Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Purdue researchers find key to rice blast fungus

01.07.2005


Efforts to halt a fungus that deprives about 60 million people a year of food have led Purdue University scientists to discover the molecular machinery that enables the pathogen to blast its way into rice plants.



The fungus, Magnaporthe grisea, which is known as rice blast fungus, is the most deadly of the pathogens that attack rice, reducing yields by as much as 75 percent in infected areas. Learning how the fungus tricks rice’s natural defenses against pathogens to penetrate the plant is an important part of controlling the disease, said Jin-Rong Xu, a Purdue molecular biologist.

Xu, Xinhua Zhao, Yangseon Kim and Gyungsoon Park, all of Purdue’s Department of Botany and Plant Pathology, found that an enzyme is a key player in coordinating the fungus’ attack. The enzyme, called a pathogenicity mitogen-activated protein (MAP) kinase, flips the switch that starts the cellular communication necessary to launch the fungal invasion that kills rice plants or causes loss of grain.


"We found that this MAP kinase controls the penetration process, which is the beginning of a signal transduction pathway," said Xu, who also was a member of an international research team that published the rice blast fungus genome in the April 21 issue of Nature. This pathway is the communications highway that passes information and instructions from one molecule to another to cause biochemical changes.

The fungus spreads when its spores are blown to rice plants and stick on the leaves. Once on the plant, the spore forms a structure called an appressorium. This bubble-like structure grows until it has so much pressure inside that it blasts through the plant’s surface.

"The penetration structure has enormous force, called turgor pressure, that is 40 times the pressure found in a bicycle tire," Xu said. "It’s like driving nails through the plant surface."

The researchers found that a pathway, which includes three genes that form a cascade of communication events, drives the infection process. Xu and his team reported that when they blocked the genes, the fungus couldn’t develop appressoria and infect the plant.

The pathway holds enormous potential of being used to produce new fungicides or new resistant rice plants to hold this pathogen at bay. However, rice blast fungus is able to quickly evolve new tricks to tackle rice plants, apparently because the fungus and the grain developed side by side over centuries, according to genetic experts. To overcome the fungus’ wiles, researchers need to know more than just the one pathway.

"We want to know how the plant and the fungus talk," Xu said. "We need to know the signal, or ligand, the rice plant gives to the receptor on the fungus that allows the penetration process to proceed. We need to understand the whole communication among all the genes in the rice blast penetration pathway before we can design a rice plant that resists this fungus."

Researchers already have some additional pieces of the puzzle gleaned from sequencing the rice blast genome. They learned that the pathogen has a unique family of proteins that acts as feelers to tell the fungus when it has a good host plant and how the plant might fight a fungal invasion. These feelers are called G-protein-coupled receptors (GPCR). In humans, GPCRs are found on the tongue and in the nose and are part of what makes foods taste different.

The scientists discovered that rice blast fungus has more than 40 GPCRs that probably are regulating the signals at the beginning of the penetration pathway.

"We are working on the basic infection process," Xu said. "We want to know what genetic mechanisms regulate this process, how the fungus spores recognize the plant surface, and how they know to penetrate it."

Once the fungus enters the rice leaf cells, the infected cells attempt to defend the plant by dying. This means death for young plants, while in older plants, rice grain is lost.

The biggest rice blast problem is in Asia and Latin America where rice is an important food staple. About two-thirds of the people in the world rely on the grain, according to the United States Department of Agriculture (USDA) Agricultural Research Service. Rice supplies 23 percent of the total calories that the world’s population consumes, according to the International Rice Research Institute.

In addition to the countries that rely on rice for food, the pathogen also is found in the United States, especially in Arkansas, Louisiana and California, where rice blast recently evolved in order to foil a rice blast resistance gene, according to the USDA. Resistance in rice plants varies in different regions due to climate variation and in strains of the pathogen.

Xu said that an important area of his future research will be to learn the interaction among several signaling pathways in rice blast fungus that allows the pathogen to communicate with the plant.

Grants from the USDA Agriculture National Research Initiative and the National Science Foundation supported this study, which was published in the May issue of Plant Cell.

Susan A. Steeves | EurekAlert!
Further information:
http://www.purdue.edu

More articles from Life Sciences:

nachricht A novel socio-ecological approach helps identifying suitable wolf habitats
17.02.2017 | Universität Zürich

nachricht New, ultra-flexible probes form reliable, scar-free integration with the brain
16.02.2017 | University of Texas at Austin

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>