What color is your carrot?

MADISON — Sevie Kenyon: Shelby, carrots are not just orange anymore, what colors are there?

Shelby Ellison: You can find carrots in red, yellow, you can have some purple varieties and actually carrots, before they were domesticated, were white.

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Sevie Kenyon: What would the difference be between one color and another?

Shelby Ellison: So typically, the color of carrot that you’re eating, it directly corresponds with the nutritional value or the nutritional compound found in that carrot. For instance, an orange carrot would be high in alpha and beta-carotene. A yellow carrot would be high in lutein and xanthophyll. A red carrot would be high in lycopene. Purple carrots have high levels of anthocyanins which are antioxidants and white carrots, while they don’t really confer much nutritional benefit, they’re very high in fiber.

Sevie Kenyon: Shelby, where are people going to encounter carrots other than orange carrots?

Shelby Ellison: Right now, one of the best places you can go to find a diversity of carrot colors is your local farmer’s market. You can also get them through community-supported agriculture. They’re growing many different varieties of carrots and some of the co-ops and smaller seed companies will sell heirloom varieties of different carrot colors.

Sevie Kenyon: For the home grower, is there anything they need to know about the different carrot varieties?

Shelby Ellison: Just a lot of them, because they’re more of the heirloom varieties, they’re not going to have the same uniformity that you’d find in a lot of the orange cultivars.

Sevie Kenyon: Shelby, can you tell us a little bit about what you’re looking for in your work?

Shelby Ellison: Because the colors do correspond with the nutritional content, I’m interested in looking at the genetics controlling each of these compounds. So understanding what gene or genes control beta-carotene accumulation in an orange carrot, or what controls lycopene accumulation in a red carrot and then through understanding the genetics of those traits you can make new improved varieties with improved nutritional quality.

Sevie Kenyon: Shelby, have we seen improved varieties on the market yet?

Shelby Ellison: There are improvements being constantly made through traditional breeding. There was a big change in the last twenty years or so where we started increasing the amount of beta carotene but now we are seeing if you’re adding the anthocyanins or the purple compounds into the orange varieties, you’re not only getting the benefit of the alpha and beta carotene in the orange carrot but you’re improving the antioxidants

Sevie Kenyon: Shelby, look into your crystal ball, what do you see carrots looking like 5, 10, 20 years from now?

Shelby Ellison: We’re probably going to be seeing a lot more colors in the grocery stores. Just how people really like the idea of having the baby carrots, I think we’ll see more of the different colors in the baby carrot packages.

Sevie Kenyon: We’ve been visiting with Shelby Ellison, Department of Horticulture, University of Wisconsin Madison and the College of Agricultural and Life Sciences and I’m Sevie Kenyon.

Are you smarter than an Otter?

On November 23rd, Faculty Associate, Claudia Irene Calderon, and Postdoctoral Fellow, Shelby Ellison, organized a carrot tasting with 12 three to five year olds from the UW Preschool Lab Otter class. The event took place in the DC Smith Conservatory where the children tasted orange, purple, red, white, and yellow carrots and learned about how the carrot color translates into the nutritional benefit it can provide when eaten.

Many of the children were excited to taste the different colored carrots and a few appeared to favor the less traditional purple types. In addition to tasting, the Otters enjoyed carrot themed story time, were able to pick out vegetable stamps, and enjoyed exploring the DC Smith Conservatory. The children returned to the UW Preschool lab with more carrots to sample and a nutritional fact sheet to share with their families.

Photos by Florencia Bannoud

 

Carrot genomes

Carrot genome paints picture of domestication, could help improve crop 

Carrot color arrangement

Carrots derive their color from pigment compounds called carotenoids. Orange carrots are colored by alpha- and beta-carotene, while red carrots get their color from lycopene, yellow from lutein and purple from anthocyanin. These pigments also provide the nutrition found in carrots. PHOTO COURTESY OF PHIL SIMON, UW–MADISON, USDA-ARS

Sometimes, the evolutionary history of a species can be found in a fossil record. Other times, rocks and imprints must be swapped for DNA and genetic fingerprints.

The latter is the case for the good-for-your-eyes carrot, a top crop whose full genetic code was just deciphered by a team of researchers led by University of Wisconsin–Madison horticulture professor and geneticist Phil Simon. Simon is also a research scientist with the U.S. Department of Agriculture’s Agricultural Research Service, which helped fund the work. The study is published today in the journal Nature Genetics.

It tells a story of how the carrot has been touched by domestication and breeding practices and influenced by environmental and geologic change, and it fills in a family tree of relatives that otherwise appear distinct. It also reveals how carrots have become so good at accumulating carotenoids, the pigment compounds that give them their characteristic colors and provide them with their nutritional strength.

Photo: Phil Simon

Phil Simon

“The carrot has a good reputation as a crop and we know it’s a significant source of nutrition — vitamin A, in particular,” Simon says. “Now, we have the chance to dig deeper and it’s a nice addition to the toolbox for improving the crop.”

The knowledge gained from the study could also lead to the improvement of similar crops, from parsnip to the yellow-fleshed cassava, a staple food throughout much of Africa.

“This was an important public-private project, and the genomic information has already been made available to assist in improving carrot traits such as enhanced levels of beta-carotene, drought tolerance and disease resistance,” says co-author Allen Van Deynze, director of research at the University of California, Davis’ Seed Biotechnology Center. “Going forward, the genome will serve as the basis for molecular breeding of the carrot.”

Carrots have a long history as a domesticated root crop. The first cultivated carrots appeared 1,100 years ago in Central Asia. These carrots were — unlike their white wild ancestors — purple and yellow. The canonical orange carrot appeared later, in Europe in the 1500s, providing at the time an aesthetic subject for German and Spanish art. Even before domestication, wild carrot seeds showed up in 3,000- to 5,000-year-old primitive campsites in Germany and Switzerland.

The study cannot answer why the first crops were purple and yellow, though it can verify that it is not because of flavor. The genes for color and the genes associated with preferred flavors are not connected. But that colored carrots became popular is fortuitous: The pigments are what make them nutritious, and orange carrots are the most nutritious of all, Simon says. Carrots are the richest crop source of vitamin A in the American diet.

The new study reveals how that orange color happens. “The accumulation of orange pigments is an accumulation that normally wouldn’t happen,” says Simon, one of just a few carrot researchers around the world, along with another UW–Madison scientist, Irwin Goldman, who was not part of this study. “Now, we know what the genes are and what they do.”

Carrots are the richest crop source of vitamin A in the American diet. Vitamin A is an essential nutrient. PHOTO COURTESY OF PHIL SIMON, UW–MADISON, USDA-ARS

Carrots are the richest crop source of vitamin A in the American diet. Vitamin A is an essential nutrient. PHOTO COURTESY OF PHIL SIMON, UW–MADISON, USDA-ARS

The research team used the Nantes carrot — a bright orange form of the vegetable named for a city in France — to assemble and analyze the full genetic sequence, peering into the machinery that drove the carrot’s evolution, and the bread crumbs left through time.

The carrot genome contains more than 32,000 genes arranged among nine chromosomes, which code for pest and disease resistance, colorful carotenoids and more. Carotenoids, like alpha- and beta-carotene, were first discovered in carrots.

The researchers uncovered features traced to distantly related plant species, from grapes and tomatoes to kiwis and potatoes. Carrots more recently split from lettuce and they are in the same family as spice crops, like parsley and fennel.

The researchers also sequenced 35 different types of carrots to compare them to their wild ancestors. They showed carrots were first domesticated in the Middle East and Central Asia, confirming the Vavilov Center of Diversity theory, which predicts cultivated plants arose from specific regions rather than randomly.

They also learned that sometime between the Cretaceous and Paleogene periods — roughly around the time dinosaurs went extinct — carrots picked up genetic advantages common to other plants of the era that allowed them to thrive.

Additionally, the study confirmed a gene called Y is responsible for the difference between white carrots and yellow or orange ones, and that a variation of it leads to the accumulation of carotenoids.

“They could keep their crops ‘clean’ from a patch of wild carrots growing 50 meters away by choosing only the purple or yellow ones. Or maybe it was the food fad of the 10th century …”

Phil Simon

But it also identified a new, previously unknown gene that contributes to the accumulation of the colorful compounds. Both genes are recessive, which means two copies of each are needed for carotenoids to build up in the plant, which is actually a defect in a metabolic pathway that appears to be related to light-sensing.

Plants derive their own nutrition through light-sensing, or photosynthesis, but roots like carrots aren’t normally exposed to light and do not need photosynthetic pigments like carotenoids. “It’s a repurposing of genes plants usually use when growing in light,” says Simon.

It appears these genes were inadvertently selected for by early growers, and Simon suggests it may have simply been to aid early domesticators — likely to have been women — differentiate between wild carrots and the plants they intended to grow.

“They could keep their crops ‘clean’ from a patch of wild carrots growing 50 meters away by choosing only the purple or yellow ones,” says Simon, who jokes: “Or maybe it was the food fad of the 10th century, with orange in the 16th.”

Global carrot consumption quadrupled between 1976 and 2013 and over the last 40 years, breeding has led to more nutritious carrots with the selection of ever more intensely orange crops. In fact, carrots have 50 percent more carotene today than they did in 1970.

While most Americans are not deficient in vitamin A, it is considered an essential nutrient and deficiency is a problem in some U.S. communities and around the world. While the study may not solve the problem, it does highlight the opportunity carrots present to improve health and economic outcomes in other nations.

“Globally, we hand out vitamin A capsules, but why not have people grow their own?” Simon asks. “In one square meter you can grow a single crop of carrots per year to feed up to a half dozen adults. 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 study also reflects a shift in how plant breeders operate, by taking advantage of new technologies to answer basic questions about cultivated crops.

“It tells us things about the genome we expected but didn’t know before,” says Simon. “Each crop has a story to tell.”

The study also includes co-authors from Michigan State University and around the world, including Poland, Spain, Italy, Turkey, China and Argentina. It was funded by several seed companies and the carrot industry, as well as the National Science Foundation, the Polish National Science Center and the Polish Ministry of Science and Higher Education. The authors declare no competing financial interests and Simon explains that industry funds make the work possible.

Reposted from: http://news.wisc.edu/carrot-genome-paints-picture-of-domestication-could-help-improve-crops/#sthash.le7Xxay2.dpuf  by Kelly April Tyrell

 

Organic approach to improving carrots

Organic carrots are coming into their own. About 14 percent of U.S.-produced carrots are now classified as organic, making carrots one of the highest ranked crops in terms of the total percentage produced organically. With production and demand increasing in recent years, organic-carrot growers need help deciding which varieties to grow. Some varieties perform well as a conventional crop, but not so well under organic conditions. While conventional growers also can fumigate to control nematodes, bacterial diseases and fungal pathogens, organic growers don’t have that option.

That’s why the work of Agricultural Research Service (ARS) plant geneticist Philipp W. Simon and his colleagues is so important. Simon, who is the research leader of ARS’s Vegetable Crops Research Laboratoryin Madison, Wisconsin, is leading the five-year Carrot Improvement for Organic Agriculture (CIOA) project that is ultimately aimed at providing information and helping breeders develop carrots that are tastier, more nutritious and better equipped to combat weeds, diseases and pathogens. It is funded with a National Institute of Food and Agriculture, Organic Agriculture Research and Extension Initiative grant.

The researchers are growing 36 carrot varieties in organic and conventional fields at four locations and comparing them for flavor, productivity, appearance, color, disease resistance and other key traits. Partners include researchers from Purdue University, the University of Wisconsin-Madison, the University of California-Riverside, Washington State University and the Organic Seed Alliance. The field trials are in Madison, Wisconsin, Pasco, Washington, West Lafayette, Indiana, and Bakersfield, California.

Carrots grow relatively slowly, and that means that faster-growing weeds are a major problem. Some large-scale organic producers in California estimate that they spend thousands of dollars per acre to weed carrot fields. A priority highlighted by the research is the need for carrots that can produce their large, above-ground leafy “tops” quickly to outcompete weeds for sunlight and moisture.

Organic growers also are more interested than conventional growers in producing carrots with novel shapes and colors—purple, red and yellow—that will attract organic consumers, according to Simon. When it comes to nutrition and health, orange carrots are always a good choice because they are high in vitamin A, an essential nutrient. But changing up your carrot color scheme once in a while might not be a bad idea, he says. Purple carrots have powerful antioxidants. Yellow ones are a good source of lutein, which could reduce the risk of macular degeneration, an all too common eye problem. Red carrots are high in lycopene, a nutrient associated with reducing the risk of certain cancers.

The researchers are still evaluating the 16 named carrot varieties and 20 scientific lines selected for the project. That includes assessing them for flavor, a major issue for consumers. When the market for baby carrots started to take off years ago (baby carrots account for about half of all the fresh carrots consumed in the United States), consumers came to expect carrots to taste good, and growers were quick to adapt, according to Simon. “That message has come through clearly. Flavor is a priority because if people don’t want to eat carrots, they’re not going to buy them.”

Dennis O’Brien, Agricultural Research Service

reposted from Vegetablegrowersnews.com