Nav: Home

When the seed becomes a plant, it has 48 hours to survive

August 02, 2018

During germination, the embryo within the seed must develop into a young seedling capable of photosynthesis in less than 48 hours. During this time, it relies solely on its internal reserves, which are quickly consumed. It must therefore rapidly create functional chloroplasts, cellular organelles that will enable it to produce sugars to ensure its survival. Researchers from the University of Geneva (UNIGE) and the University of Neuchâtel (UniNE), Switzerland, have revealed in the journal Current Biology the key elements that control the formation of chloroplasts from proplastids, hitherto poorly studied organelles. Such a mechanism ensures a rapid transition to autonomous growth, as soon as the seed decides to germinate.

The surprising propagation and diversification of flowering plants in terrestrial environments are mainly due to the appearance of seeds during evolution. The embryo, which is dormant, is encapsulated and protected in a very resistant structure, which facilitates its dispersion. At this stage, it cannot perform photosynthesis and, during germination, it will thus consume the nutritive reserves stored in the seed. This process induces the transformation of a strong embryo into a fragile seedling. "This is a critical stage in the life of a plant, which is closely regulated, notably by the growth hormone gibberellic acid (GA). The production of this hormone is repressed when external conditions are unfavorable", explains Luis Lopez-Molina, Professor at the Department of Botany and Plant Biology of the UNIGE Faculty of Science.

Import proteins submitted to the cell shredder

The awakening of the embryo causes the differentiation of its proplastids into chloroplasts, biological factories capable of producing sugar thanks to photosynthesis. "Thousands of different proteins must be imported into the developing chloroplasts, and this process can only take place in the presence of a protein called TOC159. If it is lacking, the plant will be depleted in chloroplasts and will remain albino", explains Felix Kessler, Director of the Plant Physiology Lab and Vice-Rector of the UniNE.

How does the seed decide whether to keep the embryo in a protected state or, on the contrary, to take a chance and let it germinate? "We have discovered that, as long as GA is suppressed, a mechanism is set up, which ensures that TOC159 proteins are transported to the cellular waste bin in order to be degraded", explains Venkatasalam Shanmugabalaji, researcher within the Neuchâtel group and first author of the study. In addition, other proteins needed for photosynthesis, of which TOC159 facilitates importation, suffer the same fate.

A high-performance biomechanism

When external conditions become favorable for germination, the GA concentration increases in the seed. The biologists discovered that high concentrations of this hormone indirectly block the degradation of TOC159 proteins. The latter can therefore be inserted into the membrane of the proplastids and enable the import of photosynthetic proteins cargoes, which also escape the cellular waste bin.

The genesis of the first functional chloroplasts, implemented in less than 48 hours, therefore ensures a rapid transition from a growth depending on the embryo's reserves to an autonomous development. This high-performance mechanism contributes to the survival of the seedling in an inhospitable environment, in which it will have to face many challenges.
-end-


Université de Genève

Related Photosynthesis Articles:

Even bacteria need their space: Squished cells may shut down photosynthesis
Introverts take heart: When cells, like some people, get too squished, they can go into defense mode, even shutting down photosynthesis.
Marine cyanobacteria do not survive solely on photosynthesis
The University of Cordoba published a study in a journal from the Nature group that supports the idea that marine cyanobacteria also incorporate organic compounds from the environment.
Photosynthesis -- living laboratories
Ludwig-Maximilians-Universitaet (LMU) in Munich biologists Marcel Dann and Dario Leister have demonstrated for the first time that cyanobacteria and plants employ similar mechanisms and key proteins to regulate cyclic electron flow during photosynthesis.
Photosynthesis seen in a new light by rapid X-ray pulses
In a new study, led by Petra Fromme and Nadia Zatsepin at the Biodesign Center for Applied Structural Discovery, the School of Molecular Sciences and the Department of Physics at ASU, researchers investigated the structure of Photosystem I (PSI) with ultrashort X-ray pulses at the European X-ray Free Electron Laser (EuXFEL), located in Hamburg, Germany.
Photosynthesis olympics: can the best wheat varieties be even better?
Scientists have put elite wheat varieties through a sort of 'Photosynthesis Olympics' to find which varieties have the best performing photosynthesis.
Strange bacteria hint at ancient origin of photosynthesis
Structures inside rare bacteria are similar to those that power photosynthesis in plants today, suggesting the process is older than assumed.
Just how much does enhancing photosynthesis improve crop yield?
In the next two decades, crop yields need to increase dramatically to feed the growing global population.
Algal library lends insights into genes for photosynthesis
To identify genes involved in photosynthesis, researchers built a library containing thousands of single-celled algae, each with a different gene mutation.
New molecular blueprint advances our understanding of photosynthesis
Researchers at Lawrence Berkeley National Laboratory have used one of the most advanced microscopes in the world to reveal the structure of a large protein complex crucial to photosynthesis, the process by which plants convert sunlight into cellular energy.
Structure and function of photosynthesis protein explained in detail
An international team of researchers has solved the structure and elucidated the function of photosynthetic complex I.
More Photosynthesis News and Photosynthesis Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Speedy Beet
There are few musical moments more well-worn than the first four notes of Beethoven's Fifth Symphony. But in this short, we find out that Beethoven might have made a last-ditch effort to keep his music from ever feeling familiar, to keep pushing his listeners to a kind of psychological limit. Big thanks to our Brooklyn Philharmonic musicians: Deborah Buck and Suzy Perelman on violin, Arash Amini on cello, and Ah Ling Neu on viola. And check out The First Four Notes, Matthew Guerrieri's book on Beethoven's Fifth. Support Radiolab today at Radiolab.org/donate.