( In a genomics milestone an internation...)Researchers uncover sequence of major rice pathogen

Dr. Ralph Dean, professor of plant pathology and director of North Carolina State University's Center for Integrated Fungal Research, is the lead author of a research paper that describes the M. grisea genome, published in the April 21 issue of the journal Nature.

It is estimated that rice blast, the leading cause of rice loss, is responsible each year for killing enough rice to feed 60 million people worldwide.

In the Nature paper, Dean and his co-authors shed some light on the adaptations required by a fungus to cause disease. The researchers identify novel receptors that allow the fungus to recognize its environment; secreted proteins that are likely used as offensive weapons to damage rice plants; and redundant, or duplicate, mechanisms that protect the fungus from efforts to fight against it.

"It's a clever system," Dean says. "If you have important genes, you tend to have a lot of them."

The paper also reports that the M. grisea genome contains retro-elements, or remnants of viruses, living in what Dean calls "hot spots" in the genome.

"These virus remnants live in discreet parts of the genome and have high rates of recombination, which may be why the fungus can evolve new strains so quickly," Dean says.

M. grisea undoubtedly produces toxins which may enable it to be a more effective pathogen. However our knowledge is limited to date, Dean says. The genome sequence should give researchers "a better idea of what types of genes are involved in making the toxin molecules," he says.

Some of these genes reside in clusters, Dean says, so one focus will be to take apart the clusters and learn more about toxins and their produ
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Source:North Carolina State University