植物NBS类抗病基因的进化

NBS(Nucleotide-binding site)类抗病基因是植物中最重要的一类抗病基因, 其进化模式、结构特点和功能调控一直是抗病基因研究领域的热点。这类基因具有保守的结构域, 广泛存在于植物基因组中, 在不同植物基因组中数目差异较大且具有较低的表达量。此外, 同源NBS类抗病基因之间通过频繁的序列交换产生广泛的序列多样性, 且抗病基因位点具有较差的线性。依据基因之间序列交换的频率, 抗病基因可分为TypeⅠ和TypeⅡ两类。文章从抗病基因的结构、数量、分布、序列多样性、进化模式以及表达调控等方面进行了综述, 旨在为后续NBS类抗病基因的相关研究提供参考。     

快速碱化因子类基因在茄科植物中的研究进展

植物在调控生长发育、响应外界胁迫时,细胞内外的pH变化是及时、重要的反应之一。快速碱化因子类基因（RALF）属于植物多肽类信号分子,是一类大的家族基因,它的活动引起胞外pH值快速升高,有关RALF类基因的研究在几种茄科植物中开展的较多,包括RALF蛋白信号分子的结构及加工、基因表达、受体研究以及功能等方面。最近我们在白菜和紫菜薹中的研究发现有一些脚类基因与植物的育性有关,本文就茄科植物中的这些研究进展进行介绍,为RALF的进一步研究提供参考。     

玉米籽粒淀粉含量遗传基础与调控机制*

玉米是世界上种植面积最大、总产量最高的粮食作物,其籽粒重量的70%来自于淀粉。淀粉不仅是人类及其他动物的主要能量来源,同时也是化工等行业的重要原料。利用拟南芥、水稻等模式植物,淀粉合成相关基因克隆与功能研究已取得较多进展。近年来,随着玉米淀粉含量相关遗传学研究的深入开展,通过数量性状位点(quantitative trait locus mapping,QTL)定位、全基因组关联分析(genome-wide association study, GWAS)及各种组学分析方法,发现了较多新的与淀粉含量相关的遗传位点及候选基因,但是尚缺乏归纳总结。综述了玉米籽粒淀粉合成与调控研究进展,对玉米籽粒淀粉含量相关的QTL和基因进行汇总和分析,通过构建一致性物理图谱,提炼玉米籽粒淀粉含量遗传定位热点区间,这为进一步解析玉米籽粒淀粉合成与代谢相关基因的功能提供参考,并为分子标记辅助育种提供遗传资源。     

抗逆蛋白查询系统的初步建立

运用生物信息学的手段从NCBI获得不同的植物抗逆基因,对基因的名称,功能,该基因的数据来源,及相关文献作整理,初步建立了抗逆蛋白查询系统。此系统与很多生物软件兼容,利用这些软件可方便的在该数据库中进行序列比对、抗逆蛋白同源性的比较、未知蛋白功能预测、绘制分子树等多项功能。     

陆地棉MYB类转录因子基因GhTT2克隆及功能初步分析

原花青素作为植物重要的次生代谢产物,是植物应对生物和非生物胁迫的一种重要防御手段,也是影响植物发育和品质的重要因素。原花青素作为花青素生物合成的一条末端通路在模式植物中已有研究,但是具体代谢和调控机制尚不明确;原花青素作为棕色棉纤维呈色的主要物质,其棉纤维呈色的生化与分子机制仍未完全阐明。本研究从陆地棉(Gossypium hirsutum)中克隆了一个MYB类转录因子基因GhTT2 (transparent testa 2),并对其基因结构、表达模式、亚细胞定位及功能进行了分析。结果表明：GhTT2转录因子具有典型的MYB结构域,在纤维中优势表达,其转录水平随花青素含量增加而降低;该基因可被原核诱导表达;与GFP融合的重组蛋白定位在细胞核;酵母转化结果表明GhTT2具有转录激活功能;在棉花中沉默GhTT2基因的表达,导致原花青素含量显著降低,表明其可能参与调控陆地棉原花青素的生物合成。本研究结果为深入阐明MYB类转录因子参与调控植物原花青素生物合成途径的分子机制提供参考。     

云芝全基因组SSR位点分布及比较分析

本研究采用生物信息学方法统计分析了云芝基因组中SSR位点的数量、分布及频率等信息,对云芝基因组中含SSR的基因进行了功能注释,与其他5种伞菌纲真菌(双孢蘑菇、黑管孔菌、红缘拟层孔菌、金针菇和鲜红密孔菌)基因组进行了比较。结果发现云芝基因组中共有1 224个SSR位点,相对丰度为27个/Mb,三核苷酸重复类型分布最频繁。其中编码基因序列中包含299个SSR,仅次于基因间区,但是在非编译区、基因间区和内含子中SSR分布更加频繁。通过与nr数据库比对,485个含SSR的基因获得注释,其中115个基因通过GO注释到分子功能、生物进程及细胞组分3类中,108个基因通过KEGG注释到新陈代谢、遗传信息处理、细胞过程和环境信息处理4类中。设计58对引物主要用于物种鉴定,另外23对引物主要用于活性物质代谢研究和辅助育种。与其他伞菌纲真菌相比,云芝所含SSR的数量及相对丰度较低,并证明SSR数量与基因组大小无关,而某些特定的重复类型与GC含量有关。本研究为云芝的种群遗传学及进化研究奠定了理论基础。     

有鳞类爬行动物化感受体基因研究进展

化学感觉受体在动物避免危险、识别领域、寻找食物、发现配偶和后代等行为中起着重要作用。化学感觉受体基因在鸟类和哺乳类中研究得比较系统,而在有鳞类爬行动物中的研究则相对缺乏。随着有鳞类爬行动物可获得的基因组数据越来越多,对其化学感觉受体基因的探索也逐渐兴起。本文从化感系统结构特点、化感受体基因数量分布、进化模式等方面概述了有鳞类爬行动物化学感觉(嗅觉、味觉)受体基因的初步研究进展,以期为进一步深入地、系统地研究提供参考。     

植物GH3基因家族研究进展

生长素在植物的整个生长发育过程中都具有重要的作用,其早期响应基因可归为3类:Aux/IAAs、GH3s、SAURs.通过功能基因组学的研究,特别是对相关突变体的分子遗传学与分子生物学的研究,使我们对这些基因家族的作用机理的理解更为深入.以下综述了植物GH3基因的结构、功能及表达调控模式,重点介绍了由GH3介导的生长素信号途径与其他信号转导途径之间的互作和GH3基因与植物逆境胁迫适应的关系.     

嗅觉受体基因的研究进展

嗅觉在动物的生命活动中起着重要的作用, 与嗅觉相关的基因主要是嗅觉受体(Olfactory receptor, OR)基因。文章介绍了嗅觉受体基因的结构、表达调控、分布、分子进化及其多态性研究进展, 并讨论了该基因与嗅觉功能和嗅觉障碍的关系。     

基因本体论的蟾蜍bHLH转录因子功能富集分布

基因本体论是国际上标准的基因和蛋白质功能知识词汇.利用基因本体论的功能富集分布比较和分析了两种蟾蜍bHLH基因分子功能分布特点.结果发现,两种蟾蜍的bHLH基因均有显著富集分布的GO注释语句,其中转录调控活性( GO:0030528)、转录调控(GO:0045449)、DNA结合(GO:0003677)、RNA代谢过程调控(G0:0051252)、DNA依赖的转录调控(GO:0006355)、转录(G0:0006350)和转录因子活性(GO:0003700)等频率很高,表明这些GO注释是蟾蜍bHLH基因常见的功能;此外,蟾蜍bHLH基因在肌肉器官发育、神经管和眼发育等一些重要的发育或生理过程的基因表达调控中发挥着重要的作用.     

Molecular signals in the interactions between plants and microbes.

The field of plant-microbe interactions has witnessed several recent breakthroughs, such as the molecular details of vir gene induction, identification of Nod factors, and the cloning and characterization of avr genes. Other breakthroughs, such as the cloning and characterization of R genes, appear imminent. Parallels to mammalian systems are emerging in the world of plant-microbe interactions, for example, ion channels formed by Rhizobium proteins, similarities of hrp genes to pathogenicity genes of mammalian pathogens, and plant signal transduction via calcium and protein phosphorylation. We remain, however, largely ignorant of many facets of signaling in plant-microbe interactions. We know little about how microbial signals are perceived by plants or how subsequent signal transduction occurs within plant cells and are probably unaware of many of the microbe-generated signals to which plants respond or of plant-generated signals to which bacteria and fungi respond. Contributions from those working on the genetics, molecular biology, and physiology of bacteria, fungi, and plants will be required to address these questions. The many nonpathogenic plant-microbe interactions in addition to the Rhizobium-plant interaction remain relatively unexplored. Genetic and molecular approaches are being initiated to investigate the signaling that is likely to underlie interactions such as those between mycorrhizal fungi and plant roots and between epiphytic bacteria and plant leaf surfaces. The importance of these interactions to plant growth and development makes it likely that they will figure more prominently at future symposia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Structure and function of a cellulase gene in redclaw crayfish, Cherax quadricarinatus

The most abundant organic compound produced by plants is cellulose; however, it has long been accepted that most animals do not produce endogenous enzymes required for its degradation, but rely instead on symbiotic relationships with microbes that produce the necessary enzymes. Here, we present the genomic organisation of an endogenous glycosyl hydrolase family (GHF) 9 gene in redclaw crayfish (Cherax quadricarinatus), consolidated from a cDNA sequence determined by Byrne et al. [Gene 239 (1999) 317–324.]. Comparison with several other invertebrate GHF9 genes reveals the conservation of both intron position/phase and splice sequence, which adds support to an argument for an ancestral animal cellulase gene. Furthermore, two introns in plant GHF9 genes are also identical in position, implying a more ancient origin for this class of animal cellulase.

Protein purification from redclaw gastric fluid via fast performance liquid chromatography (FPLC) indicated the presence of two endoglucanase enzymes. The molecular weights of these components were determined by matrix-assisted laser desorption/ionisation—time-of-flight (MALDI-TOF) to be 47,887 Da (Cel1) and 50,295 Da (Cel2). Cel1 is possibly the functional product of the described cellulase gene, with N-terminal amino acid residues identical to the translated amino acid sequence from the corresponding gene region. Cel2 was identical to Cel1 for 7 of 11 N-terminal residues and likely to be the product of a paralogous endoglucanase gene. These results suggest that redclaw crayfish possess at least one and possibly two functional, endoglucanase enzymes, although further work is required to confirm their origin and attributes.     

Aquaporin genes GintAQPF1 and GintAQPF2 from Glomus intraradices contribute to plant drought tolerance

Arbuscular mycorrhizal (AM) symbiosis, established between AM fungi (AMF) and roots of higher plants, occurs in most terrestrial ecosystems. It has been well demonstrated that AM symbiosis can improve plant performance under various environmental stresses, including drought stress. However, the molecular basis for the direct involvement of AMF in plant drought tolerance has not yet been established. Most recently, we cloned two functional aquaporin genes, GintAQPF1 and GintAQPF2, from AM fungus Glomus intraradices. By heterologous gene expression in yeast, aquaporin localization, activities and water permeability were examined. Gene expressions during symbiosis in expose to drought stress were also analyzed. Our data strongly supported potential water transport via AMF to host plants. As a complement, here we adopted the monoxenic culture system for AMF, in which carrot roots transformed by Ri-T DNA were cultured with Glomus intraradices in two-compartment Petri dishes, to verify the aquaporin gene functions in assisting AMF survival under polyethylene glycol (PEG) treatment. Our results showed that 25% PEG significantly upregulated the expression of two aquaporin genes, which was in line with the gene functions examined in yeast. We therefore concluded that the aquaporins function similarly in AMF as in yeast subjected to osmotic stress. The study provided further evidence to the direct involvement of AMF in improving plant water relations under drought stresses.     

GenOrigin: A comprehensive protein-coding gene origination database on the evolutionary timescale of life

The origination of new genes contributes to the biological diversity of life. New genes may quickly build their network, exert important functions, and generate novel phenotypes. Dating gene age and inferring the origination mechanisms of new genes, like primate-specific genes, is the basis for the functional study of the genes. However, no comprehensive resource of gene age estimates across species is available. Here, we systematically date the age of 9,102,113 protein-coding genes from 565 species in the Ensembl and Ensembl Genomes databases, including 82 bacteria, 57 protists, 134 fungi, 58 plants, 56 metazoa, and 178 vertebrates, using a protein-family-based pipeline with Wagner parsimony algorithm. We also collect gene age estimate data from other studies and uniformly distribute the gene age estimates to time ranges in a million years for comparison across studies. All the data are cataloged into GenOrigin (http://genorigin.chenzxlab.cn/), a user-friendly new database of gene age estimates, where users can browse gene age estimates by species, age, and gene ontology. In GenOrigin, the information such as gene age estimates, annotation, gene ontology, ortholog, and paralog, as well as detailed gene presence/absence views for gene age inference based on the species tree with evolutionary timescale, is provided to researchers for exploring gene functions.     

转辽宁碱蓬SlNAC4拟南芥差异表达基因分析

以实验室前期获得的转SlNAC4基因拟南芥(Arabidopsis thaliana)和野生型拟南芥为材料, 通过基因芯片技术检测其基因表达谱。结果表明, 与野生型拟南芥相比, 转SlNAC4基因拟南芥中差异表达的基因共有3 094个。 通过GO分析, 发现与非生物胁迫相关的差异基因共有195个, 与生长发育相关的差异基因共有47个, 其中包含MYB和WRKY转录因子基因。KEGG分析表明, 差异表达基因主要涉及植物激素信号转导和油菜素内酯合成等信号通路。进一步选择部分差异表达基因进行实时荧光定量PCR分析, 所得结果与芯片检测结果一致。该研究结果表明, SlNAC4可直接或间接地调控多个下游基因的表达, 进而调控植物的生长发育, 提高其抗逆性。