Abstract
BackgroundPlants 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.ResultsTranslational 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.ConclusionOur 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.
Highlights
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
BMC Plant Biology 2008, 8:49 http://www.biomedcentral.com/1471-2229/8/49 mutants deficient in the sucrose non-fermenting 1 (SNF1) serine-threonine protein kinase that is related to the mammalian AMP-activated protein kinase was severely inhibited by NaCl indicating a main function of the kinase in regulating adaptative mechanisms to salt stress [1,2]
Stress-inducible members within the plant family of serine-threonine protein kinases have been identified within the calciumdependent protein kinases (CDPKs), the CDPK-related kinases (CRKs), the calmodulin-dependent protein kinases (CaMKs), and the SNF1-related kinases (SnRK) that are related to SNF1 from yeast
Summary
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. Plants respond to abiotic stresses such as cold, drought, and salinity by activation of complex intracellular signaling cascades that regulate biochemical and physiological acclimation. Protein kinases are key elements involved in signal transduction responsive to metabolism, biotic and abiotic stresses inclusive the major environmental factor salinity. Stress-inducible members within the plant family of serine-threonine protein kinases have been identified within the calciumdependent protein kinases (CDPKs), the CDPK-related kinases (CRKs), the calmodulin-dependent protein kinases (CaMKs), and the SnRKs that are related to SNF1 from yeast. SnRK3 SOS2 interacts with the Ca2+ sensor SOS3 and the plasma membrane Na+/H+ antiporter SOS1 involved in regulation of intracellular Na+ homeostasis is activated via the SOS pathway [15]
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