GM "Blight-immune" potato trial approved by DEFRA

A new genetically modified potato trial has been approved by DEFRA, after advice by the Advisory Committee on Releases to the Environment (ACRE). The potato to be tried out is a variant of Desiree, into which two genes from a wild potato have been inserted; a blight-immune species from South America which produces tiny non-edible tubers.

Professor Jonathan Jones from the Sainsbury Laboratory said: "UK potato growers spray crops 10-15 times a year and in 2007 Europe ran out of chemicals to control blight, it was such a wet year".

"If our research goes ahead and is successful, this will cut chemicals and carbon dioxide generated by the use of tractors."

I am not sure that 'climate change' arguments in support of a GM trial are helpful, though I take the point about chemicals.

However, to return to the subject - the potatoes will be grown at a site in Norfolk, and the bed will be approximately 1000 square metres.

The plot will be surrounded by 'guard' non-GM potatoes (Maris Piper). The aim here is to protect the trial potatoes from the typical field edge effects of wind and rain.

Genes giving resistance to antibiotics (neomycin and kanamycin) will be inserted, as markers. ACRE states that the therapeutic effect of these antibiotics will not be compromised by the trial.

Desiree usually produces flowers and often sets seed. To prevent the escape of the anti-blight genes into the environment, the site will be monitored for three years and any self-setting potato plants, from seeds or stray tubers (known in the trade as 'volunteers') will be pulled out and destroyed. The ground will be left fallow for two years after the trial.

Anti-GM groups have been generating more heat than light about the trial.

Presumably a GM technique is being used to introduce the blight-suppressing genes because it's quicker than conventional breeding. The breeders have to keep one step ahead of pathogens, as can be shown by all previous attempts to breed long-term blight resistance into potatoes.

In their day, Majestic, Pentland Dell, Orla, and about six other potatoes bred conventionally were all blight resistant. In each case, the resistance disappeared after a relatively short period of time.

It is possible to produce (conventionally) a potato with long-term partial resistance, but it's a long and expensive process. Golden Wonder has long-term partial resistance, and there are many others. The limited resistance occurs through interaction of many genes in a complex way, and when blight mutates, the resistance is unaffected and so is called 'durable'.

Inserting only two genes, on the other hand, is unlikely, on present evidence to confer long-term resistance. When they bred Pentland Dell, three resistance genes were incorporated by conventional means. The resistance lasted seven years.

One point in the trial's favour is that the genes used are from potatoes, not a foreign organism. Any damage to the environment is therefore extremely unlikely. The antibiotic resistance in the trial is really a red herring; there is little to object to since there are already bugs in the environment immune to neomycin and kanamycin.

It will be interesting to see if the modified Desiree potatoes are indeed blight-resistant, and, if so, to discover how long it takes blue-13 (the latest blight strain) to overcome the resistance.

The above is a personal view, and is not meant to be authoritative, though I know a little about antibiotics and have followed the 'blight' saga for many years - N.D., 13 Jun 10

    FOOTNOTE ... someone is bound to ask "What about the blight-proof 'SARPO' varieties?"

    My reply is this; those potatoes were bred actively, holistically and conventionally over many years, which means that any immunity they have involves the interaction of many genes. They are ahead of the blight, for now, but there is no way of predicting how long the resistance will last.

Interesting blog with comments added by a person working on gm potatoes.

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