Protein phosphorylation, especially serine/threonine and tyrosine phosphorylation, plays significant roles in signalling during plant growth and development as well as plant responses to biotic or abiotic stresses. Dual‐specificity protein tyrosine phosphatases dephosphorylate components of these signalling pathways. Here, we report that an atypical dual‐specificity protein tyrosine phosphatase, AtPFA‐DSP3 (DSP3), negatively affects the response of plants to high‐salt conditions. A DSP3 loss‐of‐function mutant showed reduced sensitivity to salt treatment. DSP3 was primarily localized in nuclei and was degraded during salt treatment. Compared to wild type, the level of ROS was lower in the dsp3 mutant and higher in plants ectopically expressing DSP3, indicating that higher DSP3 level was associated with increased ROS production. DSP3 interacted with and dephosphorylated MPK3 and MPK6. Genetic analyses of a dsp3mpk3 double mutant revealed that DSP3's effect on salt stress depends on MPK3. Moreover, the phosphatase activity of DSP3 was required for its role in salt signalling. These results indicate that DSP3 is a negative regulator of salt responses in Arabidopsis by directly modulating the accumulation of phosphorylated MPK3 and MPK6.

中文翻译：

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AtPFA-DSP3，一种非典型的双特异性蛋白酪氨酸磷酸酶，通过调节 MPK3 和 MPK6 活性影响盐胁迫反应

蛋白质磷酸化，尤其是丝氨酸/苏氨酸和酪氨酸磷酸化，在植物生长和发育过程中的信号传导以及植物对生物或非生物胁迫的反应中起着重要作用。双特异性蛋白酪氨酸磷酸酶使这些信号通路的组分去磷酸化。在这里，我们报告了一种非典型的双特异性蛋白酪氨酸磷酸酶 AtPFA-DSP3（DSP3）对植物对高盐条件的反应产生负面影响。DSP3 功能丧失突变体对盐处理的敏感性降低。DSP3 主要位于细胞核中，并在盐处理过程中降解。与野生型相比，dsp3突变体的 ROS 水平较低，异位表达DSP3 的植物中的 ROS 水平较高，表明较高的 DSP3 水平与增加的 ROS 产生相关。DSP3 与 MPK3 和 MPK6 相互作用并使其去磷酸化。dsp3mpk3双突变体的遗传分析表明 DSP3 对盐胁迫的影响取决于 MPK3。此外，DSP3 的磷酸酶活性是其在盐信号传导中的作用所必需的。这些结果表明 DSP3通过直接调节磷酸化 MPK3 和 MPK6 的积累，是拟南芥中盐反应的负调节因子。