A group of scientists from the International Potato Center (CIP), one of the world’s largest institutions devoted to research on tubers, based in Lima, Peru, found genes from soil bacteria inserted into the genome of 291 varieties of potatoes grown in North and South America, Europe, Indonesia, China and Africa. The findings mean that the sweet potatoes we eat every day would have been genetically modified long before mankind began feeding on this species.
The work was published in the journal Proceedings of the National Academy of Science, in the United States. It explains that the genes found in sweet potatoes originated from two soil bacteria (Agrobacterium tumefaciens and Agrobacterium rhizogenes) that, curiously, are now regularly used as biological vectors by biotechnologists to obtain transgenic plants under controlled conditions.
“The evolution of the species was raised by Charles Darwin as a form of natural selection. In this context, transgenesis has always seemed unnatural and, therefore, dangerous. However, we now know that evolution is mediated by complex processes at the molecular level. The discovery of fragments of bacterial DNA inserted into the genome of some vegetables show how dynamic the exchange process of genetic material between different organisms is,” said Raul Lavado, a professor from the Faculty of Agronomy of the UBA (FAUBA) to the journal http://sobrelatierra.agro.uba.ar/
The authors of the publication believe that bacterial DNA helped in the process of domestication of the potato, because it encodes enzymes involved in the synthesis of plant hormones. Thanks to these hormones, the roots were selected for human consumption, perhaps because of their greater size and strength.
According to the work of CIP, Lavado said, “when the ancestral populations of America began growing sweet potatoes they must have noticed the advantages of these roots and thus selected the plants that had bacterial genes. From that moment, the spread of GM crop began through Polynesia and Southeast Asia, and then to the rest of the world.”
Fernando Carrari, a professor of the department of genetics at FAUBA and researcher for the INTA and CONICET, told SLT that, just as with transgenes, the genes found in sweet potatoes are functional: “That is, they express like any other gene in the same plant. Moreover, some of them were only found in cultivated sweet potatoes rather than in their wild relatives.”
“These revelations suggest that the consumers of sweet potatoes have been eating natural transgenic potatoes long before man obtained the first artificially genetically modified plant,” said Gustavo Schrauf, professor in charge of Genetics at FAUBA.
Moreover, Carrari said that, “these findings are not strange because we know that the bacteria of the genus Agrobacterium can transfer part of their DNA to plant cells of different crop species. In turn, other microorganisms also interact with plant cells through the exchange of genetic material. Therefore, expectation are that, based on the knowledge of the complete genomes of many living things, we will begin to unravel processes and mechanisms of exchanging DNA that have seemed controversial so far,” he said.
Publication date: 9/10/2015