Radiomutants of chrysanthemum (Dendranthema grandiflora Tzvelev) of the Lady group: RAPD analysis of the genetic diversity

Random amplified polymorphic DNA (RAPD) markers were used to study the molecular characterization of 10 new radiomutants of chrysanthemum. The original cultivar ‘Richmond’ differed in genetic distance from its Lady group mutants. The analysis of genetic similarity indices revealed low diversity within the radiomutants. The dendrogram obtained after cluster analysis separated the new cultivars as a group that differed from the original cultivar ‘Richmond’. The Lady group cultivars, derived from one original cultivar by radiomutation, could be distinguished from each other by using RAPD markers of only a single primer or sets of two or three primers. Polymerase chain reaction analysis proved the efficiency of the RAPD method for DNA fingerprinting of the original cultivar ‘Richmond’ and its new radiomutants.     

Variation in performance of western flower thrips populations on a susceptible and a partially resistant chrysanthemum cultivar

Variation in host plant performance among populations of a phytophagous insect pest is a potential threat to the durability of host plant resistance. Aggressive biotypes may overcome the protective properties of formerly resistant cultivars. Therefore, it is of interest to study such variation in breeding programs for host plant resistance to insects. In the present study, the performance of ten populations of Frankliniella occidentalis, the western flower thrips, was determined on a susceptible and a partially resistant cultivar of chrysanthemum, Dendranthema grandiflora. Damage, reproduction, and adult survival were determined using an excised leaf assay. Significant differences between the two cultivars and among the ten populations were found for all three characteristics. In general, damage, reproduction and adult survival were reduced on the resistant cultivar when compared to the susceptible cultivar. Some populations showed, in comparison to the reference population from the Netherlands, much higher damage and reproduction on one or both chrysanthemum cultivars. But also in these populations performance on the resistant cultivar was poor compared to the susceptible cultivar. This revised version was published online in August 2006 with corrections to the Cover Date.     

Modification of tomato taste in transgenic plants carrying a thaumatin gene from Thaumatococcus daniellii Benth

Fruit taste is an important component of fruit quality, but its genetic basis is complex, making it difficult to alter by plant breeding. Thaumatin is a sweet‐tasting, flavour‐enhancing protein produced by fruits of the African plant Thaumatococcus daniellii Benth. Agrobac‐terium‐mediated transformation was used to produce two transgenic tomato lines expressing biologically active thaumatin in fruits. Transgenic tomato fruits from the T₂ plant generation were sweeter than the controls and possessed a specific aftertaste as determined by sensory evaluation. These results demonstrate that transgenic expression of thaumatin could be useful for modifying tomato fruit taste, especially in breeding lines possessing poor fruit taste, such as those carrying a non‐ripening (nor) mutation.     

Regeneration of Chinese cabbage transgenic plants expressing antibacterial peptide gene and cowpea trypsin inhibitor gene

Summary An efficient transformation system for Chinese cabbage cotyledon explants was developed using Agrobacterium tumefaciens strains LBA4404 harbouring the plasmid pMOG 411 and the plasmid pBinΩSCK respectively. Various factors affecting the transformation efficiency and subsequent regeneration were identified. The age of seedlings, growth conditions and status of Agrobacterium suspension, preculture of explants, cocultivation time, ratio between Agrobacterium and explants, acetosyringone and concentration of kanamycin had a significant influence on transformation frequency and plant regeneration. The presences of the antibacterial peptide gene and the cowpea trypsin inhibitor gene in those selected shoots in kanamycin medium were confirmed by PCR, Southern blotting and Northern blotting, The frequency of regeneration from cotyledons was analyzed in eight parental lines of Chinese cabbage and five lines were suitable for obtaining transformed plants, among which Qingmaye C and Qingmaye D were more responsive than other lines.     

Production of fertile transgenic Brassica napus by Agrobacterium-mediated transformation of protoplasts

A protocol for Agrobacterium tumefaciens‐mediated transformation of Brassica napus mesophyll protoplasts is described. A strain with a neomycin phosphotransferase (nptII) gene and a KCS gene under control of a napin promoter was used at co‐cultivation. Transformed protoplasts were regenerated to fertile and morphologically normal transgenic plants. Transformants were confirmed by PCR of the nptII gene and NAP/KCS expression cassette, and Southern blot analysis. Seeds of the transformants showed a changed fatty acid profile: two transformants had a higher erucic acid level and differed significantly from that of B. napus. Genetic analysis of the progeny revealed that the kanamycin resistance introduced was inherited in a Mendelian fashion.     

Analysis of genomic variability in transgenic sugarcane plants produced by Agrobacterium tumefaciens infection

Three transgenic sugarcane populations produced by Agrobacterium tumefaciens infection were analysed for the presence of genomic variability. Plants of the original cultivar, plants regenerated without transformation, as well as transformed and untransformed calli were used as control treatments. Amplified fragment length polymorphism (AFLP) of DNA extracted from leaves or calli assessed genomic profiling. The average DNA polymorphism within each population was determined by calculating the polymorphism index, while the extent of genomic dissimilarity among individual plants within transgenic populations was verified in unweighted pair group method using arithmetic averages dendrograms. The results showed that the production of transgenic sugarcane plants by A. tumefaciens infection is accompanied by limited but detectable genomic changes and that, on average, these occur at the same rate in plant populations carrying different transgenes. Main factors contributing to somaclonal variation in transgenic sugarcane plants have been verified by pre-existing DNA polymorphism into the donor genotype and in vitro culture steps during the transformation procedure. The relevant practical conclusion from this finding is that the AFLP analysis may be effectively used to identify individual transgenic plants with the least genomic deviation from the parental ones. The selected genotype would be conserved as cultivated sugarcane is asexually propagated.     

棉花黄萎病菌T-DNA插入突变体库的构建及其表型分析

 以棉花强致病力黄萎病菌株V592为材料,利用农杆菌介导的T-DNA插入技术构建了一个含15000个转化子的突变体库,对突变体的生物学特性、致病力及T-DNA插入拷贝数进行研究,结果显示：(1) 突变体的菌落形态分为菌核型、中间型、菌丝型和菌膜型,分别占92.12%,4.54%,3.19%和0.15%;（2）菌核型、中间型和菌丝型菌株,在菌落生长速度和孢子大小方面无明显差异;而在产孢量方面,菌核型普遍强于中间型和菌丝型;（3）致病性测定显示,菌核型的致病力普遍强于中间型和菌丝型;（4）Southern杂交显示,T-DNA单拷贝数插入的突变体比率约为70.99%,而菌核型的单插入率为80.00%,明显高于中间型(69.23%)和菌丝型(64.71%)。以上结果表明,农杆菌介导转化技术可用于棉花黄萎病菌突变体库的快速构建,突变体的菌落表型与其产孢能力、致病力及T-DNA插入拷贝数等之间存在一定的相关性。     

Use of chrysanthemum plantlets grown in vitro to test cultivar susceptibility to white rust, Puccinia horiana P. Hennings

An efficient incubation and inoculation system for white rust was established using plantlets of chrysanthemum growing in vitro. The internal conditions of a culture vessel (plant box) were maintained at a humidity of 90‐100% and an optimum temperature of 20‐25°C, which are suitable conditions to germinate teliospores and basidiospores of the pathogen. Telia were maintained continuously on plants in the plant box and were used as an inoculum for infection experiments throughout the year, allowing differences in susceptibility to white rust among chrysanthemum cultivars to be detected. Susceptibility to white rust in the plant‐box evaluation showed a good correlation with the rating of sporulation on plants grown in a greenhouse. The method described here is a simple, space‐saving inoculation system to evaluate the susceptibility of chrysanthemums to white rust.     

Efficient production of transgenic plants by Agrobacterium-mediated transformation of cassava (Manihot esculenta Crantz)

An efficient and reproducible method was developed for Agrobacterium-mediated transformation of embryogenic suspension cultures of cassava. LBA4404(pTOK233), containing the nptII, hph and gus marker genes, was used in the experiments. Chemical selection by means of kanamycin was used to establish 1037antibiotic resistant callus lines, of which 526 showed GUS expression. Of the 241 callus lines that were transferred to maturation medium 219formed somatic embryos. Thirty-seven of the 38 lines that were transferred to germination medium produced plants. GUS-positive plants could be obtained from 31 lines; in 14 of those lines 100% of the produced plants were GUS-positive, the remaining 17 lines yielded GUS-positive plants at an average of 72%. The transgenic nature of these plants was confirmed by Southern blot analysis. This revised version was published online in July 2006 with corrections to the Cover Date.     

Production of embryogenic tissues and regeneration of transgenic plants in cassava (Manihot esculenta Crantz)

Disorganised embryogenic tissues have been utilised as target tissues for transgene insertion and transgenic plant regeneration in cassava (Manihot esculenta). The production of friable embryogenic callus in fourteen geographically diverse cassava cultivars, from which eleven were established as embryogenic suspension cultures, is reported. Embryogenic tissues were similar in nature in all cultivars tested although there was variation in the time required to generate friable callus and the growth rates of suspension cultures. Regeneration of plants has been achieved from eight cultivars but varied significantly in efficiency, with cv. TMS 60444and Line 2 from Zimbabwe being the most responsive. Tissues from the remaining eight cultivars became arrested at globular and torpedo stages of regeneration indicating that they most likely process an inherent ability to produce plants but require further research to allow this to be realised. Significant numbers of transgenic plants containing transgenes for putative resistance to important viral diseases of cassava in addition to visual marker genes have been regenerated. Transgenic plants from three the cultivars TMS 60444, Bonoua Rouge and M.Col 1505 were recovered after particle bombardment of embryogenic suspension cultures. Correlation's have been made between abnormal leaf morphology and plant vigour with the use of embryogenic suspension cultures for transgene insertion. As an result friable embryogenic callus is now being successfully utilsed as the target tissue for genetic transformation and plant regeneration at ILTAB. This revised version was published online in July 2006 with corrections to the Cover Date.     

农杆菌介导大豆遗传转化研究进展及其应用

农杆菌介导是大豆遗传转化的主要手段。近几年来大豆遗传转化方法得到了快速发展,但是仍然存在受体基因型匮乏、转化效率低,再生系统不完善等问题,为了进一步探讨大豆遗传转化的主要问题和策略,本研究归纳了近年来农杆菌介导大豆遗传转化在受体基因型及外植体选择,菌株筛选,标记基因选用和培养基组成等方面所做的改进,以得出有效的解决方法。并且介绍了农杆菌介导大豆遗传转化在作物改良和功能基因组学上的应用。     

根癌农杆菌介导的苹果遗传转化研究进展

农杆菌介导的遗传转化方法是苹果进行遗传改良的主要方法,本文综述了影响农杆菌转化苹果的各个因素,指出今后的研究重点应放在新的转化方法的提出及进一步提高转化效率的研究上。     

Variability of gene expression in transgenic tobacco

Variability in the expression of the introduced nptII gene was evaluated in transgenic tobacco. Expression analysis was performed on progeny plants of selfed primary transformants. Three different gene constructs were used, containing the nptII gene expressed by either 35S, heat shock protein (hsp80) or the hsp80 promoter including the TMV (Tobacco Mosaic Virus) omega translational enhancer element. Expression of the nptII gene in leaves collected from different developmental phases, varied up to twelve times. The variation in expression of NPTII between independent transformants, all transformed with the same gene construct was found to vary up to nine times. Expression of the nptII gene in the selfed progeny originating from one transformant varied up to four times. The 35S promoter showed a 50-100 fold higher expression of the nptII gene compared to the hsp80 promoter. The omega element enhanced the expression up to two times when compared to the same promoter without the omega element. Transformants containing multiple T-DNA inserts had generally a lower nptII expression compared to plants containing single T-DNA inserts. Implications of such variation in commercialized transgenic crops are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

农杆菌介导陆地棉转化和再生体系的研究进展

陆地棉通过体细胞胚胎发生的农杆菌介导转化体系的主要瓶颈在于:基因型限制、转化周期长、胚胎发生率低、易出现畸形胚等问题.针对这些问题,研究者对传统转化体系的各个环节进行了优化,并在拓展受体基因型、筛选高频再生品(种)系或株系、选择不同的组织或器官做受体和建立新的不依赖于组织培养和基因型限制的农杆菌转化体系等方面进行了探索...     

Degradation of oxalic acid by transgenic oilseed rape plants expressing oxalate oxidase

Summary Oxalic acid is thought to have a primary role in the pathogenicity of several plant pathogens, notably Sclerotinia selerotiorum. A gene coding for the enzyme oxalate oxidase was isolated from barley roots and introduced into oilseed rape as a means of degrading oxalic acid in vivo. This report describes the production of several transgenic plants of oilseed rape and the characterisation of these plants by Southern, Western and enzyme activity assays. Plants were shown to contain an active oxalate oxidase enzyme and were tolerant of exogenously supplied oxalic acid.     

根癌农杆菌介导的番茄高效遗传转化体系的研究

以番茄无菌苗的子叶和下胚轴为外植体,通过农杆菌介导法,对其遗传转化条件进行了优化,建立了高效番茄子叶和下胚轴农杆菌介导的遗传转化体系.结果表明:在农杆菌浸染前(浸染浓度为OD600=0.3)进行2 d的预培养浸染6 min的外植体在MS+2.0 mg/L6-BA+0.5 mg/L IAA的培养基上转化效率最高.PCR检测初步证明,NPTII基因已整合到番茄再生植株中.     

农杆菌介导的地被菊遗传转化体系的优化

本研究以地被菊‘北林黄’无菌苗叶片外植体为受体材料,以卡那霉素抗性基因为选择标记基因,对农杆菌介导的地被菊‘北林黄’的遗传转化体系进行优化。研究结果表明:选取植株中部叶片为转化受体,外植体在经过1d的预培养,用活化的OD600为0.6的农杆菌侵染10min,共培养2d,再经过3d延迟培养后转移到筛选培养基上培养,有利于提高遗传转化效率,外植体的愈伤组织获得数和抗性芽数均最高。在筛选后期,不定芽生根阶段使用的Kanamycin(Kan)选择压力为25mg/L。获得的部分Kan抗性植株经PCR检测,扩增出特异条带,初步证明目的基因已整合到‘北林黄’基因组DNA中。本研究将为进一步利用分子手段对地被菊进行遗传改良,并获得综合抗逆性提高的优异种质奠定基础。     

苹果叶盘法基因转化中抗生素种类和浓度的筛选

以苹果品种嘠拉试管苗为试材，研究了卡那霉素（Km）、潮霉素（Hm）对继代苗生长和离体叶片再生的影响，以确定叶盘法基因转化的选择压和转化体的筛选浓度以确定苹果叶盘法基因转化中的选择压和抗性芽的筛选浓度；同时研究了不同浓度的头孢霉素（Cef）和羧苄青霉素（Carb）对苹果离体叶片再生的影响及对农杆菌EHA105和LBA4404的抑菌效果，以确定苹果叶盘法基因转化中合适的抑菌抗生素种类和浓度；以确定侵菌共培养后合适的抑菌抗生素种类和浓度。。结果证明表明：Km卡那霉素10mg/L、Hm4.0 mg/L完全抑制了叶片不定芽的分化，可作为苹果叶盘法转化时抗性芽的选择压； 在Km 50mg/L、Hm5.0 mg/L达到继代苗的半致死浓度，可作为基因转化后抗性芽苗的筛选浓度，10mg/L时完全抑制供试叶片不定芽的分化。；由于抗性芽再生的选择压与抗性苗筛选浓度相差较小，Hm相对于Km更适合作为苹果基因转化的选择标记；培养基中附加潮霉素的浓度为5mg/l继代苗不再分化生长，作为基因转化后抗性芽的筛选浓度，2.0mg/L时完全抑制供试叶片不定芽的再生，作为基因转化后抗性芽的筛选浓度。头孢青霉素在Cef 300mg/L时就能完全抑制农杆菌生长，对叶片不定芽的再生影响不大；而附加Carb羧苄青霉素则需400mg/L以上时才能抑制农杆菌LBA4404的生长，同时严重抑制了叶片再生。因此，宜选用Cef作为苹果基因转化的抑菌抗生素。     

根癌农杆菌介导番茄‘白果强丰’遗传转化体系优化

以番茄无菌苗的子叶为外植体,通过农杆菌介导法对其遗传转化体系进行了优化,结果表明：外植体在MS+2 mg/L 6-BA+0.2 mg/L IAA的进行2天的预培养后,用农杆菌EHA105（浸染浓度为OD600=0.6）浸染6 min,转化效率最高,经过PCR检测初步证明NPTII基因已整合到番茄再生植株中,本研究建立了高效番茄‘白果强丰’子叶农杆菌介导的遗传转化体系。     

土壤宏基因组中抗草甘膦新基因的克隆与转化水稻的研究

EPSPS (5-烯醇丙酮莽草酸-3-磷酸合酶EC 2.5.1.19)是植物芳香族氨基酸和植物次生代谢产物生物合成中莽草酸途径的关键酶; 同时也是广谱性除草剂草甘膦的作用目标。本实验通过对草甘膦污染土壤宏基因组文库的建立及筛选, 成功克隆了一个新的草甘膦抗性的EPSPS基因(命名为soilEPSPS)。序列分析表明soilEPSPS基因全长1404 bp, 其编码的467个氨基酸中未涉及已公布专利中保护的氨基酸序列。原核功能验证表明该基因对草甘膦的耐受能力优于EPSPS CP4基因。将该基因与水稻Rubisco SSU引导肽相融合构建由actin启动子驱动的植物表达载体, 用农杆菌介导法实现了水稻的遗传转化。抗性再生植株的PCR和Southern杂交结果表明所获得的26株再生植株均为转基因阳性植株, 其中共有3个单拷贝转化事件。草甘膦抗性鉴定证明纯合体T₂代植株能够耐受高达500 mmol L^-1的草甘膦。本研究为转基因抗除草剂水稻新品种的培育奠定了基础。