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 Flow of cerebrospinal fluid regulates neural stem cell division
22.05.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Chemists at FAU successfully demonstrate imine hydrogenation with inexpensive main group metal
22.05.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

Im Focus: Light-induced superconductivity under high pressure

A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.

Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

Keeping a Close Eye on Ice Loss

18.05.2018 | Information Technology

CrowdWater: An App for Flood Research

18.05.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>