光调控植物种子萌发分子机制研究进展

萌发是种子植物进入农业生态系统的重要发育阶段。对于需光类种子,光是调控其萌发最重要的环境信号因子之一,红光促进而远红光抑制种子萌发。光敏色素是调控种子萌发的主要光受体。活化的光敏色素诱导萌发主效抑制因子PIF1发生蛋白降解,调节赤霉素和脱落酸代谢和信号途径相关基因的表达,从而促进种子的萌发。同时,一系列的表观遗传因子通过改变染色质结构,动态调节萌发相关基因的表达从而影响种子的萌发进程。该论文重点论述了光调控种子萌发的转录及表观遗传机制研究进展,并对其在农业生产中的应用进行了展望。     

miRNA在血管重塑中的调节作用

miRNA是一种内源性RNA,为长度约22个核苷酸的单链非编码RNA。胞浆中成熟的miRNA通过与靶mRNA分子结合,在转录后水平抑制其翻译或使其降解。miRNA以不同的形式存在于细胞质和细胞核中,单个miRNA可调节多个靶基因,多个miRNA也可作用于同一个靶分子。研究发现,miRNA通过直接或间接作用于血管重塑相关基因,参与体内外血管重塑过程的调节,是心血管疾病中的重要调控因子。本文主要综述了miRNA在调控血管内皮细胞、血管平滑肌细胞的功能和其在血管损伤、重塑相关疾病中的调节作用。     

植物MicroRNA功能的研究进展

MicroRNA(miRNA)是真核生物基因表达的一类负调控因子,植物miRNA主要在转录水平上通过介导靶基因的甲基化、在转录后水平介导靶mRNA的切割或降低靶mRNA的翻译来调节基因的表达,从而调控植物器官的形态建成、生长发育、激素分泌与信号转导以及植物对逆境胁迫因素的应答能力。该文主要综述了近年来植物miRNA在植物生长发育、激素调节与信号转导以及逆境胁迫应答中的重要作用,并针对miRNA的网络调控特征提出了今后miRNA功能研究的方向。     

植物激素相关microRNA研究进展

microRNA（miRNA）是22nt左右的非编码RNA,主要在转录后水平调节基因的活性。miRNA通过与靶基因的互补位点结合从而降解靶基因mRNA或抑制其翻译。近年的研究发现,miRNA在植物生长发育中发挥着重要的调控作用。目前已知一些miRNA参与植物激素信号途径的切入点,这为我们了解miRNA和植物激素在植物发育中的作用提供了新思路。本文综述了miRNA参与植物激素信号应答及生物合成的研究进展,并对一些miINA在植物激素信号应答中可能的作用进行了讨论。     

辐射相关microRNA研究进展

microRNA(miRNA)是一类由内源基因编码的长度约22核苷酸的非编码单链RNA分子,主要以碱基互补方式与靶基因mRNA的3'非翻译区特异性结合,通过降解mRNA或抑制蛋白翻译合成而实现对靶基因的转录后调控。研究发现,miRNA在电离辐射诱导的生物学反应中发挥重要作用。我们从以下层面概述辐射相关miRNA的研究进展,即辐射调节miRNA表达、miRNA对辐射后DNA损伤的调节、miRNA参与的辐射生物学效应。     

microRNAs调控骨骼肌分化的分子机制

microRNA（miRNA）是一大类广泛存在于真核细胞当中的长度约22nt的内源性单链非编码RNA,通过与靶基因mRNA的3’非翻译区（3’untranslated region,3’UTR）结合在转录后水平调控靶基因的表达。miRNA作为调控基因表达的重要分子在骨骼肌分化调控中的作用越来越受到关注,阐明miRNA在骨骼肌增殖与分化中的作用机制具有重要的理论意义,同时也可为骨骼肌相关疾病的治疗提供新的思路。文章总结了miRNA,尤其是miR-1、miR-133和miR-206等肌肉特异性miRNA,在调控骨骼肌分化过程中作用机制的研究进展,以便于进一步工作的开展。     

miRNA在植物种子发育过程中的作用

MicroRNA(miRNA)是一类小分子非编码RNA,通过降解靶基因途径在转录后水平调控基因表达,参与植物生长、发育以及逆境胁迫应答等多种细胞代谢活动。种子是植物生长的基础要素,是农业生产的重要资料。与种子发育相关的miRNA已在多种植物中得到鉴定。文章综述了参与植物种子发育过程的miRNA及其在种子发育中的具体调控机制,旨在为利用miRNA提高种子遗传特性提供研究思路。     

microRNA在玉米生长发育及非生物胁迫响应中的调控功能

microRNA（miRNA）是一类广泛存在于真核生物中长度为20~24 nt的内源非编码小RNA，它们通过对靶基因mRNA进行切割或翻译抑制，在转录后水平调控靶基因的表达。近期研究表明，miRNA参与植物生长发育与逆境胁迫响应的多个重要生物学过程，对作物的农艺性状也起到重要的调控作用。玉米作为重要的粮食、饲料和工业原料，提高其产量和品质对于保障世界粮食安全至关重要，然而与模式植物拟南芥和水稻相比，玉米中miRNA的研究仍然相对较少，理解miRNA在玉米中的功能和调控机理有助于通过分子育种对关键农艺性状进行遗传改良。本文综述了玉米中miRNA的发现与鉴定，系统总结了参与玉米miRNA代谢途径的关键蛋白DCL、AGO和HEN1的研究进展，重点阐述了在玉米生长发育和非生物胁迫响应过程中已开展功能研究miRNA的调控作用，并对玉米miRNA研究当前存在的问题和未来的发展趋势进行了讨论。     

MicroRNAs与肿瘤

microRNA(miRNA)是一类对基因具有调控功能的内源性非编码小分子RNA,通过与靶mRNA完全或不完全互补配对,引起mRNA降解或翻译抑制,从而对基因转录后水平进行调控.目前认为miRNA在多种生物学过程中起着至关重要的作用,包括细胞增殖、分化、凋亡等.研究显示miRNA的表达异常能导致疾病甚至肿瘤的发生,有类似于抑癌基因或癌基因的功能.本文就miRNA在肿瘤发生和诊断方面的研究进展作一综述.     

MicroRNA调控被子植物花发育的研究进展

MicroRNA（miRNA）是一类由内源基因编码的长度为21～23nt的非编码单链小RNA分子,通过与靶基因的互补位点结合而降解或抑制靶mRNA的翻译,从而在转录后水平上调控基因的活性。miRNA在调控植物发育方面发挥着广泛的作用。从成花诱导到花器官特征属性的形成,miRNA在整个花发育过程均发挥着关键作用。miRl72和miRl56／157参与由营养生长向生殖生长转换的调控,miRl72和miRl69在花发育的早期阶段通过界定靶基因的表达区域而调控花器官的属性,miR319、miRl59、miRl64以及miRl67在花发育的晚期阶段决定细胞的特化。文章综述了miRNA调控被子植物花发育的研究进展,为深入了解miRNA的作用机制奠定基础。     

光敏色素互作因子PIFs是整合多种信号调控植物生长发育的核心元件

光敏色素互作因子（PIFs）蛋白家族隶属于bHLH转录因子家族,参与多种信号转导途径,调控植物的生长发育进程,如抑制种子萌发、促进幼苗的暗形态建成和调控开花时间等。作为一个胞内信号调控的重要组分,PIFs广泛参与到由多种植物内源激素如赤霉素、乙烯、生长素、油菜素内酯、脱落酸和外部环境因素如高温、光等所介导的信号网络中。本文AKPIFs的结构、参与途径及调控植物发育进程3个方面,简要介绍近年来国内外对PIFs在信号网络调控方面的最新研究进展。     

Dynamic Histone Acetylation of Late Embryonic Genes during Seed Germination

Histone acetylation is involved in the regulation of gene expression in plants and eukaryotes. Histone deacetylases (HDACs) are enzymes that catalyze the removal of acetyl groups from histones, which is associated with the repression of gene expression. To study the role of histone acetylation in the regulation of gene expression during seed germination, trichostatin A (TSA), a specific inhibitor of histone deacetylase, was used to treat imbibing Arabidopsis thaliana seeds. GeneChip arrays were used to show that TSA induces up-regulation of 45 genes and down-regulation of 27 genes during seed germination. Eight TSA-up-regulated genes were selected for further analysis – RAB18, RD29B, ATEM1, HSP70 and four late embryogenesis abundant protein genes (LEA). A gene expression time course shows that these eight genes are expressed at high levels in the dry seed and repressed upon seed imbibition at an exponential rate. In the presence of TSA, the onset of repression of the eight genes is not affected but the final level of repressed expression is elevated. Chromatin immunoprecipitation and HDAC assays show that there is a transient histone deacetylation event during seed germination at 1 day after imbibition, which serves as a key developmental signal that affects the repression of the eight genes. Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

Gene Expression Profile Changes in Germinating Rice

Water absorption is a prerequisite for seed germination. During imbibition, water influx causes the resumption of many physiological and metabolic processes in growing seed. In order to obtain more complete knowledge about the mechanism of seed germination, two‐dimensional gel electrophoresis was applied to investigate the protein profile changes of rice seed during the first 48 h of imbibition. Thirty‐nine differentially expressed proteins were identified, including 19 down‐regulated and 20 up‐regulated proteins. Storage proteins and some seed development‐ and desiccation‐associated proteins were down regulated. The changed patterns of these proteins indicated extensive mobilization of seed reserves. By contrast, catabolism‐associated proteins were up regulated upon imbibition. Semi‐quantitative real time polymerase chain reaction analysis showed that most of the genes encoding the down‐ or up‐regulated proteins were also down or up regulated at mRNA level. The expression of these genes was largely consistent at mRNA and protein levels. In providing additional information concerning gene regulation in early plant life, this study will facilitate understanding of the molecular mechanisms of seed germination.     

Deep Sequencing of Maize Small RNAs Reveals a Diverse Set of MicroRNA in Dry and Imbibed Seeds

Seed germination plays a pivotal role during the life cycle of plants. As dry seeds imbibe water, the resumption of energy metabolism and cellular repair occur and miRNA-mediated gene expression regulation is involved in the reactivation events. This research was aimed at understanding the role of miRNA in the molecular control during seed imbibition process. Small RNA libraries constructed from dry and imbibed maize seed embryos were sequenced using the Illumina platform. Twenty-four conserved miRNA families were identified in both libraries. Sixteen of them showed significant expression differences between dry and imbibed seeds. Twelve miRNA families, miR156, miR159, miR164, miR166, miR167, miR168, miR169, miR172, miR319, miR393, miR394 and miR397, were significantly down-regulated; while four families, miR398, miR408, miR528 and miR529, were significantly up-regulated in imbibed seeds compared to that in dry seeds. Furthermore, putative novel maize miRNAs and their target genes were predicted. Target gene GO analysis was performed for novel miRNAs that were sequenced more than 50 times in the normalized libraries. The result showed that carbohydrate catabolic related genes were specifically enriched in the dry seed, while in imbibed seed target gene enrichment covered a broad range of functional categories including genes in amino acid biosynthesis, isomerase activity, ligase activity and others. The sequencing results were partially validated by quantitative RT-PCR for both conserved and novel miRNAs and the predicted target genes. Our data suggested that diverse and complex miRNAs are involved in the seed imbibition process. That miRNA are involved in plant hormone regulation may play important roles during the dry-imbibed seed transition.     

脱落酸调控种子休眠和萌发的分子机制

脱落酸(ABA)是调控种子休眠和萌发过程的主要植物激素。种子内源ABA含量和种胚对ABA敏感性共同调控种子休眠和萌发过程, 确保植物种子以休眠状态在逆境中保持其自身繁衍能力, 并在适宜的环境下启动萌发程序。种子ABA合成代谢和ABA信号转导途径涉及许多重要基因家族, 它们通过复杂的调控网络精确地控制着种胚发生、种子成熟、休眠及萌发进程。该文对ABA调控种子休眠和萌发的分子机制最新研究进展进行综述, 并展望了今后的研究方向。     

AtGA3ox2, a key gene responsible for bioactive gibberellin biosynthesis, is regulated during embryogenesis by LEAFY COTYLEDON2 and FUSCA3 in Arabidopsis

Embryonic regulators LEC2 (LEAFY COTYLEDON2) and FUS3 (FUSCA3) are involved in multiple aspects of Arabidopsis (Arabidopsis thaliana) seed development, including repression of leaf traits and premature germination and activation of seed storage protein genes. In this study, we show that gibberellin (GA) hormone biosynthesis is regulated by LEC2 and FUS3 pathways. The level of bioactive GAs is increased in immature seeds of lec2 and fus3 mutants relative to wild-type level. In addition, we show that the formation of ectopic trichome cells on lec2 and fus3 embryos is a GA-dependent process as in true leaves, suggesting that the GA pathway is misactivated in embryonic mutants. We next demonstrate that the GA-biosynthesis gene AtGA3ox2, which encodes the key enzyme AtGA3ox2 that catalyzes the conversion of inactive to bioactive GAs, is ectopically activated in embryos of the two mutants. Interestingly, both beta-glucuronidase reporter gene expression and in situ hybridization indicate that FUS3 represses AtGA3ox2 expression mainly in epidermal cells of embryo axis, which is distinct from AtGA3ox2 pattern at germination. Finally, we show that the FUS3 protein physically interacts with two RY elements (CATGCATG) present in the AtGA3ox2 promoter. This work suggests that GA biosynthesis is directly controlled by embryonic regulators during Arabidopsis embryonic development.