摘要
作为5大类植物激素之一的乙烯一直是科学家关注和研究的焦点。虽然结构简单,但是气态激素乙烯在植物的生长发育以及胁迫反应中具有重要的作用。通过近20年的研究,科学家已经描绘出一条近似线性的乙烯信号转导通路。在模式植物拟南芥中,这条通路的最上游是由一个多基因家族编码的乙烯的5个受体ETR1,ETR2,ERS1,ERS2和EIN4。与之相结合并共同定位于内质网上的是一个类似Raf的蛋白激酶CTR1。在没有乙烯存在的条件下,受体和CTR1的结合能够协同抑制下游乙烯信号。在这两类负调控因子的下游是乙烯信号的正调控因子EIN2。如果EIN2基因突变,即使有高浓度乙烯存在,植物黄化苗也将表现出完全的乙烯不敏感表型,显示出EIN2在乙烯信号通路中的核心地位。在EIN2的下游是乙烯信号的转录因子家族EIN3以及EILs,它们在响应乙烯信号之后会起始乙烯相关基因的表达。研究还发现,乙烯的转录因子受泛素化降解途径调控,负责识别及结合EIN3等转录因子的F-box蛋白是EBF1和EBF2。EIN5是一种5’→3’外切核酸酶,它能够通过促进EBF1和EBF2的mRNA的降解来拮抗这两个F-box蛋白对EIN3的负反馈调控。最近,有研究表明EIN2同样是一个半衰期很短并经由泛素化降解途径调控的蛋白,而执行调控EIN2任务的是另外两个F-box蛋白ETP1和ETP2。虽然人们对于乙烯信号转导通路的认识取得了巨大进步,但是该信号通路的精细调节机制以及乙烯信号与其他植物激素信号之间的交叉反应还需进行更为深入的研究。
As one of the five classical phytohormones,ethylene has been focused on by scientists since it was found.Although it has very simple structure,the gaseous phytohormone ethylene has important effects on the developmental processes and stress responses of plant.Through nearly two decades of research,scientists established a largely linear ethylene signal transduction pathway.In the model plant Arabidopsis,there are five ethylene receptors ETR1,ETR2,ERS1,ERS2 and EIN4 encoded by a multigene family in the upstream of this signaling pathway.A Raf-like protein kinase CTR1 combines with ethylene receptors and co-localizes in the ER membrane together with these receptors.In the absence of ethylene,receptors and CTR1 can inhibit the downstream ethylene signaling together.A positive regulator EIN2 is the downstream of these two negative regulators.If EIN2 gene is mutated,the etiolated seedlings of plant will show completely ethylene insensitive phenotype even when high concentration of ethylene exists,which demonstrates that EIN2 plays a key role in ethylene signaling pathway.EIN3 and EILs are transcription factors downstream of EIN2.They will start the transcription of ethylene related genes in response to ethylene signal.It was also found that these transcription factors were regulated by ubiquitin/proteasome degradation pathway.The F-box proteins,which are responsible for recognition and combination of EIN3 protein,are EBF1 and EBF2.EIN5 is a 5＇→3＇ exonuclease and antagonizes the negative feedback regulation on EIN3 by promoting EBF1 and EBF2 mRNA decay.Recently,studies have shown that EIN2 is also a short half-life protein and will be degraded by the ubiquitin/proteasome pathway.Another two F-box proteins ETP1 and ETP2 are responsible for the regulation of EIN2 protein.Although great progress was made in ethylene signal transduction pathway,further research on the fine-tuning of ethylene signal transduction and the crosstalk between ethylene and other phytohormones still need to be detected.
出处
《自然杂志》
北大核心
2012年第4期219-228,共10页
Chinese Journal of Nature
关键词
植物激素
乙烯
信号转导
phytohormone
ethylene
signal transduction
