for the nursery gardening sector, which counts on a multi-billion dollar turnover worldwide and is always looking for new products to be put on the market. The “double flowers”, with an increased number of petals, are in fact often preferred by consumers and increase the commercial value of many varieties.

During previous studies, the authors had already identified the mutation responsible for this character in the peach tree and in some roses: “It was really surprising to investigate one by one these genes and discover similar mutations in Rosa rugosa, carnations and popular “double” petunias, so much so that we coined the name “Petalosa” for this gene family” comments Dr. Gattolin. “The transfer of this information to different species was not at all obvious – the plants covered by this study are so different that their common ancestor dates back to the Cretaceous, when the world was still dominated by dinosaurs”, explains Prof. Rossini.

Over the centuries, humans, guided by their aesthetic sense, have selected natural mutations in the Petalosa genes and thus favored the spread of varieties with spectacular blooms. This knowledge can now be applied to the development of new “double flower” varieties in other plants, also through the new genome editing techniques, which allow specific gene sequences to be modified in a targeted manner.


Stefano Gattolin, Marco Cirilli, Stefania Chessa, Alessandra Stella, Daniele Bassi, Laura Rossini (2020) “Mutations in orthologous PETALOSA TOE-type genes cause dominant double-flower phenotype in phylogenetically distant eudicots”. Journal of Experimental Botany [].



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