Submitted to: The Plant Cell
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2008
Publication Date: 2/8/2008
Citation: Wan, J., Zhang, X., Neece, D.J., Ramonell, K.M., Clough, S.J., Kim, S., Stackey, M.G., Stacey, G. 2008. A LysM receptor-like kinase plays a critical role in chitin signaling and fungal resistance in Arabidopsis. The Plant Cell. 20(2):471-481. Interpretive Summary: Plants are attacked by many fungal pathogens and have developed means to recognize fungal-specific molecules and trigger defensive responses to these foreign invaders. In this manuscript, we identified a receptor in plant leaves that allows the plant to recognize chitin, a molecule that is foreign to plants, but common to fungal pathogens. Mutants that contain an inactivating insertion into this receptor gene caused the plants to no longer recognize chitin. That these chitin-receptor mutants can still recognize specific signals from other pathogens, such as bacterial produced flagellin, shows that the chitin receptor is fairly specific to chitin. This information is important as it provides another piece of the sensory network of plants and how they perceive pathogens. This work can now be used to identify similar receptors in crop plants. If present in crop plants, breeders and molecular biologists may be able to enhance resistance to pathogens.
Technical Abstract: Chitin, a polymer of N-acetyl-D-glucosamine, is found in fungal cell walls, but not in plants. Plant cells are capable of perceiving chitin fragments (chitooligosaccharides) to trigger plant defense. We identified a LysM receptor-like protein (AtLysM RLK1) that is required for the perception of chitooligosaccharides in Arabidopsis. Mutation of this gene blocked the induction of almost all chitooligosaccharide-responsive genes (CRGs) and led to more susceptibility to fungal pathogens; however, susceptibility to a bacterial pathogen was not affected by the mutation. In addition, exogenously applied chitooligosaccharides enhanced resistance against both fungal and bacterial pathogens in the wild-type plants, but not in the mutant. Together, our data strongly suggest AtLysM RLK1 is the chitin receptor to mediate plant defense against fungal pathogens. Therefore, LysM RLKs not only recognize symbiotic rhizobia but also fungal pathogens, and a possible evolutionary relationship may be existent between the perception mechanisms of Nod signals and chitin by plants.