拟南芥乙烯合成酶ACS基因家族研究进展

1-氨基环丙烷-1-羧酸(1-aminocyclopropane-1-carboxylic acid,ACC)合酶(ACC synthase,ACS)是乙烯生物合成的限速酶。ACS酶活性是ACC和乙烯调控植物生长发育的基础,其酶活性调节主要涉及转录启动、翻译后修饰、酶高级结构形成、生化特性等方面。简要总结拟南芥ACS酶活性研究进展。     

乙烯生物合成中间体——1-氨基环丙烷-1-羧酸及其丙二酸结合物的测定

乙烯是植物内源激素之一,它对植物的生长、发育、衰老、器官脱落和果实成熟等多种生理过程起着调节作用。1979年,Adams和Yang提出了苹果组织中乙烯的生物合成途径为蛋氨酸→S-腺苷蛋氨酸(SAM)→1-氨基环丙烷-1-羧酸(1-am-inocyclopropane-1-carboxylic acid简称ACC)     

外源乙烯对月季(Rosa hybrida)切花花朵开放的影响与乙烯生物合成相关基因表达的关联

以探讨外源乙烯对月季切花花朵开放的影响及其与花瓣内源乙烯生物合成相关基因表达之间的关联为目的. 试材选用外源乙烯对花朵开放进程影响截然相反的两个品种, 其中, Samantha明显被促进, 而Kardinal则明显被抑制. 经外源乙烯处理, 两品种花瓣乙烯生成量、1-氨基环丙烷-1-羧酸(1-aminocyclopropane -1-carboxylate, ACC)合成酶(ACC synthase, ACS)和ACC氧化酶(ACC oxidase, ACO)活性都被诱导升高. 但是, 以上指标两品种间变化有差异, 其中, Samantha主要表现为峰值提前, 即由未经处理对照的盛开期(开花级数4级)提早到初开期(3级); 而Kardinal主要表现为绝对值剧烈升高, 且远高于Samantha. 从花瓣中克隆到3个ACS (Rh-ACS1, Rh-ACS2和Rh-ACS3)和1个ACO(Rh-ACO1)基因的cDNA, 非放射性Northern检测结果表明, Rh-ACS3和Rh-ACO1基因的表达受到乙烯的诱导, 并且其表达变化在两个品种中都与ACS活性和乙烯生成量相一致. 由此推测, 外源乙烯对切花月季品种间花朵开放影响的差异, 可能与花瓣内乙烯生物合成关键酶转录水平上的诱导差异有关, 并且Kardinal可能对外源乙烯更为敏感. 还明确了月季切花3个ACS基因之间的表达存在发育时间和诱导方式上的特异性.     

含ACC脱氨酶的根际细菌提高植物抗盐性的研究进展

盐胁迫是抑制植物生长的主要非生物因素之一,高浓度的盐分不利于植物体的生长和发育,严重时会导致植物细胞及植物体死亡.已有大量实验结果显示含ACC脱氨酶的根际细菌可以缓解高盐对植物的危害.ACC脱氨酶可以降解乙烯的直接前体1-氨基环丙烷-1-羧酸(ACC),从而降低胁迫乙烯的合成量.胁迫乙烯是阻碍植物生长的主要原因.首先介...     

乙烯生物合成及其控制研究进展

 综述近年来对乙烯生物合成重要中间产物S-腺苷甲硫氨酸(SAM)及1-氨基环丙烷-1-羧酸(ACC)各种分流途径的研究进展,重点介绍参与这些途径的关键酶及其基因的特性,并对控制乙烯生物合成的基因工程作一总结。     

乙烯和1-氨基环丙烷-1-羧酸合酶基因参与玫瑰花发育过程中细胞程序化死亡的调控

作为植物有性繁殖器官--花的花瓣通常生命周期短,其中有一个敏感的、严格控制的细胞程序化死亡过程.为了揭示细胞程序化死亡过程中发生的反应或者其组成成分,解释玫瑰花发育过程中的细胞程序化死亡过程的机理,测定了在整个花发育过程中玫瑰花瓣的乙烯释放速率、ACC合酶基因的转录产物(mRNA)、ACC合酶活性以及ACC含量.结果显示在花发育过程前期(阶段1、2)检测不到乙烯产生,在花瓣完全绽开时花瓣中乙烯开始产生.在花发育后期(阶段4、5)花的衰老与乙烯释放速率的升高同时发生.在花发育前期没有ACC合酶基因的转录产物积累,该基因在花瓣完全绽开时开始表达,在花发育后期逐渐增强.ACC合酶活性与ACC含量的变化趋势与乙烯的一致.在玫瑰花发育后期乙烯诱导和调控花瓣的细胞程序化死亡.ACC合酶基因、ACC合酶以及ACC都是玫瑰花瓣程序化死亡过程中的重要调控因子.     

菠萝ACC氧化酶基因AcACO1的克隆与表达分析

乙烯是重要的植物激素,在植物生长发育和胁迫响应中具有重要的调节功能。1-氨基环丙烷-1-羧酸氧化酶(ACO)是植物乙烯生物合成途径中的一个关键酶。根据转录组数据,从菠萝中成功克隆到1个编码ACO的基因Ac ACO1,测序结果证实该基因全长1 094 bp,包含一个957 bp的开放阅读框,编码318个氨基酸。AcACO1蛋白具有典型的植物ACO结构特征,含有DIOX_N和2OG-FeⅡ_Oxy两个保守结构域。1 850 bp的AcACO1启动子区域含有众多应答激素和环境胁迫信号元件。实时荧光定量分析结果表明,乙烯利、低温和赤霉素均能诱导AcACO1的表达。     

控制番茄果实成熟的基因工程

乙烯是植物的一种催熟激素,其合成前体是蛋氨酸(Met),它通过三步反应形成乙烯: 乙烯通过分子克隆与异源系统表达,已鉴定了腺苷甲硫氨酸(AdoMet)合成酶[反应(1)],1-氨基环丙烷-1-羧酸(ACC)合成酶[反应(2)]与ACC氧化酶[反应(3)]的编码基因。该途径的限制步骤是ACC合成酶催化的反应(2)。应用基因工程的方法已将ACC合成酶、Acc     

植物乙烯生物合成过程中活性氧的作用

大量的研究结果表明,活性氧参与植物乙烯生物合成过程具有明显的普遍性,超氧阴离子自由基是参与乙烯生物合成过程的主要活性氧。近年来研究的焦点主要从乙烯生物合成的关键调控酶ACC合酶及ACC氧化酶的酶活性、酶动力学特性、酶蛋白空间结构、酶基因表达水平等方面来阐明活性氧调控植物乙烯生物合成的机制。最新的研究表明：植物在各种正常或应激的生长条件下首先诱导了活性氧产生水平的变化,活性氧在基因或蛋白质水平上影响ACC合酶和ACC氧化酶的活性水平,从而调节乙烯的生物合成。本文首次综述了活性氧影响植物乙烯生物合成过程的最新研究进展,并对活性氧在植物乙烯生物合成中具有诱导与抑制并存的“双重性”作用进行了探讨。     

天然反义转录物及其调控基因的表达机制

天然反义转录(NATs)是一组编码蛋白质或非编码蛋白质的RNAs, 与其他(有义)转录物具有互补序列, 可以调节有义链的表达。这种调节可以发生在转录水平或转录后水平, 调节方式有转录干扰、RNA封闭、双链依赖机制或染色质重建(修饰)等。正义链和反义链分别加工成小RNAs调节基因表达, 也是NATs调节基因表达的重要方式, 如piRNAs的“乒乓机制”。实验或计算机研究已经证明了NATs在生物中广泛存在, 是一种重要的基因表达调节方式。文章论述了NATs的重要作用和机理, 重点论述了NATs的调节机制和相关的小RNAs。     

Exogenous ethylene influences flower opening of cut roses (<Emphasis Type="Italic">Rosa hybrida</Emphasis>) by regulating the genes encoding ethylene biosynthesis enzymes

The purpose of this paper is to investigate the differential responses of flower opening to ethylene in two cut rose cultivars, ‘Samantha’, whose opening process is promoted, and ‘Kardinal’, whose opening process is inhibited by ethylene. Ethylene production and 1-aminocyclopropane-1-carboxylate (ACC) synthase and oxidase activities were determined first. After ethylene treatment, ethylene production, ACC synthase (ACS) and ACC oxidase (ACO) activities in petals increased and peaked at the earlier stage (stage 3) in ‘Samantha’, and they were much more dramatically enhanced and peaked at the later stage (stage 4) in ‘Kardinal’ than control during vasing. cDNA fragments of three Rh-ACSs and one Rh-ACO genes were cloned and designated as Rh-ACS1, Rh-ACS2, Rh-ACS3 and Rh-ACO1 respectively. Northern blotting analysis revealed that, among three genes of ACS, ethylene-induced expression patterns of Rh-ACS3 gene corresponded to ACS activity and ethylene production in both cultivars. A more dramatic accumulation of Rh-ACS3 mRNA was induced by ethylene in ‘Kardinal’ than that of ‘Samantha’. As an ethylene action inhibitor, STS at concentration of 0.2 mmol/L generally inhibited the expression of Rh-ACSs and Rh-ACO in both cultivars, although it induced the expression of Rh-ACS3 transiently in ‘Kardinal’. Our results suggests that ‘Kardinal’ is more sensitive to ethylene than ‘Samantha’; and the changes of Rh-ACS3 expression caused by ethylene might be related to the acceleration of flower opening in ‘Samantha’ and the inhibition in ‘Kardinal’. Additional results indicated that three Rh-ACSs genes were differentially associated with flower opening and senescence as well as wounding.     

Molecular and physiological evidence suggests the existence of a system II-like pathway of ethylene production in non-climacteric<Emphasis Type="Italic"> Citrus</Emphasis> fruit

Mature citrus fruits, which are classified as non-climacteric, evolve very low amounts of ethylene during ripening but respond to exogenous ethylene by ripening-related pigment changes and accelerated respiration. In the present study we show that young citrus fruitlets attached to the tree produce high levels of ethylene, which decrease dramatically towards maturation. Upon harvest, fruitlets exhibited a climacteric-like rise in ethylene production, preceded by induction of the genes for 1-aminocyclopropane-1-carboxylate (ACC) synthase 1 (CsACS1), ACC oxidase 1 (CsACO1) and the ethylene receptor CsERS1. This induction was advanced and augmented by exogenous ethylene or propylene, indicating an autocatalytic system II-like ethylene biosynthesis. In mature, detached fruit, very low rates of ethylene production were associated with constitutive expression of the ACC synthase 2 (CsACS2) and ethylene receptor CsETR1 genes (system I). CsACS1 gene expression was undetectable at this stage, even following ethylene or propylene treatment, and CsERS1 gene expression remained constant, indicating that no autocatalytic response had occurred. The transition from system II-like behavior of young fruitlets to system I behavior appears to be under developmental control.Abbreviations ACC 1-Aminocyclopropane-1-carboxylate - CsACS1, CsACS2 ACC synthase - CsACO1 ACC oxidase - CsERS1, CsETR1 Ethylene receptors - DAFB Days after full bloom - 1-MCP 1-Methylcyclopropene     

Identification of Novel Inhibitors of 1-Aminocyclopropane-1-carboxylic Acid Synthase by Chemical Screening in Arabidopsis thaliana

Ethylene is a gaseous hormone important for adaptation and survival in plants. To further understand the signaling and regulatory network of ethylene, we used a phenotype-based screening strategy to identify chemical compounds interfering with the ethylene response in Arabidopsis thaliana. By screening a collection of 10,000 structurally diverse small molecules, we identified compounds suppressing the constitutive triple response phenotype in the ethylene overproducer mutant eto1-4. The compounds reduced the expression of a reporter gene responsive to ethylene and the otherwise elevated level of ethylene in eto1-4. Structure and function analysis revealed that the compounds contained a quinazolinone backbone. Further studies with genetic mutants and transgenic plants involved in the ethylene pathway showed that the compounds inhibited ethylene biosynthesis at the step of converting S-adenosylmethionine to 1-aminocyclopropane-1-carboxylic acid (ACC) by ACC synthase. Biochemical studies with in vitro activity assay and enzyme kinetics analysis indicated that a representative compound was an uncompetitive inhibitor of ACC synthase. Finally, global gene expression profiling uncovered a significant number of genes that were co-regulated by the compounds and aminoethoxyvinylglycine, a potent inhibitor of ACC synthase. The use of chemical screening is feasible in identifying small molecules modulating the ethylene response in Arabidopsis seedlings. The discovery of such chemical compounds will be useful in ethylene research and can offer potentially useful agrochemicals for quality improvement in post-harvest agriculture.     

Exogenous Eethylene influences flower opening of cut roses (Rosa hybrida) by regulating the genes encoding ethylene biosynthesis enzymes

1 Introduction The simple gaseous phytohormone ethylene as apotent modulator has various roles in plant growth,development and in response to biotic and abioticstress, such as germination, fruit ripening, flower andleaf senescence, and responsiveness to pathogen attack and mechanical damage[1]. The opening and senes-cence of many kinds of flowers are correlated tightly to ethylene, including carnation, petunia, orchid and rose[2]. Generally, roses are classified as ethylene-sen-sitive, however…