GM Free Cymru

That famous 30% yield increase in GM wheat.........

In his speech at the Oxford Farming Conference on 3rd January 2013, Mark Lynas said: " What few people have since heard is that one of the other (GM wheat) trials being undertaken, which Greenpeace activists with their strimmers luckily did not manage to destroy, accidentally found a wheat yield increase of an extraordinary 30%."

That sounds from that extract as if there was a large open-air field trial of GM wheat in Australia which Greenpeace activists would have liked to destroy, but failed. However, it turns out that this is all very wide of the mark. The myth arose from a greenhouse trial in Australia, conducted by CSIRO. It was reported in October 2012. As far as we can gather, the CSIRO scientists were experimenting with methods designed to increase starch content, and "came up with a line of genetically modified wheat that yields 30 percent more than check varieties in greenhouse trials.
" We don't know how many plants experienced that yield increase, and we do not know whether the researchers have measured biomass (including leafy matter, roots and stalks) or grain output -- and we don't know whether this was a freak result due to some unexpected (and unrepeatable) mutatation. CSIRO put out a press release (as one might expect of an organization which has been promoting GMOs for many years) but declined requests for interviews and cross-examination. So the media had just the press release to go on, and of course they made the most of it......

As far as we can gather, the wheat was planted outside the greenhouse in two so-called "field trials" (probably not in proper field conditions) and it was a rather miserable failure. On one occasion, we understand that it was too wet, and on another it was too dry.........

The CSIRO clearly has no idea how their modification resulted in a yield increase. This is an example of an unanticipated, unintended effect of the modification. They admitted that they could not even rule out that the antibiotic resistance gene, nptII, used in the plant wasn't responsible! It is possibly an effect of a second mutation that arose during tissue culture. The only reason it was seen is because they happen to be measuring yield. If the effect were something that caused environmental or human health harm, they would be oblivious to it unless they happen to monitor for precisely the right thing, and that wasn't part of the pre-commercial program to date. This is because this harm would also arise from an unanticipated and unintended effect of the modification (so watch this space for further unanticipated phenotypic changes). What their story proves is that unintended effects are clearly important; they occur without existing scientific hypothesis to explain them; they can be profound. That CSIRO chose to emphasise this one only speaks to the selectivity of the message.

Secondary points are that the evidence for yield increase comes mainly from glasshouse trials. The two additional field trials produced some but not complete confirmation of the phenotype. There has been no demonstration of the benefit under real agricultural conditions at scale. While the latter may be an unfair criticism at this stage, the point is that one cannot claim a 30% increase in yield. The responsible claim would be 'shows promise of a yield increase' under specified trial conditions but for unknown reasons that may not be due to the genetic modification itself. And while CSIRO measured the yield under conditions of unlimited nutrient availability, the environmental sustainability of any future high yield (however this plant might achieve the yield increases) was not mentioned by CSIRO, much less measured.

(Thanks to colleagues in Australia for key information in this piece)

See also:

Accidental GM wheat surprises Australian researchers with 30% more biomass

Scientists at Australia's Commonwealth Scientific and Industrial Research Organization, while attempting to make a wheat with an enhanced starch profile, came up with a line of genetically modified wheat that yields 30 percent more than check varieties in greenhouse trials. (News release No 8233); "With this technology we see more vigorous wheat with increased vegetative growth, larger seed heads and larger seed," Bruce Lee, director of CSIRO's Food Futures Flagship, said in a news release. ......"If we can achieve significant yield increases in the field, this will have a major impact on food production on a global scale."