The Bill and Melinda Gates Foundation awarded NC State University $12.4 million to research and develop tools that will genetically improve the sweet potato crop for the next four years. 

Craig Yencho, a professor of horticulture science and the project’s leader for the grant, directs the team in developing a new set of next-generation breeding tools for sweet potato improvement. 

“Our focus is primarily on developing orange sweet potatoes for small farmers who are living in Sub-Saharan Africa,” Yencho said. “Our main target countries are Uganda, Kenya and Ghana, but there should be substantial spillover effects into other countries.”

Sweet potatoes are a staple food source to many countries in Sub-Sahara Africa. The most common sweet potato in America is a great source of Beta-Carotene, which is a carotenoid of vitamin A.  

Such Beta-Carotenes and vitamins are important for Africans of the Sub-Saharan area.

“People, particularly small farmers, consume the crop daily whether it is for breakfast, lunch, dinner and in some cases more than one meal,” Yencho said. “Vitamin A deficiency is a very serious concern across the African continent, especially in pregnant women and children. Only 125 grams of the orange flesh sweet potato will provide the daily recommended amount of vitamin A for small children.”

One of the problems currently facing the sweet potatoes being grown in Africa is that they lack vitamin A that American sweet potatoes contain. Cultural differences in taste have proven to be one of the factors for the lack of cultivation of the orange-fleshed sweet potatoes found in America.

“Most Africans do not like sweet, sweet potatoes. We are working to develop a potato with a starchier flavor. The sweet potatoes would also need disease and insect resistant characteristics,” Yencho said. “This requires a new generation of breeding tools that will help the development of this variety. We are using conventional breeding techniques to find markers that find traits of interest in order to make the breeding process more efficient and quick.”

The development of these breeding techniques will not be as simple because sweet potatoes are made by a fusion of polyploids instead of diploids like most major crops.

“The sweet potato is a hexploid, which is more complicated and very difficult to study in terms of genetics,” said Zhao-Bang Zheng, co-primary investigator for the grant project and professor in statistics and biological sciences. “What we have done in the past was mostly for diploids, and this is the first time my group will be working with polyploids.” 

This grant will be used in part for the study of genomic tools of polyploid inheritance and locating the genes, according to Zheng.

“My role is to develop statistic and information tools for polyploid communities to locate the genes,” Zheng said.

The project is also teaming up across the world with institutions such as Michigan State, the Boyce-Thompson Institute at Cornell and the University of Queensland in Australia.

“There is major partnership around the globe in both northern and southern hemispheres,” Yencho said. “It is going to be a major challenge to keep in touch and reach out to many different partners, but fortunately technology and communication has made the world much more smaller.”  

The International Potato Center in Lima, Peru and the National Agricultural Crop Research Initiative will also be involved, according to Zheng. 

“Michigan State is doing sequences in collaboration with Uganda, and the breeding process will involve Lima and be done in Africa,” Zheng said.

For Yencho, communication seems to be the next important goal for the project.

“The next step from a logistic point of view is to put the team together and work as a team to recruit the students for the project to start training,” Yencho said. “We have already started to develop reference genome for sweet potatoes, so synthesizing those populations, we are sending those materials to our collaborators at the Boyce Thompson Research Institute at Cornell University.”

Since this is major funding, there will be recruitment for post doctorates and professionals to participate in research at NC State. 

“We are working with Ghana’s Crop Science Research Institute, and we have a couple of Ph.D. and post-doctorals coming here to study with us,” Yencho said. “It seems like spillover effects will happen and other students will be conducting research and sharing knowledge.”

This grant has the potential to be renewed after four years if the project goes well. 

“For me it is an extremely exciting opportunity in sweet potato breeding as well as the opportunity to be globally recognized,” Yencho said. “We have great opportunities to move the crop forward in the next five to ten years.”