“Why are carrots orange?” sounds like a question a curious toddler would ask. But it’s also a question scientists have asked, and answered, in a recent study.
The humble carrot now joins a handful of elite veggies to have their genome sequenced. A dozen vegetables have had the honor, including the potato, cucumber, tomato, and pepper, Discovery News reported.
Scientists looked into why carrots are orange because the hearty root veg provides a critical vitamin in the human diet. Understanding its genes can help scientists both ensure the Daucus carota continues to grow in abundance, and figure out how to transfer some of its healthy qualities to other vegetables.
In studying the color, researchers were looking for the gene that creates carotenoids. They sequenced the genome of a variety called Nantes and compared the genes of 37 domestic varieties to wild carrots, which are white.
(Fun fact: many plants have 20 percent more genes than human beings)
Carotenoids are the answer to that tantalizing “why” question: they create the bright orange or red color in some fruits and veggies, and add to the carrot’s substantial nutritional value.
So what produces carotenoids? Researchers found the culprit in a gene they christened DCAR_032551. According to United Press International, this gene allows the veggie to accumulate carotenoids, which in turn produces Vitamin A and its bright yellow and orange colors.
“The accumulation of orange pigments is an accumulation that normally wouldn’t happen,” said horticulture professor and geneticist Phil Simon. “(It) has a good reputation as a crop and we know it’s a significant source of nutrition — vitamin A, in particular. Now, we have the chance to dig deeper and it’s a nice addition to the toolbox for improving the crop.”
The gene sequencing doesn’t reveal why the root veg is orange, but it didn’t find any link between the hue and color. One theory holds that farmers picked and cultivated the most colorful strains (to separate them from wild carrots) and since carotenoids produce both color and vitamins, they inadvertently encouraged the buildup of vitamins A and B.
And though science can only guess why this unique pigmentation developed, it still ensured the humble vegetable would become a critical part of the human diet.
The orange carrot is full of the natural chemical beta-carotene, which the body turns into Vitamin A. The deeper the orange, the more beta-carotene is inside. And we need it for growth and development, to support our immune system, and to sharpen our vision.
Carotenoids are also antioxidants, which protect against heart disease and some cancers by neutralizing free radicals.
And here’s why the genome of this hearty vegetable was sequenced in the first place: to possibly enrich other veggies with the same nutritive benefits as carrots. Vitamin A deficiency is actually a global health problem that the humble carrot could help fix.
Now that science knows how carotenoids accumulate, they can apply this knowledge to gene editing and augment other root vegetables, like cassava, which is widely-grown in Africa.
“These results will facilitate biological discovery and crop improvement in carrots and other crops,” said Simon.
And case you haven’t learned enough carrot facts, here are a few more.
The carrot is related to the grape and kiwi, splitting from the former 113 million years ago and the latter 10 million years ago. Its wild ancestors were white and came from Central Asia. Carrots were first cultivated there as well 1,100 years ago, and were first purple and yellow.
Now that we know the “why” to the color question, here’s the answer to “where?”: carrots got their bright hue in Europe in the 16th century.
[Photo By Olga Alyonkina/Shutterstock]