Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers identify molecular signaling system that is crucial for plant fertility

14.07.2003


University of Chicago researchers have found that a substance that functions as a neurotransmitter in humans also plays a crucial role in plant reproduction, guiding growth of the tube that transports sperm from a pollen grain on a flower’s surface to the egg cells within a plant’s ovules.



Their finding, published in the July 11, 2003, issue of the journal Cell, is a major step forward in understanding plant fertility. The discovery could also help researchers understand similar biological processes, such as now nerve cells find each other and make appropriate connections. It may even provide clues about repairing spinal cord injuries.

"Since agriculture, which supplies nearly 80 percent of the world’s food supply, depends so profoundly on plant fertility, understanding this process is fundamentally important," said Daphne Preuss, Ph.D., professor of molecular and cell biology and an investigator in the Howard Hughes Medical Institute at the University of Chicago.


When a pollen grain is deposited on the surface of a flower, it somehow has to grow a tube from the stigma of the flower, past several different cell types to where the eggs are, digesting tissue as it grows to burrow all the way inside. "While a few molecules involved in this process have been identified over the years," said Preuss, "we really still don’t understand how this tube gets from start to finish."

Working with Arabidopsis, a popular model plant, Preuss and colleagues from her lab found that plants produce a carefully controlled gradient of gamma-amino butyric acid (GABA), a molecule best known for its role in the mammalian nervous system, to lure a pollen tube toward the egg cells. GABA acts like a light at the end of a tunnel, stimulating the initial growth of the pollen tube and shining ever brighter as the tube gets closer to its goal.

The researchers found that the key to regulating GABA levels is an enzyme they named POP2 that degrades GABA. Arabidopsis flowers produce high levels of GABA then eliminate varying amounts of it from different structures, so that a small amount is present at the surface of the pistil, where it stimulates pollen tube growth. Higher concentrations are found closer to the eggs, leading the tubes toward the target.

The study grew out of the team’s chance finding of abnormal pollen tubes on plants that were later found to lack POP2.

"We saw the pollen tubes just winding around and totally missing their targets on one particular mutant," said Preuss. Co-author Laura Brass, a former Ph.D. student in the Preuss lab, analyzed the mutant strain and pinpointed the gene that caused the defect, which the researchers named POP2.

By comparing the sequence of the defective protein produced by POP2 to other known proteins, lead author Ravishankar Palanivelu, Ph.D., a post-doctoral fellow in Preuss’s laboratory, concluded that it was an enzyme called an aminotransferase. It was not until the researchers found that the mutant plant contained a hundred-fold elevation in GABA, however, that they learned which molecule the enzyme degraded.

Further studies confirmed that the chemical normally concentrates near the egg-containing ovule. In contrast, in the mutant plants, GABA is diffused throughout the tissues. In these mutants, the pollen tubes are "just overwhelmed with signal," said Preuss. Instead of a light at the end of the tunnel it was "like staring at the sun."

Finding a reproductive role for GABA in plants is a good example of nature’s ability to make the most of what’s available, said Preuss. GABA is small, comparatively simple molecule. Many plants and animals use it as a source of carbon or nitrogen or to send signals from cell to cell. Animals use it to regulate hormone secretion, inhibit certain signals between nerve cells, and perhaps even to guide embryonic neurons to their destination.

GABA is only one of several substances involved in pollen tube guidance, however, said Preuss. The researchers are analyzing other mutants with altered pollen tube growth.


###
The research was supported by the Department of Energy, the Searle Scholars Program and the University of Chicago.

John Easton | EurekAlert!
Further information:
http://www.medcenter.uchicago.edu/

More articles from Life Sciences:

nachricht Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory

nachricht How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>