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Researchers said
on Monday they have sequenced the genome of the carrot, an
increasingly important root crop worldwide, identifying genes
responsible for traits including the vegetable's abundance of
vitamin A, an important nutrient for vision.
The genome may point to ways to improve carrots through
breeding, including increasing their nutrients and making them
more productive and more resistant to disease, pest and drought,
the researchers said.
The vitamin A in carrots arises from their orange pigments,
known as carotenoids. The study identified genes responsible for
carotenoids as well as pest and disease resistance and other
characteristics. In addition to eyesight, vitamin A also is
important for immune function, cellular communication, healthy
skin and other purposes.
The researchers sequenced the genome of a bright orange variety
of the vegetable called the Nantes carrot, named for the French
city. The carrot genome contained about 32,000 genes, a typical
total for plants, which average around 30,000 genes, which is
more than the human genome.
"Carrots are an interesting crop to work on because of their
wide range of diversity. They are familiar to everyone, and
generally well-regarded by consumers, but like most familiar
things, people don't necessarily know the background stories,"
said University of Wisconsin horticulture professor and
geneticist Phil Simon, who led the study published in the
journal Nature Genetics.
Worldwide carrot consumption quadrupled between 1976 and 2013
and they now rank in the top 10 vegetable crops globally, the
researchers said. In the past four decades, carrots have been
bred to be more orange and more nutritious, with 50 percent more
nutrients.
The earliest record of carrots as a root crop dates from 1,100
years ago in Afghanistan, but those were yellow carrots and
purple ones, not orange ones. Paintings from 16th century Spain
and Germany provide the first unmistakable evidence for orange
carrots.
Knowledge of the carrot genome could lead to improvement of
similar crops, from parsnips to the cassava, the researchers
said. Close relatives of carrots include celery, parsley,
parsnips, coriander, cilantro, dill, fennel, cumin and caraway.
The common weed called Queen Anne's Lace is a wild carrot.
The wild ancestors of carrots were white, the researchers said.
While orange carrots are most commonly grown, some purple and
yellow carrots are grown from the Middle East to South Asia,
while some red carrots are grown in Asia.
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