Plants have evolved a sophisticated immunity system for specific detection of pathogens and rapid induction of measured defences. Over- or constitutive activation of defences would negatively affect plant growth and development. Hence, the plant immune system is under tight positive and negative regulation. MAP kinase phosphatase1 (MKP1) has been identified as a negative regulator of plant immunity in model plant Arabidopsis. However, the molecular mechanisms by which MKP1 regulates immune signalling in wheat (Triticum aestivum) are poorly understood. In this study, we investigated the role of TaMKP1 in wheat defence against two devastating fungal pathogens and determined its subcellular localization. We demonstrated that knock-down of TaMKP1 by CRISPR/Cas9 in wheat resulted in enhanced resistance to rust caused by Puccinia striiformis f. sp. tritici (Pst) and powdery mildew caused by Blumeria graminis f. sp. tritici (Bgt), indicating that TaMKP1 negatively regulates disease resistance in wheat. Unexpectedly, while Tamkp1 mutant plants showed increased resistance to the two tested fungal pathogens they also had higher yield compared with wild-type control plants without infection. Our results suggested that TaMKP1 interacts directly with dephosphorylated and activated TaMPK3/4/6, and TaMPK4 interacts directly with TaPAL. Taken together, we demonstrated TaMKP1 exert negative modulating roles in the activation of TaMPK3/4/6, which are required for MAPK-mediated defence signalling. This facilitates our understanding of the important roles of MAP kinase phosphatases and MAPK cascades in plant immunity and production, and provides germplasm resources for breeding for high resistance and high yield.

中文翻译：

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丝裂原激活蛋白激酶磷酸酶 1 的 CRISPR 靶向诱变可提高小麦的免疫力和产量

植物已经进化出复杂的免疫系统，用于特异性检测病原体并快速诱导可测量的防御。防御的过度或组成性激活会对植物的生长和发育产生负面影响。因此，植物免疫系统受到严格的正向和负向调节。 MAP 激酶磷酸酶 1 (MKP1) 已被确定为模式植物拟南芥中植物免疫的负调节因子。然而，人们对 MKP1 调节小麦免疫信号的分子机制知之甚少。在这项研究中，我们研究了 TaMKP1 在小麦防御两种毁灭性真菌病原体中的作用，并确定了其亚细胞定位。我们证明，在小麦中通过 CRISPR/Cas9 敲除TaMKP1可增强对条锈菌 ( Puccinia striiformis f) 引起的锈病的抗性。 sp。小麦( Pst ) 和由Blumeria graminis f.引起的白粉病。 sp。tritici ( Bgt )，表明TaMKP1负向调节小麦的抗病性。出乎意料的是，虽然Tamkp1突变体植物对两种测试的真菌病原体表现出增强的抗性，但与未感染的野生型对照植物相比，它们的产量也更高。我们的结果表明，TaMKP1 直接与去磷酸化和激活的 TaMPK3/4/6 相互作用，TaMPK4 直接与 TaPAL 相互作用。综上所述，我们证明 TaMKP1 在 TaMPK3/4/6 的激活中发挥负调节作用，这是 MAPK 介导的防御信号传导所必需的。这有助于我们认识MAP激酶磷酸酶和MAPK级联在植物免疫和生产中的重要作用，并为高抗高产育种提供种质资源。