二氧化硫保鲜剂对玫瑰香葡萄糖代谢的影响

以本地产玫瑰香葡萄果实为材料,研究SO_2对鲜食葡萄果实贮藏期间糖含量及相关代谢调控的影响。结果发现:SO_2保鲜剂能够提高葡萄果实贮藏期间的好果率,抑制果实的自溶软化,延长果实保质期。贮藏期间,对照组果实的蔗糖、葡萄糖和可溶性糖含量逐渐降低,果糖含量变化不明显,而SO_2组蔗糖、葡萄糖含量降幅低于对照,可溶性糖含量维持贮藏初期水平,果糖含量升高,致使贮藏后期SO_2组果实的葡萄糖、果糖和可溶性糖含量显著高于对照组。同期,具有蔗糖分解功能的蔗糖酸性转化酶的活性先升后降,中性转化酶和蔗糖合成酶(分解方向)活性先降后升,SO_2处理组果实酶活性始终低于对照组。基因转录检测发现,贮藏后期检出的编码转化酶和蔗糖合成酶的12个基因中9个在SO_2组下调表达,与酶活趋势一致。研究结果表明,SO_2能够从转录水平调控蔗糖代谢相关酶,抑制采后葡萄中糖的分解代谢,有效保持葡萄果实中糖分的稳定,从而维持果实的感官品质和营养价值,延长果实的贮藏期。     

水稻蔗糖转化酶基因的克隆及其功能的初步探讨

根据抑制消减杂交(suppression subtractive hybridization，SSH)方法分离到在水稻叶片中高表达的蔗糖转化酶基因片段，根据水稻基因组顺序设计引物分离到全长cDNA．测序结果表明该cDNA长度为1937bp，推测编码一个627个氨基酸的中性/碱性蔗糖转化酶．Alignment分析显示该推测蛋白质与已知的多个蔗糖转化酶具有很高的同源性．半定量PCR检测证实它在叶中的表达强于在根、花药和幼穗等组织中的表达，胁迫处理(盐和低温)使其表达上调．     

转录物组学解析植物生长发育的生物钟调控模

基于拟南芥的时间序列的基因组芯片数据,分析了植物生长的昼夜调节模式相关的基因表达规律,发现有2.4%的基因的日振幅达到了显著差异水平.从整体基因转录组水平分析,白天诱导表达的基因主要参与调控植物与环境之间的相互作用,而夜晚表达上调的基因主要参与调节植物的生长发育.此外,植物叶绿素和血红素的生物合成也受到了生物钟的调控.对整个基因组水平上生物钟核心震荡调节子CCA1/LHY和TOC1的共表达基因做了基因组水平上的扫描鉴定,得到了一些新的潜在的生物节律调节因子.这些结果为今后更为系统地完善植物的生物节律的调控网络提供了参考.     

拟南芥AtSuc3和AtSuc4基因的克隆及双价植物表达载体的构建

蔗糖转运蛋白在调节同化产物的分配过程中起重要作用。为了分析拟南芥蔗糖转运蛋白基因AtSuc3、At-Suc4的功能和协同作用,以哥伦比亚型拟南芥为材料,通过RT-PCR技术克隆了蔗糖转运蛋白基因(sucrose/H+cotransporters,SUCs)AtSuc3和AtSuc4的cDNA,利用甘薯贮藏蛋白基因(sporamin)的根部特异性启动子,构建了含有含有AtSuc3和AtSuc4 cDNA的单价植物表达载体pBI2301-q3-s3、pBI2301-q4-s4和双价植物表达载体pBI2301-q3-s3-q4-s4,为进一步分析该植物表达载体在调控库源关系中的作用以及在经济作物中的应用奠定基础。     

月季切花瓶插期间花瓣糖代谢及其相关酶活性的研究

为探究糖代谢及其酶对月季脱离母体后的生命活动的影响,以月季(Rosa hybrida Hort)切花"黑魔术"(cv.Black Magic flower)和"影星"(cv.Movie Star flower)为试验材料,分析瓶插期间花瓣糖代谢及其相关酶活性的变化.试验表明:随着月季切花瓶插时间的延长和花瓣开放,花瓣中葡萄糖(G)和果糖(F)含量显著增加,蔗糖含量随之降低,切花"影星"的己糖(G+F)含量、花径的增长和花朵鲜重都明显高于"黑魔术";花瓣中酸性转化酶(AI)活性与中性转化酶(NI)、蔗糖合成酶(SS)和磷酸蔗糖合成酶(SPS)相比具有较高的水平,AI活性与蔗糖降解指数(SDI)成正相关,AI是降解蔗糖并积累己糖的关键酶,而花瓣中己糖积累在月季切花生长发育过程中起重要作用.     

植物维管组织特异性定位启动子研究进展

组织特异性基因的启动子对该基因的组织特异性表达起重要作用 .本文综述了植物维管组织特异性定位表达启动子的研究进展 .研究表明 ,在植物维管组织特异性定位表达启动子中 ,顺式调控元件与反式作用因子协同作用 ,调控基因的表达 .     

植物MYB转录因子研究

转录因子是通过转录水平或转录后水平上调控目的基因的表达来调控植物生长发育及生理代谢的.MYB(v-myb avian myeloblastosis viral oncogene homolog)转录因子是最大的植物转录因子家族成员之一,参与了细胞分化、细胞周期的调节,激素和环境因子应答,并对植物次生代谢以及叶片等器官形态建成具有重要的调节作用.文章对MYB的发现及其结构特征和功能研究进展进行综述,为进一步开展MYB基因的克隆、功能研究和利用提供参考.     

植物MYB转录因子研究

转录因子是通过转录水平或转录后水平上调控目的基因的表达来调控植物生长发育及生理代谢的.MYB (v-myb avian myeloblastosis viral oncogene homolog)转录因子是最大的植物转录因子家族成员之一,参与了细胞分化、细胞周期的调节,激素和环境因子应答,并对植物次生代谢以及叶片等器官形态建成具有重要的调节作用.文章对MYB的发现及其结构特征和功能研究进展进行综述,为进一步开展MYB基因的克隆、功能研究和利用提供参考.     

MicroRNA与转录因子调控网络综述

MicroRNA是一类长度约为18-24nt的非编码小RNA,它在转录后水平通过调控靶基因来行使多种生物学功能,例如：细胞周期、分化、细胞增殖和凋亡等。在转录水平,转录因子作为一种重要的调控因子参与调控多种基因的表达。近些年研究表明转录因子可以直接调控miRNA的表达,并且参与了包括肿瘤疾病发生等多种生物学进程。转录因子与miRNA形成的调控网络已被广泛地研究,文中就目前已有的研究成果进行综述,以期为今后转录因子与miRNA调控通路的研究提供一定的理论基础。     

马铃薯低温启动子CIP的克隆及其功能鉴定

合适的启动子有利于基因的高效表达．本研究从鄂马铃薯-3中克隆了低温诱导的启动子（CIP）,并调控转化酶抑制子基因转化马铃薯植株,以抑制马铃薯块茎发生的“低温糖化”．实验结果表明,克隆的CIP与报道的低温诱导的启动子序列同源性达98．9％,含有启动子的典型结构．构建CIP与转化酶抑制子（St-VIF）基因的载体成功转化马铃薯并获得转基因株系．转基因株系收获块茎在4℃和20℃贮藏lm,Nothern杂交显示St-VIF基因在4℃大量表达,检测转化酶活性表明,与对照比较液泡转化酶活性大大降低,说明通过低温诱导CIP调控St-VIF基因的表达能够抑制转化酶的活性,从而降低还原糖的积累．     

木茼蒿SOC1同源基因的克隆及表达分析

SOC1基因是整合各种成花途径信号，启动植物成花转变的关键基因之一.以木茼蒿为材料，利用RT-PCR技术，克隆了木茼蒿SOC1同源基因AfSOC1;利用qRT_PCR技术，对其时空表达模式进行了分析.结果表明:木茼蒿AfSOC1 cDNA长为648bp，编码216个氨基酸，与拟南芥SOC1和金鱼草DEFH68的同源性分别为63.1%和62.1%.该蛋白含有典型的MADS-box，K-box和SOC1转录因子特异性识别序列DVETELFIGP.AfSOC1在木茼蒿的根、茎、叶、花芽及花中均有表达，在叶中和花芽中高表达.在系统进化树中AfSOC1与所有菊科植物SOC1聚在一起.该研究为了解木茼蒿的成花机制及通过分子生物学技术进行木茼蒿的遗传改良提供了理论基础.     

Quenching quorum-sensing-dependent bacterial infection by an N-acyl homoserine lactonase.

Bacterial cells sense their population density through a sophisticated cell-cell communication system and trigger expression of particular genes when the density reaches a threshold. This type of gene regulation, which controls diverse biological functions including virulence, is known as quorum sensing. Quorum-sensing signals, such as acyl-homoserine lactones (AHLs), are the essential components of the communication system. AHLs regulate virulence gene expression in a range of plant and animal (including human) bacterial pathogens. AHL-producing tobacco restored the pathogenicity of an AHL-negative mutant of Erwinia carotovora. Different bacterial species may produce different AHLs, which vary in the length and substitution of the acyl chain but contain the same homoserine lactone moiety. Here we show that the acyl-homoserine lactonase (AHL-lactonase), a new enzyme from Bacillus sp., inactivates AHL activity by hydrolysing the lactone bond of AHLs. Plants expressing AHL-lactonase quenched pathogen quorum-sensing signalling and showed significantly enhanced resistance to E. carotovora infection. Our results highlight a promising potential to use quorum-sensing signals as molecular targets for disease control, thereby broadening current approaches for prevention of bacterial infections.     

Chloroplast to nucleus communication triggered by accumulation of Mg-protoporphyrinIX

Plant cells coordinately regulate the expression of nuclear and plastid genes that encode components of the photosynthetic apparatus. Nuclear genes that regulate chloroplast development and chloroplast gene expression provide part of this coordinate control. There is evidence that information also flows in the opposite direction, from chloroplasts to the nucleus. Until now, at least three different signalling pathways have been identified that originate in the plastid and control nuclear gene expression but the molecular nature of these signals has remained unknown. Here we show that the tetrapyrrole intermediate Mg-protoporphyrin (Mg-ProtoIX) acts as a signalling molecule in one of the signalling pathways between the chloroplast and nucleus. Accumulation of Mg-ProtoIX is both necessary and sufficient to regulate the expression of many nuclear genes encoding chloroplastic proteins associated with photosynthesis.     

A new class of homoserine lactone quorum-sensing signals

Quorum sensing is a term used to describe cell-to-cell communication that allows cell-density-dependent gene expression. Many bacteria use acyl-homoserine lactone (acyl-HSL) synthases to generate fatty acyl-HSL quorum-sensing signals, which function with signal receptors to control expression of specific genes. The fatty acyl group is derived from fatty acid biosynthesis and provides signal specificity, but the variety of signals is limited. Here we show that the photosynthetic bacterium Rhodopseudomonas palustris uses an acyl-HSL synthase to produce p-coumaroyl-HSL by using environmental p-coumaric acid rather than fatty acids from cellular pools. The bacterium has a signal receptor with homology to fatty acyl-HSL receptors that responds to p-coumaroyl-HSL to regulate global gene expression. We also found that p-coumaroyl-HSL is made by other bacteria including Bradyrhizobium sp. and Silicibacter pomeroyi. This discovery extends the range of possibilities for acyl-HSL quorum sensing and raises fundamental questions about quorum sensing within the context of environmental signalling.