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.     

LFY／FLO基因与高等植物成花诱导分子机理的研究进展

高等植物开花过程极为复杂,受在子及环境因子的双重控制。近年来,从模式植物拟南芥与金鱼草中分离到一大批与开花相关的基因,其中包括开花早期表达ＬＦＹ／ＦＬＯ基因。虽然对该基因的功能进行了不断深入研究,但高等植物成花诱导的分子机理仍需进一步探讨。     

高等植物开花时程的基因调控(Ⅱ)

主要探讨如下几个问题:转基因植物中的拟南芥开花时程基因;拟南芥中的甲基化与实验胚胎学研究;高等植物开花时程控制的可能机制.目前本领域已成为植物发育分子生物学的前沿热点研究领域之一.结合有关工作,对这一世界性热门领域进行了系统的评述,希望能为国内同行提供有关参考,赶超世界的植物分子生物学先进水平,对分子水平与生物技术角度改良黄土高原生态环境有指导意义.     

拟南芥开花诱导途径分子机制研究进展

拟南芥是分子和遗传学研究的模式植物,对植物花发育及控制花形态建成的分子遗传机制的研究进展主要是建立在对拟南芥研究的基础之上,拟南芥开花主要受到4个途径(自主途径、赤霉素途径、春化作用和光周期途径)的内源和外界信号的同时诱导.该文对近年来国内外有关拟南芥开花诱导的4个途径的分子机制研究进展进行综述,并初步绘制出各开花诱导途径基因间的调控网络图,以进一步明确基因间的相互作用模式及其在整个开花过程中的作用地位.     

植物春化作用的分子机理

春化作用在控制高等植物开花中起着重要的作用。本文综述了近年来以拟南芥（Arabidopsis thaliana）和冬小麦（Triticum aestivum）为主要研究对象进行的有关春化作用分子机制的研究;概括和分析了已经分离得到的与春化有关的基因的功能及其调控方式以及各基因间的相互作用。     

拟南芥开花过程的表观遗传调节

开花是高等植物由营养生长到生殖生长的重要转变.拟南芥的开花时间受许多基因的调控,其中一些基因的表现遗传调节对开花时间的控制发挥着重要的作用.本文就这些基因以表观遗传方式调节拟南芥开花过程的最新研究进程作简要介绍.     

拟南芥下胚轴伸长与向光性的分子调控机理

下胚轴快速伸长和向光性是高等植物进行固着生活的重要适应性机制,是子叶钻出土层进行光形态发生和光合作用的必要前提。拟南芥下胚轴因其简单的生理形态结构和特异的生理功能而成为剖析植物细胞伸长和向性生长的理想模式系统。本文主要介绍光和植物激素调控拟南芥下胚轴伸长和向光性弯曲的生理基础、遗传学功能及其分子调控机理的最新进展。     

“先驱”转录因子LEC1在早期胚胎重置春化状态的机制

开花是植物由营养生长阶段向生殖生长阶段转变的重要过程,长时间低温处理即春化对开花起到非常重要的促进作用。春化控制的拟南芥(Arabidopsis thaliana)开花中,阻抑型转录因子FLC是重要的关节点,春化记忆依赖于对该基因的控制。何跃辉研究组之前对拟南芥的研究揭示了转录因子VAL1或VAL2可以识别负调控开花的关键基因FLC成核区的顺式DNA元件,协同PRC2复合体在春化过程中沉默FLC基因的表达,并在随后的常温下继续维持FLC基因沉默直至受精结束,使植物产生春化记忆。但在下一代中如何擦除这种记忆功能,使FLC重新被激活,以防止植物在过冬前或过冬时开花,相关机制目前并不清楚。近期,该研究组揭示了在植物胚胎发育早期一个种子特有的"先驱"转录因子参与擦除春化记忆,重新激活FLC基因的分子机制,并解析了胚胎中的基因激活传递到后胚胎发育(营养生长期)的表观遗传机理。该研究是开花领域的重要突破,为作物开花调控的生产应用提供了新思路。     

春化作用相关基因FLC的研究进展

拟南芥春化作用相关基因FLOWERING LOCUS C（FLC）属于MADS盒基因,它编码的蛋白转录因子对开花具抑制作用。春化作用通过负调控FLC的转录及蛋白表达水平,促进拟南芥的某些晚花生态型和晚花突变体开花。主要介绍了FLC基因在春化途径中的关键作用,及其春化作用通过FLC基因与其它开花途径相联系等内容。     

A MADS domain gene involved in the transition to flowering in Arabidopsis

Flowering time in many plants is triggered by environmental factors that lead to uniform flowering in plant populations, ensuring higher reproductive success. So far, several genes have been identified that are involved in flowering time control. AGL20 (AGAMOUS LIKE 20) is a MADS domain gene from Arabidopsis that is activated in shoot apical meristems during the transition to flowering. By transposon tagging we have identified late flowering agl20 mutants, showing that AGL20 is involved in flowering time control. In previously described late flowering mutants of the long-day and constitutive pathways of floral induction the expression of AGL20 is down-regulated, demonstrating that AGL20 acts downstream to the mutated genes. Moreover, we can show that AGL20 is also regulated by the gibberellin (GA) pathway, indicating that AGL20 integrates signals of different pathways of floral induction and might be a central component for the induction of flowering. In addition, the constitutive expression of AGL20 in Arabidopsis is sufficient for photoperiod independent flowering and the over-expression of the orthologous gene from mustard, MADSA, in the classical short-day tobacco Maryland Mammoth bypasses the strict photoperiodic control of flowering.     

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。     

The multifaceted roles of FLOWERING LOCUS T in plant development

One of the key developmental processes in flowering plants is the differentiation of the shoot apical meristem into a floral meristem. This transition is regulated through the integration of environmental and endogenous stimuli, involving a complex, hierarchical signalling network. In arabidopsis, the FLOWERING LOCUS T (FT) protein, a mobile signal recognized as a major component of florigen, has a central position in mediating the onset of flowering. FT-like genes seem to be involved in regulating the floral transition in all angiosperms examined to date. Evidence from molecular evolution studies suggests that the emergence of FT-like genes coincided with the evolution of the flowering plants. Hence, the role of FT in floral promotion is conserved, but appears to be restricted to the angiosperms. Besides flowering, FT-like proteins have also been identified as major regulatory factors in a wide range of developmental processes including fruit set, vegetative growth, stomatal control and tuberization. These multifaceted roles of FT-like proteins have resulted from extensive gene duplication events, which occurred independently in nearly all modern angiosperm lineages, followed by sub- or neo-functionalization. This review assesses the plethora of roles that FT-like genes have acquired during evolution and their implications in plant diversity, adaptation and domestication.     

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。     

Flowering in time: genes controlling photoperiodic flowering in Arabidopsis.

Successful sexual reproduction in plants relies upon the strict coordination of flowering time with favourable seasons of the year. One of the most important seasonal cues for the model plant Arabidopsis thaliana (Arabidopsis) is day length. Genes influencing flowering time in Arabidopsis have been isolated, some of which are involved in the perception and signalling of day length. This review discusses recent progress that has been made in understanding how Arabidopsis integrates environmental and internal signals to ensure a sharp transition to flowering and new insights on the role of the circadian clock in controlling the expression of genes that promote flowering in response to day length.     

An evolutionary perspective on the regulation of carpel development

The carpel, or female reproductive organ enclosing the ovules, is one of the major evolutionary innovations of the flowering plants. The control of carpel development has been intensively studied in the model eudicot species Arabidopsis thaliana. This review traces the evolutionary history of genes involved in carpel development by surveying orthologous genes in taxa whose lineages separated from that of A. thaliana at different levels of the phylogenetic tree of the seed plants. Some aspects of the control of female reproductive development are conserved between the flowering plants and their sister group, the gymnosperms, indicating the presence of these in the common ancestor of the extant seeds plants, some 300 million years ago. Gene duplications that took place in the pre-angiosperm lineage, before the evolution of the first flowering plants, provided novel gene clades of potential importance for the origin of the carpel. Subsequent to the appearance of the first flowering plants, further gene duplications have led to sub-functionalization events, in which pre-existing reproductive functions were shared between paralogous gene clades. In some cases, fluidity in gene function is evident, leading to similar functions in carpel development being controlled by non-orthologous genes in different taxa. In other cases, gene duplication events have created sequences that evolved novel functions by the process of neo-functionalization, thereby generating biodiversity in carpel and fruit structures.     

Control of reproduction by Polycomb Group complexes in animals and plants

In both mammals and plants, Polycomb Repressive Complexes 2 (PRC2) are conserved and appear to be involved in the transition between vegetative or somatic and reproductive state in plants and mammals. In plants at least three different PRC2 control temporal aspects of development, and mutations in PcG cause heterochronies. Such heterochronic mutations affect the transition to flowering. During gametogenesis the Fertilization-Independent Endosperm-MEDEA-PRC2 (FIE-MEA PRC2) complex controls gametogenesis in synergy with a Retinoblastoma-dependent pathway. Several genes of the FIE-MEA pathway are imprinted as shown by their uniparental allele expression in the endosperm, the interface controlling maternal nutrition of the embryo in the seed. Imprinting is also a major feature for genes expressed in the placenta in mammals. Recent data have shown that imprinting in both placenta and endosperm likely share similar mechanisms involving cooperation between the PRC2 complexes and DNA methylation.     

Identification of a gene involved in the juvenile-to-adult transition (JAT) in cultivated olive trees

The juvenile-to-adult transition is a complex and poorly understood process in plant development required to reach reproductive competence. For woody plants, knowledge of this transition is even scantier and no genes have been definitively identified as involved in this transition. To search for genes involved in the juvenile-to-adult transition in olive, we constructed juvenile and adult subtractive cDNA gene libraries and identified genes that were differentially expressed in the juvenile and adult phases. In the analysis of theses libraries, we found 13 differentially expressed genes. One of these genes designated as juvenile to adult transition (JAT) was of special interest because it was highly expressed at the mRNA level in the early developmental phases but repressed in the adult phase. The analysis of mutant trees altered in the juvenile-to-adult transition, as well as a segregating progeny of 31 trees from a “Picual” x “Jabaluna” cross, support the contention that its activity might be required for a non-delayed transition. The study of an Arabidopsis thaliana JAT mutant strain confirmed this hypothesis as it showed a delayed flowering phenotype. JAT is expressed in different parts of the plant, showing an unexpectedly high level of mRNA in the roots. However, the JAT expression level is not determined by the distance to the roots, but rather depends on the developmental stage of the branch meristems. JAT is a widely represented gene in plants that appears to be involved in the control of the juvenile-to-adult transition in olive.