LONDON-Scientists have discovered the secret of how the ginkgo tree can live for more than 1,000 years.

A study found the tree makes protective chemicals that fend off diseases and drought.

And, unlike many other plants, its genes are not programmed to trigger inexorable decline when its youth is over.

The ginkgo can be found in parks and gardens across the world, but is on the brink of extinction in the wild.

“The secret is maintaining a really healthy defence system and being a species that does not have a pre-determined senescence (ageing) programme,” said Richard Dixon of the University of North Texas, Denton.

“As ginkgo trees age, they show no evidence of weakening their ability to defend themselves from stresses.”

The ginkgo is native to China and the last survivor of a long line of ancient trees, with fossils known from the time of the dinosaurs

Wild populations are on the brink of extinction due to logging, with wild populations confined to Xitianmu Mountain in Zhejiang, China Listed as endangered in the IUCN red list of threatened species (Ginkgo biloba).

Researchers in the US and China studied ginkgo trees aged 15 to 667, extracting tree-rings and analysing cells, bark, leaves and seeds. They found both young and old trees produce protective chemicals to fight off stresses caused by pathogens or drought. These include anti-oxidants, antimicrobials and plant hormones that protect against drought and other environmental stressors. Genetic studies showed that genes related to ageing didn’t automatically switch on at a certain point in time as in other plants, such as grasses and annuals.