For many Americans, sweet potatoes are a Thanksgiving side dish. For millions of others, however, it’s a staple crop that offers hope for a healthy future.
Sweet potato is a globally important staple food crop, and has highly recognized potential to alleviate hunger, vitamin A deficiency, and poverty in Sub-Saharan Africa, where it is predominantly grown in small plot holdings by poor women farmers. Biofortification with pro-vitamin A-rich orange-fleshed sweet potato has led to millions of Africans being spared the devastating effects of vitamin A deficiency, a main cause of illness, blindness and death in children under five years.
An international team generated genome sequences for sweet potato wild relatives, which were published in the current issue of Nature Communications. This new research provides genomic resources for sweet potato improvement that can be shared with breeders and farmers.
“This work continues our research in the genome of root and tuber crops important to food security. For example, the information we learned from the potato genome was extremely helpful in this study with sweet potato,” said Robin Buell, Michigan State University Foundation Professor of Plant Biology and paper co-author. “A critical part of this project is engaging breeders in genomics approaches and through this work, we will enable more efficient breeding of sweet potato, a key food security crop in Africa.”
Buell was on a team of scientists that included Kin Lau and John Hamilton, MSU researchers who were co-first authors.
Sweet potatoes are hexaploid and are genetically complex. The lack of information regarding the sweet potato genome makes it difficult to “design” improvements.
“Sweet potato improvement across the world faces major constraints due to the lack of knowledge of the genetic and molecular basis of key agronomic traits,” said Zhangjun Fei, an associate professor at Cornell University and co-author. “To provide high-quality reference genome resources, we generated chromosome-scale genome assemblies of two diploid wild relatives of sweet potato.”
By developing these genome sequences, researchers created a resource that offers hope for faster turnaround times for stronger, more nutritious sweet potatoes.
“We demonstrated that the genome sequences of the two diploid wild potatoes can be used as robust references to facilitate sweet potato breeding,” said Shan Wu, Cornell University postdoctoral researcher and co-author. “The genomic resources developed in this study set the stage for increased rates of genetic gains for key traits such as yield, resistance to disease, and high beta-carotene.”
Understanding the origin of sweet potato has implications for the potential utility of wild relatives in breeding programs. Whereas others have suggested that the polyploid sweet potato was derived from a single wild relative population, multiple lines of evidence from this work suggest that at least two genetically distinct populations if not separate species had contributed to the ancestral sweet potato gene pool. In addition, this work provides insights into the evolutionary history of the sweet potato genome.
The researchers emerged from their “time travel” equipped with the necessary findings to shift their focus to contemporary Africa, where they used sequencing data to connect the past with the present.
The team resequenced 16 cultivars and landraces widely used in African breeding programs. This refined the genetic relationships, highlighting how genomic tools can enable more efficient improvement of sweet potato.
This research was supported by grants from the Bill & Melinda Gates Foundation (OPP1052983), National Natural Science Foundation of China (31461143017), National Key Research and Development Program of China (Coarse Cereal Fund), National Science Foundation (DEB-1601251), The North Carolina Sweet Potato Commission, and the North Carolina State University Agricultural Research Service. Research at CIP was undertaken as part of the CGIAR Research Program on Roots, Tubers and Bananas and supported by CGIAR Fund Donors (http://www.cgiar.org/about-us/our-funders/). This research was also supported by the use of the NeCTAR Research Cloud, by QCIF and by the University of Queensland’s Research Computing Centre. The NeCTAR Research Cloud is a collaborative Australian research platform supported by the National Collaborative Research Infrastructure Strategy.