Transferência horizontal de genes espontânea em plantas superiores

Spontaneous GMOs in Nature: Researchers Show How a Genetically Modified Plant Can Come About

ScienceDaily (Nov. 8, 2010) — Genetically modified plants can come about by natural means. A research group at Lund University in Sweden has described the details of such an event among higher plants. It is likely that the gene transfer was mediated by a parasite or a pathogen.

Festuca ovina (small, on the left) and Poa palustris (tall, on the right) growing in the researchers' greenhouses. (Credit: Image courtesy of Pernilla Vallenback)

The debate over genetically modified organisms (GMOs) is heated. One of the arguments against them is that it is unnatural to mix genes from different species. However, research in Lund, Sweden, shows that genetic modification can take place naturally among wild plants.

"In our research group we have suspected this for some time, and now my colleague Pernilla Vallenback has used DNA analysis to show that this is indeed the case," says Professor Bengt O. Bengtsson at the Department of Biology at Lund University.

The research group on evolutionary genetics has discovered that a gene for the enzyme PGIC has been transferred into sheep's fescue (Festuca ovina) from a meadow grass, probably Poa palustris, a reproductively distinct species. The DNA analyses also show that only a small part of a chromosome was transferred. This is the first proven case of the horizontal transfer of a gene with known function from the nucleus of one higher plant to another.

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Structure of the Natural Transgene PgiC2 in the Common Grass Festuca ovina

Pernilla Vallenback*, Lena Ghatnekar, Bengt O. Bengtsson

Department of Biology, Genetics, Lund University, Lund, Sweden

Abstract 

Background

A horizontal gene transfer has brought an active nuclear gene,PgiC2, from a polyploid Poa species (P. palustris or a close relative) into the common grass sheep's fescue (Festuca ovina). The donor and the receptor species are strictly reproductively separated, and PgiC2 occurs in a polymorphic state within F. ovina. The active gene copy is normally closely linked to a very similar pseudogene.

Methodology/Principal Findings

By genome walking we have obtained the up- and downstream sequences of PgiC2 and of corresponding genes in the donor and recipient species. Comparisons of these sequences show that the complete upstream region necessary for the gene's expression is included in the transferred segment. About 1 kb upstream of PgiC2 a fragment with transposition associated properties has been found (TAF). It is present in P. palustris and its polyploid relatives, though not at the homologous position, and is absent from many other grasses, including non-transgenic F. ovina plants. It is possible that it is a part of a transposing element involved in getting the gene into a transferring agent and/or into the recipient chromosome.

Conclusions/Significance

The close similarity of the up- and downstream regions with the corresponding regions in P. palustris excludes all suggestions that PgiC2 is not a HGT but the result of a duplication within theF. ovina lineage. The small size of the genetic material transferred, the complex nature of the PgiC2locus, and the associated fragment with transposition associated properties suggest that the horizontal transfer occurred via a vector and not via illegitimate pollination.

Citation: Vallenback P, Ghatnekar L, Bengtsson BO (2010) Structure of the Natural Transgene PgiC2 in the Common Grass Festuca ovina. PLoS ONE 5(10): e13529. doi:10.1371/journal.pone.0013529

Editor: Simon Joly, Montreal Botanical Garden, Canada

Received: May 10, 2010; Accepted: September 23, 2010; Published: October 20, 2010

Copyright: © 2010 Vallenback et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: This work was supported by the Nilsson-Ehle, Lindstrom, Erik Philip-Sorensen and Trygger Funds and Foundations. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

* E-mail: pernilla.vallenback@cob.lu.se

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