![\"\u2018Tanzania\u2019](\"https:\/\/cdn.sci.news\/images\/enlarge13\/image_14131e-Sweetpotato.jpg\")
<\/a><\/p>\n\u2018Tanzania\u2019 sweetpotato variety. Image credit: Benard Yada, National Crops Resources Research Institute in Uganda.<\/p>\n
The sweetpotato is a globally important stable crop that feeds millions worldwide, especially in sub-Saharan Africa, where its natural resilience to climate extremes makes it crucial for food security.<\/p>\n
But this humble root vegetable has guarded its genetic secrets for decades.<\/p>\n
Sweetpotato DNA is extraordinarily complex. While humans have two sets of chromosomes, one from each parent, sweetpotatoes have six.<\/p>\n
This condition, called hexaploidy, made deciphering their genetic code like trying to reconstruct six different, yet similar, sets of encyclopedias that have been shuffled together.<\/p>\n
Using cutting-edge DNA sequencing, along with other advanced techniques, Boyce Thompson Institute\u2019s Professor Zhangjun Fei and colleagues created the first complete genetic makeup of \u2018Tanzania,\u2019 a sweetpotato variety prized in Africa for its disease resistance and high dry matter content.<\/p>\n
The central challenge was to untangle the plant\u2019s 90 chromosomes and organize them into their six original sets, called haplotypes.<\/p>\n
The researchers succeeded in fully separating, or phasing, this complex genetic puzzle, something that had never been achieved before.<\/p>\n
\u201cHaving this complete, phased genome gives us an unprecedented level of clarity,\u201d Professor Fei said.<\/p>\n
\u201cIt allows us to read the sweetpotato\u2019s genetic story with incredible detail.\u201d<\/p>\n
According to the team, the sweetpotato genome is a mosaic assembled from multiple wild ancestors, some of which have yet to be identified.<\/p>\n
About one-third comes from Ipomoea aequatoriensis, a wild species found in Ecuador that appears to be a direct descendant of a sweetpotato progenitor.<\/p>\n
Another significant portion resembles a wild Central American species called Ipomoea batatas 4x, though the actual donor may still remain undiscovered in the wild.<\/p>\n
\u201cUnlike what we see in wheat, where ancestral contributions can be found in distinct genome sections,\u201d said Dr. Shan Wu, a researcher at the Boyce Thompson Institute.<\/p>\n
\u201cIn sweetpotato, the ancestral sequences are intertwined on the same chromosomes, creating a unique genomic architecture.\u201d<\/p>\n
This intertwined genetic heritage means that sweetpotato can be tentatively classified as a segmental allopolyploid \u2014 essentially a hybrid that arose from different species but behaves genetically as if it came from a single one.<\/p>\n
This genomic merging and recombination gives sweetpotato its remarkable adaptability and disease resistance, traits crucial for subsistence farmers worldwide.<\/p>\n
\u201cThe sweetpotato\u2019s six sets of chromosomes also contribute to its enhanced resilience,\u201d Professor Fei said.<\/p>\n
\u201cWith multiple versions of important genes, the plant can maintain backup copies that help it survive drought, resist pests, and adapt to different environments \u2014 a feature known as polyploid buffering.\u201d<\/p>\n
\u201cHowever, achieving a full understanding of sweetpotato\u2019s genetic potential will require decoding multiple varieties from different regions, as each may carry unique genetic features that have been lost in others.\u201d<\/p>\n