Plant protein 'doorkeepers' block invading microbes, s...( A group of plant proteins that shut...)

A group of plant proteins that "shut the door" on bacteria that would otherwise infect the plant's leaves has been identified for the first time by a team of researchers in Denmark, at the University of California, Davis, and at UC Berkeley.

Findings from the study, which will appear June 29 in the online journal Public Library of Science Biology, provide a better understanding of plants' immune systems and will likely find application in better protecting agricultural crops and horticultural plants against diseases.

"The ability of a plant's immune system to recognize disease-causing microorganisms is critical to the plant's survival and productivity," said Gitta Coaker, a UC Davis plant pathologist and lead author on the study.

"In this study, we identified a complex of proteins in the common research plant Arabidopsis that appear to play important roles in the biochemical mechanisms that enable plants to recognize and block out invading bacteria," Coaker said.

She noted that, over the last 20 years, scientists have identified a number of proteins that are important for regulating the plant immune system but still do not have a good sense of what protein complexes these proteins belong to and how they signal to confer disease resistance.

"Our ability to purify an immune protein complex will serve as a starting point to understand how these proteins signal in the plant," Coaker said. "A greater understanding of how these proteins function is fundamental knowledge that can be applied to prevent plant disease."

Plants are continually exposed to bacteria, viruses and other microorganisms, many of which have the ability to infect the plant and cause disease.

Animals have what are known as innate, or preformed, immune systems as well as adaptive immune systems that learn to recognize and defend against disease-causing microbes. Plants, however, only have innate
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