Investigation continued this week into how unauthorised genetically modified wheat ended up on a farm in Oregon.No varieties of GM wheat have been cleared for commerial use anywhere in the world . The wheat plant in question are believed to be the legacy of a research programme that was abandoned nine years a go . How and why they have resurfaced is unclear.The discovery last week triggered an international reaction, with both South Korea and Japan temporarily suspending imports of US wheat. South Korea has also begun testing existing wheat imports from the US for signs of GM wheat,with no positive result so far