MEKK1, MKK1/MKK2 and MPK4 function together in a mitogen-activated protein kinase cascade to regulate innate immunity in plants
MEKK1, MKK1/MKK2 and MPK4 function together in a mitogen-activated protein kinase cascade to regulate innate immunity in plants
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DOI：
10.1038/cr.2008.300
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发表时间：
2008-12-01
期刊：
影响因子：
44.1
通讯作者：
Zhang, Yuelin
中科院分区：
文献类型：
--
作者：
Gao, Minghui;Liu, Jinman;Zhang, Yuelin
丝裂原活化蛋白激酶（MAPK）级联在调节植物先天免疫应答中起着重要作用。在遗传筛选中，寻找具有组成性防御反应的突变体，我们确定了mpk4和mekk1的多个等位基因，表现出细胞死亡和组成性防御反应。双分子荧光互补（BiFC）分析表明，MPK 4和MEKK 1都与两种密切相关的MAPK激酶MKK 1和MKK 2相互作用。mkk1和mkk2单突变体植株没有明显的突变表型。为了测试MKK1和MKK2是否冗余地发挥功能，产生了mkk1 mkk2双突变体。mkk1 mkk2双突变体植株在苗期死亡，并且幼苗致死表型是温度依赖性的。与mpk4和mekk1突变体相似，mkk1 mkk2双突变体幼苗积累高水平的H2O2，显示自发细胞死亡，组成型表达致病相关（PR）基因，并表现出病原体抗性。此外，在mkk1 mkk2双突变体中，flg22对MPK4的激活受损，表明MKK1和MKK2与MPK4和MEKK1一起在MAP激酶级联中起作用，以负调节植物中的先天免疫应答。
Mitogen-activated protein kinase (MAPK) cascades play important roles in regulating plant innate immune responses. In a genetic screen to search for mutants with constitutive defense responses, we identified multiple alleles of mpk4 and mekk1 that exhibit cell death and constitutive defense responses. Bimolecular fluorescence complementation (BiFC) analysis showed that both MPK4 and MEKK1 interact with MKK1 and MKK2, two closely related MAPK kinases. mkk1 and mkk2 single mutant plants do not have obvious mutant phenotypes. To test whether MKK1 and MKK2 function redundantly, mkk1 mkk2 double mutants were generated. The mkk1 mkk2 double mutant plants die at seedling stage and the seedling-lethality phenotype is temperature-dependent. Similar to the mpk4 and mekk1 mutants, the mkk1 mkk2 double mutant seedlings accumulate high levels of H2O2, display spontaneous cell death, constitutively express Pathogenesis Related (PR) genes and exhibit pathogen resistance. In addition, activation of MPK4 by flg22 is impaired in the mkk1 mkk2 double mutants, suggesting that MKK1 and MKK2 function together with MPK4 and MEKK1 in a MAP kinase cascade to negatively regulate innate immune responses in plants.