Activation of a stress-responsive mitogen-activated protein kinase cascade induces the biosynthesis of ethylene in plants
Activation of a stress-responsive mitogen-activated protein kinase cascade induces the biosynthesis of ethylene in plants
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DOI：
10.1105/tpc.011411
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发表时间：
2003-11-01
期刊：
影响因子：
11.6
通讯作者：
Zhang, SQ
中科院分区：
文献类型：
--
作者：
Kim, CY;Liu, YD;Zhang, SQ
植物在来自生物和非生物来源的胁迫下产生增加的乙烯水平，其被乙烯受体感知并触发下游的细胞反应。基于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胁迫对乙烯诱导的调节有关。然而，涉及的激酶仍有待确定。利用条件性功能获得转基因系统，我们证明，激活SIPK，烟草丝裂原活化蛋白激酶（MAPK），由NtMEK2（DD），一个活跃的突变体的上游激酶的SIPK，导致乙烯产量的显着增加。SIPK激活后乙烯的增加与1-氨基环丙烷-1-羧酸（ACC）合酶（ACS）活性的急剧增加相一致，随后ACS和ACC氧化酶（ACO）基因的亚组被激活，这表明参与了未鉴定的ACS的激活或转录后调节。已知烟草花叶病毒（TMV）激活SIPK级联并诱导乙烯生物合成，其感染也诱导相同的ACS和ACO。在NtMEK2（DD）植物中产生乙烯后，观察到乙烯应答因子（ERF）基因的强烈激活，类似于感染TMV的NN烟草植物中的效果。与以前的报道相反，在NtMEK2（DD）转基因植物中，在SIPK/WIPK激活后没有检测到茉莉酸（JA）和茉莉酸甲酯（MJ）的显著增加。这些结果表明，NtMEK2-SIPK/WIPK途径介导的植物防御反应中乙烯的诱导而非JA/MJ的诱导。
Plants under stress from both biotic and abiotic sources produce increased levels of ethylene, which is perceived by ethylene receptors and triggers cellular responses further downstream. Protein phosphorylation and dephosphorylation were implicated in the regulation of ethylene induction by stresses based on studies using protein kinase and phosphatase inhibitors. However, the kinase(s) involved remains to be determined. Using a conditional gain-of-function transgenic system, we demonstrate that the activation of SIPK, a tobacco mitogen-activated protein kinase (MAPK), by NtMEK2(DD), an active mutant of the upstream kinase of SIPK, resulted in a dramatic increase in ethylene production. The increase in ethylene after the activation of SIPK coincided with a dramatic increase in 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) activity, which was followed by the activation of a subgroup of ACS and ACC oxidase (ACO) genes, suggesting that either the activation of unidentified ACS(s) or post-transcriptional regulation is involved. Infection with Tobacco mosaic virus (TMV), which is known to activate the SIPK cascade and induce ethylene biosynthesis, also induced the same ACSs and ACOs. After ethylene production in NtMEK2(DD) plants, strong activation of ETHYLENE-RESPONSE FACTOR (ERF) genes was observed, similar to the effect in NN tobacco plants infected with TMV. In contrast to previous reports, no major increase in jasmonic acid (JA) and methyl jasmonate (MJ) was detected after the activation of SIPK/WIPK in NtMEK2(DD) transgenic plants. These results suggest that the induction of ethylene but not JA/MJ is involved in plant defense responses mediated by the NtMEK2-SIPK/WIPK pathway.