EIN3/EIL1 cooperate with PIF1 to prevent photo-oxidation and to promote greening of Arabidopsis seedlings
EIN3/EIL1 cooperate with PIF1 to prevent photo-oxidation and to promote greening of Arabidopsis seedlings
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DOI：
10.1073/pnas.0907670106
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发表时间：
2009-12-15
影响因子：
11.1
通讯作者：
Guo, Hongwei
中科院分区：
文献类型：
--
作者：
Zhong, Shangwei;Zhao, Mantong;Guo, Hongwei
从skotomorphogenesis转换到光形态建成的能力对于幼苗发育和植物存活是必不可少的。最近的研究表明，COP 1和光敏色素相互作用因子（PIFs）通过抑制光形态发生反应和/或维持黄化幼苗的skotomorphogenic状态，是这一转变的关键调节因子。在这里，我们报告的植物激素乙烯起着至关重要的作用，从skotomorphogenesis光形态建成的过渡，促进光照射后黄化幼苗的绿化。EIN 3/EIL 1的激活对于乙烯诱导的幼苗绿化的增强以及抑制叶绿素合成的光毒性中间体原叶绿素的积累是必要的和充分的。EIN 3/EIL 1诱导叶绿素合成途径中两个关键酶原叶绿素氧化还原酶A和B（PORA/B）的基因表达。ChIP和EMSA分析表明EIN 3直接结合PORA和PORB启动子中存在的特异性元件。遗传学研究表明，EIN 3/EIL 1与PIF 1在防止光氧化损伤和促进子叶绿化中起协同作用。此外，EIN 3的激活逆转了由cop 1突变或远红光照射引发的绿色化阻断。因此，EIN 3作用于COP 1的下游，其蛋白质积累被COP 1增强，但被光降低。总之，EIN 3/EIL 1代表一类新的转录调控因子，沿着PIF 1以优化拟南芥幼苗的去黄化。我们的研究强调了乙烯通过保护黄化幼苗免受光氧化损伤在促进幼苗发育和存活方面的重要作用。
The ability to switch from skotomorphogenesis to photomorphogenesis is essential for seedling development and plant survival. Recent studies revealed that COP1 and phytochrome-interacting factors (PIFs) are key regulators of this transition by repressing the photomorphogenic responses and/or maintaining the skotomorphogenic state of etiolated seedlings. Here we report that the plant hormone ethylene plays a crucial role in the transition from skotomorphogenesis to photomorphogenesis by facilitating greening of etiolated seedlings upon light irradiation. Activation of EIN3/EIL1 is both necessary and sufficient for ethylene-induced enhancement of seedling greening, as well as repression of the accumulation of protochlorophyllide, a phototoxic intermediate of chlorophyll synthesis. EIN3/EIL1 were found to induce gene expression of two key enzymes in the chlorophyll synthesis pathway, protochlorophyllide oxidoreductase A and B (PORA/B). ChIP and EMSA assays demonstrated that EIN3 directly binds to the specific elements present in the PORA and PORB promoters. Genetic studies revealed that EIN3/EIL1 function in cooperation with PIF1 in preventing photo-oxidative damage and promoting cotyledon greening. Moreover, activation of EIN3 reverses the blockage of greening triggered by cop1 mutation or far-red light irradiation. Consistently, EIN3 acts downstream of COP1 and its protein accumulation is enhanced by COP1 but decreased by light. Taken together, EIN3/EIL1 represent a new class of transcriptional regulators along with PIF1 to optimize de-etiolation of Arabidopsis seedlings. Our study highlights the essential role of ethylene in enhancing seedling development and survival through protecting etiolated seedlings against photo-oxidative damage.