Biotech Updates

Researchers Identify Xanthomonas Signaling Molecule

November 6, 2009

In 1995, Pamela Ronals and colleagues at the University of California, Davis showed that that the rice Xa21 resistance gene confer immunity to diverse strains of the Gram-negative bacterium Xanthomonas oryzae pv. oryzae , the causal agent of the rice bacterial blight disease. Now Ronald and her team identified the bacterial signaling molecule that binds to the receptor, triggering a defense response against the bacterial disease. "The new discovery of this bacterial signaling molecule helps us better understand how the innate immune system operates," Ronald said in the paper published in this week's edition of Science.

The signaling peptide, ax21, is also found in many other species of Xanthomonas as well as in Xylella fastidiosa, a microbe that causes the devastating Pierce's disease in grapes, according to the researchers. The peptide is also produced by a bacterium that causes urinary tract infection in humans."We are hopeful that these discoveries will benefit agriculture and medicine in the United States and around the world by leading to development of treatments that will disrupt bacterial infection," she said.

The paper published by Science is available at For more information, read