Abstract：
Mitogen-activated protein kinase (MAPK) cascade is the center of plant signal transduction system that amplify immune signals into cellular responses by phosphorylating diverse substrates. The MAPK cascade consisting of MAPK kinase kinases (MAPKKKs), MAPK kinases (MAPKKs), and MAPKs is well characterized in plants, in which Raf-like kinases are generally regarded as MAPKKKs. However, it is rarely reported that Raf-like MAPKKKs function as middle regulators to link MAPK and its downstream transcription factors in plant immunity. Verticillium wilt, caused by the soil-borne vascular fungus Verticillium dahliae, is a serious disease in many plants, including cotton. The previous studies showed that GhMPK9 (a MAPK) is involved in the response to Verticillium wilt. Here, the Raf-like kinase GhRAF39_1 is reported as helper regulates the phosphorylation of WRKY transcription factor GhWRKY40a by GhMPK9. The phosphorylated GhWRKY40a can further activate the transcription of GhERF1b to up-regulate defense-related genes while inhibit the transcription of GhABF2 to regulate the stomatal opening, thus improving the resistance to Verticillium wilt in cotton. This study reveals a new signaling module of GhMPK9-GhRAF39_1-GhWRKY40a to regulate GhERF1b- and GhABF2-mediated defense responses, which triggers plant defense against Verticillium wilt.
摘要：
丝裂原活化蛋白激酶（MAPK）级联是植物信号转导系统的中心，通过磷酸化多种底物将免疫信号放大到细胞应答中。由MAPK激酶激酶（MAPKKs）组成的MAPK级联，MAPK激酶（MAPKK），MAPKs在植物中具有很好的特征，其中Raf样激酶通常被视为MAPKKs。然而,很少报道Raf样MAPKKs作为中间调节因子，在植物免疫中连接MAPK及其下游转录因子。黄萎病,由土壤传播的血管真菌黄萎病菌引起，在许多植物中是一种严重的疾病，包括棉花。以往的研讨显示GhMPK9(一MAPK)介入黄萎病的反响。这里,据报道，Raf样激酶GhRAF39_1可辅助调节GhMPK9对WRKY转录因子GhWRKY40a的磷酸化。磷酸化GhWRKY40a可以进一步激活GhERF1b的转录，上调防御相关基因，同时抑制GhABF2的转录，调节气孔开放，从而提高棉花对黄萎病的抗性。本研究揭示了GhMPK9-GhRAF39_1-GhWRKY40a调节GhERF1b-和GhABF2介导的防御反应的新信号模块，引发植物对黄萎病的防御。
