Science & Environment

Ginkgo 'living fossil' genome decoded

Ginkgo Image copyright Thinkstock

The Ginkgo tree has had its genetic code laid bare by researchers.

The tree is famed for being a “living fossil” - a term used to describe those organisms that have experienced very little change over millions of years.

In the case of the Ginkgo, there are specimens preserved in the rock record from 270 million years ago, in the Permian Period.

The Chinese-led research team says the new information should help to explain the tree’s evolutionary success.

Image copyright CC BY-SA via Wikimedia Commons
Image caption The ginkgo tree's emblematic fan-shaped leaf preserved as a 49-million-year-old fossil with modern autumn leaf overlaid

Its resilience is legendary: it was one of the few living things to survive the atomic bomb blast in the Japanese city of Hiroshima in 1945.

A Ginkgo is known to produce chemicals that are unpalatable to the insects that try to eat it, and will counter the fungi and bacteria that attempt to attack it.

Researchers can now more easily identify the mechanisms that drive these capabilities.

The specific species sequenced in the study was Ginkgo biloba. It reveals the tree’s genome to be huge, comprising some 10.6 billion DNA "letters".

By way of comparison, the human genome contains just three billion letters.

Written in the Ginkgo’s DNA code are roughly 41,840 predicted genes, the “templates” that the tree’s cells use to make the complex protein molecules that build and maintain the organism.

The initial analysis of the genome, published in the journal GigaScience, suggests there has been extensive expansion through time of gene families that provide for a variety of defensive mechanisms.

Its anti-insect arsenal is particularly smart. The Ginkgo will synthesise one set of chemicals to directly fight a pest, but also release another set of compounds that specifically attract the insect’s enemies.

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