AsianScientist (Nov. 30, 2016) – Researchers in China have sequenced the genome of Ginkgo biloba, the oldest tree species still in existence. Their work was published in GigaScience.
Ginkgo is considered a ‘living fossil,’ meaning that its form and structure have changed very little in the 270 million years since it first came into existence. As the only surviving representative of a highly unusual group of non-flowering plants from around that time, the ginkgo has retained traits over millions of years, such as the emblematic fan-shaped leaves, that are not seen in any other surviving plant species.
The ginkgo’s resilience under adverse conditions have long fascinated researchers—ginkgo trees were one of the few living things to survive the atomic bombing of Hiroshima. This hardiness likely helped the ginkgo survive periods of glaciation in China that killed many other species, and may also promote the longevity of individual trees, some living up to several thousand years.
To better understand the ginkgo’s defensive systems, the authors analyzed the repertoire of genes present in the genome that are known to play a role in fending off attackers. The researchers from BGI, Zheijiang University and the Chinese Academy of Sciences, tackled and analyzed the exceptionally large genome, totaling more than ten billion DNA ‘letters.’ The ginkgo genome stretches over more than 10 Gb, 80 times larger than the ‘model plant’ Arabidopsis thaliana’s genome.
An initial analysis of the tree’s more than 40,000 predicted genes showed extensive expansion of gene families that provide for a variety of defensive mechanisms. Genes that enable resistance against pathogens are often duplicated. Additionally, ginkgo has a double-knockout punch in its fight against insects by synthesizing chemicals that directly fight insects, and by releasing volatile organic compounds that specifically attract enemies of plant-eating insects.
These findings indicate that multiple mechanisms might be linked to the ginkgo’s extraordinary resilience. This information may then be useful to aid in understanding plant defense system with an eye to improving food security.
The article can be found at: Guan et al. (2016) De Novo Sequencing of Ginkgo biloba.
Source: GigaScience; Photo: Pixabay.
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