农杆菌介导转化黑曲霉分生孢子及产孢缺陷突变子T-DNA插入位点分析

【目的】利用农杆菌(Agrobacterium tumefaciens)T-DNA系统,建立转化黑曲霉(Aspergillus niger)分生孢子的方法,构建T-DNA插入突变子文库,为黑曲霉基因组功能注释研究打下基础。【方法】采用携带二元质粒载体pCAMBIA1301的农杆菌EHA105,诱导转化黑曲霉分生孢子,筛选具有潮霉素抗性的突变子。分析抗性稳定突变子菌株的表型,采用反向PCR方法分析T-DNA插入位点相邻位置的序列,并推测突变基因可能具有的功能。【结果】实验获得具有稳定潮霉素抗性转化子193株,转化率为5.6×102转化子/108分生孢子。部分转化子表型出现较为明显改变,其中一株不能产孢,对其T-DNA插入位点序列分析比对结果显示,突变基因属于超级转运家族(major facilitator superfamily,MFS)。【结论】本研究建立的农杆菌转化黑曲霉分生孢子平台,结合T-DNA插入突变位点分析,可以为黑曲霉基因组功能注释研究提供一种简便有效的途径。     

植物DNA断裂修复基因对农杆菌T-DNA整合的作用

转基因植物在作物新品种培育和生物制药中已发挥了巨大作用。农杆菌介导的遗传转化是广泛用于基因组分析的强大工具,也是获得转基因植物的主导技术。农杆菌介导的基因转移是极其复杂的生物学过程,需要许多农杆菌和植物的遗传因子协同参与完成。经过20多年的研究,人们对T-DNA产生和转运的分子机制以及农杆菌与寄主植物的互作已有所了解。T-DNA整合是农杆菌介导转化过程中最为关键的一步,但对于其整合机制所知仍有限。越来越多的证据表明,寄主植物细胞的DNA断裂修复基因对农杆菌T-DNA整合具有重要作用。该文首先介绍T-DNA转移的大致过程,重点讨论DNA断裂损伤修复相关基因对T-DNA整合的作用,为通过DNA损伤修复基因的遗传操纵来提高农杆菌介导植物遗传转化的效率提供参考。     

农杆菌介导的出芽短梗霉遗传转化及高效筛选聚苹果酸高产菌株

建立根癌农杆菌介导的出芽短梗霉遗传转化方法及T-DNA突变库,高效筛选聚苹果酸高产菌株及功能基因。通过含潮霉素和草铵磷抗性基因的农杆菌转化出芽短梗霉,抗性压力筛选及PCR验证建立根癌农杆菌介导的出芽短梗霉遗传转化方法,结合发酵液p H与聚苹果酸含量响应变化,微孔板高效筛选高产聚苹果酸的T-DNA插入突变株,基因组步移确定T-DNA插入位点及功能基因。结果获得遗传稳定的抗性基因菌株,每107个细胞可获得80-120个转化子,出芽短梗霉H27号T-DNA突变株聚苹果酸摇瓶发酵产量提高24.5%,基因组步移证实糖酵解途径磷酸甘油酸变位酶基因被破坏。成功建立了根癌农杆菌介导的出芽短梗霉遗传转化方法和T-DNA插入突变库,结合高效筛选方法为聚苹果酸合成功能基因挖掘及高产机制解析奠定基础。     

根癌农杆菌介导的巨大口蘑遗传转化体系的构建

以巨大口蘑菌丝为受体材料,利用含有双元质粒plasmid4的根癌农杆菌EHA105介导,首次成功建立了巨大口蘑的遗传转化体系。通过潮霉素抗性筛选、PCR鉴定和绿色荧光蛋白的检测,表明潮霉素抗性基因（Hyg）已经整合到巨大口蘑基因组中,增强型绿色荧光蛋白基因（eGFP）在巨大口蘑菌丝中获得表达,并能够稳定遗传。本研究建立了农杆菌介导的巨大口蘑遗传转化体系,为今后巨大口蘑的基因功能研究奠定了基础。     

不同启动子调控外源基因在斑玉蕈中的表达分析

启动子是控制基因转录的重要顺式元件,也是遗传转化实验中驱动外源基因表达的重要工具。在同一真菌中,不同启动子驱动外源基因表达水平可能存在明显差异。因此,选择合适的启动子是提高外源基因表达水平的关键。本研究分别应用花椰菜病毒35S RNA（cauliflower mosaic virus 35S RNA,CaMV35S）和斑玉蕈甘油醛-3-磷酸脱氢酶（Hypsizygus marmoreus glyceraldehyde-3-phosphate dehydrogenase,HmGPD）基因的启动子构建了两个遗传转化质粒,在斑玉蕈中分别驱动外源的植物花青素合成基因表达,并利用来自刺芹侧耳的萎锈灵抗性基因进行转基因筛选。两个质粒通过农杆菌介导转化斑玉蕈单核菌株后,对具有萎锈灵抗性的转化子经PCR方法进行转基因验证,并运用实时荧光定量PCR对阳性转化子中外源基因的表达水平进行比较分析。结果表明,CaMV35S和HmGPD基因的启动子均成功驱动了植物花青素合成基因在斑玉蕈中转录,为增强基因表达而引入的内含子在转录过程中均被正确切割。其中,HmGPD启动子驱动外源基因表达水平比CaMV35S启动子驱动外源基因表达水平强22-36倍。     

灰黄青霉Pa-pex11基因对青霉素产生的影响

摘要：【目的】研究灰黄青霉Pa-pex11对青霉素产生的影响。【方法】通过保守序列设计引物从灰黄青霉中克隆了含有pex11同源基因DNA片段,进而通过热不对称交错PCR(Thermal asymmetric interlaced PCR, Tail PCR )扩增得到灰黄青霉中Pa-pex11基因的全序列。利用根癌农杆菌介导的遗传转化（ATMT）系统,在灰黄青霉基因组上导入额外的Pa-pex11基因。对灰黄青霉野生型菌株和转化子进行了青霉素发酵及生物活性测定。通过荧光定量PCR(quantitative     

根癌农杆菌介导的日本曲霉转化体系的建立

【目的】通过根癌农杆菌介导的方法构建日本曲霉转化子库,从而筛选出高产甘没氧化酶的日本曲霉突变菌株。【方法】本文通过三亲杂交的方法将双元载体pBI-hphII转移至根癌农杆菌EHA105中并作为侵染菌株,以日本曲霉As5999为受体菌株,建立了农杆菌介导的日本曲霉转化体系,构建了突变体库,并对影响转化效率的根癌农杆菌浓度,乙酰丁香酮(As)加入与否,共培养时间,共培养温度等因素进行了分析。【结果】对转化子的PCR检测和Southern杂交分析表明,T-DNA已整合进日本曲霉基因组中,随机挑选的9个转化子连续转接10代后均能稳定遗传。【结论】该转化体系的建立为筛选出高产甘油氧化酶的日本曲霉突变菌株奠定了基础。     

农杆菌介导转基因植物T-DNA的整合方式

农杆菌介导的遗传转化已被广泛应用于植物转基因研究。作为外源基因的载体,农杆菌T-DNA片段在植物基因组中的整合方式,不仅影响外源基因的整合效率及稳定性,还会影响外源基因的表达特性。文章就农杆菌介导的T-DNA整合的两种主要模式、规律及相关研究手段进行综述,为农杆菌介导的转基因及T-DNA插入突变等相关研究提供借鉴。     

根癌农杆菌介导的地衣型真菌Cladonia metacorallifera的转化

以潮霉素抗性和增强型绿色荧光蛋白(enhanced green fluorescent protein,EGFP)作为筛选标记,利用地衣型真菌Cladonia metacorallifera的菌丝,成功实现了根癌农杆菌介导的遗传转化,PCR检测证明转化子中存在潮霉素抗性基因,共聚焦显微镜检测到转化子菌丝能够产生绿色荧光,证明EGFP能够在trp C启动子控制下在地衣型真菌中表达。     

双孢蘑菇耐热相关基因的表达载体构建及转化研究

构建了双孢蘑菇Agaricus bisporus耐热相关基因028-1全长cDNA序列的双元表达载体,通过农杆菌介导转化双孢蘑菇非耐热菌株8213,经潮霉素抗性筛选和PCR鉴定,获得了一批双孢蘑菇转基因菌株。对10株转基因菌株进行了不同温度下的草管走菌试验,结果显示大部分转基因菌株的耐热性能有较为明显的提高。     

根癌农杆菌介导的增强型绿色荧光蛋白基因在淡紫拟青霉中的转化

为了实现增强型绿色荧光蛋白基因 (egfp) 在生防真菌淡紫拟青霉9410菌株中的转化,借助中间质粒pcDNA3.1(-) 构建nptⅡ-egfp融合基因的表达载体pUPNGT,然后采用根癌农杆菌介导的转化法将egfp基因转化到淡紫拟青霉9410菌株中。PCR检测和Southern blotting分析结果表明,egfp基因以单拷贝形式整合到淡紫拟青霉9410的基因组中。荧光显微镜观察结果显示,转化子在488 nm下能产生绿色荧光。这些结果说明egfp基因已成功转化至淡紫拟青霉9410菌株并获得表达。这些工作可为淡紫拟青霉在不同条件下的防效评价、环境安全评价等提供新的途径和方法。     

Agrobactrium tumefaciens-mediated transformation of Monascus ruber

Agrobacterium tumefaciens-mediated transformation (ATMT) was successfully applied to Monascus ruber. The optimum cocultivation time was 84 h with an efficiency of 900 to 1,000 transformants when 1x106 spores were used with the same volume of bacteria. The stability of transformants was over 98% after five generations. When M. ruber was transformed with A. tumefaciens YL-63 containing the green fluorescent protein gene (egfp), the green fluorescent signal was observed throughout hyphae, confirming expression of the gene. This efficient transformation and expression system of M. ruber by ATMT will facilitate the study of this fungus at a molecular genetic level.     

利用双T-DNA载体系统培育无选择标记转基因烟草

建立了一种利用双T-DNA载体培育无选择标记转基因植物的方法.通过体外重组构建了双T-DNA双元载体pDLBRBbarm.载体中,选择标记nptⅡ基因和另一代表外源基因的bar基因分别位于2个独立的T-DNA.利用农杆菌介导转化烟草(Nicotiana tabacum L.),在获得的转化植株中,同时整合有nptⅡ基因和bar基因的频率为59.2%.对4个同时整合有nptⅡ和bar基因植株自交获得的T1代株系进行检测分析,发现在3个T1代株系2个T-DNA可以发生分离,其中约19.5%的转基因T1代植株中只存在bar基因而不带选择标记nptⅡ.这一结果说明双T-DNA载体系统能有效地用于培育无选择标记的转基因植物.研究还利用位于2个不同载体上的nptⅡ基因与 bar基因通过农杆菌介导共转化烟草,获得共转化植株的频率为20.0%～47.4%,低于使用双T-DNA转化的共转化频率.     

甲型肝炎病毒衣壳蛋白融合基因植物表达载体的构建 与遗传转化柑桔的研究

基因工程领域的研究进展使得植物体成为具有重要经济价值的药用蛋白的生产体系。以含甲型肝炎病毒结构基因cDNA的克隆载体pCDNAⅡA16为模板,用甲型肝炎病毒衣壳蛋白融合基因特异引物进行PCR扩增,得到全长2.2kb衣壳蛋白融合基因序列。经测序鉴定后正向克隆于植物表达载体pBI121中,衣壳蛋白融合基因位于pBI121质粒T-DNA左右边界区间内,处于CaMV35S启动子控制之下。经限制性内切酶分析和PCR鉴定后利用冻融法将重组质粒pBI121-A导入根癌农杆菌LBA4404。以锦橙 (Citrus. Sinensis Osbeck) 上胚轴为转化材料,通过根癌农杆菌介导法将衣壳蛋白融合基因转 化到植物基因组中。120株转化外植体经卡那霉素50 mg/L筛选,其中13株生长状况良好未出现白化现象的拟转化芽微嫁接到实生砧木继续培养。PCR分析证明,13株拟转化植株中有5株植物基因组中已导入甲型肝炎病毒衣壳蛋白融合基因,转化率为4.1%。此研究是对遗传转化柑桔表达外源蛋白的初步探讨,为进一步研究食用疫苗开辟了新途径。Abstract: The use of edible plants for the production and delivery of vaccine proteins could provide an economical alternative to fermentation systems. The construction of the plant expression vector pBI121-A was reported, which contained a fusion gene encoding hepatitis A capsid proteins. The gene was located between the left and right Ti border sequences under the control of CaMV35S promoter. The vector was identified via PCR and restriction enzyme analysis and was introduced into Agrobacterium tumerifacience LBA4404. The transgenic Citrus plants were produced by Agrobacterium-mediated transformation of epicotyl segments. 13 putatively transformed plants through the kanamycin selection were micrografted onto the seedlings. The presence and integration of the transgene had been verified by PCR analysis. The result showed that five transformants were integrated and the transformation efficiency was 4.1%.     

The DNA sequences of T-DNA junctions suggest that complex T-DNA loci are formed by a recombination process resembling T-DNA integration

After Agrobacterium-mediated plant transformation, multiple T-DNAs frequently integrate at the same position in the plant genome, resulting in the formation of inverted and direct repeats. Because these inverted repeats cannot be amplified and analyzed by PCR, Arabidopsis root cells were co-transformed with two different T-DNAs with distinct sequences adjacent to the T-DNA borders. Nine direct or inverted T-DNA border junctions were analyzed at the sequence level. Precise end-to-end fusions were found between two right border ends, whereas imprecise fusions and filler DNA were present in T-DNA linkages containing a left border end. The results suggest that end-to-end ligation of double-stranded T-DNAs occurs especially between right T-DNA ends and that illegitimate recombination on the basis of microhomology, deletions, repair activities and insertions of filler DNA is involved in the formation of left border T-DNA junctions. Therefore, a similar illegitimate recombination mechanism is proposed that is involved in the formation of complex T-DNA inserts as well as in the integration of the T-DNA in the plant genome.     

Agrobacterium tumefasciens-mediated transformation of the aquatic fungus Blastocladiella emersonii

Agrobacterium tumefaciens is widely used for plant DNA transformation and more recently, has also been used to transform yeast, filamentous fungi and even human cells. Using this technique, we developed the first transformation protocol for the saprobic aquatic fungus Blastocladiella emersonii, a Blastocladiomycete localized at the base of fungal phylogenetic tree, which has been shown as a promising and interesting model of study of cellular function and differentiation. We constructed binary T-DNA vectors containing hygromycin phosphotransferase (hph) or enhanced green fluorescent protein (egfp) genes, under the control of Aspergillus nidulans trpC promoter and terminator sequences. 24 h of co-cultivation in induction medium (IM) agar plates, followed by transfer to PYG-agar plates containing cefotaxim to kill Agrobacterium tumefsciens and hygromycin to select transformants, resulted in growth and sporulation of resistant transformants. Genomic DNA from the pool o resistant zoospores were shown to contain T-DNA insertion as evidenced by PCR amplification of hph gene. Using a similar protocol we could also evidence the expression of enhanced green fluorescent protein (EGFP) in zoospores derived from transformed cells. This protocol can also open new perspectives for other non-transformable closely related fungi, like the Chytridiomycete class.     

High reliability transformation of the wheat pathogen Bipolaris sorokiniana using Agrobacterium tumefaciens

Bipolaris sorokiniana, the causal agent of spot blotch of wheat, significantly reduces grain yield worldwide. In order to study pathogenic mechanisms of the fungus, conditions for efficient transformation using Agrobacterium-mediated transformation were investigated. To study different stages of hyphal fusion and pathogenic mechanisms of the fungus, two fluorescence markers viz. the red fluorescent protein (DsRed-Express) and the green fluorescent protein (EGFP1) were constitutively expressed. Southern hybridizations confirmed the presence of T-DNA in all hygromycin B or geneticin resistant transformants, and also showed random and single copy integration. Fluorescence microscopy suggested the high level expression of both DsRed and EGFP fluorescent proteins in spores and mycelia. The results signify that DsRed and EGFP can be used as efficient reporter gene for monitoring B. sorokiniana hyphal fusion as well as colonization in the host tissues. This work will be useful to develop methodologies for understanding the mechanisms of Bipolaris-wheat interaction and functional genomics of B. sorokiniana for various applications including insertional mutagenesis, targeted disruption of specific genes, ectopic complementation of loss-of-function strains and over-expression.     

无选择标记和载体骨干序列的Xa21转基因水稻的获得

利用双右边界T-DNA载体通过根癌农杆菌介导法将水稻白叶枯病广谱抗性基因Xa21导入杂交稻重要恢复系C418中。T0代共获得27个独立转基因株系,通过田间抗性鉴定与PCR分析,有17个株系的Xa21基因分子鉴定为阳性,且对白叶枯病原菌P6生理小种具有抗性。通过对17个株系的后代植株进行田间抗性鉴定,分子标记辅助选择及Southern杂交分析,结果显示4个株系的T1代植株中能分离出无潮霉素标记基因的Xa21转基因植株。无选择标记Xa21转基因株系的获得率为15%。PCR检测还表明,这些无选择标记的Xa21转基因植株不带有载体骨架序列。通过对转基因后代进一步的抗性鉴定与PCR辅助选择,获得了无选择标记和载体骨架序列的转基因Xa21纯合的抗白叶枯病水稻。