As a gardener, I welcome the announcement of UK trials of potatoes genetically modified to be resistant to blight, for reasons given below. I was rather less pleased at the reaction of the GMWatch spokeswoman on the Today programme. She used the event as a hook to hang a very standard anti-GM rant off, without dealing in any way with the specifics of this particular implementation – and this is not a standard GM trial.
There are several ways in which this particular GM trial differs from many others that have occurred in the past. The gene inserted is from a wild potato plant, not a gene from another species. The same effect might be attained through many years of careful cross-breeding in the traditional manner; genetic modification just gets it done more quickly and more surely.
The purpose of the gene transfer is to give the plants resistance to potato blight, which is a deadly disease for which there is no organic treatment (organic potato farmers are permitted to use Bordeaux Mixture, which is primarily copper sulphate, but this is a concession by the Soil Association to the fact that without using some sort of inorganic compound, it is impossible to grow potatoes in an area subject to blight.
Potatoes crop, and reproduce, not by setting seed but by producing tubers. There is therefore a much lower chance of 'contamination' with other plant species (especially as there are far fewer relatives of the potato in the wild than there are of grass-based plants such as wheat). And, as I said above, the gene is one that occurs in wild potatoes anyway, and confers resistance to a fungal infection, not a weedkiller or pesticide. So if the gene did start appearing in wild plants, what harm would it do anyway?
It is true that reports of a toxicology experiment in the past have claimed that rats fed a certain strain of GM potato had damaged immune systems. But the full results of that trial, when they were finally released, were inconclusive, and some claimed the design was flawed and the paper should not have been published. And in any case, this is a different strain and would be expected to behave differently. But how can we tell that for sure without doing the trials?