New plant gene could help allay concerns over GM crops

(2005-08-28)

A newly identified plant gene that could change the way we develop GM plants is reported in the September issue of Nature Biotechnology. The naturally antibiotic resistant gene, found in thale cress (Arabidopsis thaliana), could provide a strong alternative to current practices, say Neal Stewart and colleagues.

Traditionally, GM plants have been engineered with bacterial antibiotic resistance markers (ARMs) to help effectively identify which seedlings have taken up transgenes. The successful plants grow because of their resistance to antibiotics. This method of 'hooking up' antibiotic-resistance genes to transgenes of interest has been widely used in plant research since the 1980s. One major, theoretical health and safety concern over this practice has been the potential for 'reverse' horizontal gene transfer (HGT) back to bacteria - ingesting GM plants could increase our immunity to the antibiotics used in this engineering process.

The thale cress gene AtWBC19 has the potential to be used in place of bacterial ARMs, say the authors. Overexpression of this gene causes resistance to the common antibiotic kanamycin in tobacco plants. Belonging to a group of proteins that specialise in capturing and evicting toxins in plants, AtWBC19 works as effectively against kanamycin as conventional bacterial resistance genes - such as the nptII gene (neomycin phosphotransferase II) from Escherichia coli. Because of the difference in cell structure and the mechanisms that drive both bacterial and plant cells, the team say that it is highly unlikely that acquisition of the gene by a bacterium could confer antibiotic resistance.

As a plant gene destined for use in plants, AtWBC19 overcomes theoretical concerns over the combination of genetic material across kingdom boundaries. Also, AtWBC19 may prove a valuable substitute for nptII in the development of soybean, cotton, Brassica and Solanaceae crops (cabbage and potato family crops), as well as some forest tree species, argue the researchers.

NATURE BIOTECHNOLOGY
DOI: 10.1038/nbt1134

Other paper from Nature Biotechnology to be published online at the same time:
Genome sequence of the chlorinated compound-respiring bacterium Dehalococcoides species str

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