title: IBR5 Modulates Temperature-Dependent, R Protein CHS3-Mediated Defense Responses in Arabidopsis.
abstract: Plant responses to low temperature are tightly associated with defense responses. We previously characterized the chilling-sensitive mutant chs3-1 resulting from the activation of the Toll and interleukin 1 receptor-nucleotide binding-leucine-rich repeat (TIR-NB-LRR)-type resistance (R) protein harboring a C-terminal LIM (Lin-11, Isl-1 and Mec-3 domains) domain. Here we report the identification of a suppressor of chs3, ibr5-7 (indole-3-butyric acid response 5), which largely suppresses chilling-activated defense responses. IBR5 encodes a putative dual-specificity protein phosphatase. The accumulation of CHS3 protein at chilling temperatures is inhibited by the IBR5 mutation. Moreover, chs3-conferred defense phenotypes were synergistically suppressed by mutations in HSP90 and IBR5. Further analysis showed that IBR5, with holdase activity, physically associates with CHS3, HSP90 and SGT1b (Suppressor of the G2 allele of skp1) to form a complex that protects CHS3. In addition to the positive role of IBR5 in regulating CHS3, IBR5 is also involved in defense responses mediated by R genes, including SNC1 (Suppressor of npr1-1, Constitutive 1), RPS4 (Resistance to P. syringae 4) and RPM1 (Resistance to Pseudomonas syringae pv. maculicola 1). Thus, the results of the present study reveal a role for IBR5 in the regulation of multiple R protein-mediated defense responses.
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, National Plant Gene Research Center, China Agricultural University, Beijing, China.
authors.forename: Jingyan
authors.initials: J
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, National Plant Gene Research Center, China Agricultural University, Beijing, China.
authors.forename: Haibian
authors.initials: H
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, National Plant Gene Research Center, China Agricultural University, Beijing, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Bao
authors.affiliation: Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Kevin
authors.initials: K
authors.lastname: Ao
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, National Plant Gene Research Center, China Agricultural University, Beijing, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Yuelin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Shuhua
authors.initials: S
authors.lastname: Yang
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics; D002687:Chitin Synthase / Q000235:genetics*; D003080:Cold Temperature; D060467:Disease Resistance / Q000235:genetics*; D054637:Dual-Specificity Phosphatases / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics; D009154:Mutation; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; D018841:HSP90 Heat-Shock Proteins; C466978:Hsp90-1 protein, Arabidopsis; D010940:Plant Proteins; C095014:RPM1 protein, Arabidopsis; C452192:SGT1b protein, Arabidopsis; C097421:rps4 protein, plant; C000607112:CHS3 protein, Arabidopsis; D002687:Chitin Synthase; D054637:Dual-Specificity Phosphatases; C483728:IBR5 protein, Arabidopsis