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Title: The genome of cultivated sweet potato contains Agrobacterium T-DNAs with expressed genes: An example of a naturally transgenic food crop

Author
item KYNDT, T - Ghent University
item QUISPE, D - Ghent University
item ZHAI, H - China Agricultural University
item Jarret, Robert - Bob
item GHISLAIN, M - Ghent University
item LIU, Q - China Agricultural University
item GHEYSEN, G - Ghent University
item KREUZE, J - Ghent University

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2015
Publication Date: 4/20/2015
Citation: Kyndt, T., Quispe, D., Zhai, H., Jarret, R.L., Ghislain, M., Liu, Q., Gheysen, G., Kreuze, J. 2015. The genome of cultivated sweet potato contains Agrobacterium T-DNAs with expressed genes: An example of a naturally transgenic food crop. Proceedings of the National Academy of Sciences. 112(18):5844-5849.

Interpretive Summary: The genetic makeup of the cultivated sweetpotato contains genes that were transferred into it from a strain of a pathogenic bacteria (Agrobacterium). One of these bacterial genes has become fixed within the sweetpotato genome and is present in all 291 sweetpotatoes tested, but is not present in related species. A second bacterial gene is present in about one-third of the sweetpotatoes tested. These bacterial genes are expressed in various sweetpotato tissues. Hence, the cultivated sweetpotato is a naturally transgenic crop plant.

Technical Abstract: Agrobacterium rhizogenes and A. tumefaciens are plant pathogenic bacteria causing abnormal tissue growth such as hairy root and crown gall diseases respectively, through the transfer of DNA fragments (T-DNA) bearing functional genes into the host plant genome. This naturally occurring mechanism of gene transfer has been adapted by plant biotechnologists to develop genetically modified (GM) crops grown today on more than 10% of the world available arable land. Here, we show that at least 2 different T-DNA regions are present in the cultivated sweetpotato genome. These T-DNAs occur across the global sweetpotato gene pool, with a consistent presence of one of the T-DNAs in all 291 tested cultivated sweetpotato genotypes, whereas it is absent in 12 tested wild genotypes including the most likely progenitors. The second T-DNA, occurs in 27 of the 92 analyzed genotypes. Our data show that the T-DNA genes are expressed at variable but detectable levels in different tissues of the sweetpotato.