The Hindu. National

 GM crops: gene transfer possible through pollen

 By N. Gopal Raj

 THIRUVANANTHAPURAM JUNE 27. Research just published
 in the journal Science indicates that pollen from
 genetically modified (GM) mustard could carry artificially
 introduced genes up to 3 km away, much further than
 previously thought. On the other hand, it also shows that
 the resulting gene flow is much lower than expected.

 The study, carried out in Australia, would be of particular
 interest to scientists and environmentalists in India. The
 Centre cleared India's first GM crop for commercial release
 just a few months ago and a GM mustard could become
 the next crop to receive regulatory approval.

 Ever since the advent of GM crops, there has been
 concern about whether genes, artificially introduced into
 plants, could spread through pollen to create
 super-weeds or contaminate natural plant varieties.

 Based on trials on small experimental plots, it was thought
 that only a miniscule amount of pollen from GM crops
 would spread up to a few hundred metres.

 The Australian scientists took advantage of a unique
 opportunity when cultivation of a new herbicide resistant
 mustard began in 2000 to undertake the first large scale
 study of gene transfer through pollen.

 They collected some three lakh seed samples from each
 of the 63 fields with conventional mustard, which were
 near the plots where the new herbicide resistant variety
 had been planted. The fields of conventional and
 herbicide resistant mustard were 25 to 100 hectares in
 area.

 The Australian team found that herbicide resistance had
 spread to about 63 per cent of the fields with
 conventional mustard, some up to 3 km away. On the
 other hand, only a few fields showed a resistance level of
 more than 0.03 per cent.

 Even fields adjacent to ones where herbicide resistant
 varieties were grown showed a gene flow much less than
 one per cent, lower than what earlier studies had
 indicated.

 The use of large plots, however, also showed that there
 was no exponential decline in pollen transfer with
 distance, as had been suggested by small-scale studies.

 It could be that the far greater quantities of pollen
 generated by large fields increased the likelihood of their
 travelling farther.

 Their research indicated that pollen movement on a large
 scale could not necessarily be predicted from small-scale
 studies, says Mary Rieger, who led the Australian team of
 researchers.

 Even if the gene flow is low, the study suggests that
 once GM plants get into commercial cultivation, it may
 not be possible to completely control the spread of the
 artificially introduced genes.