Fluorescent GM potatoes say 'water me'

A potato genetically-modified with jellyfish genes which glows when it needs watering is created by Edinburgh scientists.

The team believes the plant will prevent overwatering at time when the world's water resources are being more and more heavily used.

The fluoresence is produced by the jellyfish gene.

This is activated in the plant by the production of abscisic acid, which the plant uses to rearrange its cells to prepare for a shortage of water.

However, Professor Tony Trewavas from the University of Edinburgh, is aware of some people's concern about GM crops.

He told BBC News Online: "People are worried, but these potatoes will never enter the food chain. They are sentinels and would be put in separately and harvested separately."

Speaking at the British Association's Festival of Science in Sheffield, UK, Professor Trewavas said that just sowing eight plants per hectare would allow a farmer to monitor the whole field.

The potatoes will not glow to the human eye however. The light is produced by absorbing a narrow wavelength of blue light, which is re-emitted as yellow.

A small detector, built by the Scottish Agricultural College, spots the yellow light and sets off a green signal which says "water me". If no signal is showing, then the plants have enough water.

"The problem at the moment is that farmers don't know how much water is needed - they just pour it on," said Professor Trewavas.

Six-year wait

"We believe our system would save farmers about £270 per hectare in terms of reduced water use and reduced fertiliser applied.

"You don't have to put as much nitrate on if you don't over-water and run off lots of your minerals."

Experiments so far have been confined to greenhouses and it will be about six years before the glowing potatoes go on sale.

Future plans are to include slightly different fluorescent proteins which will report on the plants' nitrate, phosphate and sucrose status.