Response to metal stress of Nicotiana langsdorffii plants wild-type and transgenic for the rat glucocorticoid receptor gene

Recently our findings have shown that the integration of the gene coding for the rat gluco-corticoid receptor (GR receptor) in Nicotiana langsdorffii plants induced morphophysiological effects in transgenic plants through the modification of their hormonal pattern. Phytohormones play a key role in plant responses to many different biotic and abiotic stresses since a modified hormonal profile up-regulates the activation of secondary metabolites involved in the response to stress. In this work transgenic GR plants and isogenic wild type genotypes were exposed to metal stress by treating them with 30 ppm cadmium(II) or 50 ppm chromium(VI). Hormonal patterns along with changes in key response related metabolites were then monitored and compared. Heavy metal up-take was found to be lower in the GR plants. The transgenic plants exhibited higher values of S-abscisic acid (S-ABA) and 3-indole acetic acid (IAA), salicylic acid and total polyphenols, chlorogenic acid and antiradical activity, compared to the untransformed wild type plants. Both Cd and Cr treatments led to an increase in hormone concentrations and secondary metabolites only in wild type plants. Analysis of the results suggests that the stress responses due to changes in the plant's hormonal system may derive from the interaction between the GR receptor and phytosteroids, which are known to play a key role in plant physiology and development.     

Genomic Resources for Gene Discovery,Functional Genome Annotation,and Evolutionary Studies of Maize and Its Close Relatives

Maize is one of the most important food crops and a key model for genetics and developmental biology. A genetically anchored and high-quality draft genome sequence of maize inbred B73 has been obtained to serve as a reference sequence. To facilitate evolutionary studies in maize and its close relatives, much like the Oryza Map Alignment Project (OMAP) (www.OMAP.org) bacterial artificial chromosome (BAC) resource did for the rice community, we constructed BAC libraries for maize inbred lines Zheng58, Chang7-2, and Mo17 and maize wild relatives Zea mays ssp. parviglumis and Tripsacum dactyloides. Furthermore, to extend functional genomic studies to maize and sorghum, we also constructed binary BAC (BIBAC) libraries for the maize inbred B73 and the sorghum landrace Nengsi-1. The BAC/BIBAC vectors facilitate transfer of large intact DNA inserts from BAC clones to the BIBAC vector and functional complementation of large DNA fragments. These seven Zea Map Alignment Project (ZMAP) BAC/BIBAC libraries have average insert sizes ranging from 92 to 148 kb, organellar DNA from 0.17 to 2.3%, empty vector rates between 0.35 and 5.56%, and genome equivalents of 4.7- to 8.4-fold. The usefulness of the Parviglumis and Tripsacum BAC libraries was demonstrated by mapping clones to the reference genome. Novel genes and alleles present in these ZMAP libraries can now be used for functional complementation studies and positional or homology-based cloning of genes for translational genomics.     

ZmGA3ox2, a candidate gene for a major QTL,qPH3.1, for plant height in maize

Maize plant height is closely associated with biomass, lodging resistance and grain yield. Determining the genetic basis of plant height by characterizing and cloning plant height genes will guide the genetic improvement of crops. In this study, a quantitative trait locus (QTL) for plant height, qPH3.1, was identified on chromosome 3 using populations derived from a cross between Zong3 and its chromosome segment substitution line, SL15. The plant height of the two lines was obviously different, and application of exogenous gibberellin A₃ removed this difference. QTL mapping placed qPH3.1 within a 4.0 cM interval, explaining 32.3% of the phenotypic variance. Furthermore, eight homozygous segmental isolines (SILs) developed from two larger F₂ populations further narrowed down qPH3.1 to within a 12.6 kb interval. ZmGA3ox2, an ortholog of OsGA3ox2, which encodes a GA3 β‐hydroxylase, was positionally cloned. Association mapping identified two polymorphisms in ZmGA3ox2 that were significantly associated with plant height across two experiments. Quantitative RT‐PCR showed that SL15 had higher ZmGA3ox2 expression relative to Zong3. The resultant higher GA₁ accumulation led to longer internodes in SL15 because of increased cell lengths. Moreover, a large deletion in the coding region of ZmGA3ox2 is responsible for the dwarf mutant d1‐6016. The successfully isolated qPH3.1 enriches our knowledge on the genetic basis of plant height in maize, and provides an opportunity for improvement of plant architecture in maize breeding.     

CO2浓度和磷对不同种植方式玉米大豆生长效应研究

通过顶置光源植物生长室控制380和760 μmol·mol-1 2个CO2浓度水平,研究了磷缺乏与正常供磷条件下,CO2浓度升高对玉米/大豆间作、玉米单作和大豆单作3种种植模式下作物株高、茎粗、叶面积及干物质积累的影响.结果表明:(1)CO2浓度升高能显著增加单/间作玉米、大豆的株高、茎粗、叶面积、根干重、地上部干重及总干重.(2)CO2浓度升高对供磷水平下单、间作玉米大豆的株高、茎粗、叶面积及干物质积累量增加的正效应均大于缺磷处理.(3)两种CO2浓度下,间作大豆与单作大豆生长差异不显著,而间作玉米较单作玉米有明显的生长优势,且供磷和CO2浓度的升高均能够促进这种优势.     

干旱高温复合胁迫下sHSPs基因在不同耐旱性玉米中的表达差异及其对ABA和H2O2的响应

以4个玉米(Zea mays L.)品种——‘郑单958’(耐干旱)、‘浚单20’(耐高温)、‘隆玉602’(耐干旱高温复合胁迫)和‘驻玉309’(对3种胁迫均敏感)为实验材料,分别采用脱落酸(ABA)及其抑制剂氟定酮(F)、H2O2及其清除剂碘化钾(I)和丙酮酸钠(P)预处理,探讨干旱高温复合胁迫下小热休克蛋白(sHSPs)在不同耐旱性玉米品种中的表达以及ABA和H2O2对其表达的影响。结果显示:(1)高温、干旱高温复合胁迫诱导的sHSP16.9、sHSP17.2、sHSP17.4、sHSP17.5、sHSP22和sHSP26等6个sHSPs基因表达增加量明显高于干旱和对照。(2)在6个sHSPs中,sHSP17.2基因仅在‘郑单958’中表达;sHSP16.9、sHSP17.4和sHSP26基因在‘隆玉602’中表达增加量最高,在‘驻玉309’中表达增量最低;sHSP17.5和sHSP22基因在‘郑单958’中表达增加量最高,在‘驻玉309’中最低。(3)ABA、F、I和P预处理后,对干旱高温复合胁迫诱导的6个sHSPs基因表达增加量仅有略微影响,但显著影响了sHSP26的蛋白表达。研究表明,sHSPs在不同耐旱性玉米品种中的表达存在显著差异,ABA和H2O2仅稍微提高了sHSPs基因表达,但显著提高了sHSP26蛋白表达,这些结果为进一步研究植物在多胁迫条件下耐逆机理奠定了基础。     

光照强度对大花旋蒴苣苔叶形态和生理指标的影响

以复苏植物大花旋蒴苣苔(Boea clarkeana)为盆栽实验材料,通过梯度遮光处理,研究不同光照强度(100%、80%、60%、40%和20%透光率)和不同处理时间(30、60、90、120和150d)对大花旋蒴苣苔叶生长指标和生理指标的影响。结果表明:随着光照强度的减弱,大花旋蒴苣苔叶的各生长指标(叶片长、叶片宽、叶柄长、叶柄直径以及叶面积)呈现先增大后减小的趋势,透光率为60%时达到最大值;全光照(100%透光率)时,大花旋蒴苣苔表现出明显的外伤症状,透光率为80%和20%时,分别表现出中度伤害和轻度伤害,透光率为40%和60%时,未出现明显的外伤症状;过氧化氢酶(CAT)、超氧化物歧化酶(SOD)和过氧化物酶(POD)3种抗氧化酶活性均较低且随着光强减弱呈现先降低后升高的趋势,随着处理时间的延长呈先上升后下降的趋势,全光照时抗氧化酶的活性最大,透光率60%处理下酶活性相对较低;丙二醛(MDA)含量、脯氨酸(Pro)含量和质膜透性随着光强减弱呈先降低后升高的趋势,随着处理时间的延长显著升高;叶绿素含量随着光强减弱呈逐渐上升的趋势,随着处理时间的延长先降低后升高。分析表明,40%～60%的透光率有利于大花旋蒴苣苔的生长,强光和弱光对大花旋蒴苣苔的生长均不利。     

Epigeic spiders are not affected by the genetically modified maize MON 88017

The genetically modified (GM) maize MON 88017 facilitates weed management owing to its tolerance to glyphosate, and resists western corn rootworm (WCR), Diabrotica virgifera virgifera, owing to the expression of Cry3Bb1 toxin. MON 88017 could therefore contribute to the solution of two major problems of European agriculture: continuous WCR spreading and high use of herbicides. To assess possible unwanted environmental impacts of MON 88017, we compared communities of spiders in plots planted in three successive years with this maize, its near isogenic non‐GM cultivar treated or not treated with an insecticide and two unrelated maize cultivars. Each of the five treatments was applied on five 0.5 ha plots in a 14 ha field. Spiders were collected in five pitfall traps per plot five times per year. Upon reaching the waxy ripening stage, all plants of first‐year cultivation were shredded to small pieces and ploughed into the soil in the respective plot, whereas in the 2nd and 3rd year the harvest was used for biogas production and only digestate was returned to the field. Out of 79 spider species, Pardosa agrestis, Pachygnatha degeeri and Oedothorax apicatus made up 28%, 25% and 23% of the total spider count in the 1st year of study; 2%, 8% and 84% in the 2nd; and 40%, 8% and 35% in the 3rd year. Statistical analysis did not reveal any influence of GM maize on the spider abundance and biodiversity. The abundance, and in two years also the species diversity, was insignificantly higher on the plots with GM maize than on plots with the insecticide‐treated non‐GM maize. The composition and size of spider community varied year to year, probably reflecting weather conditions and differences in field fertilization with organic matter.     

A Phytotoxin,Betaenone C,and Its Related Metabolites of Phoma betae Fr

For rough quantitative analysis of genetically modified maize contents, rapid methods for measurement of the copy numbers of the cauliflower mosaic virus 35S promoter region (P35S) and MON810 construct-specific gene (MON810) using a combination of a capillary-type real-time PCR system with a plasmid DNA were established. To reduce the characteristic differences between the plasmid DNA and genomic DNA, we showed that pretreatment of the extracted genomic DNA by a combination of sonication and restriction endonuclease digestion before measurement is effective. The accuracy and reproducibility of this method for MON810 content (%) at a level of 5.0% MON810 mixed samples were within a range from 4.26 to 5.11% in the P35S copy number quantification. These methods should prove to be a useful tool to roughly quantify GM maize content.     

LPS／D—GalN诱发ⅣF—KB转基因小鼠急性致死性肝损伤模型的建立

目的以NF—KB转基因BALB／c小鼠建立一个LPS／D—GaIN诱发的急性致死性肝损伤模型。方法采取腹腔注射高剂量的LPS／D-GalN建立急性致死性肝损伤小鼠模型,观察模型小鼠的促炎症细胞因子水平和NF—KB的活性改变,以及肝脏功能和病理改变情况。结果模型组小鼠生存时间为8—10h,模型建立后小鼠血清TNF—a、IL-6和MCP-1水平显著升高,在2—4h达到高峰;肝脏外观出现瘀血和出血,肝脏小叶被严重破坏,肝细胞严重坏死和出血;血清ALT／AST水平在模型诱发后持续迅速上升;整体成像显示胛-KB的活性在4～6h达到高峰。正常对照组小鼠以上指标无显著变化。结论成功建立LPS／D-GalN诱发的M-船转基因小鼠的急性致死性肝损伤模型。     

转基因小鼠和基因突变小鼠微卫星不稳定性分析

目的探讨微卫星在转基因和基因突变小鼠中的变化,为基因修饰和遗传突变动物的遗传检测和表型分析提供理论依据和技术手段。方法根据文献报道,从GenBank中选取198个等位基因数量多、富含多态性的微卫星位点,以野生型动物为对照,对6种近交系遗传背景的转基因小鼠和5种自然基因突变的近交系小鼠进行微卫星多态性检测,选用1.5%琼脂糖凝胶电泳和STR扫描技术,比较分析微卫星不稳定性。结果共有40个微卫星位点在转基因和基因突变小鼠中表现出多态性。在基因突变小鼠中,微卫星不稳定性有55.6%(10/18)是由纯合变为杂合(Ⅰ型),有3个位点(16.6%,3/18)是纯合突变(Ⅱ型),有5个位点同时存在2种类型的突变。但是在转基因动物中,大多数的微卫星多态性为Ⅰ型突变(87.5%,28/32),只有2个位点(6.2%,2/32)是Ⅱ型突变。另外有2个位点同时存在2种类型的突变。结论基因修饰或基因突变可引起小鼠相关微卫星发生不稳定性,而且某些微卫星位点对基因改变敏感性较高。