WEST LAFAYETTE, Ind. - Purdue University and USDA-Agricultural Research Service scientists have discovered that a type of gene in grain-producing plants halts infection by a disease-causing fungus that can destroy crops vital for human food supplies.
The research team is the first to show that the same biochemical process protects an entire plant family - grasses - from the devastating, fungal pathogen. The naturally occurring disease resistance probably is responsible for the survival of grains and other grasses over the past 60 million years.
The findings will stimulate the design of new resistance strategies against additional diseases in grasses and other plants. Grasses' ability to ward off pathogens is a major concern because grasses, including corn, barley, rice, oats and sorghum, provide most of the calories people consume, and some species also increasingly are investigated for conversion into energy.
A resistance gene, first discovered in corn, and the fungal toxin-fighting enzyme it produces apparently provide a biological mechanism that guards all grass species from this fungus, said Guri Johal, a Purdue associate professor of botany and plant pathology. He is senior and corresponding author of the study published this week (Jan. 28-Feb. 1) in Early Edition, the online version of the Proceedings of the National Academy of Sciences. It will appear in the Feb. 5 print edition.
"We think that if the gene Hm1 had not evolved, then grasses would have had a hard time surviving, thriving or, at least, the geographic distribution would have been restricted," Johal said. "This plant resistance gene is durable and is indispensible against this fungal group, which has the ability to destroy any part of the plant at any stage of development."
In 1943 a related fungus decimated rice crops in Bengal, causing a catastrophic famine in which 5 million people starved. The same fungal group was responsible for the other
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