The research was carried out by a team of scientists at BGI, Zheijiang University and the Chinese Academy of Sciences, who tackled and analyzed an exceptionally large genome, totalling more than 10 billion DNA “letters.” Ginkgo is considered a “living fossil,” meaning its form and structure have changed very little in the 270 million years since it first came into existence. Given its longevity as a species and unique position in the evolutionary tree of life, the ginkgo genome will provide an extensive resource for studies concerning plant defenses against insects and pathogens, and research investigating early events in tree evolution and in evolution overall.
The ginkgo genome stretches over more than 10 Gb, which is 80 times larger than the “model plant” Arabidopsis thaliana genome. The tree’s genome is also larger than other plant species known for extremely big genomes, such as maize or orchids.
Professor Yunpeng Zhao, one of the authors from Zhejiang University, explains how this evolutionary placement is of great interest to researchers: “Ginkgo represents one of the five living groups of seed plants, and has no living relatives. Such a genome fills a major phylogenetic gap of land plants, and provides key genetic resources to address evolutionary questions like phylogenetic relationships of gymnosperm lineages, evolution of genome and genes in land plants, innovation of developmental traits, evolution of sex as well as history of demography and distribution, resistance and conservation of ginkgo.”
Researchers are also fascinated by the ginkgo’s resilience under adverse conditions — it is worth noting that ginkgo trees were one of the few living things to survive the blast of 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, according to reports. The ginkgo is also able to defend itself against a wide range of attackers, employing an arsenal of chemical weapons against insects, bacteria and fungi.
To better understand the ginkgo’s defensive systems, the authors analysed the repertoire of genes present in the genome that are known to play a role in fending off attackers. Paper. (public access) – Rui Guan t al., Draft genome of the living fossil Ginkgo biloba. GigaScience, 2016; 5 (1) DOI: 10.1186/s13742-016-0154-1More.
See also: We can’t understand evolution without understanding stasis and extinction
Stasis: Life goes on but evolution does not happen
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