SOME sweet potatoes are naturally transgenic, a new study has found - in other words, they have genetically modified themselves.
Genes from naturally occurring bacteria are found in cultivated sweet potatoes around the world, according to a study published by PNAS (Proceedings of the National Academy of Sciences in the US).
Agrobacterium bacteria are common plant pathogens that display the ability to transfer segments of their DNA to plants, a property also used by plant scientists to produce transgenic crops.
This naturally occurring mechanism has been adapted by plant biotechnologists to develop genetically modified crops that today are grown on more than 10 per cent of the world’s arable land.
According to the authors, the results suggest that transgenic DNA may have arisen naturally in the sweet potato by horizontal gene transfer during infection by Agrobacterium and that the bacterial DNA may have provided traits that were selected for over thousands of years of domestication.
Jan F. Kreuze and colleagues conducted genetic analyses on 291 samples of cultivated sweet potato plants (Ipomoea batatas) from the Americas, Africa, Asia, and Oceania, nine samples of wild I. batatas plants from the Americas, and four samples from three related Ipomoea species.
The authors discovered the presence of two DNA regions from Agrobacterium species in the cultivated samples.
One of the bacterial DNA regions coded for genes that were expressed at detectable levels in all 291 cultivated plant samples, but not in any of the wild plant samples.
The other DNA region was found in 45 of 217 sweet potato genotypes examined, including both cultivated and wild species. Several of the genes are associated with biosynthesis and sensitivity to plant hormones.
