Researchers have successfully created a chromosomal-level genomic assembly of a sweet potato cultivar known as “Tanzania.”
“Tanzania” sweet potato variety. Image credit: Benard Yada from the National Crop Resources Institute in Uganda.
The sweet potato is a crucial global staple crop that supports millions of people, particularly in sub-Saharan Africa. Its inherent resilience to harsh climates significantly contributes to food security.
Despite its importance, this humble root vegetable has hidden its genetic complexities for many years.
Sweet potato DNA is exceptionally intricate. While humans have two sets of chromosomes from each parent, sweet potatoes possess six sets.
This phenomenon, known as Hexaploidy, involves deciphering genetic codes that aim to piece together a set of six distinct, albeit similar, encyclopedias mixed together.
Utilizing advanced DNA sequencing and other state-of-the-art technologies, Professor Zhangjun Fei and his team at the Boyce Thompson Institute have produced the first complete genetic blueprint of “Tanzania,” which is widely appreciated in Africa for its stress tolerance and high dry matter content.
The key challenge was organizing the 90 chromosomes of the plant into six original sets known as haplotypes.
The researchers succeeded in either completely or incrementally separating this intricate genetic puzzle.
“Having this complete gradual genome provides an unprecedented level of clarity,” Professor Fei noted.
“This allows us to explore remarkable details of the sweet potato’s genetic narrative.”
The research team found that the sweet potato genome is a mosaic formed from various wild ancestors, some of which remain unidentified.
Approximately one-third of the genome is derived from ipomoea aequatoriensis, a wild species from Ecuador believed to be a direct progenitor of sweet potato cells.
Another significant portion is similar to the wild species of Central America, Ipomoea batatas 4x, though actual wild donors have yet to be discovered.
Dr. Shan Wu, a researcher at the Boyce Thompson Institute, stated:
“In sweet potatoes, ancestral sequences are intermixed within the same chromosome, resulting in a unique genomic structure.”
This complex genetic heritage suggests that sweet potatoes can be tentatively classified as segmented allopolyploids—hybrids that effectively function as though derived from a single species while originating from different ones.
This genomic merging and recombination grant sweet potatoes exceptional adaptability and disease resistance, essential for subsistence farmers globally.
“The six sets of chromosomes in sweet potatoes also contribute to their resilience,” Professor Fei added.
“With multiple versions of key genes, these plants can retain backup copies that assist them in surviving droughts, resisting pests, and adapting to diverse environments. This phenomenon is referred to as the polyploid buffer.”
“However, to fully comprehend the genetic capabilities of sweet potatoes, we need to decode multiple varieties from various regions, as each can possess unique genetic traits absent in others.”
Survey results were published this month in the journal Nature Plants.
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S. Woo et al. Gradual chromosomal level assembly provides insight into the genomic architecture of hexaploid sweet potatoes. Nature Plants Published online August 8, 2025. doi:10.1038/s41477-025-02079-6
Source: www.sci.news
