A plant's metallic make-up could be used to identify it as genetically modified, say researchers in Brazil.

Marco Arruda and colleagues from the University of Campinas in São Paulo have used a combination of mass and x-ray spectrometries to compare metal ion quantities in eight randomly selected proteins from wild-type and Roundup Ready genetically modified soya beans. The idea behind the study was that, since genetic modification is known to change the set of proteins expressed by an organism - the proteome - it could also affect its metal ion content - the metallome.

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The team found several differences between the two types of bean, for example, copper and zinc were found at higher levels in the transgenic beans. Since these two metals are commonly found in proteins related to oxidative stress, the researchers suggest that this could indicate plant stress caused by genetic modification.

'Until now information about metals and proteins was frequently fragmented,' said Arruda. 'As some proteins are metal-dependent, for example metalloproteins or metal binding proteins, integrating metal-protein information can make elucidating processes such as oxidative stress mechanisms or detoxification mechanisms in the studied organisms easier. Additionally, as metals play an important role as signalling agents,' Arruda continued, 'such studies can point out possible biomarkers for these mechanisms or even make the identification of transgenic organisms possible.'

Joanna Stevens