Nav: Home

Unveiling the withering process

April 14, 2016

During their life, plants constantly renew themselves. They sprout new leaves in the spring and shed them in the fall. No longer needed, damaged or dead organs such as blossoms and leaves are also cast off by a process known as abscission. By doing so, plants conserve energy and prepare for the next step in their life cycle. But how does a plant know when it is the right time to get rid of unnecessary organs? Researchers from the University of Geneva (UNIGE) and the University of Oslo (UiO) now shed light on this process. It is regulated by receptor proteins located at the surface of specific cells that form a layer around the future break point. When it is time to shed an organ, a small hormone binds to this membrane receptor and, together with a helper protein, the abscission process is initiated. Their findings are now published in the journal eLife.

"It was already known that the membrane receptor protein HAESA and a small peptide -a short chain of amino acids - hormone called IDA are involved in the same signaling pathway and, together, control the shedding of floral organs. So far, however, the mechanism underlying their interaction was poorly understood", explaind Michael Hothorn, professor at the Department of Botany and Plant Biology of the Faculty of Science of UNIGE. By solving the crystal structure of HAESA (from the Greek 'to shed') in complex with IDA, Hothorn and his team found out that the receptor directly senses the peptide hormone. They observed that HAESA contains a small cleft into which IDA fits perfectly. However, it only binds halfway to the receptor. To fully initiate the abscission process, another player is needed: the helper protein SERK1. IDA then works like a double-sided Scotch tape that tethers the entire complex together. The binding of SERK1 to HAESA and IDA triggers the molecular switch that instructs the cell to shed the organ.

Multitasking helper protein

"The fascinating thing about SERK1 is that it not only plays a role in the shedding mechanism of plant organs, but also acts together with other membrane receptors that regulate totally different aspects of plant development", says Julia Santiago, first author of the study. Indeed, SERK1 is a versatile helper protein shared between different signaling pathways. When bound to another protein receptor, it can also for example signal the plant to grow.

To verify their findings, the biologists from UNIGE collaborated with Melinka Butenko's group from UiO. By studying genetically modified Arabidopsis thaliana plants, the Norwegian researchers confirmed the role of SERK1 in plant organ shedding. Their data were then statistically analyzed by professor Ludwig Hot-horn from the Leibniz University Hannover.

Now that they found out what is going on at the surface of plant cells before organ shedding, Michael Hothorn and his team want to discover what happens inside the cell. " How exactly the molecular switch for abscission works is still largely unknown", explains Michael Hothorn.

Université de Genève

Related Abscission Articles:

Chelated calcium benefits poinsettias
Cutting quality has an impact on postharvest durability during shipping and propagation of poinsettias.
Plants get a brace to precisely shed flowers and leaves
A study on how petals fall, and plants cope with the lost.
A single molecule is missing and the cell world is empty
Many diseases are related to defective cell division; cancer is one of them.
How huanglongbing affects oranges' detachment force, fruit properties
Researchers evaluated the effects of huanglongbing (HLB) symptom severity on fruit detachment force and fruit mechanical properties in sweet oranges as indicators of potential HLB-influenced preharvest fruit drop and postharvest damage and breakdown.
Unveiling the withering process
Plants constantly renew themselves. Damaged or dead organs are also cast off by a process known as abscission.
More Abscission News and Abscission Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...