赤霉素信号转导及其调控植物生长发育的研究进展

赤霉素(Gibberellins或gibberellic acid,GA)是植物生长发育所必需的植物激素之一,调控植物生长发育的多个过程。近年来随着植物分子生物学和功能基因组学的发展,有关GA信号转导途径及其调控植物生长发育的研究取得了一系列的进展。综述了GA信号转导途径的关键组分,包括GA受体GIBBERELLIN INSENSITIVE DWARF1(GID1)蛋白、F-box蛋白(拟南芥中的SLEEPY1[SLY1]和水稻中的GIBBERELLIN INSENSITIVE DWARF2[GID2])及DELLA蛋白,阐述了GA去除DELLA蛋白阻遏作用的分子模型,同时探讨DELLA蛋白通过其互作蛋白整合其它激素及环境信号调控植物生长发育的作用机理。     

植物BBX转录因子基因家族的研究进展

转录因子在调控植物生长、发育及环境适应性等方面发挥重要作用。具有B-box结构域的一类锌指结构转录因子称为BBX,它们通过调控基因转录,与同类或其他转录因子的互作参与植物光形态建成、花发育、避荫效应、植物信号转导以及非生物和生物逆境响应等。文中从BBX蛋白结构、分类以及其功能方面对该类转录因子在植物中的作用进行了综述。     

DELLA蛋白在被子植物有性生殖中的作用

DELLA蛋白是植物生长发育过程中响应赤霉素(GA)应答途径的关键调控因子, 主要行使转录调控因子的功能, 几乎参与了植物生长发育的各个重要过程。已有的研究表明, DELLA蛋白在被子植物的雄性生殖器官、雌性生殖器官和胚胎等组织中均有表达, 在植物有性生殖过程中起着极其重要的作用。该文综述了DELLA蛋白的分子结构、特性及其在植物有性生殖过程中的表达与功能, 并讨论了现存的问题及研究思路。     

赤霉素作用机理的分子基础与调控模式研究进展

赤霉素（gibberellins或gibberellic acid,GA）作为植物生长的必需激素之一,调控植物生长发育的各个方面,如：种子萌发,下胚轴的伸长,叶片的生长和植物开花时间等。近年来随着植物功能基因组学的进一步发展,有关赤霉素生物合成及其调控,赤霉素信号转导途径,以及赤霉素与其他激素和环境因子的互作等领域的研究取得了较大的进展。本文综述了赤霉素生物合成的生物学途径及其调控研究;GA信号转导通道的研究进展,特别是DELLA蛋白阻遏植物生长发育的分子机理和GA解除阻遏作用（derepress）的分子模型;GA受体研究的新进展;探讨GA与其它激素之间的相互作用,以及植物在应答环境过程中的作用。     

赤霉素作用机理的分子基础与调控模式研究进展

赤霉素(gibberellins或gibberellic acid, GA)作为植物生长的必需激素之一, 调控植物生长发育的各个方面, 如: 种子萌发, 下胚轴的伸长, 叶片的生长和植物开花时间等。近年来随着植物功能基因组学的进一步发展, 有关赤霉素生物合成及其调控, 赤霉素信号转导途径, 以及赤霉素与其他激素和环境因子的互作等领域的研究取得了较大的进展。本文综述了赤霉素生物合成的生物学途径及其调控研究; GA信号转导通道的研究进展, 特别是DELLA蛋白阻遏植物生长发育的分子机理和GA解除阻遏作用(derepress)的分子模型; GA受体研究的新进展; 探讨GA与其它激素之间的相互作用, 以及植物在应答环境过程中的作用。     

果树赤霉素代谢与信号途径研究进展

赤霉素作为5大植物激素之一,在果树的花芽分化、花序发育、开花坐果、果实的生长发育及植株的形态建成等方面扮演着重要的角色,但对果树赤霉素的分子生物学研究与其他大田作物相比差距较大。为了在果树生产中能更加合理有效地利用赤霉素调控果树花果发育,研究果树赤霉素的合成及其信号转导途径的分子调控机制十分必要。研究发现GA合成的关键酶KO、GA2ox及GA20ox的表达均与果树矮化呈负相关,而KS的含量则与植株高矮呈正相关,板栗雄性不育现象也与KO、KAO的表达量密切相关。GAMYB基因及LFY基因则在果树的成花诱导和雄蕊发育等生殖生长过程中发挥重要作用。DELLA蛋白在果树的GA信号途径中作为负调控因子可致使矮化植株形成,在果树的细胞周期循环过程、转录调控、花的形成、细胞的信号转导及许多生理过程中,DELLA蛋白泛素化降解均扮演着至关重要的角色。主要从果树赤霉素的合成及赤霉素的信号途径两大方面,着重对果树赤霉素合成过程中的关键酶基因及其定位、果树赤霉素信号途径的重要元件如赤霉素受体GID1、DELLA蛋白等进行了综述,以期为高效利用赤霉素调控果树生长发育提供重要的理论参考。     

植物WRKY转录因子家族基因抗病相关功能的研究进展

植物基因组中,数目众多的转录因子参与植物的生长发育、物质代谢、响应生物和/或非生物胁迫等多种生物进程.WRKY基因家族是植物重要的转录因子家族,在抗病信号转导途径中起重要调控作用,因而成为分子植物病理研究领域中的热点.本文综述了WRKY转录因子基因在植物抗病反应中的作用和调节机制的最新研究进展,以期为深入研究WRKY基因家族在植物抗病反应中的作用,阐明植物抗病信号转导途径提供帮助.     

甘蓝DELLA基因家族鉴定及其mRNA在嫁接体中的运输分析

DELLA基因家族参与植物激素信号转导通路的调控，其中GAI(GA insensitive)mRNA还是植物体内长距离运输的信号分子。在全基因组范围内鉴定甘蓝(Brassica oleracea var. capitata) DELLA基因家族成员并分析mRNA运输特性，可为甘蓝DELLA基因家族的开发应用提供基础数据。本研究利用甘蓝基因组数据和转录组数据，在甘蓝中鉴定了5个DELLA基因家族成员(BoRGA1、BoRGA2、BoRGL1、BoRGL2和BoRGL3)，但甘蓝基因组缺失了GAI基因。采用劈接法将甘蓝(自交系G27)接穗和菜心(Brassica campestris L. ssp. chinensis var.utilis Tsen et Lee)(四九菜心)砧木嫁接在一起，构建异源嫁接体。对砧木菜心花序轴和对应位置的实生苗菜心花序轴(对照)取样进行转录组测序。在甘蓝/菜心异源嫁接体的砧木菜心花序轴的转录组测序文库中分别鉴定到8、9、3、5、1个来自甘蓝BoRGA1、BoRGA2、BoRGL1、BoRGL2和BoRGL3的外源read。甘蓝DELLA家族基因mRNA运输并...     

石榴WRKY基因家族全基因组鉴定与表达分析

WRKY蛋白是一类在植物生长发育过程及生物与非生物胁迫过程中起重要调控作用的转录因子。该研究利用石榴全基因组数据,采用生物信息学的方法,对石榴WRKY转录因子家族成员蛋白理化性质、系统进化、基因结构、保守基序、顺式作用元件、蛋白互作及基因共表达和转录组表达模式进行系统分析。结果共鉴定出69个PgWRKY基因;分组鉴定和进化分析显示WRKY蛋白可分为Ⅰ、Ⅱ和Ⅲ共三大类型。顺式作用元件分析表明,PgWRKY基因广泛参与到非生物胁迫中;蛋白互作网络与共表达分析暗示PgWRKY基因在同一胁迫应答中可能作用一致并同时诱导表达;RNA-Seq数据分析表明,PgWRKY基因有一定的组织表达特异性,广泛参与植物营养、生殖生长以及根部逆境胁迫应答过程。     

棉花DELLA蛋白基因GhGAI3和GhGAI4启动子的克隆及序列分析

棉纤维是纺织行业的重要原材料。赤霉素能够促进棉纤维的生长发育,而DELLA蛋白又是赤霉素信号转导通路中的关键调控因子,因此研究棉花DELLA蛋白基因表达的调控模式,对阐明棉纤维生长发育的分子生物学机理具有重要意义。本研究根据两个棉花DELLA蛋白基因GhGAI3和GhGAI4序列设计特异引物,以陆地棉新陆早13号的基因组DNA为模板,用基因组步移法克隆了棉花DELLA蛋白基因GhGAI3和GhGAI4的启动子。对两个启动子进行序列分析表明,这两个启动子均具有真核生物典型的核心启动子区,同时也都具有一个或多个光响应元件和赤霉素响应元件,说明这两个基因可能受到光信号和赤霉素信号的调控,这与其它植物中DELLA蛋白的表达模式是一致的。此外,这两个启动子还具有各种转录调控相关的顺式作用元件,比如其它激素类的响应元件和逆境胁迫响应元件,说明棉花中DELLA蛋白基因可能在响应其它激素信号以及逆境胁迫中也起到一定的作用。     

珍珠黄杨矮化基因BsGAI2的克隆及功能分析

GA信号转导途径或生物合成受阻是导致植物矮化的重要因素,而DELLA蛋白是GA信号传导通路中一类重要的负调节因子。本研究利用同源克隆和RACE技术,从珍珠黄杨中克隆得到BsGAI2基因的c DNA序列,全长为2305 bp,包括1836 bp完整的ORF。实时荧光定量表达分析表明,BsGAI2基因在珍珠黄杨茎中表达量最高,在根中表达量最低;BsGAI2转基因烟草呈明显矮化,节间变短,长势较慢,延迟开花等特征。利用GFP荧光检测方法鉴定转化型烟草,发现转化苗的叶、茎中均有荧光信号,并且茎木质部有明亮富集的荧光信号。这些结果均表明BsGAI2基因可能在珍珠黄杨茎节间缩短导致矮化的过程中扮演重要角色。本研究分析了BsGAI2基因编码蛋白的理化性质和功能鉴定,为今后进一步研究BsGAI2基因及DELLA蛋白家族的功能提供了理论依据。     

PHOR1: A U-Box GA Signaling Component With a Role in Proteasome Degradation?

Recent identification of U-box proteins as E3 ubiquitin ligases suggests that the U-box arm-repeat protein PHOR1, for which we have demonstrated a role in GA signal transduction, may play a role in GA signaling by ubiquitinating one or more components of the GA response pathway to target them for proteasome degradation. Here we show that PHOR1 function in GA signaling is not exclusive of potato plants, but it is also conserved in Arabidopsis. Three PHOR1-homologs have been identified in this plant species, which would correspond to PHOR1-orthologs. Experimental evidence has recently been obtained for the involvement of proteasome-dependent protein degradation in GA-mediated destabilization of the SLN1 DELLA protein, thus pointing to this repressor as a likely substrate for ubiquitination by the PHOR1 ubiquitin ligase activity.     

Ethylene regulates arabidopsis development via the modulation of DELLA protein growth repressor function

Phytohormones regulate plant development via a poorly understood signal response network. Here, we show that the phytohormone ethylene regulates plant development at least in part via alteration of the properties of DELLA protein nuclear growth repressors, a family of proteins first identified as gibberellin (GA) signaling components. This conclusion is based on the following experimental observations. First, ethylene inhibited Arabidopsis root growth in a DELLA-dependent manner. Second, ethylene delayed the GA-induced disappearance of the DELLA protein repressor of ga1-3 from root cell nuclei via a constitutive triple response-dependent signaling pathway. Third, the ethylene-promoted "apical hook" structure of etiolated seedling hypocotyls was dependent on the relief of DELLA-mediated growth restraint. Ethylene, auxin, and GA responses now can be attributed to effects on DELLA function, suggesting that DELLA plays a key integrative role in the phytohormone signal response network.     

Arabidopsis DELLA Protein Degradation Is Controlled by a Type-One Protein Phosphatase,TOPP4

Gibberellins (GAs) are a class of important phytohormones regulating a variety of physiological processes during normal plant growth and development. One of the major events during GA-mediated growth is the degradation of DELLA proteins, key negative regulators of GA signaling pathway. The stability of DELLA proteins is thought to be controlled by protein phosphorylation and dephosphorylation. Up to date, no phosphatase involved in this process has been identified. We have identified a dwarfed dominant-negative Arabidopsis mutant, named topp4-1. Reduced expression of TOPP4 using an artificial microRNA strategy also resulted in a dwarfed phenotype. Genetic and biochemical analyses indicated that TOPP4 regulates GA signal transduction mainly via promoting DELLA protein degradation. The severely dwarfed topp4-1 phenotypes were partially rescued by the DELLA deficient mutants rga-t2 and gai-t6, suggesting that the DELLA proteins RGA and GAI are required for the biological function of TOPP4. Both RGA and GAI were greatly accumulated in topp4-1 but significantly decreased in 35S-TOPP4 transgenic plants compared to wild-type plants. Further analyses demonstrated that TOPP4 is able to directly bind and dephosphorylate RGA and GAI, confirming that the TOPP4-controlled phosphorylation status of DELLAs is associated with their stability. These studies provide direct evidence for a crucial role of protein dephosphorylation mediated by TOPP4 in the GA signaling pathway.     

DELLA Proteins and GA Signalling in <Emphasis Type="Italic">Arabidopsis</Emphasis>

Gibberellin (GA) is a classical plant hormone involved in many aspects of plant growth and development. A family of five homologs called the DELLA proteins, comprised of GAI, RGA, RGL1, RGL2 and RGL3, were recently found to act as critical GA signal mediators in Arabidopsis. Reports have shown that GAI and RGA are coupled together to repress stem elongation growth whereas RGL2 is a major negative regulator of seed germination. GA down-regulates DELLA proteins through protein degradation likely via the proteasome pathway. The conserved and functionally important DELLA domain is responsible for protein stability in response to GA.     

毛竹茎秆伸长过程中赤霉素生物合成、降解和信号转导关键基因的鉴定及表达分析

赤霉素(Gibberellin)是一类非常重要的植物激素,在高等植物生命活动的整个周期都起着重要的调控作用。从毛竹Phyllostachys edulis基因组中共鉴定出23个赤霉素途径基因,包括赤霉素生物合成相关的8个GA20ox和1个GA3ox基因、降解相关的8个GA2ox基因、参与赤霉素感知的2个GID1基因以及信号转导的2个GID2基因和2个DELLA基因。拟南芥、水稻和毛竹的系统进化树和保守基序分析显示赤霉素的合成代谢与信号转导在这些物种中是高度保守的。利用外源赤霉素处理毛竹种子和幼苗,发现赤霉素能显著提高种子的萌发率和幼苗的茎秆伸长,并且有着最佳的作用浓度。在GA3处理后,毛竹体内赤霉素生物合成基因GA20ox和GA3ox表达量均下调而降解活性赤霉素的GA2ox基因表达量上调;赤霉素受体GID1和正调控基因GID2的转录水平显著提高而负调控基因DELLA的表达受到抑制。这些基因在竹笋茎秆的不同形态学位置表达差异明显,大部分赤霉素生物合成与降解的相关基因GA20ox、GA3ox和GA2ox以及赤霉素受体GID1和正调控基因GID2都在竹笋的形态学上端大量表达,而赤霉素信号转导的阻遏基因DELLA在笋体形态学底端大量积累而顶端基本不表达。     

高等植物赤霉素代谢及其信号转导通路

赤霉素是一类重要的植物激素,对植物的生长发育,如种子的萌发、茎的延展、叶片的生长、休眠芽的萌发以及植物的花和种子的发育等生理具有重要的调控作用。从1926年被发现至今,阐明了赤霉素代谢机理及调控机制,明确了赤霉素在植物体内的信号转导途径。本文综述了赤霉素的生物合成途径及其平衡的调节;赤霉素受体GID1、DELLA蛋白在赤霉素信号转导途径中的作用及相关研究;泛素介导的DELLA蛋白降解在赤霉素信号转导中的研究进展。     

Struggling for Light: DELLA Regulation During Plant-Plant Interactions

We recently described how DELLA proteins are involved in plant growth responses to neighbors in dense stands. These responses that are called shade avoidance include enhanced stem and petiole elongation and are a classic example of adaptive phenotypic plasticity. Although much is known about neighbor detection, much less is known about the signal transduction network downstream of these signals. We will discuss here how a group of growth-supressors, called DELLA proteins, are functionally regulated upon the detection of neighbors. DELLA proteins are degraded upon binding of gibberellin (GA) to its receptor, thus releasing the restraint of GA responses. We discuss here that GA positively regulates shade avoidance by reducing DELLA protein levels. Furthermore, we will show that this is an essential step in shade avoidance, but also that reduced DELLA abundance alone is not sufficient to induce these growth responses. It is concluded that GA-dependent DELLA degradation is one essential step in the signal transduction network from light-mediated neighbor detection towards adaptive shoot elongation responses.Key Words: arabidopsis, canopy, DELLA, eco-devo, gibberellin, light, phenotypic plasticity, phytochrome, shade avoidance