Thanks to a study of 630 carrot genomes, American researchers have identified three genes involved in their color. But contrary to all expectations, these genes must be turned off to cause the orange hue.
In Turkey, purple carrots are mainly consumed. In India, red ones are preferred. Orange carrots predominate in Western countries. The color of the carrot depends on the pigments it contains. In the case of the orange one, it is called carotene and, for the first time, it was isolated in the 1800s”, as stated by Massimo Iorizzo, a researcher at the University of North Carolina (United States), for Sciences et Avenir et Avenir.
With his team, he analyzed the genetics of carrots. In 2016, scientists were able to sequence the genome of this vegetable for the first time. The objective of the new study is to shed light on its domestication history. What traits did our ancestors select for this vegetable to look the way it does today? How do you explain the color? Their results were published in the journal Nature plants.
Gene inactivate
“Thanks to a statistical analysis, we have identified three genes responsible for the orange color of carrots. But, contrary to all expectations, they must be deactivated in order to function,” says the researcher. How does it work? The orange carrot owes its color to the high concentration of carotene: alpha and beta, two pigmented chemical compounds. They are stored in small organs: the chromoplasts, which are very numerous in the root.
“Two of the highlighted genes are estimated to regulate the number and size of these chromoplasts, Massimo Iorizzo indicates. The third would be involved in the biosynthesis of α-carotene and β-carotene.” These two compounds are precursors of vitamin A, an essential nutrient for our body. “It allows in particular the maintenance of a healthy immune system, good growth and normal development,” explains the scientist, even while reducing the risk of eye diseases.
The study also sheds light on the factors that guided the selection of the orange carrot as we know it. At the end of selective scans, processes that reveal genetic variation between two groups, the researchers concluded that genes related to flowering had undergone strong selection. “For example, comparing carrots from a wild population (usually with annual flowering) to those from a cultivated population (usually with biannual flowering), shows that selection has reduced the flowering time,” the geneticist elaborates. And for good reason: flowering makes the carrot root woody and inedible.
And historically? “It was, so to speak, domesticated at the beginning of the Middle Ages in the region that stretched from Western Asia to Central Asia,” emphasizes Massimo Iorizzo. Purple and yellow carrots were then common and imported to Europe. However, the taste of yellow carrots makes them more popular.
Probably the result of a cross between white and yellow carrots, the orange variety appeared in Western Europe during the Renaissance. The color and sweeter taste make it particularly popular, so much so that farmers prefer it. Since the 16th century, different types of orange carrots have been developed in northern Europe. This is proven by the paintings of the era. As scientists explored the role of carotene and the benefits of vitamin A, the popularity of the orange carrot grew, reaching the success it enjoys today.
And what about the purple carrot? The researchers hope to elucidate, and for this, the molecular origin of the color and its history in a future study.
2023-10-28 05:41:45
#carrots #orange
