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。     

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。     

microRNA在植物生长发育中的研究进展

microRNA(miRNA)是一类广泛存在于植物体内,长约20-25个核苷酸的内源性非编码小分子RNA,通过定向降解靶基因mRNA和抑制其翻译,从而在转录后水平控制靶向基因的表达来调控多种多样的生物功能,包括植物的生长发育、生殖和对逆境胁迫的响应。已有的研究表明,miRNA及其靶基因不仅在植物的时序转换中是一个关键调控因子,也在茎尖发育、叶形态建成、花器官发育和开花时间等过程中发挥着重要调控作用。重点介绍mi RNA在调控植物生长发育过程以及发育可塑性过程中的研究进展,并对植物miRNA研究中有待进一步阐明的问题进行了探讨和展望,以期为深入解析miRNA在调节植物组织和器官模式中的功能,以及植物形态多样性中的作用和分子调控网络提供参考。     

植物MicroRNA

MicroRNA (miRNA)是一类长度约为22个核苷酸的内源单链非编码RNA,在结构上相当保守,因而可以借助生物信息学方法进行预测. 从2002年证实miRNA在植物中的存在以来,关于植物miRNA的研究进展异常迅速,短短几年内就已发现200多种. 植物miRNA主要通过切割靶mRNA,或抑制靶mRNA翻译,来调控植物个体生长发育并影响其生理过程,是一种新的基因调控方式. 本文将就植物miRNA的形成、特征、作用机制、生物功能及其与siRNA的关系进行综述.     

MicroRNAs在动物皮肤和毛发发育中的调控作用

MicroRNAs(miRNAs)是近年来发现的一类由19～25个核苷酸组成的非编码单链小RNA分子,它们通过与靶基因mRNA的3′非编码区相互配对结合,在转录后水平负调控靶基因的表达.miRNA参与了包括细胞增殖、分化和凋亡及免疫系统应答在内的一系列发育调控和生物学过程.最近几年研究发现,miRNA在多种哺乳动物皮肤中均表达,并参与了哺乳动物皮肤及毛发发育的调控过程.本文综述了近几年来miRNA在各种动物皮肤及毛发发育中的表达谱以及miRNA在皮肤形态发生中的重要作用.     

植物miRNA的分子特征及其在逆境中的响应机制

逆境胁迫是影响植物生长发育、生物产量与品质形成的主要因素之一。通过诱导表达抗逆有关的编码基因与部分非编码基因是植物响应逆境的主要方式。miRNA作为一种非编码基因在植物生长、发育以及抗逆等过程中起重要的调控作用。研究表明:逆境胁迫下miRNA可以形成miRNA诱导沉默复合物(miRNA-induced silencing complex,miRISC),并与靶mRNA互补配对结合,进而引起靶mRNA的降解或者抑制其翻译,从而实现对下游抗逆相关基因表达的调控,最终引起代谢与信号转导途径的变化实现对逆境的响应。本文从植物逆境胁迫下诱导miRNA的产生、靶基因的识别以及作用机制等方面进行了综述。     

microRNA172参与植物生长发育及逆境响应的研究进展

microRNA(miRNA)是一类长约20~25个核苷酸的非编码小分子RNA,通过和靶基因mRNA上的一些特定序列结合,诱导靶基因mRNA被剪切或抑制其翻译,从而在转录后水平调控植物的生长发育和对逆境的响应。microR172(miR172)是植物中一个保守的miRNA家族,通过靶向调控AP2和AP2-Like基因在植物发育和环境适应中发挥着不可或缺的作用。已有的研究表明,miR172及其靶基因不仅在植物的时序转换中是一个关键调控因子,也在花器官发育、土豆块茎形成、豆科结瘤和逆境响应等过程中发挥着重要调控作用。现将重点阐述这个明星miRNA在植物生长发育及对环境因子应答过程中的研究进展,以期为深入解析miR172靶基因的作用机理和分子调控网络提供参考。     

动物 microRNA 靶基因的筛选与鉴定研究进展

miRNA（microRNA）是一类在生物体内广泛存在的长度约22nt的小分子非编码RNA,其在转录后水平调控靶基因的表达,在生物体生长发育过程中起重要的调控作用。近年来,miRNA的功能研究越来越受到人们的重视,而miRNA功能研究的关键在于其调控靶基因的确定。miRNA主要作用于靶基因mRNA的3’UTR区的结合位点．但由于miRNA和靶基因的作用位点并不完全匹配,没有明显的规律可寻,导致应用传统方法鉴定靶基因十分困难。近年来,人们开发了各种特异的、灵敏度高的高通量miRNA靶基因筛选与鉴定方法,极大地促进了miRNA的功能研究。     

植物miRNA参与调控作物农艺性状的研究进展

植物microRNA (miRNA)是一类长度约为20～24 nt的内源非编码小RNA,它们通过在转录后水平调控靶基因的表达,在植物的生长发育、逆境响应和环境适应等过程中起着关键作用. miRNA对水稻、玉米、大豆等重要经济作物的农艺性状也起着重要的调控作用,在改良农作物性状上具有重大的应用潜能.本文重点介绍了参与作物农艺性状(如株型、花期、种子发育及抗逆等)调控的关键miRNA及其调控途径,同时总结了miRNA参与作物性状改良的主要研究方法和手段,并讨论了miRNA在作物性状改良应用中的前景.     

植物miRNA靶基因验证研究进展

植物microRNA(miRNA)可以利用碱基互补配对原则对靶基因进行识别并介导靶基因(mRNA)的切割或翻译抑制,以此机制来调控靶基因的表达。主要从作用方式及实验体系两大方面入手,综述了植物miRNA与其靶基因的作用机制,以及植物miRNA靶基因验证方法的研究进展,旨在更深入的探究miRNA与其靶基因的作用关系。     

Identification of miRNAs and Their Target Genes in Peach (Prunus persica L.) Using High-Throughput Sequencing and Degradome Analysis

MicroRNAs play critical roles in various biological and metabolic processes. The function of miRNAs has been widely studied in model plants such as Arabidopsis and rice. However, the number of identified miRNAs and related miRNA targets in peach (Prunus persica) is limited. To understand further the relationship between miRNAs and their target genes during tissue development in peach, a small RNA library and three degradome libraries were constructed from three tissues for deep sequencing. We identified 117 conserved miRNAs and 186 novel miRNA candidates in peach by deep sequencing and 19 conserved miRNAs and 13 novel miRNAs were further evaluated for their expression by RT-qPCR. The number of gene targets that were identified for 26 conserved miRNA families and 38 novel miRNA candidates, were 172 and 87, respectively. Some of the identified miRNA targets were abundantly represented as conserved miRNA targets in plant. However, some of them were first identified and showed important roles in peach development. Our study provides information concerning the regulatory network of miRNAs in peach and advances our understanding of miRNA functions during tissue development.     

Cloning and characterization of miRNAs from maize seedling roots under low phosphorus stress

MicroRNAs (miRNAs) are a class of small, non-coding regulatory RNAs that regulate gene expression by guiding target mRNA cleavage or translational inhibition in plants and animals. In this study, a small RNA library was constructed to identify conserved miRNAs as well as novel miRNAs in maize seedling roots under low level phosphorus stress. Twelve miRNAs were identified by high throughput sequencing of the library and subsequent analysis, two belong to conserved miRNA families (miRNA399b and miRNA156), and the remaining ten are novel and one of latter is conserved in gramineous species. Based on sequence homology, we predicted 125 potential target genes of these miRNAs and then expression patterns of 7 miRNAs were validated by semi-RT-PCR analysis. MiRNA399b, Zma-miR3, and their target genes (Zmpt1 and Zmpt2) were analyzed by real-time PCR. It is shown that both miRNA399b and Zma-miR3 are induced by low phosphorus stress and regulated by their target genes (Zmpt1 and Zmpt2). Moreover, Zma-miR3, regulated by two maize inorganic phosphate transporters as a newly identified miRNAs, would likely be directly involved in phosphate homeostasis, so was miRNA399b in Arabidopsis and rice. These results indicate that both conserved and maize-specific miRNAs play important roles in stress responses and other physiological processes correlated with phosphate starvation, regulated by their target genes. Identification of these differentially expressed miRNAs will facilitate us to uncover the molecular mechanisms underlying the progression of maize seedling roots development under low level phosphorus stress.     

Identification of novel microRNAs in rice (Oryza sativa) based on the cleavage signals in precursors

MicroRNAs (miRNAs) are crucial regulators of gene expression in plants and a growing number of novel miRNA genes have been cloned in rice in recent years. However, there is no evidence that all miRNAs have been discovered, especially for those low expression ones which are difficult to be found by conventional methods. By taking advantage of the finding that DCL1-mediated cleavage signals for the processing of the miRNA precursors could be used as the clues for novel miRNAs’ discovery, a genome-wide search for rice miRNA candidates was carried out. As a result, 51 previously validated miRNAs and 24 novel miRNA candidates were discovered. After target prediction and degradome sequencing data-based validation, coupled with reverse approach retest, 10 miRNA candidate–mRNA target pairs were further identified, providing a basis for in-depth functional analysis of these miRNA candidates. Besides, some isomiRs found in this study showed more likely to be the real miRNAs. We also found an exceptional example which did not obey the rule that 22-nt miRNAs have the ability to trigger the phased siRNAs production from the cleaved targets.     

Analysis of miRNA-seq combined with gene expression profile reveals the complexity of salinity stress response in <Emphasis Type="Italic">Oryza sativa</Emphasis>

High salinity is a major abiotic stressor that affects crop productivity and quality. While proper seedling growth is critical for crop reproduction under high salinity stress. Nowadays, genes/miRNAs expression is used for studying salinity stress response in rice seedlings. However, analysis of miRNA combined with gene expression is rare. To this end, we used miRNA-seq and gene expression profile to ascertain 6335 genes (3276 genes up-regulated, 3059 genes down-regulated) and 126 miRNAs (47 miRNAs up-regulated, 79 miRNAs down-regulated) that respond to salinity stress in rice seedlings. We then used these 126 miRNAs (including the novel miRNA osa-Chr12_1506) to identify 121 differentially expressed predicted target genes. In addition, we identified 34 miRNA-target RNA pairs, consisting of 9 differentially expressed miRNAs with complementary expression patterns. Combined with previous studies, we proposed a simple model for the molecular mechanism of a 12-h salinity stress response in rice seedlings. The findings lead to a deeper understanding of the function of miRNAs and genes that respond to salinity, and contributed to the elucidation of the complex mechanisms activated by salinity stress.     

Microarray-based screening of the microRNAs associated with caryopsis development in Oryza sativa

Plant microRNAs modulate diverse developmental processes by regulating expression of their target genes. To explore potential miRNA-guided gene regulation in developing rice (Oryza sativa L.) caryopses, a miRNA microarray was used to identify miRNAs present at the different developmental stages. We found that 27 miRNAs, of which 16 were conserved miRNAs, were present in developing caryopses. High expression levels were detected for miR159, miR167, and miR530 at the morphogenesis stage and for miR169, miR435, and miR528 at the stage of accumulation of metabolites. Next, 26 target genes were predicted for seven of the detected miRNAs and the expression profiles of these miRNAs and their corresponding target genes were examined in developing caryopses. Our results suggest that the miRNAs and their target genes examined at the two distinct stages could contribute to the developmental progress of rice caryopses in concert with phytohormone signalling.     

Expression patterns of microRNAs in different organs and developmental stages of a superhybrid rice LYP9 and its parental lines

Heterosis is an important phenomenon, and the molecular mechanisms underlying heterosis are still enigmatic. microRNAs (miRNAs) play vital roles in many aspects of plant development. A set of miRNAs was selected to investigate the roles of miRNAs in heterosis displayed in a superhybrid rice. We analysed the expression patterns of miRNAs in different organs and developmental stages of the superhybrid rice and its parental lines. All possible modes of miRNA action were observed, including additive, high‐ and low‐parent value, above high‐ and below low‐parent value. Different organs and developmental stages exhibited different modes of miRNA expression. Overall, the non‐additive mode is the predominant expression pattern of miRNAs observed in this superhybrid. Many heterotic QTL intervals harbour miRNAs, whose expression patterns reveal their specific roles in different organs and developmental stages. miRNAs regulate the expression levels of target genes that have important functions in plant development. The predominant non‐additive mode of miRNA expression pattern in the hybrid suggests that miRNAs play critical roles in hybrid development, in particular, those miRNAs located in the heterotic QTL intervals may have important roles in heterosis. Our research sheds new light on understanding of the molecular mechanisms of heterosis.