MicroRNAs and Their Cross-Talks in Plant Development

Plant development is a complex process influenced by exogenous and endogenous elements. A series of postembryonic developmental events is involved to form the final architecture and contend with the changing environment. MicroRNA (miRNA) is one of endogenous non-coding RNAs, which plays an important role in plant developmental regulation. In this review, we summarized 34 miRNA families that are closely associated with plant development. Among these families, nine are expressed only in specific organs, whereas 20 families are expressed in at least two different organs. It is known that some miRNAs are expressed across most processes of plant growth, while some appear only at particular developmental stages or under special environmental conditions such as drought, waterlogging and short-day time. These miRNAs execute their diverse functions by regulating developmental gene expression levels, interacting with phytohormone signaling response, participating in the biogenesis of ta-siRNAs and affecting the production of miRNAs.     

Future Prospects for Developing Disease Resistant Plants

Transgenic Research -     

转基因植物中报道基因GUS的活性检测及其应用

GUS基因是目前转基因植物中应用最为广泛的报道基因。GUS基因在转基因植物中的活性检测方法有组织化学定位法、分光光度法、荧光分析法、聚丙烯酰胺凝胶原位分析法等。     

Developing a Photoautotrophic Micropropagation System for Woody Plants

in vitro including cotyledonary stage somatic embryos have the ability to grow photoautotrophically (without sugar in the culture medium), and that the low or negative net photosynthetic rate of plants in vitro is due not to poor photosynthetic ability, but to the low CO₂ concentration in the air-tight culture vessel during the photoperiod. Furthermore, we have shown that the photoautotrophic growth of several woody plants in vitro can be significantly promoted by increasing the CO₂ concentration and light intensity in the vessel, by decreasing the relative humidity in the vessel, and by using a fibrous or porous supporting material with high air porosity instead of gelling agents such as agar. In this paper, the advantages of photoautotrophic micropropagation in a conventional, small culture vessel with a microporous gas filter for enhancing natural ventilation and in a large culture vessel with a forced ventilation unit are described for woody plants such as acacia (Acacia mangium), coffee (Coffea arabusta), eucalyptus (Eucalyptus camaldlensis), mangosteen (Garcinia mangostana), neem (Azadirachta indica), paulownia (Paulownia fortunei), and pine (Pinus radiata). Received 30 August 2001/ Accepted in revised form 27 September 2001     

植物成熟microRNA转录后修饰与降解的研究进展

microRNA(miRNA)是一类长度为20–24 nt的内源小RNA,广泛存在于各种植物体内,参与调控植物器官的形态建成、激素应答、逆境胁迫和营养代谢等一系列过程。虽然miRNA生物合成和功能研究已取得了很大进展,但关于植物成熟miRNA的转录后修饰和降解的研究却报道较少。一方面miRNA如同其它RNA存在半衰期,其降解对于调控细胞内miRNA含量起重要作用,从而调控植物的生长发育或胁迫响应等过程;另一方面,成熟miRNA存在转录后修饰,可影响miRNA的稳定性,最终影响其活性。该文着重从植物成熟miRNA的转录后修饰和降解等方面进行了综述。     

植物体中一氧化氮的检测方法及其应用

文章介绍植物体中NO的各种检测方法及其应用的研究进展。     

Gene Structure Analysis of Rice ADP-ribosylation Factors (OsARFs) and Their mRNA Expression in Developing Rice Plants

ADP-ribosylation factors (ARFs) have been widely identified as being involved in regulation of cell differentiation, intracellular vesicle transport, and cytoskeleton organization in animals and plants. To systematically clarify the ARF gene family in rice, eight putative rice ARF genes (OsARFs) were detected by searching the rice genome database. The OsARFs can be classified into class I (OsARFA1a-OsARFA1e) and class II (OsARFB1a-OsARFB1c) by comparing their deduced amino acid sequences with other known ARFs. Most OsARFs are composed of six exons and five introns, though OsARFB1b has three exons and two introns. The OsARFs are usually expressed in various developing organs, whereas OsARFA1a is predominantly expressed in young roots and in caryopses at early development stages. The histochemical localization of OsARFs in various developing organs was confirmed in young leaves, the pericycle of young roots, and the aleurone layer of developing caryopses. Furthermore, the expression of OsARFA1a was confirmed specifically in the aleurone layer and immature embryos of developing caryopses. The present work provides a foundation for further clarifying the physiological functions of OsARFs in rice growth and development.     

植物中microRNA的合成及在发育和抗逆中的作用

介绍了植物microRNA（miRNA）的结构、合成、作用机制及其在植物生长发育和逆境胁迫中作用的研究进展。     

Phytohormone Priming: Regulator for Heavy Metal Stress in Plants

Phytohormones act as chemical messengers and, under a complex regulation, allow plants to sustain biotic and abiotic stresses. Thus, phytohormones are known for their regulatory role in plant growth and development. Heavy metals (HMs) play an important role in metabolism and have roles in plant growth and development as micronutrients. However, at a level above threshold, these HMs act as contaminants and pose a worldwide environmental threat. Thus, finding eco-friendly and economical deliverables to tackle this problem is a priority. In addition to physicochemical methods, exogenous application of phytohormones, i.e., auxins, cytokinins, and gibberellins, can positively influence the regulation of the ascorbate–glutathione cycle, transpiration rate, cell division, and the activities of nitrogen metabolism and assimilation, which improve plant growth activity. Brassinosteroids, ethylene and salicylic acid have been reported to enhance the level of the anti-oxidant system, decrease levels of ROS, lipid peroxidation and improve photosynthesis in plants, when applied exogenously under a HM effect. There is a crosstalk between phytohormones which is activated upon exogenous application. Research suggests that plants are primed by phytohormones for stress tolerance. Chemical priming has provided good results in plant physiology and stress adaptation, and phytohormone priming is underway. We have reviewed promising phytohormones, which can potentially confer enhanced tolerance when used exogenously. Exogenous application of phytohormones may increase plant performance under HM stress and can be used for agro-ecological benefits under environmental conditions with high HMs level.

     

造血干细胞相关microRNAs的筛选及其促分化研究

为了获得人脐血造血干细胞(HSCs)的microRNAs(miRNAs)表达谱,并对相关miRNAs功能进行初步鉴定.利用免疫磁珠(MACS)和流式细胞仪(FACS)细胞分选技术分离人脐血造血干细胞(HSCs),分别提取细胞总RNA并分离小分子RNA,经荧光标记后与miRNAs基因芯片杂交,获得HSCs的miRNAs表达谱,集落形成实验(CFC)研究在HSC中高表达miR-520h对HSC的促分化作用.成功分离人脐血CD34 细胞和HSC,经基因芯片杂交获得31个造血干细胞相关miRNAs,其中22个为低表达,9个为高表达;经实时定量RT-PCR验证miR-520h显著升高,CFC实验表明其可增加多种集落形成,具有促进HSC向祖细胞分化的作用.上述结果表明,人脐血HSC具有自身特征性miRNAs,参与并调控HSC生物学功能,为深入探讨miRNAs在造血系统发育中的作用打下基础.     

Global Identification of MicroRNAs and Their Targets in Barley under Salinity Stress

Salinity is a major limiting factor for agricultural production worldwide. A better understanding of the mechanisms of salinity stress response will aid efforts to improve plant salt tolerance. In this study, a combination of small RNA and mRNA degradome sequencing was used to identify salinity responsive-miRNAs and their targets in barley. A total of 152 miRNAs belonging to 126 families were identified, of which 44 were found to be salinity responsive with 30 up-regulated and 25 down-regulated respectively. The majority of the salinity-responsive miRNAs were up-regulated at the 8h time point, while down-regulated at the 3h and 27h time points. The targets of these miRNAs were further detected by degradome sequencing coupled with bioinformatics prediction. Finally, qRT-PCR was used to validate the identified miRNA and their targets. Our study systematically investigated the expression profile of miRNA and their targets in barley during salinity stress phase, which can contribute to understanding how miRNAs respond to salinity stress in barley and other cereal crops.