Secret of how some trees can live for 1,000 years is unravelled by scientists
It’s not quite immortality, but some trees achieve something close to it, living for more than 1,000 years.
Now scientists might know why, after a study investigated the famously long-lived gingko tree.
The tree is known to be very resistant to pests and pollution and is planted in parks and gardens around the world - although it was unknown in the West until the past few hundred years.
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Research published in Nature shows how the tree can live for so long by making protective chemicals which combat diseases and natural threats such as drought.
The researchers also found that older trees respond to threats differently to young trees, by studying gingkos ranging from 15 to 667 years old.
They analysed tree rings, bark and seeds.
So even if a tree looks aged and damaged, it’s still chemically healthy under the surface, the researchers said.
They hope that the study will contribute to understanding other long-lived tree species.
The researchers found that older trees produced less of a plant hormone, auxin, which stimulates growth, and more of the hormone abscisic which helps plants respond to stress.
Old trees also photosynthesise just as efficiently as young ones, and produce seeds which are just as viable.
"The secret is maintaining a really healthy defence system and being a species that does not have a pre-determined senescence (ageing) programme," Richard Dixon of the University of North Texas, Denton told the BBC.
"As ginkgo trees age, they show no evidence of weakening their ability to defend themselves from stresses.
"Hopefully, our study will encourage others to dig deeper into what appear to be the important features for longevity in ginkgo and other long-lived trees.”
Unlike other species, the trees didn’t seem to be ‘programmed’ for genetic decline.
The researchers wrote: “Gene activity in old trees also resembled that of their younger counterparts: older trees activated genes related to age-related decline, disease resistance, and the production of defensive compounds, such as antioxidants, at the same level as young trees.”
