DNA stability in plant tissues: implications for the possible transfer of genes from genetically modified food

The potential for transfer of antibiotic resistance genes from genetically modified (GM) plant material to microbes through genetic recombination in t he human or animal gut is a consideration that has engendered caution in th e use of GM foods. This study was aimed at defining the optimal physical an d chemical conditions necessary to ensure sufficient fragmentation of DNA i n plant tissues to a size where it would be unlikely to be stably transferr ed to bacterial gut microflora, The ribulose 1,5-bisphosphate carboxylase/o xygenase small subunit (Rubisco SS) genes are of similar size (approximatel y 1.4 kb) to transgenes present in GM plants, DNA analysis and PCR amplific ation of Rubisco SS genes showed that fresh maize and maize silage containe d high molecular weight DNA and intact Rubisco SS genes, Relatively high te mperatures and pressurised steam were necessary to degrade fully genomic DN A and Rubisco SS genes in maize and wheat grains, the source of most animal feedstuffs, Furthermore, chemical expulsion and extrusion of oilseeds resu lted in residues with completely degraded genomic DNA, These results imply that stringent conditions are needed in the processing of GM plant tissues for feedstuffs to eliminate the possibility of transmission of transgenes, (C) 2000 Federation of European Biochemical Societies. Published by Elsevie r Science B.V. All rights reserved.