A spray that would help plants survive droughts could be available within years, Canberra scientists say.

Researchers from the Australian National University have discovered an enzyme in plants that acts as a "stress sensor", as part of a decade-long project involving dozens of international scientists.

Although plants can adapt to difficult conditions, lead researcher, Kai Xun Chan, said damage occurred when they did not react fast enough.

Dr Chan's team hopes to speed up the plant's natural protection mechanisms by using a chemical spray to trigger the enzyme.

"We try to manipulate the properties of this sensor to make it basically function more sufficiently during drought stress," he said.

Dr Chan said the discovery could help struggling farmers by reducing crop damage.

"[Future drought] is forecast to cost our agricultural sector about five-and-a-half-billion dollars a year."

It is expected to take two or three years to develop a compound that would be used in the spray.

"We are starting efforts to identify candidate chemical compounds that can target this particular sensor ... that we can then try and perfect," Dr Chan said.

"For instance making them more stable, more easily absorbed by the plant, or cheaper to manufacture."