Researchers from Purdue, Cornell and Michigan State universities, the International Maize and Wheat Improvement Center (CIMMYT) and HarvestPlus have teamed up to develop corn varieties that have naturally higher levels of nutrients that help stave off vitamin A deficiency, a condition that plagues sub-Saharan Africa. (Video by Natalie van Hoose and Steve Doyle; edited by Kelsey Getzin)

​​The Power of Orange

Naturally Nutritious Orange Corn Counters Africa's "Hidden Hunger"

By ​Natalie van Hoose - Published May 18, 2015​

Purdue plant geneticist Torbert Rocheford owes a lot to cow manure. Unsure of what to do with his life after college, he took on grunt work at a dairy farm in Maine, contemplating a graduate degree in animal breeding. But the more manure he spread over the fields around the farm, the keener his interest in plants became.

Plus, he reasoned, plants don't kick.

His interest was piqued by plant breeding courses offered by the University of Maryland, and he enrolled in the school's agronomy program, a subject he had never heard of before. The legacy of Norman Borlaug, the iconic plant breeder whose semi-dwarf cereal crops helped spark the Green Revolution, inspired him.

"I wanted to feed the world," he says.

Rocheford worked with several crops before settling on corn. Decades of work have not dulled his admiration for its rich genetic diversity—DNA sequences differ wildly between corn varieties—or the bounty of kernels studding each ear.

Amping Corn's Nutritional Clout

Torbert Rocheford examines ears in his stand of orange corn at Purdue's Agronomy Center for Research and Education.Torbert Rocheford examines ears in his stand of orange corn at Purdue's Agronomy Center for Research and Education. (Photo by Tom Campbell)

Now the Patterson Endowed Chair at Purdue, Rocheford focuses on boosting the nutritional quality of corn, a process known as biofortification. His open-pollinated variety of maize growing at the edge of the Purdue Agronomy Center for Research and Education (ACRE) boasts a unique quality: Its kernels are a deep orange hue. This corn, the product of 10 years of natural plant breeding, is packed with carotenoids, organic pigments that range from pale yellow to dark red.

Carotenoids offer more than color. They are also antioxidants and sources of key nutrients. Humans and animals—with the exception of the pea aphid—cannot make their own carotenoids and rely on their diet to supply them.

The orange corn bred by Rocheford's lab and his collaborators has unusually high levels of provitamin A carotenoids, substances such as beta-carotene and beta-cryptoxanthin, which can be converted by the human body into vitamin A. Stored in the liver, vitamin A is essential to the immune system, reproduction, communication between cells and the synthesis of certain hormones. It also becomes retinal, the primary light-absorbing pigment in the eye.

The diets of Western countries generally supply enough vitamin A, but vitamin A deficiency plagues parts of the world such as sub-Saharan Africa, leading to blindness and an increased susceptibility to infections, which can prove fatal. Children, who need the vitamin for development, and pregnant or nursing women, who require it for sustenance, are especially vulnerable. The World Health Organization estimates that every year 250,000-500,000 children go blind as a result of a lack of vitamin A. Half of them die within a year of losing their eyesight.

To help combat the deficiency, Rocheford and his fellow researchers teamed up to develop nutritionally richer varieties of corn with HarvestPlus and the International Maize and Wheat Improvement Center (CIMMYT), institutes that are part of the CGIAR global partnership of organizations working to improve food security. Corn is a staple crop and a dietary mainstay in countries that suffer most from vitamin A deficiency. Many people in sub-Saharan Africa eat nshima, a grits-like dish made from corn, three times a day.

"The point of biofortification is to look at what people are eating, what their staples are, and make those more nutritious," Rocheford says.

Orange Corn Gallery

The Roots of "Hidden Hunger"

For much of history, malnutrition was a caloric problem—people simply weren't getting enough food. But in the last half-century, hunger has changed. People eat larger quantities of food than their ancestors, but they suffer from severe vitamin and mineral deficiencies, a problem sometimes referred to as "hidden hunger."

Howarth Bouis, director of HarvestPlus, believes that the roots of these deficiencies may lie in agriculture.

While the Green Revolution of the last century caused cereal yields in the developing world to skyrocket—bringing affordable food to hungry populations—the productivity of non-staple foods did not make a similar leap. This pushed up prices of foods such as pulses, produce, fish and animal products. As a result, many people in poverty could put more calories on their plate, but at the expense of getting the diversity of the nutrients they needed.

"Agriculture must play a major role in the solution to vitamin and mineral deficiencies that the food system may have inadvertently caused," Bouis says.

Biofortification could be a crucial component of that solution. About 75 percent of the world's poor live in rural areas, too far from urban hubs to be effectively reached with supplementation. But giving rural farmers ways to grow their own more nutritious crops can enrich the diet of many.

"It's the power of a seed," Bouis says.

Corn of a Different Color

The research team had to adapt their biofortification efforts to encompass two additional challenges: The corn had to be all-natural to ensure that the people who needed provitamin A the most would eat it—and a new color was in order.

Consumers in sub-Saharan Africa have a strong cultural preference for white corn, which contains almost no carotenoids. Yellow corn is more nutritious than white, but it is fed almost exclusively to animals in most African countries. Rocheford's team and colleagues at CIMMYT would have to develop a type of corn that did not resemble yellow corn in order for the crop to pass the muster of deeply entrenched traditions.

Examining a set of diverse lines of corn from all over the world provided by Ed Buckler of the U.S. Department of Agriculture's Agricultural Research Service, Rocheford noticed that ears of orange corn from Thailand had naturally high amounts of carotenoids, providing a genetic base with which breeders could work. The distinct color of the corn was an added benefit.

Texcoco, MexicoRocheford identifies genes that International Maize and Wheat Improvement Center (CIMMYT) plant breeders in Texcoco, Mexico, can select to increase corn’s carotenoid levels. (Photo by Jennifer Stewart)

The team has spent years identifying and characterizing genes in corn's carotenoid biosynthetic pathway in hopes of pinpointing the factors behind provitamin A production. So far, Rocheford and colleagues at Cornell and Michigan State universities have identified several genes that can be selected to rapidly convert high-yielding white corn varieties into orange corn that contains large amounts of provitamin A. Breeders at CIMMYT and Rocheford's group are using the genes to strategically select and breed for varieties that have higher levels of these nutrients and are suitable for Africa's growing conditions.

"The faster we can get favorable forms of these genes into orange corn, the faster we can save human lives," he says.

Transgenic biotechnology could potentially speed the biofortification process, but the team was concerned that genetically modifying the corn would prevent consumers in Africa from accepting it. To sidestep any potential controversy, the team uses natural selection and breeding methods used for thousands of years.

Their efforts have brought the provitamin A levels in high-yielding, orange corn hybrids up to 12 parts per million, nearly a tenfold increase over levels in most yellow corn varieties. Experimental lines at CIMMYT that trace back to the orange corn grown at ACRE can contain up to 35 parts per million when the most favorable form of one of the first identified genes is crossed in.

Testing Corn on African Taste Buds

Three varieties were released in Zambia in 2012, and acceptance studies that measure consumer response to orange corn have been positive, Rocheford says. HarvestPlus works with local breeders and growers to spread awareness of the corn, its nutritional benefits, and how to grow it. More than 10,000 farming households in Africa now know about orange corn.

Rocheford's favorite example of orange corn's success is a story told to him by Eliab Mupongwe, the HarvestPlus country manager for Zambia. Mupongwe held a field day for orange corn and provided local women with enough ground orange corn to make 100 servings of nshima for lunch. But when the meal was served, there was only one platter of orange nshima, which was offered to dignitaries and politicians—all the other platters had nshima made from white corn. He asked the kitchen staff what had happened. The head cook replied that when they heard the orange corn contained vitamins, they took it home and fed it to their children.

"That's no statistical test or formal study, but it sums up nicely that there's good potential for consumer acceptance," Rocheford says.

Considering cultural issues in addition to plant genetics and field management practices should be common practice for good plant breeders, he says. Scientists on the team have had to contend not only with plant biology, but also with consumer behavior, cultural preferences, logistics of seed delivery and local politics. Rocheford sees all these factors as part of the job.

The HarvestPlus and CIMMYT teams are preparing to introduce orange corn into Zimbabwe and Ethiopia where varieties will need to be able to withstand drought and the low nitrogen conditions of the soil.

Rocheford's ultimate dream is to see orange corn sown all across sub-Saharan Africa. He also aims to bring orange corn to growers in the U.S. The corn contains the carotenoids lutein and zeaxanthin, which may help prevent macular degeneration, a leading cause of impaired vision in the elderly. CIMMYT is now sending him improved versions of the genetic materials he helped discover and develop to cross into Midwestern corn germplasm.

"That's a total paradigm shift," he says. "This shows the value of thinking globally—trying to help your neighbors may in turn help you some day."

Related Link

Natural gene selection can produce orange corn rich in provitamin A for Africa, U.S.

Global Partners in Research Combat Malnutrition

By ​Jennifer Stewart - Published May 18, 2015​

Thanda DhliwayoThanda Dhliwayo, a HarvestPlus plant breeder who works at CIMMYT, focuses on raising the provitamin A content of orange corn and developing drought-resistant varieties. (Photo by Jennifer Stewart)

On a breezy day just outside of Texcoco, Mexico, passersby can hear the rustle of food crops growing in the research plots surrounding the International Maize and Wheat Improvement Center, or CIMMYT.

Pulling back the husks on some of the corn plants reveals bright orange kernels—evidence of a long-standing collaboration between CIMMYT and Purdue Agriculture. Orange corn, rich in provitamin A, is part of a HarvestPlus-funded project led by Purdue Agronomy Professor Torbert Rocheford. The goal: To get provitamin A into the diets of severely deficient populations, starting in Zambia.

Rocheford says the task would be impossible without his international partners. Indiana weather patterns, disease pressures and soil types don't lend themselves to testing plants adapted to very different climates. "For example, corn adapted to Indiana is generally not going to have the kind of disease resistance needed for Zambia."

Enter CIMMYT. Rocheford, with collaborators at Cornell and Michigan State universities working on a complementary National Science Foundation-sponsored project, identify natural forms of the target genes that will efficiently increase orange color, provitamin A and total carotenoids. They share the results with CIMMYT, where researchers take the genetic information and put it into corn ideally suited for growth in Zambia.

Relationships like this one have a variety of benefits, says Purdue's Jess Lowenberg-DeBoer, associate dean and director of International Programs in Agriculture.

"International collaborations enhance Purdue's research in several ways, including partnerships with cutting-edge researchers located outside the U.S. Our research benefits from their skills and insights," Lowenberg-DeBoer says. "Sometimes these partnerships also give us access to scientific equipment and infrastructure that we do not have at Purdue, and field research opportunities to test theories or hypotheses in a very different environment from what we have in the U.S."

Corn to Conquer Climate Change

Orange corn isn't Purdue Agriculture's only work with CIMMYT. The two have partnered on a handful of other studies, including a project called Heat Tolerant Maize for Asia (HTMA), led by Mitch Tuinstra, a Purdue professor of plant breeding.

Like Rocheford, Tuinstra needs access to the right maize varieties and growing conditions. His lab is working to identify the genes and traits for heat-stress tolerance. The research team partners with CIMMYT on access to germplasm and testing environments. HTMA is tested in field plots at CIMMYT's sister institution, the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), in Andhra Pradesh, India.

HTMA is a Global Development Alliance project funded by the U.S. Agency for International Development with matching funds from Purdue and public- and private-sector maize breeding programs in India, Pakistan, Bangladesh and Nepal.

The project is vital as researchers race to understand how crops react to climate change. "We know almost nothing about crop adaptation to high-temperature stress, and climate change is a big concern in Southeast Asia," Tuinstra says. "This presents serious challenges for the ability to produce enough food."

Boundless Benefits

Purdue Agriculture works with public and private institutions, foundations and companies worldwide, including the Gates Foundation, the Tropical Agricultural Research and Higher Education Center in Costa Rica, and Kabul University in Afghanistan.

The results of those partnerships not only improve lives elsewhere, but in the U.S., too, Lowenberg-DeBoer says.

"Any strategy that results in new knowledge and better understanding of the world around us benefits everyone," he says. "Sometimes those benefits are in Indiana. In other cases, the benefits are elsewhere in the U.S. or in other countries. Even the research benefits in other countries often have spinoffs for Indiana citizens."

Orange Corn Lends an Ear to America

If Rocheford has his way, people all over Africa, the U.S. and beyond will one day hear the rustle of orange corn dancing in the breeze. HarvestPlus already has taken the crop to Zambia and Zimbabwe and is beginning a program in Ethiopia. The development of orange corn hybrids for the U.S. has started.

While Americans don't typically lack provitamin A, Rocheford says orange corn has high total carotenoids, a type of antioxidant, which could be good for the eyes.

"The U.S. population doesn't really need any more vitamin A," Rocheford says. "But we may be deficient in the carotenoids lutein and zeaxanthin, which are good for eye health. It's still unclear whether the increasing rates of macular degeneration are due to lower levels of lutein and zeaxanthin in the diet, but the macular is full of them. It would be good to have more carotenoids in our diet."