温度和光周期对水稻抽穗期调控的交互作用

光周期和温度是植物开花的2个关键的调控因素,植物成花转变决定于植物对光周期和温度变化的精确测量.作为短日照植物,水稻在长日低温条件下抽穗期推迟,为了阐明温度和光周期对水稻开花时间的调控效应,本文利用1个光周期不敏感的突变体及其野生型,系统地分析了不同温度和光周期处理条件下,调控水稻开花时间几个关键基因（Hd3a,RFT1,Ehd1,Ghd7,RID1/Ehd2/OsId1,Se5）的表达调控模式,结果表明Ehd1-Hd3a/RFT1通路在光周期和温度调控水稻开花途径中保守.Ehd1,Hd3a和RFT1的表达在低温（23℃）条件下急剧下降,表明Ehd1,Hd3a和RFT1表达阻抑是低温条件下水稻开花推迟的主要原因.另外,在长日照条件下,低温（23℃）处理促进了水稻开花抑制子Ghd7的表达,表明低温条件和长日照条件对Ghd7的表达具有协同作用.此外,本文还分析了Hd1与光周期开花调控途径中几个关键基因的调控关系,发现Hd1在长日照条件下负向调控Ehd1的表达而正向调控Ghd7的表达,表明在长日照条件下,Hd1-Ghd7-Ehd1-RFT1通路也是水稻抽穗期调控的一条重要途径.     

光周期影响植物花时的分子机制

日长感知是植物所具有的重要的生物学功能,光周期是决定植物开花时间的关键环境因子之一。光周期的暗期长度是决定植物成花的决定因素。通过形态学和遗传学研究,揭示了光周期敏感的一些遗传特性,并确定了光敏感指数的标准。构建了光周期性状相关的分子标记连锁图谱,是进行基因定位、克隆和分子标记辅助选择的重要基础工作,也是进行光周期机理研究的有效途径。通过模式植物拟南芥的研究,建立了一个长日促进开花的遗传途径。它的机理可以综合为:光和感光信息体系结合产生信号并传导,CO表达被激活。在每日日长循环、光体系及遗传背景的变化基础上,如果CO的表达和日长状况协调,那么CO激活FT表达,随后开花。水稻、小麦、玉米等作物在光周期机理研究方面也取得了一些进展。     

水稻开花期调控的分子机理研究进展

水稻准确地感知外部环境信号,通过内部复杂的基因网络做出反应,在一年中最适合的时候开花繁殖。与长日促进长日模式植物拟南芥开花相反,短日促进短日模式植物水稻开花。通过对水稻和拟南芥的开花期调控机理的对比分析,发现水稻和拟南芥有着一些相对保守的开花期控制基因,其调控机理也是相似的。另外,水稻也有一些独特的开花期控制基因和开花途径。本文着重从光周期对水稻开花期的调控途径和作用机理角度进行了阐述,并对水稻开花期的自然变异与其育种应用、生物钟关联基因、光中断现象和临界日长现象以及开花期与产量的关系进行了总结。     

高等植物开花时程的调控与光受体Ⅰ.开花时程的基因与光受体调控

系统评述了高等植物开花时程的调控与植物光受体的联系.重点说明了控制开花时程的遗传途径以及光周期途径的有关基因的研究进展.影响高等植物开花的最重要的因子之一便是光周期,光周期对高等植物开花的调控是通过相关基因间的相互作用来实现的,这些基因包括参与花启动发育控制基因,昼夜节律时间钟调控基因及光受体信号转导基因.近5年左右的时间通过对拟南芥及其一系列突变体的研究为我们展示了这一热门领域的广阔的前景.     

高等植物开花时程的调控与光受体Ⅱ.光受体调控开花时程的分子机制与昼夜节律时间钟

系统评述了高等植物开花时程的调控与植物光受体的联系.重点说明了控制开花时程的遗传途径以及光周期途径的有关基因的研究进展.而且对植物光受体调控高等植物开花里程的分子机制作了深入的探讨.高等植物从营养生长向生殖生长及发育转变的时程具有重要意义.控制高等植物开花时程及其性别表达的关键就在此过程中.植物光受体参与了高等植物开花时程的调控并起到了重要作用.植物光受体主要包括植物光敏素受体(光敏素A、B、D、E受体)和隐色素受体.近5年左右的时间通过对拟南芥及其一系列突变体的研究展示了这一热门领域的广阔的理论与应用前景.     

菘蓝IiEMF基因的克隆与功能分析

该研究以菘蓝(Isatis indigotica Fort.)转录组数据为基础,克隆得到菘蓝EMF基因的cDNA全长,命名为IiEMF。(1)序列分析表明,IiEMF基因开放阅读框长度为1896 bp,编码631个氨基酸。进化树分析表明,菘蓝IiEMF蛋白与甘蓝(Brassica oleracea)EMF蛋白亲缘关系最为接近。(2)实时定量PCR结果显示,IiEMF在菘蓝不同器官中均有表达,且在叶中表达量最高,果实中表达量最低;IiEMF基因在菘蓝抽薹开花过程中叶内的表达量呈先升后降的趋势,并于初花期表达量达到最高后逐渐降低回落;在花/果期IiEMF基因表达量较花蕾中明显降低。(3)成功构建了超表达载体pCAMBIA1300-EMF,经农杆菌介导侵染拟南芥,PCR鉴定表明,有7株为超表达转IiEMF基因植株。(4)表型观察发现,在长日照和短日照条件下,与野生型相比2个转IiEMF基因拟南芥株系的开花时间都明显较早(提前6~10 d),且转IiEMF基因株系的莲座叶数比野生型多10片以上,叶片也比野生型大而肥厚。(5)qRT-PCR检测结果显示,在拟南芥营养生长过程中,过表达IiEMF显著抑制了拟南芥AtAP1、AtCO和AtLFY的表达,而促进了AtFLC的表达;当拟南芥开花时,转基因株系中的AtAP1和AtFLC表达量均高于野生型,AtCO和AtLFY的表达量显著低于野生型。研究表明,过量表达IiEMF基因能够促使拟南芥提前开花,且IiEMF可能是通过影响多种开花途径来共同调节促进拟南芥的早花。     

高等植物开花诱导研究进展

高等植物由营养生长向生殖生长转换的过程称为开花诱导。开花诱导过程由遗传和外界环境两个因素决定, 受错综复杂的网络信号传导途径调控。近年来, 在双子叶模式植物拟南芥中, 开花诱导研究取得了很大进展, 探明了控制开花诱导的4条主要途径(光周期途径、春化途径、自主途径和GA途径)及调控机制。研究也表明, 开花基因在拟南芥、水稻以及其他高等植物之间具有很高的保守性。文章对相关研究的最新进展作一综述, 并指出了目前研究中存在的问题及相应的研究对策。     

模式植物拟南芥开花时间分子调控研究进展

植物从营养生长到生殖生长的转变是开花发育的关键,在合适的时间开花对植物的生长和繁衍极为重要,植物开花时间的调控对农业生产发展意义重大。植物开花是由遗传因子和环境因子协同调节的一个复杂过程。近年来,对不同植物开花调控的研究,特别是对模式植物拟南芥（Arabidopsis thaliana（L.） Heynh.）的开花调控研究取得了显著进展,已探明开花时间分子调控的6条主要途径分别是光周期途径、春化途径、自主途径、温度途径、赤霉素途径和年龄途径。各遗传调控途径既相互独立又相互联系,构成一个复杂的开花调控网络。本文综述了模式植物拟南芥开花时间调控分子机制相关研究的最新进展,并对未来的研究进行了展望。     

国外大刊重要论文简介

通过比较双突变体和三突变体分析拟南芥中控制开花时间的模型ＲｅｅｖｅｓＰＨ ,ＣｏｕｐｌａｎｄＧＰｌａｎｔＰｈｙｓｉｏｌｏｇｙ 2 0 0 1 ,1 2 6:1 0 85～ 1 0 91在长日照光周期条件下 ,拟南芥中诱导开花的遗传途径至少有三条 ,即 :长日照途径、自主途径和赤霉素依赖途径 ,     

诱导植物开花的基因

美国的两组研究人员已从路边杂草拟南芥中分离出2种植物基因(“Leafy”和“Apetalal”(APl)),它们是诱导一些植物开花的主要开关。通过调控植物提前开花,遗传学家用上述基因加速果实的形成。 这项基因技术最终可用于生产早熟的遗传改良作物,使其可栽种于象加拿大这样生长季太短而使很多类植物难以生长的国家。上述基因还有助于更好地了解日照长度和温度等环境因素如何影响植物的发育。 Salk Inst.的研究人员指出,Leafy基因的超量表达对于诱导拟南芥苗开花既必需又必要。与此同时,圣     

植物开花时间调控的信号途径

开花是植物从营养生长到生殖生长的一个重要转折点。花启动的时机对生殖生长的成功至关重要。开花时间受内在因子和环境因子的共同调节。通过对拟南芥的分子遗传学研究,确定至少存在4条调控开花时间的信号途径,即光周期途径、春化途径、自主途径和赤霉素途径。本文以拟南芥 (Arabidopsis thaliana) 为主要研究对象简要综述了近年来在开花时间调控领域的研究进展。     

小麦耐逆基因-TaLEA2转化拟南芥的研究

研究小麦第3组LEA基因中T aLEA2对耐旱和耐盐性能的影响.将小麦第3组LEA基因T aLEA2连接在双元表达载体pB I121 C aM V 35S启动子下游,构建了能在植物中高效表达的载体pB I121-T aLEA2.通过农杆菌介导的真空渗透法,将其转入野生拟南芥中,经抗性筛选及PCR验证,获得T0代转基因植株,并用不同浓度的PEG 4000和N aC l对转基因拟南芥的耐逆性进行检测.结果表明,这些转基因植株可明显改进拟南芥在10%PEG及0.8%N aC l培养基上的生长状态.在实验条件下,转基因拟南芥的耐旱性及耐盐性均有所提高,提示T aLEA2基因在植物水分调节方面有重要作用.     

Ecotype-Specific Expression of a Flowering Mutant Phenotype in Arabidopsis thaliana

The majority of mutations that delay flowering in Arabidopsis thaliana have been identified in studies of the Landsberg erecta (Ler) ecotype. In this report we describe a gene (referred to as FLD) that, when mutated, delays flowering in the Columbia ecotype but has a minimal phenotype in the Ler genetic background. The late-flowering phenotype of fld mutants requires a non-Ler allele of another gene involved in the control of flowering time, Flowering Locus C. fld mutants retain a photoperiod response, and the flowering time of fld mutants can be reduced by cold treatment and low red/far-red light ratios.     

Wheat SOC1 functions independently of WAP1/VRN1, an integrator of vernalization and photoperiod flowering promotion pathways

Heading time in bread wheat ( Triticum aestivum L.) is determined by three characters – vernalization requirement, photoperiodic sensitivity and narrow-sense earliness (earliness per se) – which are involved in the phase transition from vegetative to reproductive growth. The wheat APETALA1 ( AP1 )-like MADS-box gene, wheat AP1 ( WAP1 , identical with VRN1 ), has been identified as an integrator of vernalization and photoperiod flowering promotion pathways. A MADS-box gene, SUPPRESSOR OF OVEREXPRESSION OF CO 1 ( SOC1 ) is an integrator of flowering pathways in Arabidopsis . In this study, we isolated a wheat ortholog of SOC1 , wheat SOC1 ( WSOC1 ), and investigated its relationship to WAP1 in the flowering pathway. WSOC1 is expressed in young spikes but preferentially expressed in leaves. Expression starts before the phase transition and is maintained during the reproductive growth phase. Overexpression of WSOC1 in transgenic Arabidopsis plants caused early flowering under short-day conditions, suggesting that WSOC1 functions as a flowering activator in Arabidopsis . WSOC1 expression is affected neither by vernalization nor photoperiod, whereas it is induced by gibberellin at the seedling stage. Furthermore, WSOC1 is expressed in transgenic wheat plants in which WAP1 expression is cosuppressed. These findings indicate that WSOC1 acts in a pathway different from the WAP1 -related vernalization and photoperiod pathways.     

Functional conservation and divergence of FVE genes that control flowering time and cold response in rice and Arabidopsis

Recent molecular and genetic studies in rice, a short-day plant, have elucidated both conservation and divergence of photoperiod pathway genes and their regulators. However, the biological roles of rice genes that act within the autonomous pathway are still largely unknown. In order to better understand the function of the autonomous pathway genes in rice, we conducted molecular genetic analyses of OsFVE, a rice gene homologous to Arabidopsis FVE. OsFVE was found to be ubiquitously expressed in vegetative and reproductive organs. Overexpression of OsFVE could rescue the flowering time phenotype of the Arabidopsis fve mutants by up-regulating expression of the SUPPRESSOR OF OVEREXPRESSION OF CO1 (SOC1) and down-regulating FLOWERING LOCUS C (FLC) expression. These results suggest that there may be a conserved function between OsFVE and FVE in the control of flowering time. However, OsFVE overexpression in the fve mutants did not rescue the flowering time phenotype in in relation to the response to intermittent cold treatment.     

The Arabidopsis ELF3 gene regulates vegetative photomorphogenesis and the photoperiodic induction of flowering

Flowering in Arabidopsis thaliana is promoted by long-day (LD) photoperiods such that plants grown in LD flower earlier, and after the production of fewer leaves, than plants grown in short-day (SD) photoperiods. The early-flowering 3 ( elf 3) mutant of Arabidopsis , which is insensitive to photoperiod with regard to floral initiation has been characterized. elf 3 mutants are also altered in several aspects of vegetative photomorphogenesis, including hypocotyl elongation. When inhibition of hypocotyl elongation was measured, elf 3 mutant seedlings were less responsive than wild-type to all wavelengths of light, and most notably defective in blue and green light-mediated inhibition. When analyzed for the flowering-time phenotype, elf 3 was epistatic to mutant alleles of the blue-light receptor encoding gene, HY 4. However, when elf 3 mutants were made deficient for functional phytochrome by the introduction of hy 2 mutant alleles, the elf 3 hy 2 double mutants displayed the novel phenotype of flowering earlier than either single mutant while still exhibiting photoperiod insensitivity, indicating that a phytochrome-mediated pathway regulating floral initiation remains functional in elf 3 single mutants. In addition, the inflorescences of one allelic combination of elf 3 hy 2 double mutants form a terminal flower similar to the structure produced by tfl 1 single mutants. These results suggest that one of the signal transduction pathways controlling photoperiodism in Arabidopsis is regulated, at least in part, by photoreceptors other than phytochrome, and that the activity of the Arabidopsis inflorescence and floral meristem identity genes may be regulated by this same pathway.