London (July 4th, 2005) – A major part of the arguments against cultivation of GM crops is the risk of “contamination”, the possible spread of the transgenic trait by cross-pollination.

Genes do, indeed, spread in nature; those introduced into plants by recombinant DNA technology are not likely to behave differently from any others so they, too, will be spread with pollen if they are indeed present in the pollen DNA.

This spread is of concern particularly to organic farmers whose accreditation agencies, justifiably or not, demand an absence of any such material in all produce labelled ‘organic”. Although European Union legislation does not provide an official threshold content of GM material in organic products (and parts of the organic sector themselves demand zero), the regulations do specify that if any ingredient in a food or food product exceeds 0.9% transgenic content it must be so labelled. This applies de facto to organic products which accordingly seek to be below that limit.

Most but not all transgenic spread is likely to be by wind- and insect-borne pollination; while spillage and transport on vehicles, clothing and by other means will offer some contribution, it is likely to be very small.

Cross-pollination may not be totally avoidable even with buffer zones. But if the pollen is not able to transmit the transgene, the problem is avoided.

In areas where most farmers have turned to biotech seeds, others who want to grow non-biotech corn sometimes encounter a costly problem because the biotech pollen can drift from neighbouring fields; that can be a particular problems in large areas of North America where a high proportion of the commodity crops are genetically modified.

A small Nebraska firm called Hoegemeyer Hybrids has now patented a breed of non-biotech corn that the company says is resistant to such contamination. PuraMaize, the new hybrid corn, rejects pollen from all other strains of maize except its own -- thus any GM pollen that happened to drift by could not “contaminate”.

Tom Hoegemeyer, the inventor of the new strain, developed the idea after seeing the scepticism around the globe toward biotech crops in the mid-1990s. He researched races of exotic corn used hundreds and thousands of years ago and, after obtaining the gene materials he needed, began tests in 2000, along with developmental breeding and research.

"This has largely been a traditional breeding process," Hoegemeyer said. "Genes exist and have been known about since the '30s that have impact on the pollination process. It was a matter of going out and getting the right materials working together."

The new development may not be a total barrier to cross-pollination but with the high level of effectiveness of existing coexistence techniques, this new development should abolish concern for all but the most fastidious.


Joy Powell (June 29th, 2005). New corn is a breed apart. Star Tribune (


  A sensible approach to cross-pollination