Diédhiou Calliste J, Popova Olga V, Dietz Karl-Josef, Golldack Dortje
Department of Physiology and Biochemistry of Plants, Faculty of Biology, University of Bielefeld, 33615 Bielefeld, Germany.
BMC Plant Biol. 2008 Apr 28;8:49. doi: 10.1186/1471-2229-8-49.
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.
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.
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.
植物通过激活复杂的细胞内信号级联反应来应对细胞外感知到的非生物胁迫，如低温、干旱和盐度，这些信号级联反应调节适应性生化和生理变化。蛋白激酶是主要的信号转导因子，在介导真核生物对环境变化的适应中起核心作用。在本研究中，我们对水稻蔗糖非发酵1相关蛋白激酶2（SnRK2）SAPK4在盐胁迫响应中的功能进行了表征。
SAPK4与绿色荧光蛋白（GFP）的翻译融合显示其亚细胞定位在细胞质和细胞核中。为了研究SAPK4在耐盐性中的作用，我们构建了在CaMV-35S启动子控制下过表达水稻SAPK4的转基因水稻植株。SAPK4的诱导表达导致幼苗和成熟植株在盐胁迫下的萌发、生长和发育得到改善。响应盐胁迫，过表达SAPK4的水稻积累较少的Na+和Cl-，并表现出光合作用改善。鉴定出了具有离子稳态和氧化应激反应功能的SAPK4调控基因：液泡H+-ATP酶、Na+/H+反向转运蛋白NHX1、Cl-通道OsCLC1和一种过氧化氢酶。
我们的结果表明，SAPK4在盐胁迫下调节离子稳态以及生长和发育，并表明SAPK4作为植物盐胁迫适应中的调节因子发挥作用。鉴定植物中参与胁迫适应的信号元件是一种强有力的方法，可用于识别对环境变化的适应性机制的转录激活因子，这些因子有可能提高作物的耐受性。
