光周期途径成花关键基因GIGANTEA和CONSTANS的研究进展

GIGANTEA(GI)和CONSTANS(CO)在植物光周期开花诱导途径中起促进作用。GI和CO基因受生物钟调控,表达量在一天内呈规律性变化。在长日照条件下,GI和CO基因促进拟南芥开花,但在短日照条件下,对拟南芥开花时间的影响不大。GI是影响生物节律钟输出和植物进行正常生命活动的重要基因,编码一个核蛋白,GI正调控CO基因的表达。CO是编码一个B-box锌指蛋白,是监测日照长度的重要元件,并激活FT基因表达,诱导植物开花。本综述概括了近年来GI和CO基因的结构和功能,为GI和CO基因的深入研究提供参考。     

高等植物CO基因研究进展

开花是植物由营养生长向生殖生长转变的重要时程。光周期和温度在这一过程中起主要作用。在拟南芥和水稻中,CONSTANS(CO)基因位于生物钟的输出途径,是生物钟和开花时间基因之间监测日照长度的重要元件,它可以整合光信号和生物钟信号,节律性地激活FLOWERINGLOCUST(FT)的表达,从而诱导开花。本文作者在追踪国内外对该基因的研究中发现,目前研究者已经从30余个物种中克隆到CO同源基因并对其序列特征、表达模式和功能特性进行了研究。CO基因编码的蛋白均包含两个保守的结构域:靠近氨基端的B-box结构域即锌指结构域和靠近羧基端的CCT结构域。CO基因的表达受昼夜节律钟调控。不同物种中该基因拷贝数不同,CO基因不同拷贝之间的功能存在差异。系统进化分析表明,该基因在双子叶植物和单子叶植物,以及不同科、属的植物中也存在分化。国内外这些关于CO基因家族的研究成果为进一步研究该基因功能和进化关系,并通过转基因调节植物开花期提供了有价值的参考资料。     

GmNMH7基因在大豆成花诱导、花发育和开花逆转过程中的表达

大豆[Glycine max(L．) Merrill]是典型的短日照植物，光周期反应敏感品种在一定的短日一长日条件下可发生开花逆转。本实验室以大豆品种自贡冬豆为材料，将SD(短日)、LD(长日)和SDl3d-LD相结合，建立了大豆光周期反应机制研究的新的实验系统。本研究通过筛选自贡冬豆成熟花的cDNA文库得到MADS-box基因家族的一个成员GmNMH7，采用RNA原位杂交技术分析了不同光周期条件下GmNMH7基因在大豆顶端分生组织分化过程中的表达，并观察了GmNMH7基因在幼叶、幼茎、根瘤等器官中的表达情况。主要结果总结如下：在短日照(SD)条件下，自贡冬豆植株可在较短时间内完成开花诱导、正常开花和结实。GmNMH7基因在可观察到的花芽分化出现之前即开始在大豆顶端分生组织中表达，其表达时间贯穿成花诱导、花芽分化、花器官发育及种子形成的全过程。在长日照(LD)条件下，植株持续进行营养生长，没有任何形式的花器官出现，GmNMH7基因在顶端分生组织中一直不表达。在短日照13天一长日照(SDl3d-LD)条件下，60％以上的植株出现花序逆转和花逆转，另一部分植株顶端出现短花序，开花期比持续短日处理的植株晚。在出现开花逆转的植株中，GmNMH7基因的表达可随长日处理日数的增加和营养器官的出现而减弱。当顶端分生组织完全恢复叶片分化时，GmNMH7基因的表达停止。在出现短花序的植株中，GmNMH7基因一直表达，但表达量低于持续短日处理。对部分时期GmNMH7基因在幼叶、幼茎和根瘤中表达情况的研究未发现明显的规律性。GmNMH7基因在大豆花芽分化启动之前就开始表达的现象为大豆开花诱导提供了早期证据，该基因在顶端分生组织中的表达受光周期调控的事实说明，GmNMH7与大豆光周期反应、成花诱导及花器官发育有密切关系。我们推测，GmNMH7基因在上述过程中可能发挥着类似于分生组织特征基因的作用。实验结果进一步证明，本实验室利用开花(短日处理)、持续营养生长(长日处理)、开花逆转(短日-长日处理)三种发育状态(光照处理)建立的实验系统在大豆(短日植物)光周期反应和个体发育研究中有重要的利用价值。     

西双版纳植物园揭示赤霉素与光周期途径协同调控开花诱导的信号转导机理

正植物激素是植物体内重要的生长调节物质,广泛参与调控植物的生长发育和抗逆境反应。在模式植物拟南芥中,赤霉素(GA)促进植物的开花诱导过程。目前研究表明,GA可与光周期信号协同调控植物在长日照条件下的开花诱导,然而,GA和光周期信号在植物开花诱导过程中的相互作用机理仍不清楚。中国科学院西双版纳热带植物园植物分子生物学研究组和植物环境适     

γ-氨基丁酸促进拟南芥开花的机理研究

为了探讨γ-氨基丁酸(GABA)对拟南芥植物开花的影响机制,以3种不同浓度（1 mmol/L,5 mmol/L和10 mmol/L）的GABA采用隔天喷施的方法,处理7天龄的拟南芥幼苗至4周龄,以双蒸水作为对照,观察拟南芥的开花时间的变化。结果表明,在长日照（16 h光照/8 h黑暗）和短日照（8 h光照/16 h黑暗）条件下,GABA能不同程度地促进拟南芥早开花2~5天。运用荧光定量PCR技术,对开花途径的开花抑制因子基因Flowering Locusc C（FLC）、自主开花途径基因FCA(FLOWERING TIME CONTROL PROTEIN FCA)和花序分生组织特征基因LEAFY（LFY）的表达进行研究。与对照相比,GABA处理下调FLC的表达2~5倍,而促进FCA（1.5~6倍）和花序分生基因LFY（3~11倍）的表达。初步的实验结果表明,GABA对拟南芥开花的促进作用有可能通过上调FCA的表达,抑制FLC从而促进LFY的表达而最终促进植物提早开花。     

中科院揭示植物激素赤霉素与光周期途径协同调控开花诱导的信号转导机理

正植物激素是植物体内重要的生长调节物质,广泛参与调控植物的生长发育和抗逆境反应。在模式植物拟南芥中,赤霉素激素促进植物的开花诱导过程。目前研究表明,GA可与光周期信号协同调控植物在长日照条件下的开花诱导。然而,GA和光周期信号在植物开花诱导过程中的相互作用机理仍不清楚。中国科学院西双版纳热带植物园植物分子生物学研究组和植物环境适应性研究组联合研究发现,GA诱导成     

中科院昆明植物所等在植物开花调控研究中取得新进展

<正>在拟南芥中,长日照条件诱导开花启动因子Flowering Locus T(FT)的表达来加速植物开花。光周期条件对FT的激活主要依赖于转录因子CONSTANS(CO)的活性,对CO的转录水平、蛋白质稳定性以及生物钟的调控是植物能够响应光周期并诱导植物成花的关键机制。ABI5结合蛋白2     

GmELF3s调控大豆开花时间和生物钟节律的功能分析

大豆是典型的短日照作物,光周期的敏感性严重影响大豆的开花时间和产量,制约大豆的种植范围,但调控大豆光周期和生物钟节律的机制尚不十分清楚。在模式植物拟南芥中,ELF3与ELF4、LUX一起,形成ELF4-ELF3-LUX (Evening Complex, EC)生物钟晚间复合物,在生物钟节律和开花时间调控等方面发挥重要作用。本研究通过CRISPR/Cas9基因编辑系统获得大豆Gmelf3a/j、Gmelf3b-1和Gmelf3b-2的突变体材料。通过观察Gmelf3a/j、Gmelf3b-1和Gmelf3b-2各突变体材料在短日照和长日照下的开花时间发现, GmELF3b-1在长日照下对大豆开花时间起调控作用;通过观察非纯合双突变体的表型发现,GmELF3a/J与GmELF3b-1和GmELF3b-2之间在调控大豆开花时间方面存在功能冗余。通过qRT-PCR对大豆生物钟节律相关基因的表达进行检测发现,GmCAB、GmPRR9a和GmPRR7a的表达模式发生改变,这表明GmELF3a/J、GmELF3b-1和GmELF3b-2可能是通过GmPRR9a和GmPRR7a对大豆生物钟节律和开花...     

谷子SiCCT基因的表达及其与主要农艺性状的关联分析

为了揭示SiCCT基因可能的功能效应,并进一步研究该基因在光温互作调控谷子开花过程中所起的作用。以光周期敏感谷子品种黄毛谷为材料,利用荧光定量PCR技术分析了SiCCT基因在长日照高温(LD,27℃)、长日照低温(LD,22℃)、短日照高温(SD,27℃)、短日照低温(SD,22℃)4个光温组合条件下的昼夜表达规律,并在连续2 a调查10个主要农艺性状的基础上,开展了基于候选基因的关联分析。结果表明,光照期SiCCT基因表达不受温度影响,长日照条件表达水平整体高于短日照,而黑暗期表达受温度影响,特别是短日照条件下SiCCT基因在低温环境的表达水平明显高于高温环境。基于候选基因关联分析发现,SiCCT基因中共检测到11个多态性位点与8个主要农艺性状显著关联(P0.05),其中SNP-10在河南洛阳、吉林吉林与抽穗期、叶片数和穗粒质量显著关联;SNP-100和SNP-104在河南洛阳同时都关联到株高、叶片数和穗长3个性状;SNP-51连续2 a在海南乐东、河南洛阳、吉林吉林都检测到,但关联到的性状不同,在海南乐东与穗粗关联,在河南洛阳与穗码数关联,在吉林吉林与叶片数关联。SiCCT基因表达受光周期调控,温度也影响其在短日照条件黑暗期的表达;SiCCT基因具有多效性,但其作用受光周期环境影响。     

高等植物开花时间的蓝光调控:隐花色素介导的光信号传导

外界光环境的变化为研究植物开花时间的调控机制提供了重要线索。蓝光能够促进成花转变,植物主要通过隐花色素感受外界蓝光信号从而触发光反应。植物体隐花色素的主要功能是通过调控泛素化连接酶Constitutive photomorpho-genesis 1(COP1)和CRY-interacting b HLH1(CIB1)蛋白的活性来实现对光诱导基因的表达调控,从而控制植物的成花转变。本文通过追踪国内外关于隐花色素基因家族的研究进展发现,目前的研究人员已经从10余个物种中分离到了隐花色素的同源基因,并对其结构和功能进行了研究。隐花色素基因主要由N端的PHR结构域和C端的CCT结构域组成,通过调节光周期途径影响植物的开花时间。目前的研究结果表明,隐花色素主要通过3条信号传导途径实现对光周期途径的调控。这些关于隐花色素基因家族的研究成果为进一步研究这些基因的功能和互作关系,并通过转基因技术调节植物开花期提供了有价值的参考资料。     

A mutant annual cabbage

An annual-flowering cabbage, the result of mutation, occurred in 1956 among heading plants of the Morden Midget variety. Monogenic dominance for the annual character was indicated by an inheritance test. The classification of annual and normal type progeny plants from the annual × Morden Midget cross used in the test, was complicated by biennial growth factors. The time of flowering varied markedly among annual plants. Also, the ability to set seed in the field varied in the early flowering group. In a large proportion of plants, fertility increased as daylength decreased in autumn, indicating a probable seasonal improvement in self- and cross-compatibility Some plant forms among the annual plants resembled sprouting broccoli.Contribution 33, Research Branch, Canada Agriculture Experimental Farm, Morden, Manitoba     

Effect of Temperature and Photoperiod on the Development of Lupinus albus L. in a Controlled Environment

An experiment to determine the effect of temperature and photoperiod on Lupinus albus under controlled environmental conditions was carried out, using the three Lupinus albus genotypes 'Tifwhite', 'Esta' and 'Kiev', and three temperature (10/20, 18/28 and 20 °C continuously) and two photoperiod (8 and 16 h daylength) regimes, in all combinations. Half of the seeds were vernalized for 21 days at 4 °C to alleviate the obligate vernalization requirement of Tifwhite. Although Esta and Kiev do not have obligate vernalization requirements, they were influenced by this vernalization period. Observations included the duration of the period from planting to seedling emergence, the duration of the period from planting to the beginning of flowering and the duration of flowering. The vernalization treatment accelerated plant development in all genotypes. The period from planting to emergence was shorter under the higher temperature regime. For all genotypes, the period from planting to flowering was shorter under the longer photoperiod, the same trend as would be expected for long-day plants. Duration of flowering periods were, in contrast to pre-flowering periods, shorter for all genotypes at cooler temperatures. The results of this study confirm that photoperiod does contribute to the growth period from planting to flowering in L. albus and that this species does behave as a long-day plant.     

Variation between genotypes of carnation (Dianthus caryophyllus cultivars and interspecific hybrids) in time of flowering and response to long days. I. Variation in yield distribution

Summary Early flowering carnation cultivars, responding to artificial long days, can assist the grower to plant the onset of flowering and achieve a better distribution of flower production over the year.A comparative trial is described of 20 carnation genotypes (cultivars and backcrosses of interspecific hybrids), representing a wide variation in flowering time and response to long days. The trial was planted in September in a phytotron under a winter light intensity of 15 W/m² for eight hours per day. In one half of the trial, daylength was increased to 24 hours for 25 days in December-January. At the end of February the plants were transferred to a glasshouse where they were observed until all primary shoots had flowered. The main purpose of the experiment was to analyse the genetic factors responsible for the large differences in flowering behaviour between genotypes. Average flowering dates varied from 132 days from pinching in a Dianthus chinensis hybrid to 181 days in the mediterranean cultivar Raggio di Sole. LD response was most pronounced in the earliest flowering Diantini selections and least in the traditional commercial cultivars. In the former the LD effect was evident in all shoots of a plant, but mostly so in the lower (older) shoots; in the traditional cultivars only the higher placed shoots responded to LD. As a result, the proportion of the shoots actually responding to LD varied from 28% in the traditional cultivars to 54% in the Diantini x D. Allwoodii cv Doris group of genotypes.     

小麦穗分化过程中的光温组合效应研究

在Ｃｏｎｖｉｒｏｎ生长箱控制条件下,利用６个来自不同生态区的春小麦品种,研究了４种光温组合下（高温长日,高温短日,低温长日,低温短日）穗人化期持续天数与积温的反应,结果表明,日照对缩短各穗分化期起主要作用。（２）温度对光周期反应有强烈的调节作用,主要表现,长日照下。高温加快生育进程,短日照下,高温使短日抑制穗分化效应更为显著,常导致幼穗中途死亡,低温虽然延缓了小麦的生育进程,但却可以减轻短日对穗分     

大豆GmCOL4基因的克隆与分析

CONSTANS(CO)是植物光周期开花途径中的关键基因之一。通过RT-PCR和生物信息学的方法,克隆了大豆GmCOL4基因并分析其结构特征,用实时荧光定量PCR(quantitative real-time RT-PCR,qRT-PCR)研究了其转录特点。结果表明,GmCOL4的4个外显子编码一个具有B-box和CCT保守结构域的CO-like蛋白,在序列上与拟南芥(Arabidopsis thaliana)COL9相似性最高,为64.3%。分析其转录特征发现,GmCOL4表达主要受生物节律的影响,受光的调节作用较弱。器官特异性表达分析发现,GmCOL4主要在大豆叶片中表达,表达模式与COL9相似。这为大豆中CO基因家族的功能研究提供了重要的依据。     

水稻C815S及其同源株系的育性光温特性

对C815S及其同源株系通过12种人控光温组合处理、短日遮光处理以及分期播种试验,就其育性光温特性、发育感光性以及两者之间的关系进行了研究。结果表明,C815S及其同源株系不育起点温度低,均在23℃以下。在长沙自然长日条件下没有明显不育向可育的转换;在长沙短日条件下,育性出现轻微波动。其育性受光温双因子共同作用,且这种作用的程度与发育感光性强弱似乎存在密切联系。提出了光温敏不育系光温双因子互作量化的光温效应连动假设。这一假设能提供每一光长条件下与之对应的育性转换温度,对光温敏核不育系的选育、制种和繁殖具有实际指导意义。     

Inheritance of duration from sowing to first flowering in pigeonpea

Duration from sowing to flowering is the most important trait influencing adaptation in pigeon pea (Cajanus cajan), but the inheritance of this trait has not been elucidated clearly. Crosses were made between two early (60 to 70d) and one late (160 to 170d) flowering pigeonpea genotype and F₁, F₂ and BC₁ populations produced. These populations, comprising 60 to 100 parents, 30 F₁, 400F₂ and 40 to 50 BC₁ plants, were grown under natural (mean13.4 hd^-1) and artificially extended (to 15 hd^-1) daylength and duration from sowing to first flowering recorded. Genetic analysis of the segregation ratios, supported by Chi-square tests, indicated that the duration from sowing to flowering in each of the crosses was controlled by two genes assorting independently and with predominantly additive quantitative effects. The segregation patterns were most clearly defined in the 15 hd^-1 daylength. This revised version was published online in July 2006 with corrections to the Cover Date.     

Chickpea evolution has selected for contrasting phenological mechanisms among different habitats

Arguably the most important adaptive criterion in annual crops is appropriate phenology that minimizes exposure to climatic stresses and maximizes productivity in target environments. To date this has been achieved empirically by selecting among diverse genotypes in target locations. This approach is likely to become inadequate with pending climate change because selection is imposed on the outcome (flowering time) rather than the underlying mechanism (i.e. responses to daylength, ambient or vernalizing temperatures). In contrast to the cereals, in legumes the interaction between phenological mechanisms and environmental selection pressure is largely unknown. This paper addresses this shortcoming through photothermal modelling of chickpea germplasm from the world’s key production areas using a meta-analysis of multi-environment trials located from 49° N to 35° S. Germplasm origin had significant effects on temperature and daylength responsiveness, the former strongly correlated to vegetative phase temperatures at the collection or development site (r = 0.8). Accordingly, temperature responses increase from winter- to spring-sown Mediterranean and Australian material, and then to north, central & southern India. Germplasm origin also affects the relationship between photoperiod and temperature response. In Eastern Mediterranean material a strong negative relationship (r = −0.77) enables temperature insensitive genotypes to compensate through a strong photoperiod response. Clearly, chickpea evolution has selected for different phenological mechanisms across the habitat range. Given that under the anticipated global warming temperature sensitive cultivars will flower relatively earlier than those responding largely to photoperiod, it is important to exploit this diversity in developing better-adapted genotypes for future cropping environments.     

芒果MiCO基因逆境胁迫下表达模式分析及转基因株系的获得

CONSTANS(CO)基因是调控植物开花光周期途径的关键基因,近来有研究发现其与植物的逆境胁迫也有关。目前CO参与植物逆境胁迫的作用尚不清楚。为了探究CO在芒果逆境胁迫中的功能,我们利用实时荧光定量技术对MiCO基因在芒果2℃低温胁迫、盐胁迫和PEG-6000模拟干旱胁迫后0 h、6 h、12 h、24 h、48 h和72 h的表达模式进行分析。结果显示,这三种逆境处理均诱导芒果MiCO基因的表达,其中盐胁迫处理条件下MiCO基因的表达水平上调,2℃低温和PEG胁迫条件下MiCO基因的表达水平下调。说明该基因参与了芒果逆境胁迫的调控。为了验证MiCO基因在芒果逆境胁迫中的功能,本研究构建了MiCO超量表达载体,将MiCO基因转化到拟南芥中,获得阳性植株,经过三代筛选得到了纯合株系,为进一步验证MiCO基因在逆境胁迫中的作用提供实验材料。     

小麦光敏色素基因TaPhyB3的克隆和表达分析

从小麦品种中国春中克隆了编码光敏色素基因B的脱辅基蛋白,将其定位于4D染色体的长臂上,并命名为TaPhyB3。TaPhyB3的开放阅读框为3501bp,编码一个128kD、具有1165个氨基酸的蛋白质。它与水稻、玉米和拟南芥在氨基酸水平上的一致性分别为93%、90%和73%。对不同光线处理7d小麦植株表达的分析表明,TaPhyB3在黑暗中表达最低、在白光下的表达水平最高,在远红光、红光、蓝光和白光下的表达水平分别是黑暗中的2.2、7.7、7.4和37.3倍。组织特异性表达分析表明,TaPhyB3在小麦幼苗所有组织中都表达,叶片中的表达水平是根的11.4倍。推测TaPhyB3的表达水平与小麦的光形态建成的程度呈正相关。