Understanding the Sweet Potato: A Proteogenomic Approach

Sweet, starchy, orange sweet potatoes are tasty and nutritious ingredients for fries, casseroles, and pies. But despite the fact that humans have been cultivating sweet potatoes for thousands of years, scientists still don’t know much about their protein makeup. In a study published recently in the ACS’s Journal of Proteome Research, scientists have analyzed the proteomes of the sweet potato’s leaves and roots, and, in the process, have revealed insights into the plant’s genome.

The sweet potato, Ipomoea batatas, is a staple food in some parts of the world. It is also commonly used for animal feed as well as industrial products such as biofuels. Its genome is surprisingly complex—encoding more predicted genes than the human genome—and it has a complex chemical composition.

The roots of the sweet potato (the parts that we eat) have low protein content, and the leaves have many secondary metabolites. This makes extracting sufficient quantities of proteins for analysis difficult. Sorina and George Popescu of Mississippi State University and their colleagues wanted to see whether a proteogenomics approach—analyzing both the protein and genetic data together—could help them gain a better understanding of the compositions of sweet potato roots and leaves.

The team extracted proteins from root and leaf samples using two different methods before cutting them into peptides. The samples were then analyzed with liquid chromatography and mass spectrometry, and the team identified 3,143 unique proteins in the sweet potato leaves and 2,928 in the roots.

When they compared the proteomic data with the sweet potato genome, they identified certain regions of the published genome sequence for which their data could provide enhanced information. For example, the analysis predicted 741 new protein-coding regions that previously were not thought to be genes.

The group says the results could be used to help further characterize and biofortify the tuber.