Plants whose roots had been inoculated with Bacillus subtillis remained healthy when exposed to Pseudomanas syringae bacteria. B subtillis is often added to soil to protect plants in commercial environments.
When attacked by the bacteria a signal travels from the leaves to the roots of the plant and the roots excrete malic acid. The carbon rich malic acid attracts b subtillis.
11:39 a.m., Oct. 17, 2008—-Researchers at the University of Delaware have discovered that when the leaf of a plant is under attack by a pathogen, it can send out an S.O.S. to the roots for help, and the roots will respond by secreting an acid that brings beneficial bacteria to the rescue.
The finding quashes the misperception that plants are “sitting ducks”–at the mercy of passing pathogens–and sheds new light on a sophisticated signaling system inside plants that rivals the nervous system in humans and animals.
The research was led by Harsh Bais, assistant professor of plant and soil sciences at UD, former postdoctoral researcher Thimmaraju Rudrappa, who is now a research scientist at the DuPont Co., Kirk Czymmek, associate professor of biological sciences and director of UD’s Bio-Imaging Center, and Paul Paré, a biochemist at Texas Tech University.
The study is reported in the November issue of Plant Physiology and also is featured on the journal’s cover. Rudrappa is the lead author of the research paper. . . .