title: Elucidation of XA21-mediated innate immunity.
abstract: In the early 1970s, the Xa21 gene from the wild rice species Oryza longistaminata drew attention of rice breeders because of its broad-spectrum resistance to diverse strains of a serious bacterial disease of rice in Asia and Africa, called 'bacterial blight disease', caused by the Gram-negative bacterium, Xanthomonas oryzae pv. oryzae (Xoo). In 1995, we isolated the gene controlling this resistance and in 2009 demonstrated that XA21 recognizes a highly conserved peptide, called 'Ax21' (activator of XA21-mediated immunity). Tyrosine sulfation of Ax21 is required for recognition by rice XA21. A decade of genetic, molecular and biochemical studies have uncovered key components of the XA21-mediated signalling cascade. Ax21 recognition by XA21 at the cell surface induces phosphorylation-mediated events, which are predicted to alter subcellular localization and/or DNA-binding activity of a WRKY family of transcription factors. Because XA21 is representative of the large number of predicted pattern recognition receptors (PRRs) in rice (n = 328), Arabidopsis (n = 35) and other plant species, further characterization of XA21-mediated signalling pathways will contribute to elucidation of these important defence responses.
authors.affiliation: Department of Plant Pathology, University of California Davis, Davis, CA 95616, USA.
authors.forename: Chang-Jin
authors.initials: CJ
authors.lastname: Park
authors.forename: Sang-Wook
authors.initials: SW
authors.lastname: Han
authors.forename: Xuewei
authors.initials: X
authors.lastname: Chen
authors.forename: Pamela C
authors.initials: PC
authors.lastname: Ronald
mesh_terms: D018506:Gene Expression Regulation, Plant; D007113:Immunity, Innate; D008954:Models, Biological; D012275:Oryza / Q000235:genetics / Q000276:immunology*; D010766:Phosphorylation; D010935:Plant Diseases / Q000276:immunology*; D010940:Plant Proteins / Q000235:genetics / Q000276:immunology*; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000276:immunology*; D015398:Signal Transduction
chemical_list: D010940:Plant Proteins; C097148:Xa21 protein, Oryza sativa; D017346:Protein Serine-Threonine Kinases