Led by Professor Yuichiro Watanabe, a research team from the University of Tokyo found critical genetic component that can regulate plant reproduction.
Liverworts grow all over the world and resemble moss, spreading on moist soil under some shade. Male and female versions of liverwort are recognized by unique, umbrella-shaped structures that shoot up from the base of the plant.
"Liverworts have the maximum power with the least structure," said Professor Yuichiro Watanabe from the University of Tokyo's Department of Life Sciences, an expert in plant molecular biology.
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 abilities to regulate them.
Upon examination, researchers discovered that the liverwort has about 100 different genetic molecules 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.
One of the microRNAs that helps flowering plants control the shift to the reproductive stage is also one of the eight microRNAs shared between thale cress and liverworts.
Watanabe鈥檚 research team created a genetically modified version of liverwort lacking that specific microRNA 156/529 to determine its role as an evolutionarily conserved microRNA. In the absence of the microRNA, liverworts produced reproductive cells on their vegetative tissues rather than developing the normal umbrella-shaped reproductive structures that distinguish males and females.
"This was amazing to us. Those liverworts skipped some part of the reproductive process and the body itself becomes the reproductive organ," said Watanabe.
This study reveals that microRNA156/529 and the other molecules it interacts with are part of an important control module used by potentially all land plants to regulate their reproductive timing.
Watanabe imagines that in the future, farmers could measure the amount of microRNA156/529 in crops to predict harvest times.
"We hope our results inspire others to develop new applications for plant reproduction," said Watanabe.
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