氣態(tài)植物激素——乙烯是植物生長過程的主要操控者,。最為人熟知的是它的果實(shí)催熟功能。乙烯還能夠誘導(dǎo)種子萌發(fā)和保護(hù)植物抵抗病原菌和環(huán)境壓力,。然而這種激素卻引起切花產(chǎn)業(yè)和農(nóng)業(yè)的重大損失。由加速植物腐爛的信號產(chǎn)生的乙烯,，在加速果實(shí)成熟的同時也引起它們變質(zhì),。在切花運(yùn)輸和處理過程中，乙烯誘導(dǎo)了花朵的提前凋謝,。
近年來,，科學(xué)家對于細(xì)胞內(nèi)乙烯信號有了很多了解。美國Salk研究所的研究人員如今鑒定出乙烯響應(yīng)的重要調(diào)節(jié)子——EIN2的功能,。以前的研究一直沒能闡明EIN2在乙烯信號通路中的作用,。
Salk研究所的Joseph Ecker科學(xué)小組發(fā)現(xiàn),，乙烯的存在,，使“短命”的EIN2可以聚集到足夠濃度來傳遞乙烯信號。如果沒有乙烯,，一種CTR1蛋白將與EIN2結(jié)合抑制乙烯通路,。一旦乙烯與其受體結(jié)合，EIN2將被激活,。但是EIN2的激活機(jī)制仍不清楚,。但已知有兩個F-box蛋白：ETP1和ETP2，介導(dǎo)EIN2的降解,。 乙烯的存在使這兩個蛋白失活,，因此EIN2不再被降解。
“這類調(diào)控好比把腳同時踩在油門和剎車上,，然后慢抬剎車”Ecker解釋說,，“這能使細(xì)胞對接下來的信息立即作出響應(yīng)。”這一發(fā)現(xiàn)還可能有利于改良植物對病原體和干旱的抗性,。（生物谷Bioon.com）
生物谷推薦原始出處：
Genes & Dev.February 4, 2009, doi:10.1101/gad.1765709
Interplay between ethylene, ETP1/ETP2 F-box proteins, and degradation of EIN2 triggers ethylene responses in Arabidopsis
Hong Qiao, Katherine N. Chang, Junshi Yazaki and Joseph R. Ecker,1
Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
Abstract
The gaseous plant hormone ethylene can trigger myriad physiological and morphological responses in plants. While many ethylene signaling pathway components have been identified and characterized, little is known about the function of the integral membrane protein ETHYLENE-INSENSITIVE2 (EIN2), a central regulator of all ethylene responses. Here, we demonstrate that Arabidopsis thaliana EIN2 is a protein with a short half-life that undergoes rapid proteasome-mediated protein turnover. Moreover, EIN2 protein accumulation is positively regulated by ethylene. We identified two F-box proteins, EIN2 TARGETING PROTEIN1 (ETP1) and EIN2 TARGETING PROTEIN2 (ETP2), that interact with the EIN2 C-terminal domain (EIN2-CEND), which is highly conserved and sufficient to activate most ethylene responses. Overexpression of ETP1 or ETP2 disrupts EIN2 protein accumulation, and these plants manifest a strong ethylene-insensitive phenotype. Furthermore, knocking down the levels of both ETP1 and ETP2 mRNAs using an artificial microRNA (amiRNA) leads to accumulation of EIN2 protein, resulting in plants that display constitutive ethylene response phenotypes. Finally, ethylene down-regulates ETP1 and ETP2 proteins, impairing their ability to interact with EIN2. Thus, these studies reveal that a complex interplay between ethylene, the regulation of ETP1/ETP2 F-box proteins, and subsequent targeting and degradation of EIN2 is essential for triggering ethylene responses in plants.
