The sweet potato is a natural GMO that may have sailed with Polynesians
Long before any lab spliced genes, a soil bacterium slipped its DNA into the ancestors of the sweet potato, and those borrowed genes still work in cultivated plants. The crop also reached Polynesia before Columbus sailed, and the Quechua word kumara matches the Polynesian name almost exactly.
Ipomoea batatas belongs to the morning glory family and is only a distant cousin of the potato; true yams, monocots in a separate order, are even further removed. It arose in tropical South America, in what is now Ecuador, from a cross involving a tetraploid and a diploid parent followed by a further doubling of the whole genome. Its closest wild relative is Ipomoea trifida. Remains from caves in Peru's Chilca Canyon are radiocarbon dated to about 8080 BC, and domesticated sweet potatoes grew in Central America at least 5,000 years ago.
Cultivated plants carry transferred DNA from an Agrobacterium related to Rhizobium rhizogenes, with the genes actively expressed. Close wild relatives lack them, so farmers apparently domesticated a plant that had already been naturally modified, making it the first known naturally transgenic food crop.
In the Cook Islands, sweet potato has been dated to between 1210 and 1400 CE. The leading explanation is that Polynesians sailed to South America and returned with vine cuttings, then spread them to Easter Island, Hawaii and New Zealand. Genetic links with the Zenú people of Colombia's Pacific coast support pre-Columbian contact. Māori grew white-skinned kumara, and the most common New Zealand variety is now the red Owairaka.
Europe met it through Columbus in 1492, and the Taíno word batata stuck; Spanish blended it with Quechua papa to make patata for the unrelated potato. Manila galleons carried it to the Philippines, and after a crop failure it reached Fujian around 1594. In Japan it became famine insurance when rice failed; the shogunate spread Aoki Konyō's guide to growing it, and Tokugawa Yoshimune planted some in his own garden. Enslaved Africans in North America called soft varieties yams after an African crop they resembled, and the name stuck.
Source: Sweet potato
