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Paris, April 21, 2005

Analysis of the genome of the rice pathogenic fungus

Magnaporthe grisea is the fungus responsible for the main disease that affects rice, rice blast. It causes devastating and recurring epidemics and leads to economic and humanitarian problems in all rice-growing regions. CNRS and Bayer researchers are working on this microorganism in cooperation with American, English and Korean laboratories. In an article published on April 21 in Nature, the researchers analyzed the genome of Magnaporthe grisea, the first fungus that is pathogenic to plants to be fully sequenced. This study brings a better understanding of the processes involved in the interactions between this microorganism and its host plant. These results should allow for the development of new methods to fight it.

Fungi are responsible for the main plant diseases. Fungi alone contaminate and kill a large share of animal and human food supplies. In a field of rice affected by Magnaporthe grisea 50% of its production may be destroyed. The methods currently used to fight it are not totally efficient. Furthermore, despite the progress made over the past ten years, the identification of the functions involved in the infection process or in the recognition of the fungus by the plants remains limited. Only a few molecular mechanisms are known. The sequencing and decoding of the Magnaporthe grisea genome should now accelerate the pace of discoveries in this area.

 

 

 

magnaporthe

Field of rice in the Camargue attacked by the Magnaporthe grisea fungus.

 

 

The entirely sequenced Magnaporthe grisea genome will facilitate the systematic analysis of its genes and its proteins by a growing number of laboratories. This biological system should become a model for the study of plant-fungus pathogenic interactions and lead to significant progress in the understanding of its infectious processes.

 

By comparing Magnaporthe grisea with other model fungi such as brewer's yeast (Saccharomyces cerevisae), the project researchers revealed the complexity and originality of its genome. The research team of the mixed CNRS-Bayer Cropscience Laboratory in Lyons focused its research on a comparison of the Magnaporthe grisea genome with that of the related fungus Neurospora crassa(1). This analysis revealed specific gene evolutions and functions of Magnaporthe grisea: the genome has an amplification of gene families involved in the biosynthesis of secondary metabolites (toxins, antibiotics, signals). The other project teams also found amplifications of gene families encoding secreted proteins or membrane proteins involved in the recognition of external signals. Some of these genes are specifically expressed in cells specialized in the penetration of the fungus into the host plant, which suggests their involvement in the infection. The sequencing of the Magnaporthe grisea genome also allowed for the construction of ADN chips that are representative of the 11,109 genes of this organism. The first results obtained with this type of tool show that this fungus has relatively complex regulation networks that allow it to express sets of particular genes at different stages in the infection process.

 

These first genomic analyses of a fungus that is pathogenic to plants are very encouraging. They should bring new understanding of these microorganisms and the diseases that they cause and thus lead to the development of new methods to fight against them.

 

Notes:

(1) This fungus is not pathogenic to plants and lives in the soil.

References:

“The genome sequence of the rice blast fungus Magnaporthe grisea” by Ralph A. Dean, Nicholas J. Talbot, Daniel J. Ebbole, Mark L. Farman, Thomas K. Mitchell, Marc J. Orbach, Michael Thon, Resham Kulkarni, Jin-Rong Xu, Huaqin Pan, Nick D. Read, Yong-Hwan Lee, Ignazio Carbone, Doug Brown, Yeon Yee Oh,Nicole Donofrio, Jun Seop Jeong, Darren M. Soanes, Slavica Djonovic, Elena Kolomiets, Cathryn Rehmeyer, Weixi Li, Michael Harding, Soonok Kim, Marc-Henri Lebrun, Heidi Bohnert, Sean Coughlan, Jonathan Butler, Sarah Calvo, Li-Jun Ma, Robert Nicol, Seth Purcell, Chad Nusbaum, James E. Galagan & Bruce W. Birren
Nature, April 21, 2005

Contact information:

Researcher Contact:
Marc-Henri Lebrun
Bayer Cropscience Laboratory
Telephone: 04 72 85 24 81 - E-mail: marc-henri.lebrun@bayercropscience.com

Press Contact:
Géraldine Véron
Telephone: 01 44 96 46 06 - E-mail: geraldine.veron@cnrs-dir.fr

Life Sciences Department Contact:
Jean-Pierre Ternaux
Telephone: 01 44 96 43 90 - E-mail: jean-pierre.ternaux@cnrs-dir.fr

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