INSTITUTE OF SCIENCE IN SOCIETY– ISIS has drawn attention to the instability of GMOs and GM constructs all along. Prof. Joe Cummins offers this latest verdict, all GM crops may be unstable.

It is repeatedly claimed that genetically modified (GM) crops are altered with single genes that are stable and equivalent to the genes that have been selected and bred into the crops. In every case the GM crops originated from cell cultures that have been know to be vexed with a phenomenon called somaclonal variation. Somaclonal variation has been encountered in genetic transformation using both biolistic and Agrobacterium transformation followed by cell culture to isolate desirable agricultural characteristics.

The phenomenon is that cell cultures leading to isolate individual clones and plants are plagued by genetic instability caused both by gene mutation and chromosome rearrangement. In extreme responses plants may be infertile and the extensive mutation leads to undesirable toxic natural products being produced. Furthermore, the transgenes introduced into the modified crop are recognized as invaders by the crop being transformed and the invading genes are silenced by mechanisms including DNA methylation or gene inactivation at transcription.

The evidence that the genetic instability resulting in somaclonal variation is caused by activation of inactive virus like genetic elements called transposons is currently very compelling (see Courtial et al 2001). Activated transposons create both gene mutation and chromosome rearrangement.

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© ISIS, 2001

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