Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Purdue researchers find key to rice blast fungus


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:

More articles from Life Sciences:

nachricht ‘Farming’ bacteria to boost growth in the oceans
24.10.2016 | Max-Planck-Institut für marine Mikrobiologie

nachricht Calcium Induces Chronic Lung Infections
24.10.2016 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

All Focus news of the innovation-report >>>



Event News

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

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Oasis of life in the ice-covered central Arctic

24.10.2016 | Earth Sciences

‘Farming’ bacteria to boost growth in the oceans

24.10.2016 | Life Sciences

Light-driven atomic rotations excite magnetic waves

24.10.2016 | Physics and Astronomy

More VideoLinks >>>