PLoS Genetics解析植物抗白粉病信号级联

　　

　　植物与病原微生物间存在信息的相互识别和相互干扰，并通过生物间信息流构成了复杂的相互关系，其中蕴藏着丰富的生物学问题。这是生物信息流先导专项的主要研究内容之一。植物对种间信息进行识别和解码，使其在与病原微生物共同进化的过程中进化出与动物相似的先天免疫及防卫系统。

 在这个过程中，科学家们已经发现，丝裂原活化蛋白激酶MAPK级联信号通路在调控植物抗性方面发挥重要作用，然而，植物如何调控MAPK信号通路还不清楚。

　　近日，“作物病虫害的导向性防控－生物间信息流与行为操纵”先导专项在上述领域取得了重要研究进展。参与该专项的中国科学院遗传与发育生物学研究所唐定中课题组利用拟南芥与白粉菌互作的研究体系，解析了植物调控MAPK信号通路的分子机理，为MKK4/MKK5参与植物抗病性提供了直接的遗传证据，并揭示出植物通过EDR1负调控MAPK信号通路以精细调控植物抗病性的分子机制。

   该研究发现EDR1蛋白与MAPK激酶MKK4和MKK5直接互作，并负调控MKK4/MKK5、MPK3/MPK6的蛋白积累及MPK3/MPK6的磷酸化水平。EDR1功能缺失突变体的抗病性依赖于MPK3，MKK4和MKK5，而MKK4和MKK5功能缺失突变体对白粉菌感病，过量表达MKK4或MKK5表现与edr1类似的白粉病抗性和白粉菌诱导的细胞死亡。这项研究为阐明植物先天免疫的分子机制和分子调控网络奠定了基础，并为未来选择新型农药的作用靶标提供了科学依据。

　　该研究获得中科院战略性先导专项（B类）主要资助，研究结果近日已在国际遗传学专业学术期刊PLoS Genetics上在线发表。

　　论文信息：Zhao CZ, Nie HZ, Shen QJ, Zhang SQ, Lukowitz W, Tang DZ. 2014. EDR1 physically interacts with MKK4/MKK5 and negatively regulates a MAP kinase cascade to modulate plant innate immunity. PLoS Genetics. DOI:10.1371/journal.pgen.1004389.

原文摘要：

EDR1 Physically Interacts with MKK4/MKK5 and Negatively Regulates a MAP Kinase Cascade to Modulate Plant Innate Immunity

Mitogen-activated protein (MAP) kinase signaling cascades play important roles in the regulation of plant defense. The Raf-like MAP kinase kinase kinase (MAPKKK) EDR1 negatively regulates plant defense responses and cell death. However, how EDR1 functions, and whether it affects the regulation of MAPK cascades, are not well understood. Here, we showed that EDR1 negatively regulates the MKK4/MKK5-MPK3/MPK6 kinase cascade in Arabidopsis. We found that edr1 mutants have highly activated MPK3/MPK6 kinase activity and higher levels of MPK3/MPK6 proteins than wild type. EDR1 physically interacts with MKK4 and MKK5, and this interaction requires the N-terminal domain of EDR1. EDR1 also negatively affects MKK4/MKK5 protein levels. In addition, the mpk3, mkk4 and mkk5 mutations suppress edr1-mediated resistance, and over-expression of MKK4 or MKK5 causes edr1-like resistance and mildew-induced cell death. Taken together, our data indicate that EDR1 physically associates with MKK4/MKK5 and negatively regulates the MAPK cascade to fine-tune plant innate immunity.