A rice fungal MAMP-responsive MAPK cascade regulates metabolic flow to antimicrobial metabolite synthesis.
A rice fungal MAMP-responsive MAPK cascade regulates metabolic flow to antimicrobial metabolite synthesis.
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DOI：
10.1111/j.1365-313x.2010.04264.x
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发表时间：
2010-08
期刊：
影响因子：
--
通讯作者：
Hirochika H
中科院分区：
文献类型：
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作者：
Kishi-Kaboshi M;Okada K;Kurimoto L;Murakami S;Umezawa T;Shibuya N;Yamane H;Miyao A;Takatsuji H;Takahashi A;Hirochika H
植物通过微生物相关分子模式（MAMPs）识别潜在的微生物病原体并激活一系列防御反应，包括细胞死亡、活性氧（ROS）和多种抗微生物次级代谢产物的产生。已知丝裂原活化蛋白激酶（MAPK）级联在介导MAMP信号中起关键作用;然而，对从MAPK级联到激活防御反应的信号通路知之甚少。在这里，我们在水稻中发现甲壳素诱导子（一种真菌MAMP）激活两种水稻MAPKs（OsMPK 3和OsMPK 6）和一种MAPK激酶（OsMKK 4）。OsMPK 6在几丁质诱导剂诱导的二萜类植物抗毒素生物合成中起重要作用。OsMKK 4的活性形式（OsMKK 4DD）的条件表达诱导基因表达的广泛改变，这意味着代谢流从糖酵解到次级代谢物生物合成的动态变化，同时抑制基本的细胞活动，如翻译和细胞分裂。OsMKK 4DD还诱导多种防御反应，如细胞死亡、二萜类植物抗毒素和木质素的生物合成，但不产生胞外ROS。OsMKK 4DD诱导的细胞死亡和二萜类植物抗毒素途径基因的表达依赖于OsMPK 6，而苯丙烷类途径基因的表达不依赖于OsMPK 6。总的来说，OsMKK 4-OsMPK 6级联在MAMP触发的防御反应期间重编程植物代谢中起关键作用。
Plants recognize potential microbial pathogens through microbial-associated molecular patterns (MAMPs) and activate a series of defense responses, including cell death and the production of reactive oxygen species (ROS) and diverse anti-microbial secondary metabolites. Mitogen-activated protein kinase (MAPK) cascades are known to play a pivotal role in mediating MAMP signals; however, the signaling pathway from a MAPK cascade to the activation of defense responses is poorly understood. Here, we found in rice that the chitin elicitor, a fungal MAMP, activates two rice MAPKs (OsMPK3 and OsMPK6) and one MAPK kinase (OsMKK4). OsMPK6 was essential for the chitin elicitor-induced biosynthesis of diterpenoid phytoalexins. Conditional expression of the active form of OsMKK4 (OsMKK4DD) induced extensive alterations in gene expression, which implied dynamic changes of metabolic flow from glycolysis to secondary metabolite biosynthesis while suppressing basic cellular activities such as translation and cell division. OsMKK4DD also induced various defense responses, such as cell death, biosynthesis of diterpenoid phytoalexins and lignin but not generation of extracellular ROS. OsMKK4DD-induced cell death and expression of diterpenoid phytoalexin pathway genes, but not that of phenylpropanoid pathway genes, were dependent on OsMPK6. Collectively, the OsMKK4–OsMPK6 cascade plays a crucial role in reprogramming plant metabolism during MAMP-triggered defense responses.