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Posted 13 August 2004. PMN Crop News.

Newly Explored Rice Gene Could Help "Blast" Killer Fungus

Agricultural Research Service, United States Department of Agriculture.

Washington, D.C. (August 12, 2004) - Rice plants could soon be getting their own version of "caller ID." Agricultural Research Service scientists are providing plants of this important world crop with the genetic tools needed to recognize and identify incoming attacks from the damaging pathogen known as rice blast. The fungus, Magnaporthe grisea, causes rice yield losses of up 30 percent each year worldwide.

Two-thirds of the global population relies on rice. And while many
farmers around the world are growing record amounts of the staple
grain--thanks to new rice varieties and advances in nutrient and pest
management--they can't compete with the blast fungus' will to survive.

According to ARS chemist Sally Leong, blast is so adaptable that it can
defeat a rice cultivar, specially bred to resist the fungus, after just
one growing season. Leong works at the agency's Cereal Crops Research
Unit in Madison, Wis.

Trying to escape the tug-of-war scenario that rice breeders find
themselves in when searching for new, blast-resistant plants every one
to three years, Leong is working to arm important rice varieties with
more certain, long-lasting genetic advantages.

She's been studying two key genes--one from a resistant rice cultivar
and one from the M. grisea pathogen--to understand precisely how hardy
rice plants defend themselves when confronted with infectious spores of
the blast fungus. Early recognition of the fungal perpetrator is key to
successful plant protection.

Having evolved alongside each other in many parts of the world, rice and its blast pathogen possess genes with a unique history. As such, a rice
plant will launch a strong defense response against M. grisea if its
resistance gene matches a related, counter-resistance gene in the

Leong is developing rice plants with the resistance gene. She and
colleagues are also researching how to optimally apply the M. grisea
gene to already-resistant rice plants to achieve even greater blast-readiness in rice.


Erin Peabody

Agricultural Research Service, USDA
(301) 504-1624