乙烯受体差异性协作与Raf-like蛋白CTR1负调控的乙烯信号转导

以拟南芥为模式植物研究植物激素乙烯信号转导,在过去20年来取得了长足进展,并以遗传学与生物化学为基础建立了一个线性的信号转导途径模型．虽然这个模型基本上解释了乙烯信号组分参与的信号传递过程,但是,其中仍然存在若干问题亟待进一步研究．例如,上游的多个乙烯受体家族成员与CONSTITUTIVETRIPLE—RESPONSE1蛋白如何协同作用,下游的ETHYLENEINsENsITIVE2（EIN2）如何将乙烯信号传递给转录激活因子EIN3,以及是否存在其他的信号途径调控乙烯反应等．本文将着重阐述不同乙烯受体家族成员的协作对乙烯信号途径的差异性调控,植物利用多个乙烯受体感受乙烯的生物学意义,以及乙烯受体除了通过CTR1蛋白调节EIN2功能外,是否还存在其他的信号转导途径．     

乙烯受体在果实成熟及花衰老中的研究进展

乙烯受体是乙烯信号转导网络的第一个转导元件,通过调控受体基因的表达,可以调节植物对乙烯的敏感性,以调控果实的成熟及花衰老进程的响应.随着人们对乙烯受体研究的深入,乙烯受体突变体及受体抑制剂在采后果实和切花保鲜上的应用已受到广泛关注.就近年来关于乙烯受体的相关研究进展进行综述,重点介绍了乙烯受体的分子调控机制及乙烯受体在...     

植物乙烯信号转导研究进展

过去10年,对模式植物拟南芥的分子遗传学研究建立了植物乙烯信号转导线性模型.乙烯结合到受体上,经一条MAPK级联反应和转录级联途径将信号转导而产生乙烯反应.拟南芥乙烯受体家族由5个成员构成,ETR1、ERS1、ETR2、ERS2和EIN4.乙烯受体包括三个结构域:乙烯结合结构域、组氨酸激酶结构域和反应调控结构域.乙烯受体定位于内质网,与CTR1协同负调控乙烯反应.ENI2、EIN3/EIL、ERF1依次位于CTR1下游,正调控乙烯反应.EIN3属于转录激活因子调控蛋白家族,受转录后调控.乙烯稳定EIN3结构,EBF1/EBF2促进EIN3分解.ERF1是转录调控因子家族成员之一,是EIN3/EIL的直接作用目标.     

花衰老相关的乙烯信号转导基因研究进展

乙烯在许多切花衰老过程中起着重要的调节作用,不同的植物乙烯信号转导组分在花衰老过程中有不同的转录调节特性。根据乙烯信号转导标准模式,通过调节乙烯信号转导基因表达能够调控花对乙烯的敏感性,深入研究乙烯信号转导机制;可能有多条途径可延缓切花衰老。综述了香石竹和月季等几种观赏植物在花衰老过程中乙烯受体和乙烯信号转导基因表达及特性。     

铜离子与乙烯受体关系研究进展

许多年前 ,人们一直推测金属离子如锌、铜为受体感受乙烯所必需 ,但苦于没有直接证据。最近对拟南芥的生化和遗传学研究证实铜离子参与了乙烯信号的感受和转导。RAN1蛋白与酵母 CCC2蛋白和 Wilson &Menkes疾病蛋白同源 ,这些蛋白为转运铜离子的 P-型ATP酶。RAN1将铜离子整合到乙烯受体中 ,受体才能正常感受乙烯。铜离子投送可能是调节乙烯感受的重要因素     

拟南芥乙烯信号传递途径

植物激素乙烯早在一百多年前就已经被确认,相关的研究使得乙烯广泛地被应用于农业上.一直到十年前第一个植物激素乙烯受体拟南芥ETR1基因被发现之后,人们对于乙烯信号传递的研究并才真正开始有所突破.以遗传学为基础对乙烯反应突变体所做的分析,使得乙烯信号传递已经成为目前植物信号传递领域中被研究得最清楚的信号传递途径之一.该文着重于回顾乙烯信号传递途径上各个元件的发现和确认,以及如何利用遗传学的方法将现有的突变体相关基因构建出目前广为接受的信号传递的遗传模式.最后,该文就目前所知的乙烯信号传递理论及相关研究,做了总结和深入的讨论.     

Compounds Interacting with the Ethylene Receptor in Plants

Abstract: Some of the compounds binding to the ethylene receptor induce an ethylene response, but others prevent it. The compounds preventing an ethylene response have been developed into a means for protecting plants against ethylene and extending the life of some plant material. 1-Methylcyclopropene (1-MCP), a compound now commercially available under the names EthylBloc and SmartFresh™, is currently being used on flowers, fruit and vegetables with great success. In ethylene sensitive flowers, among other responses, it prevents senescence and abscission of plant organs; in fruit and vegetables it slows down the ripening process. Other similar compounds are now being developed for a range of methods of application.     

Serine/threonine kinase activity in the putative histidine kinase-like ethylene receptor NTHK1 from tobacco

A histidine kinase-based signaling system has been proposed to function in ethylene signal transduction pathway of plants and one ethylene receptor has been found to possess His kinase activity. Here we demonstrate that a His kinase-like ethylene receptor homologue NTHK1 from tobacco has serine/threonine (Ser/Thr) kinase activity, but no His kinase activity. Evidence obtained by analyzing acid/base stability, phosphoamino acid and substrate specificity of the phosphorylated kinase domain, supports this conclusion. In addition, mutation of the presumptive phosphorylation site His (H378) to Gln did not affect the kinase activity whereas deletion of the ATP-binding domain eliminated it, indicating that the conserved His (H378) is not required for the kinase activity and this activity is intrinsic to the NTHK1-KD. Moreover, confocal analysis of NTHK1 expression in insect cells and plant cells suggested the plasma membrane localization of the NTHK1 protein. Thus, NTHK1 may represent a distinct Ser/Thr kinase-type ethylene receptor and function in an alternative mechanism for ethylene signal transduction.     

乙烯信号转导的分子机制

气态植物激素乙烯在植物生长发育和应对生物及非生物胁迫过程中起着重要作用。在过去的十几年中, 对模式植物拟南芥的分子遗传研究已建立从信号感知到转录调控的乙烯信号转导线性模型。拟南芥共有5个乙烯受体ETR1、ERS1、ETR2、ERS2和EIN4, 目前已知ETR1定位在内质网上, 与类似于Raf的蛋白激酶CTR1协同负调控乙烯反应。EIN2和EIN3/EILs位于CTR1下游, 正调控乙烯反应。两个F-box蛋白EBF1和EBF2通过泛素/26S蛋白体降解途径调控EIN3的稳定性。5’→3’的外切核酸酶EIN5通过启动EBF1和EBF2 mRNA的降解, 拮抗EBF1和EBF2对EIN3的负反馈调控。目前对于乙烯信号转导途径关键组分的生化功能和乙烯下游反应途径的了解甚少, 乙烯信号转导途径与其它途径之间还存在着广泛的交叉反应, 这些问题的解决将大大增加我们对乙烯信号转导途径的了解。     

番茄乙烯受体结构和功能研究进展

综述了近年来番茄乙烯受体研究方面的最新进展。以拟南芥的乙类受体为探针,从番茄加筛选得到Le-ETR1、Le-ETR2、Le-ETR3、Le-ETR4、Le-ETR55个有功能的乙烯受体基因。番茄乙类受体与细菌的双组分感受系统高度相似,同乙烯结合需要铜离子的协同作用。植物株发育期间通过激活某些受体基因的表达和（或）控制铜离子的转运调节乙烯敏感性。调节乙烯受体表达的基因工程显示了广阔的前景。但各个受体的功能及基因分析与活体标记的关系还需进一步研究。     

Possible modulation of Arabidopsis ETR1 N-terminal signaling by CTR1

The mitogen-activated protein kinase kinase kinase (MAPKKK) Constitutive Triple-Response1 (CTR1) plays a key role in mediating ethylene receptor signaling via its N-terminal interaction with the ethylene receptor C-terminal histidine kinase (HK) domain. Loss-of-function mutations of CTR1 prevent ethylene receptor signaling, and corresponding ctr1 mutants show a constitutive ethylene response phenotype. We recently reported in Plant Physiology that expression of the truncated ethylene receptor Ethylene Response1 (ETR1) isoforms etr11-349 and dominant ethylene-insensitive etr1-11-349, lacking the C-terminal HK and receiver domains, both suppressed the ctr1 mutant phenotype. Therefore, the ETR1 N terminus is capable of receptor signaling independent of CTR1. The constitutive ethylene response phenotype is stronger for ctr1-1 than ctr1-1 lines expressing the etr11-349 transgene, so N-terminal signaling by the full-length but not truncated ETR1 is inhibited by ctr1-1. We address possible modulations of ETR1 N-terminal signaling with docking of CTR1 on the ETR1 HK domain.     

Calcium Requirement for Ethylene-Dependent Responses

Ethylene, a gaseous plant hormone, plays a role in plant development, defense, and climacteric fruit ripening. Both genetic and biochemical evidence suggest that the response of plants to ethylene is mediated by a specific ethylene receptor. The signal emanating from the receptor-effector complex is then presumably transduced via an unknown cascade pathway. We have used the plant pathogenesis response, exemplified by the induction of the pathogenesis-related gene chitinase, as a paradigm to investigate ethylene-dependent signal transduction in the plant cell. We showed that calcium is necessarily involved in the ethylene-mediated pathogenesis response. Blocking calcium fluxes with chelators inhibited ethylene-dependent induction of chitinase accumulation, but not ethylene independent induction. Artificially increasing cytosolic calcium levels by treatments with the calcium ionophore ionomycin or the calcium pump blocker thapsigargin stimulated chitinase accumulation. Plants grown in calcium-poor soil showed a 10-fold reduction in leaf extractable calcium. Their leaves exhibited a reduced pathogenesis reaction to ethylene and were impaired in another hormone response mediated by calcium, i.e., abscisic acid-controlled closure of guard cells. The addition of calcium to leaves excised from calcium-deficient plants restored their sensitivity to ethylene. Ethylene participates in the control of seedling growth, promoting the so-called "triple response" that results in distinct morphological development, such as hypocotyl hook formation. This effect, similar to the ethylene-promoted pathogenesis response, was found to be calcium dependent. The results indicate that calcium is required for a variety of ethylene-dependent processes.     

Role of ethylene receptors during senescence and ripening in horticultural crops

The past two decades have been rewarding in terms of deciphering the ethylene signal transduction and functional validation of the ethylene receptor and downstream genes involved in the cascade. Our knowledge of ethylene receptors and its signal transduction pathway provides us a robust platform where we can think of manipulating and regulating ethylene sensitivity by the use of genetic engineering and making transgenic. This review focuses on ethylene perception, receptor mediated regulation of ethylene biosynthesis, role of ethylene receptors in flower senescence, fruit ripening and other effects induced by ethylene. The expression behavior of the receptor and downstream molecules in climacteric and non climacteric crops is also elaborated upon. Possible strategies and recent advances in altering the ethylene sensitivity of plants using ethylene receptor genes in an attempt to modulate the regulation and sensitivity to ethylene have also been discussed. Not only will these transgenic plants be a boon to post-harvest physiology and crop improvement but, it will also help us in discovering the mechanism of regulation of ethylene sensitivity.     

Ethylene-binding activity, gene expression levels, and receptor system output for ethylene receptor family members from Arabidopsis and tomato

Ethylene signaling in plants is mediated by a family of ethylene receptors related to bacterial two-component regulators. Expression in yeast of ethylene-binding domains from the five receptor isoforms from Arabidopsis thaliana and five-receptor isoforms from tomato confirmed that all members of the family are capable of high-affinity ethylene-binding activity. All receptor isoforms displayed a similar level of ethylene binding on a per unit protein basis, while members of both subfamily I and subfamily II from Arabidopsis showed similar slow-release kinetics for ethylene. Quantification of receptor-isoform mRNA levels in receptor-deficient Arabidopsis lines indicated a direct correlation between total message level and total ethylene-binding activity in planta. Increased expression of remaining receptor isoforms in receptor-deficient lines tended to compensate for missing receptors at the level of mRNA expression and ethylene-binding activity, but not at the level of receptor signaling, consistent with specialized roles for family members in receptor signal output.     

果实成熟乙烯相关基因工程研究进展(综述)

果实成熟是一个复杂的生理生化过程,而乙烯是引发果实成熟的主要因素.本文简述乙烯合成过程中S-腺苷甲硫氨酸水解酶、ACC合成酶与ACC氧化酶、ACC脱氨酶基因和乙烯受体突变体的特性及克隆;同时,评述利用基因工程技术控制果实成熟的应用前景.     

Characterization of an ethylene receptor homolog gene from rice

Ethylene is a gaseous hormone and plays important roles in plant growth and development, including seed germination, root hair development, flowering, pollination, abscission, and fruit ripening[1]. It is also involved in plant responses to biotic stress such as pathogen attack, and abiotic stresses such as wounding, drought and freezing[1]. Mutational and genetic analysis of Arabidopsis has led to the identification of five ethylene receptor genes, i.e. ETR1, ERS1, ETR2, EIN4 and ERS2. …