Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Genetic defenders protect crops from fungal disease

18.11.2005


Like waves of soldiers guarding a castle gate, multiple genetic defenders cooperate to protect plant cells against powdery mildew disease, according to a new study. Powdery mildew is a common fungal infection in plants that attacks more than 9,000 species, including many crops such as barley and wheat, and horticultural plants such as roses and cucumbers. The researchers, including Shauna Somerville and Mónica Stein of the Carnegie Institution’s Department of Plant Biology, are the first to document how these defense genes team up in plants. The discovery could help combat fungal parasites that devastate crops and cost growers billions of dollars in pesticides every year.


Arabidopsis plants inoculated with Erysiphe pisi fungal spores are shown here. From left to right, plants with no mutations (WT), a disabled PEN2 gene, disabled PAD4 and SAG101 genes, and all three disabled genes together are increasingly vulnerable to the fungus. This last variant is the most susceptible to infection; it allowed E pisi to proliferate as well as it does on pea plants, its normal host. (Images printed with permission from the American Association for the Advancement of Science, Science, November 18, 2005, issue.)



The study, published in the November 18 issue of the journal Science, describes powdery mildew infection in the mustard relative Arabidopsis thaliana. Each species of mildew is host-specific, meaning it can infect some plant species, but not others. By disabling protective genes in Arabidopsis, the researchers were able to infect the plants with species of powdery mildew that normally attack peas or barley, revealing much about how plants use genes to fight infection.

"Most plants are resistant to the majority of pathogens they encounter, but the basis for this resistance was unknown," Somerville said. "Identifying these genes has provided us with the first insight into how plants defend against multiple pathogens."


Once a powdery mildew infection takes hold, it covers the plant with fuzzy splotches, while sapping precious nutrients. At the cellular level, the fungal spores invade healthy plant cells and form root-like feeding structures called haustoria. The plant cell wall is the primary barrier to this invasion and one of the defense genes described in the current study, called PEN2, prevents the fungus from penetrating cell walls in the first place.

If this first line of defense breaks down, as it does in about 5 to 25 percent of normal Arabidopsis plants (depending on the mildew species), a second set of genes jumps into the fray. These genes, called EDS1, PAD4, and SAG101, work together in a complex inside the cell, and can signal infected cells to die. By sacrificing these fallen cells, the defense genes can spare healthy ones from infection.

Somerville, Stein, and colleagues at the Max Planck Institute for Plant Breeding in Köln disabled the protective genes in Arabidopsis by introducing mutations, one at a time and in various combinations. They infected these mutants with one of two species of powdery mildew: Blumeria graminis hordei, a species that attacks barley, and Erysiphe pisi, one that thrives on the leaves and pods of pea plants.

"Disabling just three genes allowed the pea powdery mildew to reproduce as well on Arabidopsis as it does on its normal host," Somerville remarked. "Thus, the resistance barriers limiting the growth of inappropriate pathogens are much less complex than expected, relying on just a limited number of genes."

The EDS1, PAD4, and SAG101 gene complex’s ability to signal cell death is relatively well known to scientists. However, very little is known about how PEN2 behaves in the cell. The current study demonstrates that the PEN2 protein is a catabolic enzyme--a protein that breaks down other molecules--though its specific target remains unknown.

The study expands on the researchers’ previous work with a gene called PEN1. As its name suggests, PEN1 and PEN2 seem to share a common purpose. However, they seem to act via different mechanisms, and PEN2 protects against a wider range of fungal pathogens. For example, Arabidopsis plants with a disabled PEN2 gene are also more susceptible to Phytopthora infestans, the fungus responsible for the notorious Irish Potato Famine of the mid-19th century.

"The resistance mechanisms operating at the cell wall seem to be surprisingly simple," Somerville said. "This suggests it might be possible to reverse engineer crops like wheat with Arabidopsis PEN genes to help control powdery mildew and other destructive diseases, thus minimizing the need for pesticides."

Dr. Shauna Somerville | EurekAlert!
Further information:
http://www.carnegieinstitution.org
http://www.stanford.edu

More articles from Life Sciences:

nachricht Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory

nachricht Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>