Function of a mitogen-activated protein kinase pathway in N gene-mediated resistance in tobacco
Function of a mitogen-activated protein kinase pathway in N gene-mediated resistance in tobacco
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DOI：
10.1046/j.1365-313x.2003.01664.x
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发表时间：
2003-02-01
期刊：
影响因子：
7.2
通讯作者：
Zhang, SQ
中科院分区：
文献类型：
--
作者：
Jin, HL;Liu, YD;Zhang, SQ
植物对病原体的主动防御通常包括快速和局部的细胞死亡，称为过敏反应（HR）。基于使用蛋白激酶和磷酸酶抑制剂的研究，蛋白磷酸化和去磷酸化与该事件有关。最近的瞬时功能获得性研究表明，水杨酸诱导的蛋白激酶（SIPK）和创伤诱导的蛋白激酶（WIPK），两种烟草丝裂原活化蛋白激酶（MAPK）通过其上游MAPK激酶（NtMEK 2）的激活导致HR样细胞死亡。在这里，我们报告说，保守的激酶相互作用基序（KIM）的MAPKKs是NtMEK 2功能所需的。该基序中保守的碱性氨基酸的突变或含有该基序的N-末端64个氨基酸的缺失显著损害或消除NtMEK 2（DD）在体内激活SIPK/WIPK的能力。这些突变体在与SIPK和WIPK的相互作用中也有缺陷，这表明蛋白质-蛋白质相互作用是该MAPK级联的功能完整性所必需的。为了消除已知在瞬时转化实验中激活许多防御反应的农杆菌，我们产生了永久性转基因植物。地塞米松诱导NtMEK 2（DD）表达在T-1和T-2植物中均诱导HR样细胞死亡。此外，通过使用PVX诱导的基因沉默，我们证明了NtMEK 2-SIPK/WIPK途径中所有三个已知组分的抑制减弱了N基因介导的TMV抗性。结合前人报道的SIPK和WIPK被TMV以基因对基因依赖的方式激活，我们认为NtMEK 2-SIPK/WIPK途径在N基因介导的抗病性中起着积极的作用，可能通过调节HR细胞的死亡。
The active defense of plants against pathogens often includes rapid and localized cell death known as hypersensitive response (HR). Protein phosphorylation and dephosphorylation are implicated in this event based on studies using protein kinase and phosphatase inhibitors. Recent transient gain-of-function studies demonstrated that the activation of salicylic acid-induced protein kinase (SIPK) and wounding-induced protein kinase (WIPK), two tobacco mitogen-activated protein kinases (MAPKs) by their upstream MAPK kinase (MAPKK), NtMEK2 leads to HR-like cell death. Here, we report that the conserved kinase interaction motif (KIM) in MAPKKs is required for NtMEK2 function. Mutation of the conserved basic amino acids in this motif, or the deletion of N-terminal 64 amino acids containing this motif significantly compromised or abolished the ability of NtMEK2(DD) to activate SIPK/WIPK in vivo . These mutants were also defective in interacting with SIPK and WIPK, suggesting protein-protein interaction is required for the functional integrity of this MAPK cascade. To eliminate Agrobacterium that is known to activate a number of defense responses in transient transformation experiments, we generated permanent transgenic plants. Induction of NtMEK2 (DD) expression by dexamethasone induced HR-like cell death in both T-1 and T-2 plants. In addition, by using PVX-induced gene silencing, we demonstrated that the suppression of all three known components in the NtMEK2-SIPK/WIPK pathway attenuated N gene-mediated TMV resistance. Together with previous report that SIPK and WIPK are activated by TMV in a gene-for-gene-dependent manner, we conclude that NtMEK2-SIPK/WIPK pathway plays a positive role in N gene-mediated resistance, possibly through regulating HR cell death.