Since they first arrived on land, plants have likely been using the same genetic tools to regulate whether they grow bigger or reproduce. The discovery was made using liverwort, one descendant of the first plants to move out of the ancient oceans and onto land…
The liverwort genome is structurally simple compared to the flowering plants that are commonly used in research laboratories, like tobacco and thale cress (Arabidopsis). Flowering plants are evolutionarily “younger” plants than liverworts, with gene duplications and redundancies that make studying their genomes more complicated.
Despite that simplicity, the liverwort genome appears to have all the same life-cycle stages and powers to regulate them. The entire genome of the liverwort species Marchantia polymorpha was first sequenced in 2017 by an international team, which included several researchers who also participated in the recently published gene analysis.
When they examined the full genome, researchers discovered that even the simple liverwort has about 100 different types of a small molecule, called microRNA, which regulate the activity of other genes.
About eight of the liverwort microRNAs were nearly identical to known thale cress microRNAs. These eight microRNAs fascinated researchers because the ancestral plants that evolved into modern liverworts and modern thale cress split over 450 million years ago.
“So, why keep them? We want to know what those shared microRNAs are doing, and liverworts are now a convenient model for us to investigate,” said Watanabe. Paper. (open access) – Masayuki Tsuzuki, Kazutaka Futagami, Masaki Shimamura, Chikako Inoue, Kan Kunimoto, Takashi Oogami, Yuki Tomita, Keisuke Inoue, Takayuki Kohchi, Shohei Yamaoka, Takashi Araki, Takahiro Hamada, Yuichiro Watanabe. An Early Arising Role of the MicroRNA156/529-SPL Module in Reproductive Development Revealed by the Liverwort Marchantia polymorpha. Current Biology, 2019; DOI: 10.1016/j.cub.2019.07.084 More.
It turned out that one of the conserved microRNAs from 450 million years go was involved in plant reproduction. It’s almost like the land plants were given a kit when they started out or something. But nah… 😉
See also: Stasis: Life goes on but evolution does not happen
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