Why Are Carrots Orange? Genome Sequencing Reveals Gene Behind Vegetable's Color
Carrots are widely associated with the orange color and are known as a good source of beta-carotene. Now, researchers have discovered a new gene in the vegetable that can be attributed for their color and nutritional content.
In a new study published in Nature Genetics on May 9, Phil Simon, from the University of Wisconsin, and colleagues conducted a genetic sequencing of the Nantes carrot, a bright orange variety of the vegetable, which contained about 32,000 genes.
The researchers then sequenced the genomes of 35 other carrot specimens and subspecies to determine how carrots evolved.
Simon and colleagues eventually found DCAR_032551 gene, which is responsible for the vegetable's high concentration of beta-carotene. The compound gives fruit and vegetables the yellow, orange or red color as well as their rich vitamin A content.
"We identified a candidate gene, DCAR_032551, that conditions carotenoid accumulation (Y) in carrot taproot and is coexpressed with several isoprenoid biosynthetic genes," the researchers wrote in their study.
The results of the study may help boost beta-carotene in carrots and the nutritional quality of other crops such as lettuce and celery since beta-carotene gets converted by the human body to vitamin A, which plays a key role for normal vision, reproduction and immune system.
The findings may likewise help address global health problems given the prevalence of Vitamin A deficiency. Simon noted that the carrot is a significant source of nutrients and the findings offer researchers a chance to improve the crop.
"In one square meter you can grow a single crop of carrots per year to feed up to a half dozen adults," Simon said. "You can grow half now and half in six months to give you a sustainable source of vitamin A and a valuable crop in the marketplace."
The results may also aid genome editing technologies that could increase the levels of beta-carotene in crops such as the cassava, which is a staple food in developing countries.
Researchers said that the wild ancestors of carrots were white. Domesticated purple and yellow carrots from around 1,000 years ago were discovered in Central Asia. An orange version surfaced in Holland in the late 16th century, likely from cross-breeding yellow carrots with purple carrots.
Although orange carrots are currently the most widely grown, some regions in other parts of the globe such as the Middle East and South Asia grow purple and yellow carrot breeds.