We finally know what makes orange carrots orange

Three genes are turned off to make carrots produce high levels of alpha and beta-carotene, which make them a rich source of vitamin A and give them their orange hue

By Chen Ly

28 September 2023

Genetic variation gives carrots a range of different colours

Addictive Creative/Shutterstock

The genes that make carrots orange have finally been identified, giving biologists a better understanding of what makes them so nutritious.

The first domesticated carrots were grown in central Asia during the 10th century, and they were originally purple or yellow. Orange carrots first appeared in western Europe in the 1400s, probably as a result of crossing yellow and white carrots.

Since then, orange carrots have surged in popularity, due to their bright colour and sweetness. “By the early 1900s, there was an understanding that the juice of orange carrots was medically active,” says Massimo Iorizzo at North Carolina State University. “This all contributed to carrots’ status as an iconic healthy vegetable.”

Advertisement

Now, Iorizzo and his colleagues have uncovered the science behind their distinctive colour. The researchers sequenced the genomes of 630 types of carrot, then looked for gene variants associated with particular traits.

They found three specific genes where orange carrots had variants that resulted in the gene being switched off. In purple, yellow or white carrots, at least one of the three genes was turned on.

These genes regulate levels of alpha-carotene and beta-carotene – chemicals that belong to a group of pigments called carotenoids. Alpha and beta-carotene are converted to vitamin A in the human body, which is important for the health of the eyes, immune system and other parts of the body.