Cloning and Characterization of Putative Hd6 Ortholog Associated with Zea mays L.Photoperiod Sensitivity

The photoperiod response of fowering is critical to the survival and successful reproduction in crops.The Hd6 gene,encoding a protein similar to the Arabidopsis α-subunit of CASEIN KINASE2α(CK2α)has been reported to affect flowering time through the photoperiodic pathway in rice.In this study,the maize ortholog,ZmHd6,has been cloned and its role in the photoperiodic pathway was investigated.ZmHd6 encodes 332 amino acids with six distinct domains: two CK2 active domains,a nuclear localization signal sequence,a N terminal domain,an ATP binding site,and an active site of serine/threonine protein kinase.ZmHd6 was constitutively expressed in the leaves and shoot apical meristem(SAM)with the highest expression in SAMs of plants with seven leaves under long and short day conditions.Delayed flowering time under long day(LD)conditions were observed in ZmHd6 overexpression transgenic Arabidopsis plants compared to the wild type.In transgenic Arabidopsis plants,ZmHd6 was expressed in a circadian oscillatory pattern,TOC1 peak expression was delayed,new G1,CO,and FT expressions reached to peak after 3 h while entering illumination period and oscillatory expression patterns of CO and FT were created during the dark phase.These results suggested that ZmHd6 might negatively regulate flowering time under LD conditions by delaying TOC1 peak expression and disrupting CO and FT expression in transgenic Arabidopsis plants.     

Distinct roles of CONSTANS target genes in reproductive development of Arabidopsis

In plants, flowering is triggered by endogenous and environmental signals. CONSTANS (CO) promotes flowering of Arabidopsis in response to day length. Four early target genes of CO were identified using a steroid-inducible version of the protein. Two of these genes, SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1) and FLOWERING LOCUS T (FT), are required for CO to promote flowering; the others are involved in proline or ethylene biosynthesis. The SOC1 and FT genes are also regulated by a second flowering-time pathway that acts independently of CO. Thus, early target genes of CO define common components of distinct flowering-time pathways.     

光周期诱导马铃薯块茎形成的分子机理研究进展

马铃薯块茎形成机理不仅是植物发育生物学研究的重要内容之一,也是提高马铃薯产量、品质的重要保障。早期研究发现,光周期是诱导马铃薯块茎形成的一个关键环境因子,短日照利于马铃薯块茎形成。近10多年来,光周期调控马铃薯块茎形成机理研究取得了重要进展。已有研究发现,马铃薯块茎形成与拟南芥等植物的开花过程有较多相似之处。大量参与植物开花的重要基因,如光敏色素、CONSTANS (CO)、FLOWERING LOCUS T (FT)、LOV蓝光受体蛋白家族及CDF转录因子等在马铃薯块茎形成过程中都起到重要的调控作用。此外,马铃薯中发现的同源异型框基因POTH1及其相互作用基因StBEL5也在光调控马铃薯块茎形成过程中扮演重要角色。本文主要从马铃薯光信号感知及与光周期信号传递有关的基因调控等领域综述了光周期诱导的马铃薯块茎形成最新研究进展。     

Photoreceptor regulation of CONSTANS protein in photoperiodic flowering

Many plants flower in response to seasonal fluctuations in day length. The CONSTANS (CO) gene of Arabidopsis promotes flowering in long days. Flowering is induced when CO messenger RNA expression coincides with the exposure of plants to light. However, how this promotes CO activity is unknown. We show that light stabilizes nuclear CO protein in the evening, whereas in the morning or in darkness the protein is degraded by the proteasome. Photoreceptors regulate CO stability and act antagonistically to generate daily rhythms in CO abundance. This layer of regulation refines the circadian rhythm in CO messenger RNA and is central to the mechanism by which day length controls flowering.     

CO/FT调节元件与植物开花时间调节研究进展

综述了CO/FT调节元件与植物开花时间调节的最新研究进展。开花是植物由营养生长向生殖生长转变的关键过程。光周期和温度在植物开花时间控制中起主要作用。在拟南芥和水稻中,CONSTANS（CO）对植物的日照长度测定至关重要,它与其靶基因FLOWERING LOCUS T（FT）构成的调节元件（regulon）在依赖于光周期的开花过程中起重要作用。目前已从多种植物中鉴定出CO和FT基因,并对其在开花时间的调控作用进行了深入研究。     

3种FT基因诱导杨树早期开花比较

为了促进杨树早期开花,缩短杨树遗传育种周期,采用农杆菌AGL1介导的转化方法及热激诱导方法,进行了热激启动子HSP控制下的3类FT基因转化2种杨树无性系(353与717)诱导杨树早期开花的比较研究.结果表明:来自拟南芥的FT基因促花效果优于来自杨树的FT1和FT2基因;FT类基因与受体基因型/性别之间互作明显,开花较好...     

高等植物开花基因FT研究进展

FT是光周期途径植物开花时间决定关键基因,FT基因编码的蛋白产物是可以长距离转运的成花激素,在花形成过程中起关键作用。目前,已经证明FT基因的表达可促进植物提早开花。主要对植物开花基因FT研究进展及其在花发育转换过程中的功能等研究现状进行综述,并对该基因研究前景提出展望。     

水稻成花素Hd3a及其受体分子机制研究进展

成花素是有一个控制开花位点的基因FT(FLOWERING LOCUS T)编码的产物,成花素FT是植物开花途径中的关键整合因子。而水稻中的Hd3a(HEADING DATE 3a)是拟南芥FT的同源基因,Hd3a蛋白即是水稻中的成花激素,其在叶片中表达并通过微管组织运输到顶端分生组织,同成花素受体14-3-3蛋白结合,然后又附着到另一种转录因子OsFD1(FLOWERING LOCUS D)上形成成花素激活复合体,使开花基因OsMADS15功能活跃起来。文中对水稻成花素Hd3a及其受体14-3-3蛋白分子作用机制的研究进展进行了综述,为进一步研究植物开花分子生物学提供参考。     

成花素的移动性及其在育种中的应用

开花是植物从营养生长进入生殖生长的转折点。近年的研究表明,FT就是寻找多年的成花素。FT蛋白在叶片合成,通过韧皮部从芽接部位移动到接穗或根部,其过表达常导致植物提早开花,以上特点在促进木本植物提早开花、缩短童期、加速育种具有重要价值。综述FT蛋白的移动为成花必须,FT蛋白芽接移动性在一年生及多年生植物的差异、FT促进观赏植物提早开花、利用FT加速育种进程等方面的进展,为相关研究提供参考。     

Hd3a protein is a mobile flowering signal in rice

Florigen, the mobile signal that moves from an induced leaf to the shoot apex and causes flowering, has eluded identification since it was first proposed 70 years ago. Understanding the nature of the mobile flowering signal would provide a key insight into the molecular mechanism of floral induction. Recent studies suggest that the Arabidopsis FLOWERING LOCUS T (FT) gene is a candidate for encoding florigen. We show that the protein encoded by Hd3a, a rice ortholog of FT, moves from the leaf to the shoot apical meristem and induces flowering in rice. These results suggest that the Hd3a protein may be the rice florigen.     

The mRNA of the Arabidopsis gene FT moves from leaf to shoot apex and induces flowering

Day length controls flowering time in many plants. The day-length signal is perceived in the leaf, but how this signal is transduced to the shoot apex, where floral initiation occurs, is not known. In Arabidopsis, the day-length response depends on the induction of the FLOWERING LOCUS T (FT) gene. We show here that local induction of FT in a single Arabidopsis leaf is sufficient to trigger flowering. The FT messenger RNA is transported to the shoot apex, where downstream genes are activated. These data suggest that the FT mRNA is an important component of the elusive "florigen" signal that moves from leaf to shoot apex.     

Multiple roles of Arabidopsis VRN1 in vernalization and flowering time control

Arabidopsis VRN genes mediate vernalization, the process by which a long period of cold induces a mitotically stable state that leads to accelerated flowering during later development. VRN1 encodes a protein that binds DNA in vitro in a non-sequence-specific manner and functions in stable repression of the major target of the vernalization pathway, the floral repressor FLC. Overexpression of VRN1 reveals a vernalization-independent function for VRN1, mediated predominantly through the floral pathway integrator FT, and demonstrates that VRN1 requires vernalization-specific factors to target FLC.     

光周期途径成花关键基因CONSTANS的进化机制

CONSTANS（CO）是植物响应光周期调节的重要基因和监测日照长度的重要元件,可将光信号和生物钟信号转变为开花信号,激活下游基因（FT）的表达,从而诱导植物开花。选取14个已被测序的物种,采用生物信息学手段,从外显子-内含子结构、基因重复、基因差异表达等方面开展CO基因家族研究。结果表明:14个物种共鉴定到159个CO家族成员,CO基因常以多拷贝的形式存在,多数含2~4个外显子,在进化过程中表现出多样性。CO家族重复基因的扩张与基因组重复相关。CO在水稻Oryza sativa根、旗叶、花和种子中均有表达,花芽到花的转变过程中OsCO3的表达量上升,而OsCO7下降,说明水稻CO家族成员之间存在功能差异。