一个水稻蛋白激酶的过表达分析及表达调控

对一个预测的具有光反应活性的丝氨酸/苏氨酸蛋白激酶STK进行过表达研究,构建了STK过表达载体,并用农杆菌介导的方法进行遗传转化,获得T0代转基因植株.对转基因阳性植株进行表达分析的结果表明,转基因植株STK基因的表达量显著高于对照,说明目的基因得到了过表达.另外,利用获得的过表达转基因植株对STK调控水稻中光周期相关的开花基因Hd1和Hd3a的表达进行分析,结果表明,Hd1及Hd3a的表达在转基因植株中明显上调,表明该蛋白激酶的基因可能位于Hd1和Hd3a上游,对于Hd1和Hd3a的表达具有重要的调控作用.     

Adaptation of photoperiodic control pathways produces short-day flowering in rice

The photoperiodic control of flowering is one of the important developmental processes of plants because it is directly related to successful reproduction. Although the molecular genetic analysis of Arabidopsis thaliana, a long-day (LD) plant, has provided models to explain the control of flowering time in this species, very little is known about its molecular mechanisms for short-day (SD) plants. Here we show how the photoperiodic control of flowering is regulated in rice, a SD plant. Overexpression of OsGI, an orthologue of the Arabidopsis GIGANTEA (GI) gene in transgenic rice, caused late flowering under both SD and LD conditions. Expression of the rice orthologue of the Arabidopsis CONSTANS (CO) gene was increased in the transgenic rice, whereas expression of the rice orthologue of FLOWERING LOCUS T (FT) was suppressed. Our results indicate that three key regulatory genes for the photoperiodic control of flowering are conserved between Arabidopsis, a LD plant, and rice, a SD plant, but regulation of the FT gene by CO was reversed, resulting in the suppression of flowering in rice under LD conditions.     

CONSTANS mediates between the circadian clock and the control of flowering in Arabidopsis

Flowering is often triggered by exposing plants to appropriate day lengths. This response requires an endogenous timer called the circadian clock to measure the duration of the day or night. This timer also controls daily rhythms in gene expression and behavioural patterns such as leaf movements. Several Arabidopsis mutations affect both circadian processes and flowering time; but how the effect of these mutations on the circadian clock is related to their influence on flowering remains unknown. Here we show that expression of CONSTANS (CO), a gene that accelerates flowering in response to long days, is modulated by the circadian clock and day length. Expression of a CO target gene, called FLOWERING LOCUS T (FT), is restricted to a similar time of day as expression of CO. Three mutations that affect circadian rhythms and flowering time alter CO and FT expression in ways that are consistent with their effects on flowering. In addition, the late flowering phenotype of such mutants is corrected by overexpressing CO. Thus, CO acts between the circadian clock and the control of flowering, suggesting mechanisms by which day length regulates flowering time.     

F-box proteins in flowering plants

In eukaryotes, the ubiquitin-mediated protein degradation pathway has been shown to control several key biological processes such as cell division, development, metabolism and immune response. F-box proteins, as a part of SCF (Skp1-Cullin (or Cdc53)-F-box) complex, functioned by interacting with substrate proteins, leading to their subsequent degradation by the 26S proteasome. To date, several F-box proteins identified in Arabidopsis and Antirrhinum have been shown to play important roles in auxin signal transduction, floral organ formation, flowering and leaf senescence. Arabidopsis genome sequence analysis revealed that it encodes over 1000 predicted F-box proteins accounting for about 5% of total predicted proteins. These results indicate that the ubiquitin-mediated protein degradation involving the F-box proteins is an important mechanism controlling plant gene expression. Here, we review the known F-box proteins and their functionsin flowering plants.     

细胞分裂素对马铃薯块茎形成的影响

玉米素(ZT)和玉米素核苷(ZR)抑制马铃薯黄化萌条节段或匍匐茎切段的块茎形成,激动素(KT)作用相反;ZT和KT都可以提高匍匐茎中碳水化合物的含量,降低蔗糖酶活性,对淀粉酶活性基本无影响;ZT和KT均不促进完整植株的块茎形成,ZT可破除LD条件下植株的顶端优势.认为内源细胞分裂素不是诱导块茎形成的物质.     

Regulation of flowering time by light quality

The transition to flowering in plants is regulated by environmental factors such as temperature and light. Plants grown under dense canopies or at high density perceive a decrease in the ratio of red to far-red incoming light. This change in light quality serves as a warning of competition, triggering a series of responses known collectively as the 'shade-avoidance syndrome'. During shade avoidance, stems elongate at the expense of leaf expansion, and flowering is accelerated. Of the five phytochromes-a family of red/far-red light photoreceptors-in Arabidopsis, phytochrome B (phyB) has the most significant role in shade-avoidance responses, but the mechanisms by which phyB regulates flowering in response to altered ratios of red to far-red light are largely unknown. Here we identify PFT1 (PHYTOCHROME AND FLOWERING TIME 1), a nuclear protein that acts in a phyB pathway and induces flowering in response to suboptimal light conditions. PFT1 functions downstream of phyB to regulate the expression of FLOWERING LOCUS T (FT), providing evidence for the existence of a light-quality pathway that regulates flowering time in plants.     

水稻花期干旱胁迫应答基因Os07g0422100启动子的克隆及鉴定

水稻作为需水量最大的作物之一,对于水分的胁迫异常敏感.对处于花期的水稻进行干旱胁迫处理,利用基因芯片技术筛选出在水稻花穗中特异性表达的应答干旱胁迫的基因Os07g0422100.在对该基因的研究中发现,该基因的表达图谱有较高的专一性,且该基因的启动子属于诱导型启动子,仅在受到干旱胁迫的水稻花穗中表达.利用Os07g04...     

The ELF3 zeitnehmer regulates light signalling to the circadian clock

The circadian system regulates 24-hour biological rhythms and seasonal rhythms, such as flowering. Long-day flowering plants like Arabidopsis thaliana, measure day length with a rhythm that is not reset at lights-off, whereas short-day plants measure night length on the basis of circadian rhythm of light sensitivity that is set from dusk, early flowering 3 (elf3) mutants of Arabidopsis are aphotoperiodic and exhibit light-conditional arrhythmias. Here we show that the elf3-7 mutant retains oscillator function in the light but blunts circadian gating of CAB gene activation, indicating that deregulated phototransduction may mask rhythmicity. Furthermore, elf3 mutations confer the resetting pattern of short-day photoperiodism, indicating that gating of phototransduction may control resetting. Temperature entrainment can bypass the requirement for normal ELF3 function for the oscillator and partially restore rhythmic CAB expression. Therefore, ELF3 specifically affects light input to the oscillator, similar to its function in gating CAB activation, allowing oscillator progression past a light-sensitive phase in the subjective evening. ELF3 provides experimental demonstration of the zeitnehmer ('time-taker') concept.     

Can transgenic rice cause ecological risks through transgene escape?

Alien transgene escape from genetically engineered rice to non-transgenic varieties or close wild relatives (including weedy rice) may lead to unpredictable ecological risks. However, for transgene escape to occur three conditions need to be met: (i) spatially, transgenic rice and its non-transgenic counterparts or wild relatives should have sympatric distributions; (ii) temporally, the flowering time of transgenic rice and the non-transgenic varieties or wild relatives should overlap; and (iii) biologically, transgenic rice and its wild relative species should have such a sufficiently close relationship that their interspecific hybrids can have normal generative reproduction. This paper presents research data on the geographic distribution, flowering habits, interspecific hybridization, and gene flow of cultivated rice (Oryza sativa) and its closely related wild relatives containing the AA genome. The objective is to estimate the possibility of transgene escape to non-transgenic rice varieties and wild relatives of rice, which may result in unpredictable ecological risks.     

Cloning and characterization of rice RH3 gene induced by brown planthopper

Histones are basic low molecular weight proteins found in all eukaryotic genomes. The histones include five classes of basic proteins (H1, H2A, H2B, H3 and H4) that interact with each other and nuclear DNA to form the nucleosome. The H3 and H4 histone proteins are highly conserved and form the central tetrameric block of the core-nucleosome. Histone H3 has several post-transcrip- tional modifications such as methylation, acetylation, phosphonation, and ADP-ribosylation and it plays impor…     

拟南芥中一个新的constans等位基因及特性

植物开花是由内外信号途径共同调控的,CONSTANS是长日照途径上控制开花的基因.在筛选拟南芥滞绿突变体的过程中筛选到一个晚花突变体,工作名称为fnc25.后来证实为一个新的constans突变体co-9.在长日照条件下该突变体植株高大,叶片呈深绿色,莲座叶数目增多,开花延迟,寿限显著延长;春化处理和外源施加赤霉素对其开花时间几乎没有响应,在短日照条件下开花时间几乎不变.测序发现co-9中CO基因编码区中有10个碱基的缺失导致了CO蛋白C末端92个氨基酸没有被合成,这其中包含一个CCT结构域.CO基因的功能缺失很可能是导致co-9晚花的原因.RT-PCR实验表明co-9中CO直接调控的基因FT的mRNA水平显著下调,而另一个调控的基因SOC1的mRNA水平和野生型相比没有改变.说明CO通过不同的结构域作用于下游目的基因,一个结构域的改变只影响下游一个目的基因的表达,导致co-9的晚花表型.     

拟南芥开花时间的分子遗传调控

拟南芥开花主要受四种遗传途径调控,即:光周期途径,春化途径,自主途径和赤霉素途径。各种途径之间通过CO,FLC,FT,SOC1等主效基因的相互作用,最终调节花特异性基因AP1和LFY的表达,从而调控拟南芥的开花时间,其中各种突变体的研究揭示了相关基因的功能。这些主效基因中,CO基因对光周期途径是特异的,FLC基因对开花起抑制作用。其它因素如环境、基因染色质结构的改变、酶等对拟南芥开花时间的影响有待进一步的研究。     

SPL转录因子调控植物花发育及其分子机制研究进展

SPL(squamosa promoter-binding protein-like)转录因子是植物所特有的一类基因家族,广泛存在于绿色植物中,在植物生长发育中具有重要作用。花发育是植物生殖发育中最为重要的一个过程,涉及不同发育方式的转变,即开花决定、花的发端和花器官发生与发育。简要综述了SPL基因的结构与功能并着重阐述了SPL基因在植物花发育过程中的分子机制及生物学功能。最后总结出: SPL转录因子可直接或间接通过参与光周期途径,赤霉素途径及年龄途径来调控植物的开花时间; SPL基因可通过直接激活下游花分生组织特异基因,如LEAFY(LFY),从而调控植物的成花转变; SPL基因可通过与下游花器官特征基因相互作用来调控花器官及其育性的发育,如调控花序、花柄的长度与外形及花器官的大小; SPL基因可调控植物大小孢子发生及雌雄配子体发育。据拟南芥的相关研究结果,初步构绘出拟南芥开花调控中的分子机制。     

FKF1 is essential for photoperiodic-specific light signalling in Arabidopsis

Adaptation to seasonal change is a crucial component of an organism's survival strategy. To monitor seasonal variation, organisms have developed the capacity to measure day length (photoperiodism). Day-length assessment involves the photoperiodic control of flowering in Arabidopsis thaliana, whereby the coincidence of light and high expression of CONSTANS (CO) induces the expression of FLOWERING LOCUS T (FT), leading to flowering in long-day conditions. Although controlling CO expression is clearly a key step in day-length discrimination, the mechanism that generates day-length-dependent CO expression remains unknown. Here we show that the clock-controlled FLAVIN-BINDING, KELCH REPEAT, F-BOX (FKF1) protein has an essential role in generating the diurnal CO peak and that this function is dependent on light. We show that a recombinant FKF1 LIGHT, OXYGEN OR VOLTAGE (LOV) domain binds the chromophore flavin mononucleotide and undergoes light-induced photochemistry, indicating that FKF1 may function as a photoperiodic blue-light receptor. It is likely that the circadian control of FKF1 expression and the light regulation of FKF1 function coincide to control the daytime CO waveform precisely, which in turn is crucial for day-length discrimination by Arabidopsis.     

褐飞虱NADH泛醌氧化还原酶51kDa亚基cDNA片段的克隆及表达分析

NADH泛醌氧化还原酶是动物体内呼吸链电子传递系统的第一个酶，克隆水稻害虫褐飞虱的NADH泛醌氧化还原酶基因，及研究其在褐飞虱与水稻互作中的表达变化，将为科学防治褐飞虱提供新的线索。利用反转录多聚酶链式反应（RT-PCR）技术克隆了褐飞虱NADH泛醌氧化还原酶51kDa亚基基因的cDNA片段，并进行了序列测定；使用NoRhem杂交技术检测了该基因对两种不同抗性水稻的分子反应。分子杂交结果表明，在取食抗性水稻品种B5后，褐飞虱的NADH泛醌氧化还原酶51kDa亚基基因表达水平明显升高，而取食感虫水稻TN1后，该基因的表达水平没有明显变化。     

Cloning and expression of a cDNA encoding ribosomal protein S4 from Rice (Oryza sativa)

A cDNA clone, pS4, has been isolated from a cDNA library prepared from rice anthers of about 1.0 mm in length. DNA sequence analysis and database search show that the cDNA encodes a protein which is highly homologous to eukaryotic 80S ribosomal protein subunit 4 (S4). Northern hybridization indicates that this gene expresses in all tissues analyzed although the expression level varies and it cannot be induced by mechanical wounding in leaves. Southern blot analysis demonstrates that this rice S4 gene is from a multigene family.     

Association of dwarfism and floral induction with a grape 'green revolution' mutation

The transition from vegetative to reproductive growth is an essential process in the life cycle of plants. Plant floral induction pathways respond to both environmental and endogenous cues and much has been learnt about these genetic pathways by studying mutants of Arabidopsis. Gibberellins (GAs) are plant growth regulators important in many aspects of plant growth and in Arabidopsis they promote flowering. Here we provide genetic evidence that GAs inhibit flowering in grapevine. A grapevine dwarf mutant derived from the L1 cell layer of the champagne cultivar Pinot Meunier produces inflorescences along the length of the shoot where tendrils are normally formed. The mutated gene associated with the phenotype is a homologue of the wheat 'green revolution' gene Reduced height-1 (ref. 6) and the Arabidopsis gene GA insensitive (GAI). The conversion of tendrils to inflorescences in the mutant demonstrates that the grapevine tendril is a modified inflorescence inhibited from completing floral development by GAs.     

丙型肝炎病毒NS3基因真核质粒的构建及其在人肝细胞中的诱导表达

目的：进行丙型肝炎病毒非结构蛋白3基因真核表达载体的构建,并分析其在体外培养的人肝细胞中的表达。方法：从含有丙肝病毒全长基因的重组质粒pBRTM／HCV1-3011表达载体中PCR扩增出HCVNS3基因片段,将其与表达载体pcDNA3．1（-）重组,得到重组的真核表达载体pcDNA3．1（-）／NS3。然后采用阳离子多聚体将其转染人肝细胞QSG7701,以免疫组织化学SP法及Western Blotting检测HCVNS3蛋白的表达。结果：所得到的NS3片段正确,序列正确,所构建的真核质粒成功转染QSG7701细胞并表达蛋白,表达的NS3蛋白相对分子质量为70000。结论：成功构建了丙型肝炎病毒非结构蛋白3基因的真核表达载体pcDNA3．1（-）／NS3,并且该载体在体外培养的人肝细胞中能有效表达特异性HCVNS3蛋白。