CHAPEL HILL -- Plants respond to infections by activating one or more genetic "master switches" that in turn simultaneously control scores of genes that protect the plants against disease, scientists at the University of North Carolina at Chapel Hill and Syngenta of Research Triangle Park, N.C., have discovered. Until recently, Syngenta was called Novartis Agribusiness Research Inc.
"Because their core sets of genes are so similar, a genetic 'footprint' like the one we found could be a binding site for a universal switch for the immune system among many plant species," said Dr. Jeffery L. Dangl, John N. Couch associate professor of biology at UNC-CH. "This discovery, on this scale, is a first for plant biology."
Working with Arabidopsis, a member of the mustard family widely considered the "laboratory mouse" of the plant kingdom, the scientists analyzed expression of about 8,000 plant genes and tested them under 14 different conditions that either turned on or turned off the plant's immune system. New genomics technology enabled them for the first time to simultaneously test the large group of genes, which are a third of the total number of genes in Arabidopsis.
"We found a small group of about 30 genes that all behaved the same way under the different treatments we subjected them to," Dangl said. "That meant that they were responding to something in common. We found that each gene in this group has one short sequence of DNA, in essence a footprint, in a position called the promoter, which controls when the genes are turned on and off. "
A report on the discovery appears in the Dec. 1 issue of Nature Genetics, a major scientific journal. Besides Dangl, other UNC-CH authors are former undergraduate Aaron Levine and postdoctoral fellow Dr. Thomas Eulgem. Syngenta authors are Drs. Klaus Maleck, Allen Morgan, Jurg Schmid, Kay Lawton and Robert A. Dietrich, a former postdoctoral fellow at UNC-CH.