Prof. Pamela Ronald, a Professor in Plant Pathology at University of California, Davis and director of Grass Genetics at the Joint Bioenergy Institute, studies genes that control the plant response to stress.
In her presentation for the Frontiers in Life Sciences symposium at Cornell University, Ronald described the isolation of a novel bacterial signal that is key to bacterial communication. In a process called quorum sensing, bacteria use this molecule, called Ax21, to communicate with each other, essentially transforming these single celled organisms into a coordinated team of fierce invaders. Remarkably, the rice XA21 receptor can detect these small molecules. That detection triggers a robust defense response. As she said, “Bacteria talk, plants listen.”
In 1995, the Ronald Laboratory isolated and characterized the XA21 immune receptor (Song et al. Science 1995; Lee et al., Science 2009). Subsequent discoveries in flies (Lemaitre et al., 1996), humans (Medzhitov, et al. 1997), mice (Poltorak et al, 1998), and Arabidopsis (Gomez-Gomez, 2000) revealed that animals and other plant species also carry membrane-anchored receptors with striking structural similarities to XA21 and that these receptors also play key roles recognition of microbial signatures and host defense (Ronald and Beutler, Science 2010). The importance of this work is reflected in the 2011 Nobel Prize in Physiology or Medicine to Beutler and Hoffman, who discovered the animal receptors.