The insertion of the Agrobacterium rhizogenes rolC gene in tomato (Solanum lycopersicum L.) affects plant architecture and endogenous auxin and abscisic acid levels

In the present paper we report on the effects of the insertion of the Agrobacterium rhizogenes rolC gene in the tomato (Solanum lycopersicum L., formerly Lycopersicon esculentum Mill.) cultivar Tondino. Several transgenic lines were successfully obtained, between which two clones, rolC1 and rolC3, were chosen for the analysis of morpho-productive traits as well as of the endogenous levels of auxin and abscisic acid. Consistent with the known phenotypic effect of this gene, the transformed tomato plants were significantly shorter than the corresponding controls. On the other hand, even if yield was not affected by the transformation in terms of average number of fruits produced, fruit weight was significantly lower in the transgenics with respect to the controls. Therefore, insertion of the rolC gene does not lead to an improvement in plant productivity.     

拟南芥At-pri-miR828 基因的克隆及其对番茄的遗传转化

 MicroRNA828（miRNA828）是一种新近发现的生物学功能还未全面研究的miRNA。为从 不同角度阐明miRNA828 的生物学功能,从拟南芥中克隆到At-pri-miR828 基因并构建了该基因过量表达 的植物表达载体pC2300-pOT2-At-pri-miR828,通过农杆菌介导的叶盘法将pC2300-pOT2-At-pri-miR828 导入异源植物番茄品种‘Ailsa Craig’中。PCR 鉴定结果显示,外源基因At-pri-miR828 已成功整合到转 基因番茄基因组中,共获得9 个转基因株系,67 株转基因植株。定量PCR 检测结果显示,与野生型番茄 植株相比,转基因植株中miR828 的表达量显著增加,而生物信息学所预测的miR828 靶基因Sly-myb-like1 的表达水平则相应降低。花青素含量测定结果显示,miR828 过量表达的转基因番茄植株花青素含量明显 低于野生型植株,表明miR828 参与了番茄花青素的生物合成调控。     

番茄AP2/ERF超家族重鉴定及过表达SlERF.D.3株系表型分析

基于番茄基因组数据库的更新,系统地对番茄AP2/ERF超家族成员进行了更新,并对其进行了染色体定位、保守基序、基因结构和对灰霉菌及生长素胁迫响应的分析。共鉴定出141个ERF家族基因,其中新鉴定出的ERF亚家族成员42个;随机分布在12条染色体上,大都只含有外显子而无内含子,部分基因不同程度的受到灰霉菌和生长素处理的诱导表达。作为拟南芥AtERF109在番茄中的同源基因,SlERF.D.3的表达可被灰霉菌抑制且可迅速强烈地响应生长素处理。为进一步明确SlERF.D.3的生物学功能,以番茄‘Ailsa Craig’为材料克隆了此基因的编码区,构建过表达载体并转化番茄,获得了3个T0代过表达株系。与野生型相比,转基因株系的叶片较细长、向下卷曲,且果实出现乳状突起。这为研究SlERF.D.3在调节番茄的生长发育和胁迫响应过程中的作用奠定了基础。     

番茄生长素响应因子基因SlARF12在果实发育过程中的功能分析

以番茄‘Micro-Tom’为材料,研究了生长素响应因子基因SlARF12 （序列号：HM565127.1）在果实发育过程的生物学功能。实时定量PCR 检测表明,SlARF12在花蕾中表达量逐渐降低,而在授粉后的子房中显著高于去雄后未授粉的子房。利用RNA干扰（RNAi）技术抑制SlARF12表达,对番茄植株营养生长与花的发育没有显著影响,但SlARF12 RNAi果实显著大于野生型与空载转化植株的果实,且开花前去雄未授粉不能形成单性结实的果实。利用半薄切片观察转基因番茄果实早期发育细胞学特性发现,转化植株的果实果皮细胞显著大于对照果实细胞,但是两者果皮细胞层数没有显著差异。基因表达分析发现在SlARF12 RNAi的子房与幼果中细胞分化相关基因CycB1.1和CDKB2.1等的表达水平同对照相比下降,而SlPEC等细胞膨大基因表达量显著高于对照。所以抑制SlARF12可增强果实中细胞膨大相关基因的表达,从而促进果实膨大。以上结果表明,SlARF12可负调控番茄果实膨大但不参与坐果启动调控过程,显示了生长素通过ARF信号精细调控果实发育的各个阶段。     

Genetic transformation of Citrus sinensis cv. Hamlin with hrpN gene from Erwinia amylovora and evaluation of the transgenic lines for resistance to citrus canker

Transgenic Citrus sinensis (L.) Osb. cv. Hamlin plants expressing the hrpN gene were obtained by Agrobacterium tumefaciens (Smith and Towns) Conn-mediated transformation. hrpN encodes a harpin protein, which elicits the hypersensitive response and systemic acquired resistance in plants. The gene construct consisted of gst1, a pathogen-inducible promoter, a signal peptide for protein secretion to the apoplast, the selection genes nptII or aacC1 and the Nos terminator. The function of gst1 in citrus was evaluated in transgenic C. sinensis cv. Valencia harboring the reporter gene uidA (gus) driven by this promoter. Histochemical analysis for gus revealed that gst1 is activated in citrus leaves by both wounding and inoculation with Xanthomonas axonopodis Starr and Garces pv. citri (Hasse) Vauterin et al. Genetic transformation was confirmed by Southern blot hybridization in eight cv. Hamlin acclimatized plants. RT-PCR confirmed hrpN gene expression in seven cv. Hamlin transgenic lines before pathogen inoculation. Some hrpN transgenic lines showed severe leaf curling and abnormal growth. Six hrpN transgenic lines were propagated and evaluated for susceptibility to X. axonopodis pv. citri. RT-PCR confirmed gene expression in all six hrpN transgenic lines after pathogen inoculation. Several of the hrpN transgenic lines showed reduction in susceptibility to citrus canker as compared with non-transgenic plants. One hrpN transgenic line exhibited normal vegetative development and displayed very high resistance to the pathogen, estimated as up to 79% reduction in disease severity. This is the first report of genetic transformation of citrus using a pathogen-inducible promoter and the hrpN gene. Further evaluations of the transgenic plants under field conditions are planned. Nevertheless, the evidence to date suggests that the hrpN gene reduces the susceptibility of citrus plants to the canker disease.     

Fruit yield and quality of strawberry plants transformed with a fruit specific strawberry pectate lyase gene

Two transgenic strawberry lines (Pel 1 and Pel 3) containing the open reading frame of a fruit specific strawberry pectate lyase gene (FaplC) under the control of the CaMV35S promoter have been obtained to evaluate the role of this gene on fruit softening. Ripen fruits from both lines showed a significant down-regulation of FaplC, being the percentage of silencing of 84 and 71% on Pel 1 and Pel 3, respectively. The agronomic behaviour of transgenic plants was evaluated during two consecutive years. Fruit set increased in the two transgenic lines when compared with control plants, although Pel 1 showed a significant reduction on fruit weight. Firmness of full ripen fruits from Pel lines was significantly higher than control fruits, while color and soluble solids were not affected. The increase of firmness in Pel lines was maintained when ripe fruits were stored for 3 days at 25 °C. Histological analysis of ripe fruits showed lower intercellular spaces and a higher degree of cell to cell contact area in transgenic fruits when compared with controls. Altogether, these results suggest a direct relationship between pectate lyase gene expression and strawberry fruit softening.     

超表达草生欧文氏菌crtB基因促进转基因番茄类胡萝卜素合成的研究

利用重组PCR 技术,将草生欧文细菌八氢番茄红素合成酶基因crtB 与豌豆质体定位序列ts-rbcS 融合,插入质粒载体PMV 中,构建了植物表达载体pBI-ts-rbcS-crtB,并通过根瘤农杆菌EHA105介导转化番茄。PCR 检测、Southern 杂交和RT-PCR 分析表明,外源基因crtB 已整合到番茄基因组中,并在转基因植株中得到表达。转基因番茄果实中的类胡萝卜素总量增加1.3 ~ 2.5 倍,八氢番茄红素、番茄红素、β–胡萝卜素和α–胡萝卜素分别增加了4.3、1.8、2.2 和2.3 倍。转化株系中内源类胡萝卜素合成基因的表达也受到广泛的影响。crtB 基因过量表达有效促进了番茄果实中类胡萝卜素的合成和积累。     

Enhanced thermotolerance of the vegetative part of MT-sHSP transgenic tomato line

Transgenic tomato (Lycopersicon esculentum Mill.) line was developed that over-expressed tomato MT-sHSP to study the role of MT-sHSP in imparting tolerance to high temperature to vegetative part. T₀ and T₁ generation lines of transgenic tomato and wild type were used for molecular and physiological characterization for thermotolerance. Plants were grown at optimum (26/20 °C) and two supra-optimum, viz. ST₁ (30/22 °C) and ST₂ (32/25 °C) day/night temperature cycles. Plant height, leaf area, as well as assimilation (P_N), leaf cell membrane thermostability (LCMT), and night respiration were recorded. The T₀ and T₁ lines showed increased thermotolerance under both supra-optimum temperatures. Moreover, P_N did not limit the vegetative and reproductive growth under elevated temperatures. After exposure to heat-shock, the wild type and during growth at elevated temperature the transgenic line accumulated proline in the leaf, though more in wild type. Results of the LCMT clearly showed that wild type possessed more heat acclimation potential during growth at elevated temperature than the transgenic line. Further, the expression of MT-sHSP by both the transgenic and wild type under optimum temperature and after heat-shock, respectively, showed that transformation of tomato genome for high temperature tolerance could be a reality; the transformation by itself did not affect the expression of the gene for MT-sHSP. We found that a correlation exists between thermotolerance and both T₀ and T₁ generations of tomato plants and also inheritance of the MT-sHSP gene in T₁ progeny. It is assumed that MT-sHSP is just not expressed by plants under heat-shock, but has a unique function involved in thermotolerance. Specific role of the MT-sHSP in thermotolerance, however, need to be ascertained by in vitro studies.     

超量表达欧李ChPSY基因促进转基因番茄类胡萝卜素合成的研究

将从欧李果实中分离的ChPSY cDNA经过序列分析、酶切之后,连接到植物表达载体PMV,构建了植物重组载体pBI-ChPSY,并通过根瘤农杆菌EHA105介导转化番茄,获得了12株抗性植株。PCR检测和Southern杂交结果显示,12株抗性植株均为阳性,说明外源基因ChPSY整合到转化植株的基因组中。RT-PCR分析表明,ChPSY基因在转化植株果实中得到表达。HPLC分析表明,转ChPSY基因番茄果实中总类胡萝卜素含量增加了1.62 ~ 3.04倍,八氢番茄红素、番茄红素、β–胡萝卜素和α–胡萝卜素含量分别增加了4.87、2.10、2.59和3.25倍。转化植株中内源类胡萝卜素合成基因的表达也受到广泛的影响。ChPSY基因超量表达有效促进了番茄果实中类胡萝卜素的合成和积累。     

Alteration of tomato fruit quality by root inoculation with plant growth-promoting rhizobacteria (PGPR): Bacillus subtilis BEB-13bs

In this study the effect of inoculation of tomato (Lycopersicon esculentum Mill.) roots with plant growth-promoting rhizobacteria (PGPR) on yield and fruit quality was evaluated. The control treatment was non-inoculated (CTL) and the PGPR treatment was inoculated with Bacillus subtilis BEB-lSbs (BS13). Yield per plant and marketable yield, as well as fruit weight and length were increased by the BS13 treatment when compared to the CTL treatment. Texture of red fruits was also enhanced by the BS13 treatment compared to that in the CTL treatment. These results demonstrated that PGPR have positive effects on tomato fruit quality attributes, particularly on size and texture.     

利用amiRNA 技术沉默矮牵牛查尔酮合成酶基因

 转基因介导的基因沉默技术是进行基因功能分析和利用基因工程改良作物的重要手段。在植物中,amiRNA（artificial microRNA）是具有高度特异性的基因沉默技术。根据amiRNA设计的原则设计了用于沉默矮牵牛查尔酮合成酶（chalcone synthase,CHS）基因的amiRNA：amiRchs1,用拟南芥miR319a的前体作为表达amiRchs1的骨架,重叠PCR扩增,将天然miR319a序列替换成amiRchs1,合成的DNA片段置于35S启动子之后,转化导入矮牵牛。转基因植株花色变淡,花冠出现弥散的白色斑点或不规则的白色斑块,严重的几乎呈纯白色,花色素苷含量明显下降,CHS的mRNA含量明显降低,表明拟南芥miR319a的前体作为表达amiRNA的骨架在矮牵牛中可行,且能有效沉默结构基因。     

苹果MdFT基因对番茄的遗传转化

 通过RT2PCR扩增, 从苹果叶片cDNA中克隆了^FT基因的同源基因^MdFT, 构建了花椰菜病毒35S启动子驱动的MdFT植物表达载体35S: : MdFT, 并利用根癌农杆菌介导法将其导入番茄栽培品种‘中蔬四号’; 同时转化拟南芥A tFT基因作为阳性对照。从添加卡那霉素的筛选培养基上再生了抗性植株,PCR扩增证明, 外源基因MdFT和AtFT已经整合到转基因番茄的基因组, 半定量RT-PCR则证明它们已经在转基因番茄中得到异位过量表达。形态鉴定发现, 转基因番茄植株比非转基因对照植株开花早, 表明成功地从苹果中克隆了成花素基因MdFT, 该基因具有通过转基因缩短苹果树童期的潜在价值。     

番茄漆酶基因LeLACmiR397的克隆与表达分析

通过BLAST分析,获得了番茄漆酶（Laccase,LAC）基因相关的15个EST片段,并对这些EST进行了同源比较和序列拼接,得到1个含有小分子RNA miR397识别位点的LAC片段,命名为LeLACmiR397。根据蛋白质结构域推测,LeLACmiR397蛋白存在1个Cu–氧化酶结构域。LeLACmiR397时空表达分析表明,其在番茄根、花、成熟果实和愈伤组织中特异性表达,而在叶中不表达。根据该片段的核苷酸序列信息进行5′-和3′-RACE扩增,得到了番茄LAC基因的全长cDNA（LeLACmiR397,登录号EU503151）,其在番茄基因组中对应的基因为Solyc07g049460.2.1。通过在番茄中过表达miR397a基因,发现转基因番茄中LeLACmiR397表达量降低,同时其PPO、POD、SOD含量也有所下降。用丁香酸和芥子酸处理转基因植株幼苗,其根系比非转基因植株更长,抗性增强,表明LeLACmiR397与番茄植株的抗性反应有关。     

Production of transgenic sweetpotato plants resistant to stem nematodes using oryzacystatin-I gene

Stem nematode (Ditylenchus destructor Thorne) is one of most serious diseases limiting sweetpotato (Ipomoea batatas (L.) Lam.) production, and it is urgent to develop sweetpotato varieties resistant to this disease. In present study, we have developed transgenic sweetpotato (cv. Xushu 18) plants resistant to stem nematodes using oryzacystatin-I (OCI) gene with Agrobacterium tumefaciens-mediated transformation. A. tumefaciens strain EHA105 harbors a binary vector pCAMBIA1301 with OCI gene, uidA gene and hptII gene. Selection culture was conducted using 7 mg/l hygromycin. A total of 2119 plants were produced from the inoculated 1710 cell aggregates of Xushu 18 via somatic embryogenesis. GUS assay and PCR analysis of the regenerated plants randomly sampled showed that 92.8% of the regenerated plants were transgenic plants. Transgenic plants exhibited enhanced resistance to stem nematodes compared to the untransformed control plants by the field evaluation and the inoculation test with stem nematodes and stem nematode-resistant plants were selected from the transgenic plants. Stable integration of the OCI gene into the genome of resistant transgenic plants was confirmed by Southern blot analysis, and the copy number of integrated OCI gene ranged from 1 to 3. High level of OCI gene expression in the resistant transgenic plants was demonstrated by real-time quantitative PCR analysis. This study provides a way for improving stem nematode resistance of sweetpotato.     

抗黄萎病基因StVe转化番茄的研究

 为了验证克隆自水茄（Solanum torvum Swartz）的StVe基因功能,将StVe连入中间载体p35S-2300::gus::noster的BamHⅠ和SacⅠ位点,取代gus基因构建植物双元表达载体p35S-2300::StVe::noster;用农杆菌介导法转化樱桃番茄22号获得了72株卡那霉素抗性植株,PCR和Southern blot检测确认有5株为阳性植株;RT-PCR结果显示,StVe在转基因番茄植株间的转录水平表达存在差异;PDA平板抑菌实验显示,转StVe基因番茄叶片总可溶蛋白具有抑制番茄黄萎病菌生理小种1（Verticillium dahliae race 1）生长的作用。     

Genetic transformation of Prunus domestica L. using the hpt gene coding for hygromycin resistance as the selectable marker

The study and development of transformation technology with new selection schemes is important for various fundamental studies and for crop trait improvement via genetic engineering. Here we have shown that hygromycin resistance is an effective system for plum genetic transformation. Embryonic axes of mature seeds were co-cultivated with Agrobacterium strain LBA4404 containing the pC1381 plasmid carrying the hygromycin phosphotranferase gene (hpt) and β-glucuronidase (GUS) gene or with strain EHA105 containing the plasmid pC1301 carrying the same marker and reporter genes. The latter strain containing a pC2301 plasmid carrying the neomycin phosphotransferase gene (nptII) gene was used as a control. Infected explants were placed on shoot induction medium containing either 5 mg L⁻¹ hygromycin or 75 mg L⁻¹ kanamycin for selection. Green shoots developed from the explants under hygromycin pressure. These shoots showed continued and vigorous growth and development upon transfer onto fresh hygromycin medium. PCR using hpt sequence primers, and Southern blot analysis using a probe from the hpt gene, confirmed the presence of the transgenes and their stable integration in regenerated plants. Full transgenic plants were obtained in a greenhouse. Hygromycin selection was very effective and no escapes were observed. The study demonstrated that hygromycin resistance can be used as an effective selectable marker for plum transformation. The new system developed here is important and useful for multiple gene transformation in plum.     

拟南芥耐寒基因AtCOR15a在番茄中异源表达增强其耐寒性

拟南芥耐寒基因AtCOR15a由冷诱导启动子RD29A控制后,重组进双元表达载体,经根癌农杆菌介导,将该基因导入‘Ailsa Craig’番茄。研究发现,筛选出的3个高表达转基因株系的耐寒性比野生型显著增强;外源基因AtCOR15a的表达量在低温处理过程中呈现先增后降的变化趋势,且在处理6h达到最大值;在冷胁迫下,该基因的表达促进了转基因植株中SlDehydrin-like(Sl DEHL)和SlDehydrin Ci7(SlCi7)等内源冷诱导基因的表达,降低了细胞膜透性和丙二醛(MDA)含量,减少了活性氧H_2O_2和O_2~.的积累,增强了超氧化物歧化酶、过氧化物酶和过氧化氢酶等活性氧清除酶的活性,提高了游离脯氨酸含量。因此,AtCOR15a异源表达能够显著增强转基因番茄的耐寒性。     

Evaluation of alternative RNA labeling protocols for transcript profiling with Arabidopsis AGRONOMICS1 tiling arrays

Background

The genus Populus is accepted as a model system for molecular tree biology. To investigate gene functions in Populus spp. trees, generating stable transgenic lines is the common technique for functional genetic studies. However, a limited number of genes have been targeted due to the lengthy transgenic process. Transient transformation assays complementing stable transformation have significant advantages for rapid in vivo assessment of gene function. The aim of this study is to develop a simple and efficient transient transformation for hybrid aspen and to provide its potential applications for functional genomic approaches.

Results

We developed an in planta transient transformation assay for young hybrid aspen cuttings using Agrobacterium-mediated vacuum infiltration. The transformation conditions such as the infiltration medium, the presence of a surfactant, the phase of bacterial growth and bacterial density were optimized to achieve a higher transformation efficiency in young aspen leaves. The Agrobacterium infiltration assay successfully transformed various cell types in leaf tissues. Intracellular localization of four aspen genes was confirmed in homologous Populus spp. using fusion constructs with the green fluorescent protein. Protein-protein interaction was detected in transiently co-transformed cells with bimolecular fluorescence complementation technique. In vivo promoter activity was monitored over a few days in aspen cuttings that were transformed with luciferase reporter gene driven by a circadian clock promoter.

Conclusions

The Agrobacterium infiltration assay developed here is a simple and enhanced throughput method that requires minimum handling and short transgenic process. This method will facilitate functional analyses of Populus genes in a homologous plant system.