WELLINGTON (AFP) -- Scientists in New Zealand and Japan have created a ""tear-free"" onion using biotechnology to switch off the gene behind the enzyme that makes us cry, one of the leading researchers said Friday.

The discovery could signal an end to one of cooking's eternal puzzles: why does cutting up a simple onion sting the eyes and trigger teardrops?
The research institute in New Zealand, Crop and Food, used gene-silencing technology to make the breakthrough which it hopes could lead to a prototype onion hitting the market in a decade's time.
Colin Eady, the institute's senior scientist, said the project started in 2002 after Japanese scientists located the gene responsible for producing the agent behind the tears.
""We previously thought the tearing agent was produced spontaneously by cutting onions, but they proved it was controlled by an enzyme,"" he told AFP from his home outside Christchurch.
""Here in New Zealand we had the ability to insert DNA into onions, using gene-silencing technology developed by Australian scientists. ""The technology creates a sequence that switches off the tear-inducing gene in the onion so it doesn't produce the enzyme. So when you slice the vegetable, it doesn't produce tears.""