Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Plant hormone 'switch' unravels chromatin to form flowers, penn biologists find

14.10.2015

Because plants cannot pick up and move, they have evolved a plethora of strategies to cope with environmental stresses, whether they bring a harsh spell of drought or a browsing deer.

One of these strategies is plants' ability to continue growing new, diverse organs, including roots, branches and flowers, throughout their lifespan. But of course flowers don't develop just anywhere on the plant; they only grow from certain cells, which must receive a particular signal to begin the process. While researchers knew that flower formation was governed by the activity of the hormone auxin, they didn't understand precisely how it signaled the plant to form blooms.


Instead of flowers, plants with mutations in certain chromatin remodeling genes developed pin-like structures (right).

Credit: University of Pennsylvania

Now University of Pennsylvania researchers have filled in the gaps and identified a hormone-mediated "chromatin switch" that directs a plant to form flowers. In the absence of auxin, genes that initiate flower formation are tucked away in tangled chromatin, a tightly packed bundle of DNA. But, in the hormone's presence, proteins are recruited to unravel chromatin and make the genes responsible for flower formation more accessible.

The findings could be useful in efforts to strategically boost flower formation as a means of increasing yield in agricultural crops. And the study's contribution to understanding basic mechanisms of chromatin regulation, which may be similar across species and even kingdoms of living things, could have implications for many biological processes, including human health.

... more about:
»flower »genes »hormone »proteins

"This one hormone auxin is very famous because it has many roles, in embryo, root and flower development, in vein formation, in growth -- it's doing all of these things," said Doris Wagner, senior author on the work and a professor of biology in Penn's School of Arts & Sciences. "The question is always, How can one hormone do all these different things? Now we see that, by helping open up chromatin, it can allow a variety of other proteins to come in and initiative these different pathways. All of a sudden these very diverse processes are not so hard to explain anymore."

Wagner collaborated with Penn's Miin-Feng Wu, Nobutoshi Yamaguchi, Jun Xiao and Yi Sang as well as Bastiaan Bargmann and Mark Estelle of the University of California, San Diego.

Their research is published in the journal eLife.

In work published in 2013, Wagner and colleagues began to piece together how auxin regulated flower formation. They already knew that auxin activated the transcription factor MONPTEROS, and went on to identify that factor's direct targets, which included three genes involved in flower development.

But the researchers believed the process was not that simple because those genes were packed tightly away in chromatin, which would prevent them from being activated. There must be another factor that makes those genes available to be transcribed, the team reasoned.

"So we looked on purpose for proteins that are required for making flowers and were also chromatin regulators that might overcome this repressive environment," Wagner said.

Performing experiments in Arabidopsis, the researchers showed that plants with double mutations in SWI/SNF proteins, BRM and SYD, which are known chromatin remodelers, failed to initiate flower formation. Because they can't make flowers, these plants had pointy "pin-like" forms.

The team also showed that BRM and SYD, which are part of a chromatin remodeling complex, bound to the same locations as MONOPTEROS does in the regulatory regions of various genes required for flower development. They also demonstrated that MONOPTEROS physically interacts with BRM and SYD, likely recruiting them to the proper site in the chromatin.

Once at the proper site, the team showed that BRM and SYD, in the presence of auxin, reshape chromatin in a way that makes the flower-formation genes more accessible for transcription and expression.

Wagner's group next artificially guided BRM and SYD to the correct locations in the genome in plant cells. Those cells showed increased expression of flower formation genes, just as cells exposed to auxin did.

When they repeated this experiment in a mutant plant that normally fails to form flowers, they were able to coax it to develop flowers, almost identically to a normal plant.

"We were very surprised to see the flowers come back so dramatically," Wagner said. "And, though we didn't study other aspects exhaustively, it appears that this chromatin-remodeling complex may also rescue leaf formation and perhaps some other plant development processes regulated by auxin."

The findings suggest that this process could be strategically manipulated in order to pack more flowers on one plant, potentially increasing agricultural yields.

There are signs that the auxin pathway and these SWI/SNF proteins are present even in ancient plants, so the process of recruiting chromatin remodelers could be universal in plants.

Auxin is not made in humans, but, as Wagner noted, the chromatin remodelers her team studied are and are known to be tumor suppressors -- proteins that, when mutated, can allow tumors to grow unchecked. Thus, it's conceivable that one could design a hormonal switch, using auxin, to regulate them.

Media Contact

Katherine Unger Baillie
kbaillie@upenn.edu
215-898-9194

 @Penn

http://www.upenn.edu/pennnews 

Katherine Unger Baillie | EurekAlert!

Further reports about: flower genes hormone proteins

More articles from Life Sciences:

nachricht Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

Im Focus: Newly proposed reference datasets improve weather satellite data quality

UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration

"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...

Im Focus: Repairing defects in fiber-reinforced plastics more efficiently

Fiber-reinforced plastics (FRP) are frequently used in the aeronautic and automobile industry. However, the repair of workpieces made of these composite materials is often less profitable than exchanging the part. In order to increase the lifetime of FRP parts and to make them more eco-efficient, the Laser Zentrum Hannover e.V. (LZH) and the Apodius GmbH want to combine a new measuring device for fiber layer orientation with an innovative laser-based repair process.

Defects in FRP pieces may be production or operation-related. Whether or not repair is cost-effective depends on the geometry of the defective area, the tools...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Multiregional brain on a chip

16.01.2017 | Power and Electrical Engineering

New technology enables 5-D imaging in live animals, humans

16.01.2017 | Information Technology

Researchers develop environmentally friendly soy air filter

16.01.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>