Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Gene Discovered for Male Fertility in Plants

01.08.2002


A new gene shown to be essential for pollen production in flowering plants has been discovered by scientists at Penn State University. A paper describing the team’s discovery of the gene, whose activity they found is necessary for the formation of cells required for pollen production, will be published in the 1 August 2002 issue of the journal Genes and Development.

"This research is the first indication that a specific kind of protein known as a receptor-linked protein kinase, which results from the gene, is important for pollen production in the anther - the male reproductive organ in flowers," says Hong Ma, professor of biology and the leader of the research team that made the discovery. "Plant breeders eventually may be able to use this information to control pollination in important agricultural crops such as wheat, rice, and soybeans, where such control previously has not been feasible."

To identify the gene, the team worked with the Arabidopsis weed--a plant widely used in research laboratories and one of the few whose DNA has been so thoroughly studied that scientists know the order, or sequence, of essentially all its component nucleotide compounds, which make up the plant’s genome. Although they have completely sequenced its genome, scientists are just beginning the process of discovering the function of the plant’s 25,000 or so individual genes--the various groups of nucleotides strung end to end along its DNA.



To discover both the gene that is required for pollen development and its specific effect on the plant’s anther cells, the researchers first generated a group of plants with different mutations and identified among them one plant with a mutation that disabled its ability to produce pollen. They then observed how the development of the mutant plant’s pollen-production cells differed from that of a normal plant and they also used genetic techniques to determine specifically which gene was disabled by the mutation. "We deduce what the gene is doing in the normal plant by looking at what the mutant plant is unable to do," Ma explains.

As they studied the development of pollen grains in the mutant plant, the researchers examined the behavior of cells called microsporocytes, which normally undergo a process called meiosis during which they each divide into four daughter calls called microspores that later develop into pollen grains. The scientists found that meiosis in the mutant plant proceeded completely normally until the very last step, when the cells failed to divide and the pollen grains never formed.

"In normal plants, a shell-like structure in the anther of a flower, called the tapetum, provides a kind of nest where the pollen cells form. The microsporocytes fill the interior of this tapetum nest before they divide to form the microspore cells that develop into pollen grains," Ma explains. "But we found that no cells in the developing anther of our mutant plants ever grew into tapetum cells," he says.

To determine for sure whether the cells they observed were tapetum cells or microspore cells, the researchers tested them for the presence of two molecular markers--one that is known to be active only in tapetum cells and the other that is known to be active only in microsporocyte cells. "These molecular tests indicate that our mutant plants have absolutely no tapetum cells and that they have additional microsporocytes where the tapetum cells normally should be," Ma says. Ma and his team have named the gene "Excess Microsporocytes 1" (EMS1), to indicate its effect in the anther of a flower when this gene is not working properly.

The mutation in the research plants was caused by a gene known as a transposon that has the distinctive ability to jump to different locations along the DNA molecule, inserting itself inside one gene or another. Ma and his team cultivated plants that contained this jumping gene and found one plant that did not produce pollen. Then, using standard molecular techniques, they revealed the identity of the jumping gene’s location in that plant--within the gene whose pollen-production function they suspected was being disabled by the presence of the jumping gene. The researchers then allowed the transposon to jump away from the gene, and they found that the plant’s ability to produce pollen was restored to normal, proving that the jumping gene’s former location was within a gene that is essential for pollen production.

The scientists then went on to determine the nature of the protein that the cellular machinery produces from the code contained in the EMS1 gene, and to speculate on its function. They found that the EMS1 protein has three parts--one part that extends outside the surface of the cell membrane, another part that extends into the interior of the cell, and a third part that connects the two and is embedded in the cell membrane. "This protein has the characteristics of a fairly common group of proteins found in plants, known as receptor-kinase proteins, which have a receptor extending outside the cell membrane that binds to certain molecules there," Ma explains. The change produced by this coupling triggers the interior portion of the protein--called a protein kinase--to catalyze reactions between phosphate groups and other proteins inside the cell," Ma says.

"Based on our research and the well-known function of similar proteins in animal cells, we speculate that the EMS1 protein that results from the EMS1 gene we discovered behaves like a protein kinase in the developing anther cells to promote the formation of the tapetum layer that appears to be critically important for the formation of pollen grains," Ma explains. He also speculates that these cells are programmed to become microsporocytes unless the signal from the EMS1 protein tells them to become tapetum cells, and that the formation of microspores requires the presence of the tapetum shell around the microsporocytes, which cannot divide without it. "If our speculations are confirmed, this is the first gene coding for a receptor kinase found to control plant fertility specifically by controlling the development of the anther cells," Ma says.

Ma expects that genes of this type are likely to be found in important crop plants, and that male-sterile plants might possibly be made by inactivating the appropriate gene. "Now that we have identified this gene and its function, plant breeders can disable it with more stable methods that do not involve using genes that can jump around," he says.

One advantage of male-sterile plants is in the production of hybrid varieties of some species that currently are difficult and expensive to produce in quantity. In many crop plants, the male and female organs are packed closely together into the same tiny flower, plus some plants like rice and grains produce only one seed per flower. "For rice, wheat, soybeans, and most other crop plants, it is not economically feasible to produce large quantities of hybrid seeds by removing the tiny anthers," Ma explains. If these plants were male sterile, however, it would not be necessary to remove the anthers in order to control the pollination process.

Another potential use of male-sterile plants is in crops that are valuable mostly for their flowers and not for their seeds or fruits, such as ornamental plants. "If we can limit the production of pollen, and the resulting production of seeds and fruits, we may allow the plant to put all its resources into making more robust or more numerous flowers or perhaps extending the length of the flowering season," Ma says.

Crop plants that are genetically engineered to be male sterile also could be useful in controlling the spread of genes from genetically modified organisms into wild plants. "Male sterility could prevent the spread of a genetically modified plant because, since it would not produce pollen, it could not cross-pollinate any of its wild relatives," Ma explains.

In addition to Ma, other members of the research team include Da-Zhong Zhao, a postdoctoral associate; Guan-Fang Wang, a graduate student; and Brooke Speal, an undergraduate student. This research was supported by the National Science Foundation, the U. S. Department of Agriculture, the National Institutes of Health, and Penn State.

CONTACTS: Hong Ma: phone (+1) 814-863-6414, e-mail hxm16@psu.edu Barbara K. Kennedy (PIO): phone (+1) 814-863-4682, e-mail science@psu.edu

Barbara K. Kennedy | EurekAlert!
Further information:
http://www.science.psu.edu/alert/Ma7-2002.htm

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>