Scientists discover why carrots are orange

Scientists at the University of Wisconsin recently unveiled that a gene in carrots, dubbed DCAR_032551, gives rise to carotenoids — a critical source of vitamin A and the pigment that turns some fruits and vegetables bright orange or red.

Although the genomes of several other vegetables, including the potato, cucumber, tomato and pepper have previously been sequenced, this was the first time the carrot’s full genetic code has been revealed.

"The carrot has a good reputation as a crop and we know it's a significant source of nutrition — vitamin A, in particular," Phil Simon, the lead researcher on the project said in an article. "Now, we have the chance to dig deeper and it's a nice addition to the toolbox for improving the crop."

The knowledge gained from the study could also lead to the improvement of similar crops, from parsnip to the yellow-fleshed cassava, a staple food throughout much of Africa.

"This was an important public-private project, and the genomic information has already been made available to assist in improving carrot traits such as enhanced levels of beta-carotene, drought tolerance and disease resistance," says co-author Allen Van Deynze said. "Going forward, the genome will serve as the basis for molecular breeding of the carrot."

Carrots have a long history as a domesticated root crop, first cultivated about 1,100 years ago in Central Asia. These carrots were — unlike their white wild ancestors — purple and yellow. The typical orange carrot didn’t appear appeared until the 1500s, the article explains.

While the study cannot answer why the first crops were purple and yellow, scientists know the genes for color and the genes associated with flavors are not connected. However, it is known that the pigments are also what makes them nutritious, and orange carrots are the most nutritious of all. In fact, the deeper the orange color, the more beta-carotene, a natural chemical that the body can transform into vitamin A.

Vitamin A is essential for normal growth and development, the proper functioning of the immune system, and vision, the article explains. Carotenoids are also antioxidants, which are thought to protect against heart disease and some forms of cancer by neutralizing so-called “free radicals”, single oxygen atoms that can damage cells.

Interestingly, carrots — along with many other plants — have about 20% more genes than humans.

Looking back at the plant’s family tree, scientists have been able to determine that it split with the grape about 113 million years ago and from the kiwi about 10 million years after that. Global crop production of the root has quadrupled in the last 40 years and today is eaten everywhere in the world.

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