水稻逆境相关转录因子研究进展

干旱、盐碱、高温和低温等逆境因子胁迫水稻的生长发育,进而影响水稻的产量和品质。因此,研究水稻的抗逆性,尤其是揭示其抗逆分子机理具有重要的生物学意义。近年来,水稻抗逆分子机理的研究主要集中在转录因子及其分子调控机制方面。在水稻中,目前研究较多的转录因子类型主要有b ZIP、MYB/MYC、WRKY、AP2/EREBP和NAC,它们的结构通常由DNA结合结构域、转录活化结构域、寡聚化位点和核定位信号组成。转录因子在水稻逆境信号转导途径中起着中心调节作用,它们将逆境信号传递和放大,通过与目的基因启动子区中顺式作用元件特异结合,调控下游多个逆境相关基因的表达,从而引起水稻对逆境应答反应,最终实现水稻获得综合抗逆性的提升。该文简要概述了植物转录因子的调控机制、结构特点、分类与功能特性,重点论述了转录因子在水稻抗逆中的作用,指出了转录因子应用过程中转基因水稻产生的负效应问题,并提出了解决负效应问题的研究思路,同时展望了今后转录因子的研究前景,以期为挖掘和应用新的水稻转录因子基因以及阐明其抗逆调控机制提供理论依据。     

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。     

Genome-wide identification and analysis of rice genes to elucidate morphological agronomic traits

Molecular understanding of morphological agronomic traits is very important to improve grain yield and quality. According to the literature information summarized in Overview of Functionally Characterized Genes in Rice online database, 430 genes related to these traits have been functionally characterized in rice, while the functions of other genes remain to be elucidated. Gene indexed mutants are available for at least half of the genes identified in the rice genome, and are very useful resources to study gene function. To suggest candidate genes for functional studies associated with morphological agronomic traits, we identified genes with tissue/organ-preferred expression patterns through meta-analysis of microarray data, and identified 781 genes for roots, 1,084 for leaves, 1,029 for calluses, 927 for anthers, 241 for embryos, and 343 for endosperms. Additionally, 4,243 genes expressed in all tissue types were allocated to a ubiquitously-expressed gene group (‘housekeeping’ genes). The estimated tissue/organ-preferred and housekeeping genes accounted for 40% of the characterized genes associated with morphological agronomic traits, indicating that identification of tissue/organ-preferred genes is an effective way to provide putative gene function. In this study, we reported the information of gene-indexed mutants for 84% of the identified candidate genes. Our candidate genes and relating indexed mutant resources can potentially be used to improve morphological agronomic traits in rice.     

Nitric oxide-modulated marker gene expression of signal transduction pathways in lung endothelial cells

Nitric oxide (NO) is a signal molecule involved in regulation of physiological and pathophysiological functions of the vascular endothelium such as apoptosis. We examined whether NO-modulates marker gene expression of signal transduction pathways in cultured pulmonary artery endothelial cell (PAEC). Cells were exposed to a NO donor, 1 mM NOC-18, for 0.5, 5, and 24 h, thereafter, expression levels of 96 marker genes associated with 18 signal transduction pathways were assessed using a signal transduction pathway-finder microarray analysis system. NO modulation of apoptotic pathways and nuclear factor (NF) microarray were further analyzed. Gene array analyses revealed that 17 genes in 13 signal pathways were up- or down-regulated in cells exposed to NO, four of which were significantly altered by NO and are associated with apoptotic pathways. Apoptotic pathways resulted in identification of 11 genes in this group. Nuclear factor microarray studies demonstrated that NO-modulated expression of these signal transduction genes was associated with regulation of NF-binding activities. Gel shift analysis verified the effects of NO on DNA-binding activity of NF. These results demonstrated that NO signaling modulates at least 13 signal transduction pathways including apoptosis-related families in PAEC.     

水稻籽粒灌浆速率的分子机制与遗传调控研究进展

水稻(Oryza sativa)的高产优质是我国粮食安全的重要保障,也是育种家一直追求的目标。水稻籽粒灌浆速率(GFR)是一个重要而复杂的农艺性状,直接影响籽粒充实度、粒重和米质。目前,快速灌浆的优良水稻品种缺乏,可供育种利用的相关优异基因资源有限,已成为制约水稻产量和品质进一步提高的瓶颈。相对于水稻的其它农艺性状,G...     

Development of a high-throughput yeast two-hybrid screening system to study protein-protein interactions in plants

We have developed a high-throughput yeast two-hybrid screening system (HTP-YTH) that incorporates yeast gap-repair cloning, multiple positive ( ADE2, HIS3, lacZ) and negative ( URA3-based) selection schemes to reduce the incidence of negative and false positive clones, and automation of laboratory procedures to increase throughput. This HTP-YTH system has been applied to the study of protein-protein interactions that are involved in rice defense signal transduction pathways. More than 100 genes involved in plant defense responses were selected from DuPont's rice expressed sequence tag (EST) databases as baits for HTP-YTH screening. Results from YTH screening of eight of these rice genes are presented in this paper. Not only have we identified known protein-protein interactions, but we have also discovered novel interactions, which may ultimately reveal the regulatory network of host defense signal transduction pathways. We have demonstrated that our HTP-YTH method can be used to map protein-protein interaction networks and signal transduction pathways in any system. In combination with other approaches, such efficient YTH screens can help us systemically to study the functions of known and unknown genes in the genomics era.