He-Ne激光对小麦ROP GTPase经增强UV-B辐射造成的损伤的修复研究

采用He-Ne激光辐照对增强UV-B辐射后小麦幼苗ROP GTPase损伤修复作用进行了研究。采用了SDS-PAGE电泳法检测各组ROP GTPase的含量和激光共聚焦显微镜对小麦微丝进行FITC荧光强度标记的测定。研究结果表明:经增强UV-B辐射后,小麦幼苗的Rop GTPase含量降低,LCSM扫描细胞原生质体形状发生改变,细胞骨架受到破坏,其被标记的荧光变暗,强度减弱,在整个UV-B处理期间均低于对照组(CK),再以He-Ne激光处理后,其含量,形状和强度均有所提高,但仍低于对照组。由此说明,UV-B辐射能使小麦幼苗的Rop GTPase含量下降,微丝骨架受到破坏,一定剂量的激光对UV-B辐射后小麦的蛋白含量和细胞骨架有一定修复作用。Rop GTPase参与了微丝骨架重组的过程。

Optimization of Extraction Methods of ROP GTPase from Young Leaves of Wheat

All of the Rho GTPase seems to form a special sub-family,because such a sub-family has so far only found in plants,and then named Rop GTPase,which directly involved in and regulated of muscle actin cytoskeletal reorganization,such as a series of signal transductions.The efficient purification technology and the means of ROP GTPase in wheat are the key basis of the studies on its functions and prosperities.And it has a very important theoretical and practical significance in the signal transduction and F-act...

百脉根小GTPaseROPs基因反转座子插入突变体的分离和鉴定

为研究ROP(Rho-related GTPase of plants,ROP)在豆科植物共生固氮过程中的功能和作用机制,从百脉根逆转录转座子LORE1插入突变体库(http://www.kazusa.or.jp/lotus)中搜索到6个ROP相关基因突变体,通过分离和鉴定,得到不同突变体的M1代和M2代纯合体种子,对M2代进行表型鉴定及统计分析。结果表明:在早期共生表型的鉴定中,突变体与野生型植株相比,rop-like1植株的根瘤原基数明显下降,rop-like4植株的侵入线数和侵入线密度也明显下降;但仅rop-like1植株在接种14d后的结瘤数明显减少。

小麦幼叶ROP GTPase提取方法的优化

所有RhoG TPase组成一个特殊的亚家族,命名为ROP GTPase,这个家族参与并调控肌动蛋白细胞骨架的重组等一系列信号转导过程。小麦ROP GTPase的高效纯化技术和手段是对其功能和性质等进行研究的重要基础和关键,并且这对小麦ROP GTPase关于信号转导以及F-actin的研究有着极为重要的理论和实践意义。采用凝胶过滤层析和分辨率较高的非变性聚丙烯酰胺凝胶电泳(Native-PAGE)等技术对小麦的ROP蛋白进行了提取、纯化和鉴定。

小G蛋白ROP的研究进展

小G蛋白(small GTPases)是近年来研究细胞信号转导过程的热点问题,包括Ras、Rab、Rho、Arf和Ran5个亚家族,其中ROP蛋白是Rho家族成员,为植物特有,在调控细胞生长、发育及调节植物对环境响应等各方面起重要作用.对ROP蛋白的活性调节和功能进行了重点介绍.

植物小G蛋白基因ROP生物学功能研究进展

ROP(Rho-related GTPases from plants)是高等植物中惟一一类分布广泛的信号小G蛋白,在植物生长、发育、抗逆、抗病和激素信号转导过程中起重要调控作用,被称为"分子开关"。该文综述了近年来植物ROP蛋白的生物学功能研究进展,为其它植物ROP蛋白功能研究提供借鉴。

Preliminary Characterization of Function of Rac /Rop GEF1 in Arabidopsis

[Objective]The aim was to research the function of AtGEF1 in Rac/Rop GTPses mediate auxin signal passway.[Method]Using the transgenic plants of AtGEF1 promotor fused with GUS reporter gene and the over-expression plants of Rac/Rop GEF1 under the control of 35S promoter as materials,which were constructed from our lab,the expression pattern of GEF1 was analyzed by GUS assay using histochemical staining,and the development of seedling roots of over-expression plant of GEF1 was observed.[Result]GEF1 expression was mainly detected in root meristem,root vascular tissue,lateral roots and root hair.Furthermore,the expression level of GEF1 was highly increased with the induction of NAA.Over-expression of GEF1 was observed to enhance lateral root formation.[Conclusion]GEF1 may be involved in the regulation of development of root and root hair,and it may have redundant function in the control of lateral root development.

拟南芥Rac/Rop GEF7基因功能研究

[目的]对拟南芥Rac/Rop GEF7(简称GEF7)基因在Rac/Rop GTPse介导的生长素信号途径等方面所起的作用进行初步探索。[方法]利用实验室已构建的稳定表达的拟南芥GEF7基因启动子与GUS融合的转基因植株和GEF7基因过表达的转基因植株,通过GUS组织化学染色分析GEF7基因的表达模式,并对GEF7基因过表达植株的幼苗根系发育情况进行分析。[结果]GEF7基因主要在幼苗根的分生组织和维管组织细胞、侧根原基和根毛细胞表达;经生长素(NAA)诱导处理后,在上述细胞中的表达显著增强。过表达GEF7基因促进侧根的形成。[结论]GEF7基因的功能与根和根毛细胞的发育有关,GEF7基因可能参与对侧根发育的调控。

ROPs:植物细胞内多种信号通路的分子开关

植物RHO相关蛋白GTPases(RHO-related GTPases of plants,ROPs)是广泛存在于植物中的一类信号转导G蛋白(又称GTP结合蛋白),其通过结合GDP或GTP在非活性和活性状态间进行切换,进而在细胞极性控制、形态发育、激素水平调控、逆境反应等诸多植物生命活动的信号转导过程中扮演重要的分子开关角色。本文对ROP蛋白的结构域及基于蛋白质结构分类进行了介绍,并对拟南芥、玉米、水稻和大麦中的ROP家族蛋白质进行了系统进化分析。分析结果表明,这些植物中的ROP蛋白根据蛋白质结构域组成可分为Ⅰ类(typeⅠ)和Ⅱ类(typeⅡ)两种类型,而根据蛋白质序列的保守性可将其在植物中的ROP蛋白划分为4个进化枝。本综述不但对ROP蛋白作为分子开关在细胞内调控各种信号通路的机制进行了叙述,还对ROP在花粉管、根毛及植物表皮铺盖细胞极性发育,以及其他抗逆反应中的具体作用和机制及研究进展进行了阐述。本文还对ROP蛋白在ABA、IAA、BR等植物激素信号传导过程中的调控作用及研究进展进行了阐述。本文对植物ROP蛋白研究过程中尚未解决的问题,例如不同的ROP蛋白在同一个信号通路中的作用为何如此不同,以及ROP是如何协调不同的信号通路以共同调控一个植物发育或者生理过程等问题进行了总结,并在此基础上对未来的研究方向进行了展望。

植物小G蛋白的研究进展

小G蛋白(small GTPases)是近年来细胞信号转导的研究热点,包括Ras、Rho、Rab、Arf和Ran等5个亚家族.植物中存在一种特殊的小G蛋白ROP(Rho-related GTPase from plants)是Rho家族成员,在调控细胞生长发育及植物防御反应体系的建立等方面起重要作用.在植物细胞中ROP存在两种形式,一种是与GTP结合的激活态,另一种是与GDP结合的非激活态,通过这种激活态与非激活态之间的转变,ROPs作为植物生长发育过程中重要的分子开关"参与调控多种信号转导过程.本文主要对国内外近年来有关小G蛋白的种类及其调节机制,以及植物小G蛋白ROP在花粉管生长、根毛发育、H2O2的产生、脱落酸(ABA)以及防御应答反应中的调节作用等方面的研究进展进行综述.

植物小G蛋白研究进展

小G蛋白是和异三聚体G蛋白α亚基偶联的单体鸟苷酸结合蛋白,所有的小G蛋白从属于Ras超家族.植物小G蛋白超家族尤其是ROP家族在信号转导及生长发育中起了重要的"分子开关"作用,它们参与调控花粉管的伸长、根毛的发育及激素信号转导等过程.主要介绍了小G蛋白的种类、调节机制、ROP家族的功能及靶物,旨在揭示植物小G蛋白功能的多样性.

聚合物PDMS片表面特性的AFM和XPS初步研究

本文用原子力显微镜(AFM),研究常用固化模具材料玻璃、有机玻璃(PMMA)和塑料制作的PDMS盖片的表面特性。并用XPS分析PDMS表面的化学组成,表明在优化的PDMS芯片制作条件下,PDMS芯片的自粘粘合力取决于盖片的表面粗糙度。

ROP11 GTPase is a Negative Regulator of Multiple ABA Responses in Arabidopsis

The phytohormone abscisic acid （ABA） plays crucial roles in plant development and plant responses to environmental stresses. Although ABA receptors and a minimal set of core molecular components have recently been discovered, understanding of the ABA signaling pathway is still far from complete. In this work, we characterized the function of ROP11, a member of the plant-specific ROP small GTPases family, in the ABA signaling process. ROP11 is preferentially expressed in guard cells in all plant organs with stomata. Expression of a constitutively active ROP11 （CA-ROP11） suppresses ABA-mediated responses, whereas reduced expression of ROP11 or expression of its dominant-negative form （DN-ROP11） causes the opposite phenotypes. The affected ABA-mediated responses by ROP11 include seed germination, seedling growth, stomatal closure, induction of ABA-responsive genes, as well as plant response to drought stress. Furthermore, we showed that ROP11 and its closest-related family member, ROP10, act in parallel in mediating these responses. ABA treatment does not affect ROP11 transcription and protein abundance; however, it causes the accumulation of CA-ROP11 in the nucleus. These results demonstrated that ROP11 is a negative regulator of multiple ABA responses in Arabidopsis.

ROP GTPase-mediated auxin signaling regulates pavement cell interdigitation in Arabidopsis thaliana

In multicellular plant organs, cell shape formation depends on molecular switches to transduce developmental or environmental signals and to coordinate cell-to-cell communi- cation. Plants have a specific subfamily of the Rho GTPase family, usually called Rho of Plants （ROP）, which serve as a critical signal transducer involved in many cellular processes. In the last decade, important advances in the ROP-mediated regulation of plant cell morphogenesis have been made by using Arubidopsis thaliana leaf and cotyledon pavement cells. Especially, the auxin-ROP signaling networks have been demonstrated to control interdigitated growth of pavement ceils to form jigsaw-puzzle shapes. Here, we review findingsrelated to the discovery of this novel auxin-signaling mecha- nism at the cell surface. This signaling pathway is to a large extent independent of the well-known Transport Inhibitor Response （TIR）-Auxin Signaling F-Box （AFB） pathway, and instead requires Auxin Binding Protein 1 （ABP1） interaction with the plasma membrane-localized, transmembrane kinase （TMK） receptor-like kinase to regulate ROP proteins. Once activated, ROP influences cytoskeletal organization and inhibits endocytosis of the auxin transporter PINt. The present review focuses on ROP signaling and its self-organizing feature allowing ROP proteins to serve as a bustling signal decoder and integrator for plant cell morphogenesis.

ROP11 GTPase Negatively Regulates ABA Signaling by Protecting ABI1 Phosphatase Activity from Inhibition by the ABA Receptor RCAR1/PYL9 in Arabidopsis

The phytohormone abscisic acid （ABA） regulates many key processes in plants, such as seed germina- tion, seedling growth, and abiotic stress tolerance. In recent years, a minimal set of core components of a major ABA signaling pathway has been discovered. These components include a RCAR/PYR/PYL family of ABA receptors, a group of PP2C phosphatases, and three SnRK2 kinases. However, how the interactions between the receptors and their targets are regulated by other proteins remains largely unknown. In a companion paper published in this issue, we showed that ROP11, a member of the plant- specific Rho-like small GTPase family, negatively regulates multiple ABA responses in Arabidopsis. The current work demonstrated that the constitutively active ROP11 （CA-ROP11） can modulate the RCAR1/PYL9-mediated ABA signaling pathway based on reconstitution assays in Arabidopsis thaliana protoplasts. Furthermore, using luciferase complementation imaging, yeast two-hybrid assays, co- immunoprecipitation assays in Nicotiana benthamiana and bimolecular fluorescence complementation assays, we demonstrated that CA-ROP11 directly interacts with ABI1, a signaling component downstream of RCAR1/PYL9. Finally, we provided biochemical evidence that CA-ROP11 protects ABI1 phosphatase activity from inhibition by RCAR1/PYL9 and thus negatively regulates ABA signaling in plant cells. A model of how ROP11 acts to negatively regulate ABA signaling is presented.

植物小G蛋白功能的最新研究进展

小G蛋白超家族包括Ras、Rab、Rho、Arf和Ran亚家族,不同成员间在结构和功能方面又呈现明显的多样性。小G蛋白作为重要的分子开关,其结构域主要包括4个鸟苷酸(GTP/GDP)结合域、1个效应区,其鸟苷酸结合域起着关键作用且保守性最高,在植物、动物和酵母中均有较高的保守性。小G蛋白成员凭借其多样性和不同鸟苷酸结合态的功能调控(结合GTP时为活性状态,而结合GDP时为非活性状态),参与多种细胞生命活动,履行不同的生物学功能,例如基因表达调控,细胞骨架重组,囊泡运输的调节,出芽过程,核-质运输及微管形成。本文主要阐述植物中研究小G蛋白各个家族功能的最新进展。

水稻Rop基因OsRac5的表达特性

Rop在植物生长、发育、免疫及环境信号应答等多种生物学过程中具有重要作用。已有研究显示水稻Rop基因OsRac5可能与育性控制有关,但是该基因的表达特性,以及非生物胁迫和植物生长物质对其表达的影响尚不清楚。本文采用qRT-PCR技术检测了OsRac5在水稻生长发育过程中、非生物胁迫以及植物生长物质处理条件下的表达特性,结果显示OsRac5在水稻生长发育过程中在多种组织广泛表达,尤其在根和雌雄蕊形成期的幼穗中高表达;干旱、高盐和低温等非生物胁迫均能诱导OsRac5的表达;ABA、GAs、6-BA等植物生长物质能上调OsRac5基因表达,提示该基因与水稻幼穗发育、抗逆性及细胞生长等过程相关。

AtPRK2 Promotes ROP1 Activation via RopGEFs in the Control of Polarized Pollen Tube Growth

The ROP1 GTPase-based signaling network controls tip growth in Arabidopsis pollen tubes. Our previous studies imply that ROP1 might be directly activated by RopGEF1, which belongs to a plant-specific family of Rho guanine nucleotide exchange factors （RopGEFs） and in turn may be activated by an unknown factor through releasing RopGEFI＇s auto-inhibition. In this study, we found that RopGEF1 forms a complex with ROP1 and AtPRK2, a receptor-like protein kinase previously shown to interact with RopGEFs. AtPRK2 phosphorylated RopGEF1 in vitro and the atprkl,2,5 tri- ple mutant showed defective pollen tube growth, similar to the phenotype of the ropgef1,9,12,14 quadruple mutant. Overexpression of a dominant negative form of AtPRK2 （DN-PRK2） inhibited pollen germination in Arabidopsis and reduced pollen elongation in tobacco. The DN-PRK2-induced pollen germination defect was rescued by overexpressing a constitutively active form of RopGEF1, RopGEF1（90-457）, implying that RopGEF1 acts downstream of AtPRK2. Moreover, AtPRK2 increased ROP1 activity at the apical plasma membrane whereas DN-PRK2 reduced ROP1 activity. Finally, two mutations at the C-terminal putative phosphorylation sites of RopGEF1 （RopGEF1S460A and RopGEF1S480A） eliminated the function of RopGEF1 in vivo. Taken together, our results support the hypothesis that AtPRK2 acts as a positive regula- tor of the ROP1 signaling pathway most likely by activating RopGEF1 through phosphorylation.

Arabidopsis ROP1 and ROP6 Influence Germination Time, Root Morphology, the Formation of F-Actin Bundles, and Symbiotic Fungal Interactions

The RHO-related GTPases ROP1 and ROP6 and the ROPl-interacting protein RIC4 in Arabidopsis are involved in various processes of F-actin dynamics, cell growth, and plant/microbe interactions. The knockout ropl and ropl rop6 seeds germinate earlier and are impaired in root hair development. Also root hair branching is strongly affected by manipulation of the RHO-related GTPase （ROP） levels. Furthermore, in the double knockout line ropl rop6, no actin bundle formation can be detected. We demonstrate that these proteins are required for establishing a mutualistic interaction between the root-colonizing endophytic fungus Piriformospora indica and Arabidopsis. The fungus promotes growth of wild-type plants, ropl, rop6, ropl rop6, ric4, 35S：：ROP1, and 35S：：ROP6 seedlings are impaired in the response to the fungus. Since the different root architectures have no effect on root colonization, the impaired response to P. indica should be caused by ROP-mediated events in the root cells. In wild-type roots, P. indica stimulates the formation of F-actin bundles and this does not occur in the ropl rop6 knockout line. Furthermore, the fungus stimulates the expression of the calmodulin-binding protein gene Cbp60g, and this response is severely reduced in the rop mutants. We propose that ROP1 and ROP6 are required for F-actin bundle formation in the roots, which is required for P. indica-mediated growth promotion in Arabidopsis.

Arabidopsis SYP121 acts as an ROP2 effector in the regulation of root hair tip growth

Tip growth is an extreme form of polarized cell expansion that occurs in all eukaryotic kingdoms to generate highly elongated tubular cells with specialized functions, including fungal hyphae, animal neurons, plant pollen tubes, and root hairs (RHs). RHs are tubular structures that protrude from the root epidermis to facilitate water and nutrient uptake, microbial interactions, and plant anchorage. RH tip growth requires polarized vesicle targeting and active exocytosis at apical growth sites. However, how apical exocytosis is spatially and temporally controlled during tip growth remains elusive. Here, we report that the Qa-Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) SYP121 acts as an effector of Rho of Plants 2 (ROP2), mediating the regulation of RH tip growth. We show that active ROP2 promotes SYP121 targeting to the apical plasma membrane. Moreover, ROP2 directly interacts with SYP121 and promotes the interaction between SYP121 and the R-SNARE VAMP722 to form a SNARE complex, probably by facilitating the release of the Sec1/Munc18 protein SEC11, which suppresses the function of SYP121. Thus, the ROP2-SYP121 pathway facilitates exocytic trafficking during RH tip growth. Our study uncovers a direct link between an ROP GTPase and vesicular trafficking and a new mechanism for the control of apical exocytosis, whereby ROP GTPase signaling spatially regulates SNARE complex assembly and the polar distribution of a Q-SNARE.