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 Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery
20.01.2017 | GSI Helmholtzzentrum für Schwerionenforschung GmbH

nachricht Seeking structure with metagenome sequences
20.01.2017 | DOE/Joint Genome Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>