Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Models show gene flow from crops threatens wild plants

23.07.2003


In a river valley just southwest of Mexico City stands a small patch of teosinte - a wild, weedy grass thought to be the ancient ancestor of corn. As a gentle breeze blows gene-carrying pollen from a nearby crop of maize to its wild relative, the genetic integrity and even survival of this ancient plant and others could be jeopardized, according to new mathematical models.

The models, described in the July 23 online edition of the Proceedings of the Royal Society of London and developed by scientists at the University of Wisconsin-Madison and the University of Minnesota-St. Paul, show that genes from crops rapidly can take over those in related wild plants. The end result, say the researchers, could be major changes in the genetic make-up of wild plants, decreases in their population size and the permanent loss of natural traits that could improve crop health.

Although gene flow from crops to wild relatives has occurred ever since humans started farming, few studies before the 1980s examined the effects of this evolutionary process in a scientific manner. Most of the people concerned up until then were farmers, not researchers, says Ralph Haygood, a UW-Madison postdoctoral fellow and lead author of the paper.



But, as genetic engineering developed and emerged as both a biological and political issue, gene flow from crops containing transgenes - genetic information from other species that’s artificially inserted - to wild plants gained more scientific attention.

"Most of the concern about crop-wild gene flow," says Haygood, "is driven by concern about transgene escape," the idea that these artificially inserted genes in a crop plant can leak into the genomes of wild relatives. According to Haygood, growers around the world have planted 145 million acres of transgenic crops.

Conserving the genetic integrity of wild plants, explains Haygood, is important for two reasons: protecting the survival of the plants themselves and maintaining their repository of advantageous traits. These traits, he adds, can be used to improve crop health: "The fact is that most genes for crop improvement have come from wild relatives of those same crops."

To begin to understand the effects of gene flow from crop to wild plant populations, Haygood and his colleagues Anthony Ives from UW-Madison and David Andow from UM-St. Paul, developed mathematical models based on fundamental principles of population genetics.

"The key to the models," says Ives, "is that they summarize fundamental properties of evolutionary change. They show what is likely to happen."

Specifically, the models examine how rates of pollen flow and how the selective effects of crop genes on wild plants alter two evolutionary processes: genetic assimilation, wherein crop genes replace genes in wild populations, and demographic swamping, wherein wild populations shrink in size because crop-wild hybrids are less fertile.

"Genetic assimilation and demographic swamping could change a wild plant in some way that might be important for its survival in some habitats or for other organisms that depend on them for their survival," says Haygood. "The potential ramifications are huge and diverse."

The research team starts with a simple model, where a wild population of large and constant size receives pollen from a crop that differs genetically by only one gene. They then add complexity, or, as Ives says, "more realism." That is, they consider a crop that is more different genetically and a wild population that is small or varies in size.

The researchers are quick to point out that the models do not distinguish between crops developed through traditional breeding and genetic engineering. "How the genes get in the crops doesn’t matter," explains Haygood. "What’s important is what they do once they’re there."

In both the basic and expanded models, the researchers find that crop genes rapidly can take over wild populations and, sometimes, just a small increase in the rate of pollen flow can make a big difference in the spread of a crop gene. When this happens, says, Ives, "There’s no going back. It’s irreversible."

The findings, explains Haygood, show that few conditions are needed to enable genetic assimilation and demographic swamping. "You don’t need high rates of pollen flow or strongly favored traits," he says. "Crop genes, even fairly deleterious ones, can easily become common in wild populations within 10 to 20 generations."

At the same time, the combined forces of these two processes on the wild populations can change their genetic make-up in unfavorable ways and drastically shrink their population size, leading to what evolutionary biologists call a "migrational meltdown."

Although the models look at gene flow from a crop plant to a wild relative, the researchers say that the models probably also could apply to gene flow from a commercial to a landrace crop raised each season from the previous year’s seed. But they add that more investigation is needed.

The goal of the gene flow models, explain the researchers, is to provide qualitative insight that they hope will enhance the public dialogue on gene flow from crop to wild plants.

"Gene flow from crops to wild relatives is one of a host of environmental issues that humans must deal with," says Haygood. "These models are a resource that can contribute to the discussion."

Contact:

Emily Carlson +1-608-262-9772, emilycarlson@wisc.edu
Ralph Haygood, +1-608-262-9226, rhaygood@wisc.edu
Tony Ives, +1-608-262-1519, arives@wisc.edu

Ralph Haygood | EurekAlert!
Further information:
http://www.wisc.edu

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 >>>