Differential Expression of Alternative Oxidase Genes in Soybean Cotyledons during Postgerminative Development

The expression of the alternative oxidase (AOX) was investigated during cotyledon development in soybean (Glycine max [L.] Merr.) seedlings. The total amount of AOX protein increased throughout development, not just in earlier stages as previously thought, and was correlated with the increase in capacity of the alternative pathway. Each AOX isoform (AOX1, AOX2, and AOX3) showed a different developmental trend in mRNA abundance, such that the increase in AOX protein and capacity appears to involve a shift in gene expression from AOX2 to AOX3. As the cotyledons aged, the size of the mitochondrial ubiquinone pool decreased. We discuss how this and other factors may affect the alternative pathway activity that results from the developmental regulation of AOX expression.     

Factors Affecting the Enhancement of Oxidative Stress Tolerance in Transgenic Tobacco Overexpressing Manganese Superoxide Dismutase in the Chloroplasts

Two varieties of tobacco (Nicotiana tabacum var PBD6 and var SR1) were used to generate transgenic lines overexpressing Mn-superoxide dismutase (MnSOD) in the chloroplasts. The overexpressed MnSOD suppresses the activity of those SODs (endogenous MnSOD and chloroplastic and cytosolic Cu/ZnSOD) that are prominent in young leaves but disappear largely or completely during aging of the leaves. The transgenic and control plants were grown at different light intensities and were then assayed for oxygen radical stress tolerance in leaf disc assays and for abundance of antioxidant enzymes and substrates in leaves. Transgenic plants had an enhanced resistance to methylviologen (MV), compared with control plants, only after growth at high light intensities. In both varieties the activities of FeSOD, ascorbate peroxidase, dehydroascorbate reductase, and monodehydroascorbate reductase and the concentrations of glutathione and ascorbate (all expressed on a chlorophyll basis) increased with increasing light intensity during growth. Most of these components were correlated with MV tolerance. It is argued that SOD overexpression leads to enhancement of the tolerance to MV-dependent oxidative stress only if one or more of these components is also present at high levels. Furthermore, the results suggest that in var SR1 the overexpressed MnSOD enhances primarily the stromal antioxidant system.     

盐胁迫诱导的大麦基因差异性表达

大麦幼苗经 0 .2 0mol·L- 1 的NaCl溶液胁迫后 ,从幼根中提取细胞总RNA ,选择OligodT1 2 CA为锚定引物 ,反转录合成cDNA第一链 ,并以此为模板 ,用随机引物进行PCR扩增 ,琼脂糖电泳分离扩增产物 ,得到 5个在胁迫组中特异性表达而未经盐胁迫组中不表达的片段。结果表明大麦幼苗在盐胁迫时发生特异性基因表达     

磷胁迫对烤烟高亲和磷转运蛋白基因表达及磷素吸收利用的影响

为探明缺磷胁迫对烤烟磷吸收的影响机理,以烤烟品种‘豫烟10号’为材料,采用盆栽试验设置不施磷(-P)和正常供磷(+P)2个处理,分析了烟草生育后期根系和叶片中高亲和磷转运蛋白基因NtPht1;1、NtPht1;2(简称PT1、PT2)的表达差异性及其表达量与烟草磷含量、磷积累量的关系。结果表明:(1)随生育期的推进,烤烟根系和叶片的PT1基因相对表达量、PT2基因相对表达量、干物质重和磷素积累量逐渐增加,烟叶的磷含量逐渐降低,根系磷含量无明显的变化规律。(2)磷胁迫促使PT1、PT2基因的表达量上调,其中叶片PT1基因的相对表达量高于根系,叶片PT2基因的相对表达量显著低于根系。(3)磷胁迫限制了烤烟对干物质和磷素的积累,在移栽后90d,-P处理烤烟根系和叶片的干物质重、磷素积累量不到+P处理的一半,处理间差异极显著。研究认为,在缺磷环境下,烟草高亲和磷转运蛋白基因PT1和PT2表达量的增加,是由磷胁迫下烟草体内磷积累量降低所引起的系统性调控。     

Cu,Zn-Superoxide Dismutase Gene Dosage and Cell Resistance to Oxidative Stress: A Review

It is well established that superoxide dismutase (SOD) is the irresplaceable enzyme for aerobic lifestyle. Our understanding of its role has made strides recently as the result of gene transfection approach. Available data on consequences of Cu,Zn-SOD gene transfection in cell resistance to oxygen toxicity are reviewed. There are data that increasing only Cu,Zn-SOD can be toxic, and the balance between Cu,Zn-SOD and peroxide-removing enzymes is supposed to be of prime importance in the antioxidant defence. Role of Cu,Zn-SOD deregulation in carcinogenesis is discussed.     

NaCl胁迫下宁夏枸杞光合作用相关基因差异表达分析

宁夏枸杞是著名的耐盐药用植物,该研究通过室内水培试验,利用高通量测序技术和qRT-PCR技术检测了不同浓度NaCl胁迫(0、100、200、300 mmol/L)下宁夏枸杞叶片光合作用相关基因差异表达,并分析了其叶绿素含量、净光合速率、Rubisco活性的变化,以揭示宁夏枸杞在盐胁迫条件下光合机构及光合作用相关基因差异表达规律,为深入解析宁夏枸杞响应盐胁迫的光合机理奠定基础。结果表明：(1)用100、200、300 mmol/L NaCl胁迫处理7 d时宁夏枸杞分别有14、26、55个光合作用相关基因差异表达,且随着NaCl胁迫程度的增加下调表达基因多于上调表达基因。(2)qRT-PCR结果显示,宁夏枸杞的3个光合作用相关基因ATPε、CLH2、Lhcb3的相对表达量均随着NaCl胁迫程度的加深总体呈显著下降的趋势,qRT-PCR验证结果与RNA-seq测序结果基本一致。(3)随着NaCl胁迫程度的增加,宁夏枸杞叶片中的叶绿素a和叶绿素b含量以及净光合速率和Rubisco活性均呈显著下降的趋势,而类胡萝卜素含量变化不显著。研究认为,宁夏枸杞能通过诱导光合作用相关基因的差异表达来调控叶片...     

Different Expression Patterns of the Promoters of the NgrolB and NgrolC Genes during the Development of Tobacco Genetic Tumors

Hybrids (F1) between Nicotiana glauca and N. langsdorffii areprone to develop tumorous tissues on normaltype F1 tissues,namely, genetic tumors. To investigate the patterns of expressionof Ngrol genes during the development of genetic tumors, weperformed an analysis of transgenic genetic tumors that harboredthe promoters of the NgrolB and NgrolC genes fused to a reportergene for rß-glucuronidase (GUS) using a tumorization-redifferentiationsystem derived from F1 plants in vitro. Histochemical analysis of the expression of NgrolB-GUS in normal-typeF1 transgenic plants revealed GUS activity in meristematic zones,while in NgrolC-GUS transformed plants the activity was detectedmainly in the vascular systems of various organs. Tumorous tissues,which arose spontaneously as a consequence of aging or wereinduced by cutting, showed high levels of GUS expression underthe control of promoters of both the NgrolB and the NgrolC gene.Time course analysis during tumorization that followed cuttingof leaves of normal-type F1 plants showed clearly that NgrolB-GUSwas expressed in all dividing cells in the cut region after3 days. By contrast, the expression of NgrolC-GUS was detectedin organized tissues, such as procambium in teratomatous tumors,7–10 days after cutting treatment. During redifferentiationfrom genetic tumors to normal-type plants, the expression ofGUS under control of both Ngrol promoters decreased and expressionresembled that in normal-type tissues. These results suggestthe possibility that the Ngrol genes might be involved in formationof genetic tumors and, moreover, that the expression of NgrolBmight be linked to mitosis and while that of NgrolC might berelated to differentiation of tissues, such as the vascularsystem, in F1 plants. (Received January 19, 1996; Accepted March 24, 1996)     

Classification of Genes Differentially Expressed during Water-deficit Stress in Arabidopsis thaliana: an Analysis using Microarray and Differential Expression Data

Many changes in gene expression occur in response to water-deficitstress. A challenge is to determine which changes support plantadaptation to conditions of reduced soil water content and whichoccur in response to lesions in metabolic and cellular functions.Microarray methods are being employed to catalogue all of thechanges in gene expression that occur in response to specificwater-deficit conditions. Although these methods do not measurethe amount or activities of specific proteins that functionin the water-deficit response, they do target specific biochemicaland cellular events that should be detailed in further work.Potential functions of approx. 130 genes of Arabidopsis thalianathat have been shown to be up-regulated are tabulated here.These point to signalling events, detoxification and other functionsinvolved in the cellular response to water-deficit stress. Asmicroarray techniques are refined, plant stress biologists willbe able to characterize changes in gene expression within thewhole genome in specific organs and tissues subjected to differentlevels of water-deficit stress.     

长柄链格孢四个二甲酰亚胺类杀菌剂胁迫差异表达基因的克隆与序列分析

为了阐明烟草赤星病病原真菌长柄链格孢Alternaria longipes对二甲酰亚胺类杀菌剂(DCFs)抗性的分子机理,前期克隆了16个DCFs胁迫差异表达基因的部分cDNA片段.为了利用基因敲除技术进一步分析这些差异表达基因的功能,本研究选取4个差异表达基因,即AlATP7、AlCIT1、AlGLUT和AlHSP88,应用DNA Walking技术对它们两侧的未知序列进行克隆.DNA测序和Blast搜索表明,AlATP7基因开放阅读框为712 bp,含4个外显子和3个内含子,编码169个氨基酸;AlCIT1、AlGLUT和AlHSP88基因未克隆到全长序列,5′末端还有200-300bp才到达翻译起始密码子ATG;在这些DNA序列中,AlCIT1基因长1 214 bp,含1个内含子,编码386个氨基酸;AlGLUT基因长1 308 bP,含1个内含子,编码417个氨基酸;AlHSP88基因长2 087bp,含2个内含子,编码628个氨基酸.与其他丝状真菌的氨基酸序列同源性比对发现,AlATP7和线粒体ATP合酶D亚基、AlCIT1和柠檬酸合成酶、AlGLUT和主要易化子超家族(MFS)类型葡萄糖转运子、AlHSP88和热休克蛋白HSP88分别具有很高的同源性.同时,还对4个DCFs胁迫差异表达基因的系统发育进行分析.基于这些蛋白功能的文献报道和前期的研究,推测A.longipes存在着一种新的DCFs抗性机制:A.longipes利用MFS类型葡萄糖转运子将DCFs排除到细胞外解毒,线粒体ATP合酶和柠檬酸合成酶参与能量供给,而热休克蛋白AlHSP88可能在该机制中促进一些重要蛋白的正确折叠和修复过程中发挥重要作用.     

应用基因表达芯片分析水稻高温胁迫相关基因

非生物逆境,如低温、高温、干旱通常会严重影响到农作物的生长及产量,其中高温胁迫则是造成植物伤害的主要原因之一.为深入了解水稻高温胁迫反应的分子机理,发现新的耐高温相关功能基因,为水稻生物工程育种提供候选材料,采用Affymetrix水稻表达芯片分析了超级稻两优培九母本培矮64S(Oryza sativa L.)在高温逆境胁迫下,孕穗期、抽穗开花期的叶片全基因组表达谱,得到大量高温诱导表达基因.应用实时定量PCR方法对其中一部分基因的表达水平进一步分析,所得结果与基因芯片结果基本吻合,证明芯片分析数据是可靠的,为下一步耐高温相关基因的克隆、功能分析等研究提供了基础.     

Differential in Situ Expression of Three ABA-Regulated Genes of Rice, RAB16A, REG2 and OSBZ8, during Seed Development

The spatial and temporal expression patterns of three ABA-regulatedgenes of rice in the developing seeds of wild type and embryonicmutants were studied by in situ hybridization. By the use ofan embryo-less mutant, we found that the expression of thesegenes in the aleurone layers was independent of embryonic tissues. (Received August 24, 1998; Accepted January 23, 1999)     

转铁蛋白基因烟草中内源铁蛋白基因的差异表达及含铁量的变化

铁蛋白是一种由24个亚基组成的高分子贮藏蛋白质,可以储存多达4500个铁原子,在动植物及微生物的新陈代谢中起着非常重要的作用。有研究表明,外源铁蛋白的大量表达可以提高植物储存铁离子的能力。为了明确外源铁蛋白基因转化植物中内源铁蛋白基因差异表达与植物含铁量的关系,本研究在成功获得2个烟草铁蛋白基因的全长cDNA克隆NtFerl（登录号：ay083924）和NtFer2（登录号：ay141105）的基础上,以烟草品种SR-1（Nicotiana tabacum cv．Petit Havana SR-1）为受体,培育了转铁蛋白基因烟草。将双元载体pBI121中的GUS基因用来自大豆的铁蛋白基因SoyFer1（登录号：m64337）置换,利用农杆菌介导法转化烟草叶盘,获得在CaMV35S启动子驱动表达的大豆铁蛋白基因转化烟草植株。Northern杂交和Western杂交分析表明外源铁蛋白基因在转基因烟草中得到了正确表达。比较转基因烟草和非转基因烟草的内源铁蛋白基因表达强度、叶片铁含量、根系铁还原酶活性、株高和鲜重表明,外源铁蛋白基因不但促进了NtFer1的表达,提高转基因植株的储存铁的能力和根系铁还原酶活性,而且促进植株的生长速度。以上结果说明,外源铁蛋白基因转化烟草中内源铁蛋白基因的表达、铁离子的还原吸收及光和作用都得到了进一步的提高。     

Differential Expression of Endogenous Ferritin Genes and Iron Homeostasis Alteration in Transgenic Tobacco Overexpressing Soybean Ferritin Gene

For studying the effects of endogenous ferritin gene expressions (NtFer1, GenBank accession number ay083924; and NtFer2, GenBank accession number ay141105) on the iron homeostasis in transgenic tobacco (Nicotiana tabacum L.) plants expressing soybean (Glycine max Merr) ferritin gene (SoyFer1, GenBank accession number m64337), the transgenic tobacco has been produced by placing soybean ferritin cDNA cassette under the control of the CaMV 35S promoter. The exogenous gene expression was examined by both Northern- and Western-blot analyses. Comparison of endogenous ferritin gene expressions between nontransformant and transgenic tobacco plants showed that the expression of NtFer1 was increased in the leaves of transgenic tobacco plants, whereas the NtFer2 expression was unchanged. The iron concentration in the leaves of transgenic tobacco plants was about 1.5-folds higher than that in nontransformant. Enhanced growth of transgenic tobacco was observed at the early development stages, resulting in plant height and fresh weights significantly greater than those in the nontransformant. These results demonstrated that exogenous ferritin expression induced increased expression of at least one of the endogenous ferritin genes in transgenic tobacco plants by enhancing the ferric chelate reductase activity and iron transport ability of the root, and improved the rate of photosynthesis.