title: The SNF1-type serine-threonine protein kinase SAPK4 regulates stress-responsive gene expression in rice.
abstract: BACKGROUND
  Plants respond to extracellularly perceived abiotic stresses such as low temperature, drought, and salinity by activation of complex intracellular signaling cascades that regulate acclimatory biochemical and physiological changes. Protein kinases are major signal transduction factors that have a central role in mediating acclimation to environmental changes in eukaryotic organisms. In this study, we characterized the function of the sucrose nonfermenting 1-related protein kinase2 (SnRK2) SAPK4 in the salt stress response of rice.
  
  
  RESULTS
  Translational fusion of SAPK4 with the green fluorescent protein (GFP) showed subcellular localization in cytoplasm and nucleus. To examine the role of SAPK4 in salt tolerance we generated transgenic rice plants with over-expression of rice SAPK4 under control of the CaMV-35S promoter. Induced expression of SAPK4 resulted in improved germination, growth and development under salt stress both in seedlings and mature plants. In response to salt stress, the SAPK4-overexpressing rice accumulated less Na+ and Cl- and showed improved photosynthesis. SAPK4-regulated genes with functions in ion homeostasis and oxidative stress response were identified: the vacuolar H+-ATPase, the Na+/H+ antiporter NHX1, the Cl- channel OsCLC1 and a catalase.
  
  
  CONCLUSIONS
  Our results show that SAPK4 regulates ion homeostasis and growth and development under salinity and suggest function of SAPK4 as a regulatory factor in plant salt stress acclimation. Identification of signaling elements involved in stress adaptation in plants presents a powerful approach to identify transcriptional activators of adaptive mechanisms to environmental changes that have the potential to improve tolerance in crop plants.
authors.affiliation: Department of Physiology and Biochemistry of Plants, Faculty of Biology, University of Bielefeld, 33615 Bielefeld, Germany. calliste.diedhiou@uni-bielefeld.de
authors.forename: Calliste J
authors.initials: CJ
authors.lastname: Diédhiou
authors.forename: Olga V
authors.initials: OV
authors.lastname: Popova
authors.forename: Karl-Josef
authors.initials: KJ
authors.lastname: Dietz
authors.forename: Dortje
authors.initials: D
authors.lastname: Golldack
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects*; D031751:Festuca / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D017343:Genes, Plant; D018525:Germination / Q000187:drug effects; D048292:Mitogen-Activated Protein Kinase 13 / Q000378:metabolism*; D012275:Oryza / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D030821:Plants, Genetically Modified; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D012965:Sodium Chloride / Q000494:pharmacology*; D013347:Subcellular Fractions / Q000187:drug effects / Q000201:enzymology
chemical_list: D012333:RNA, Messenger; D012965:Sodium Chloride; D048292:Mitogen-Activated Protein Kinase 13; C071570:SNF1-related protein kinases; D017346:Protein Serine-Threonine Kinases