title: The XA21 binding protein XB25 is required for maintaining XA21-mediated disease resistance.
abstract: Plant genomes encode a large number of proteins that potentially function as immune receptors in the defense against pathogen invasion. As a well-characterized receptor kinase consisting of 23 tandem leucine-rich repeats, a transmembrane domain and a serine/threonine kinase, the rice (Oryza sativa) protein XA21 confers resistance to a broad spectrum of Xanthomonas oryzae pv. oryzae (Xoo) races that cause bacterial blight disease. We report here that XA21 binding protein 25 (XB25) belongs to the plant-specific ankyrin-repeat (PANK) family. XB25 physically interacts, in vitro, with the transmembrane domain of XA21 through its N-terminal binding to transmembrane and positively charged domain (BTMP) repeats. In addition, XB25 associates with XA21 in planta. The downregulation of Xb25 results in reduced levels of XA21 and compromised XA21-mediated disease resistance at the adult stage. Moreover, the accumulation of XB25 is induced by Xoo infection. Taken together, these results indicate that XB25 is required for maintaining XA21-mediated disease resistance.
authors.affiliation: Department of Plant Pathology, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Yingnan
authors.initials: Y
authors.lastname: Jiang
authors.forename: Xiuhua
authors.initials: X
authors.lastname: Chen
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Ding
authors.forename: Yongsheng
authors.initials: Y
authors.lastname: Wang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Chen
authors.forename: Wen-Yuan
authors.initials: WY
authors.lastname: Song
mesh_terms: D000595:Amino Acid Sequence; D017089:Ankyrin Repeat; D060467:Disease Resistance; D015536:Down-Regulation; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics* / Q000276:immunology / Q000502:physiology; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D018515:Plant Leaves / Q000235:genetics / Q000276:immunology / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013045:Species Specificity; D020798:Two-Hybrid System Techniques; D014974:Xanthomonas / Q000502:physiology*
chemical_list: D010940:Plant Proteins; C097148:Xa21 protein, Oryza sativa; D017346:Protein Serine-Threonine Kinases