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 A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>