Immortal Trees: Ginkgo biloba

An unusual fan-shaped tree, Ginkgo biloba, is remembered by many in one of two ways - as something they learned in school to be a "living fossil" and as an ingredient in memory-enhancing pills.
Although the description of a "living fossil" has never been too clear to anyone, because it is a bit oxymoronic, this species is it - an organism that with its more primitive structure and characteristics resembles the organisms that once inhabited the planet and became extinct.Fossils of ginkgo-related plants date from the Permian, some 270 million years ago. This species is long-lived and can live for over 1000 years, and scientists have discovered something else - this species looks immortal, thanks to its genes.A paper published in mid-January in the Proceedings of the National Academy of Sciences, entitled "Multifeature analyzes of vascular cambial cells reveal longevity mechanisms in old Ginkgo biloba trees" showed that there were no differences in the expression of certain genes in cambium trees in old and young specimens of this species. .

The cambium is the tissue of plants whose cells have the ability to divide, and is found in the root and stem. By dividing the cells in the cambium, the conductive elements of plants are formed - xylem and phloem. In fact, these are plant stem cells, very important for tree growth.

Examining growth rings, the team of Li Wang, a molecular biologist at Yangzhou University in China, found that the growth of ginkgo trees does not slow down even after hundreds of years - in fact, it even happens that growth accelerates.

To find out what happens at the genetic level, scientists compared gene expression in leaves and cambium. The team sequenced tree RNA, analyzed hormone production, and examined miRNA - molecules that can turn certain genes on and off - in trees aged 3 to 667 years.

The expression of genes associated with aging was higher in the leaves, which will soon fall off. But when scientists examined the expression of the same genes in the cambium, they found no difference between young and old trees. This suggests that although organs like leaves decay, the trees themselves are unlikely to die of old age. It is more likely to be damaged by external factors, such as wind, being cut down and the like.

However, the trees do experience some changes as they age. older trees had lower levels of plant growth hormone - indole-3-acetic acid and higher levels of growth inhibitory hormone, abscisic acid. Trees older than 200 years have reduced expression of genes associated with cell division and differentiation. This means that cambium stem cells in older trees do not divide as easily as in younger trees.