Carrots are able to produce high levels of alpha- and beta-carotene by turning off three genes. This gives them their orange color and makes them a good source of vitamin A.
Scientists have now identified the genes responsible for making carrots orange, allowing them to understand better what makes them nutritious.
In the 10th Century, central Asia was home to the first domesticated carrots. They were initially purple or yellow. Orange carrots were first seen in Western Europe around the 1400s. They are likely to be a result of crossing white and yellow carrots.
Orange carrots are now very popular due to their vibrant color and sweetness. “By early 1900s there was a general understanding that orange carrot juice was medicinally active,” says Massimo Iorizzo from North Carolina State University. This all contributed to carrots being a healthy, iconic vegetable.
Iorizzo has now revealed the science behind this distinctive color. Researchers sequenced the genomes for 630 carrot types and then searched for gene variants that were associated with specific traits.
The researchers found that orange carrots have variants of three genes, which result in the gene being turned off. At least one of these three genes is turned on in purple, yellow, or white carrots.
These genes control the levels of alpha and beta-carotene, chemicals that are part of a pigment group called carotenoids. In the human body, alpha- and beta-carotene are converted into vitamin A, which has a positive impact on the health of the eyes, the immune system, and other body parts.