植物基因分离方法

植物基因分离一直是当今生物技术研究的热点。分离作物重要农艺性状的功能基因利于对基因的结构和表达进行研究,并可以经转基因技术进行分子育种。根据中心法则,介绍了从DNA、RNA到蛋白质的三个层次进行植物基因分离的方法。     

利用类萜代谢工程改良作物风味

类萜是从植物中分离出的一类类异戊二烯物质。其中挥发性萜类除了在吸引授粉媒、异株克生和植物防御中起到一定的生态作用外,还影响到水果、蔬菜和其他作物的香味形成。对类萜生物合成及其代谢工程的最新研究进展进行了综述,探讨了代谢过程中的关键酶基因,尤其是类萜合成酶(TPSs)基因的表达特性以及操纵类萜生物合成途径提高产量的几种可能的策略。随着更多相关基因的分离,利用代谢工程人工改良作物风味将指日可待。     

十字花科多肽激素类基因RALF的同源基因克隆及进化分析

多肽激素类基因是对植物生长发育起重要作用的一类基因,RALF是其中的重要一员,而十字花科在中国蔬菜作物中是重要的一大类群。为了摸清十字花科多种蔬菜作物的RALF同源基因信息,该文根据前期研究从油菜中扩增到的多肽激素类基因RALFbn的序列设计引物,从提取的十字花科芸薹属、萝卜属、蔊菜属、山芥属的7份重要蔬菜作物的基因组DNA中分别克隆到了RALF的同源序列。结果表明:7种蔬菜作物的RALF同源基因编码区均在300 bp左右,且无内含子,编码的蛋白质由79个氨基酸组成,说明RALF在十字花科4个属内的保守性较强;对RALF同源基因在十字花科4个属中的表达分析表明,该类基因在根、茎、叶、花序轴等营养器官中不表达或弱表达,但主要在生殖器官中表达,其中在总花蕾和开放花中的表达量普遍高于嫩角果中的表达量,表明该类基因在十字花科中的生理活跃期是花发育时期。同时,构建了十字花科4个属中RALF同源基因的系统树,芸薹属的油菜、甘蓝和芥蓝形成一个分支,而茎瘤芥和分蘖芥形成另外一个分支,且与萝卜属、山芥属、蔊菜属的材料聚在一支,该基因的进化途径在一定程度上也反映出这几种作物的遗传背景关系。该研究结果丰富了RALF家族信息,增添了十字花科植物的分子进化数据。     

图位克隆技术在农作物基因分离中的应用与评价

图位克隆(Map-based cloning)作为分离基因的有效方法, 已在小基因组作物的基因分离中得到了广泛应用和发展, 而在具有大量重复DNA序列的大基因组作物中的应用仍存在挑战。基于图位克隆在基因分离中的重要性, 文章就图位克隆技术的基本内容及发展做简要概述, 着重对图位克隆技术在大基因组作物中的应用进行分析和评价, 同时对它今后可能的发展方向进行了讨论, 以期为大基因组作物基因的分离提供借鉴。     

十字花科蔬菜抽薹开花性状的调控机理和分子育种研究进展

十字花科植物抽薹开花是植株由营养生长向生殖生长转变的关键时期,其相关性状涉及作物繁殖和产品器官形成,它们大都是由多基因控制的数量性状,并受到环境信号和内源因素多路径的调控。本文从十字花科蔬菜作物抽薹开花性状的分子标记和分子调控机理两方面进行综述,并就研究中存在的问题和发展方向进行了探讨,以期为全面阐明十字花科蔬菜抽薹开花机制提供综合信息和新线索,为蔬菜作物抽薹开花遗传改良和高产优质栽培提供理论依据。     

争议不断的转基因作物

今天,转基因作物正在逐渐而广泛地进入我们的生活。转基因作物的含义是,将人工分离（克隆）和修饰过的基因（外源性基因）导入到作物的基因组中,使导入的基因得到表达,引起作物的性状产生可遗传的修饰。     

图谱克隆寻找抗病基因

利用一种新技术鉴定到番茄抗病基因。该技术能提高作物产量、增强抗病性及果实香味。 美国康乃尔大学Steven Tanksley博士及同事发现了一种能使番茄抗细菌烂斑病(杀伤作物,降低作物产量的病害)的基因。研究结果发表在“科学”杂志。利用这种图谱克隆新技术分离主要作物抗病基     

争议不断的转基因作物

<正>今天,转基因作物正在逐渐而广泛地进入我们的生活。转基因作物的含义是,将人工分离(克隆)和修饰过的基因(外源性基因)导入到作物的基因组中,使导入的基因得到表达,引起作物的性状产生可遗传的修饰。     

细胞生物学杂志2004年第26卷总目录

何祖平 郑永波 叶晓峰 刘钟滨 成国祥 梁越欣 兵野静 张钱齐 函 胚胎肝干细胞的研究进展 肠上皮干细胞研究进展 类泛素蛋白—SUMO 幽门螺杆菌基因组特征及研究进展 ZN一4N嵌合体小鼠及其在基因功能研究上的应用 有丝分裂细胞死亡 线粒体膜间隙蛋白在细胞凋亡中的作用 植物。一3脂肪酸去饱和酶的研究进展 类黄酮化合物在植物胁迫反应中作用的研究进展 蔬菜作物重要农艺性状相关基因分离的研究进展 体细胞杂交技术在蔬菜育种中的研究与应用 称猴桃的组织培养和遗传转化研究进展 实时定量PCR技术及其应用 端粒酶活性检测的几种方法 磷脂酶c…     

豇豆原生质体遗传转化的研究(简报)

豆科植物中有重要的粮食,油料及蔬菜作物,一直是国内外学者热衷研究的对象。豆科作物遗传转化的研究,虽已取得一些进展,但有关籽粒型豆科重要作物细胞转化的报道仍不多。我们以豇豆下胚轴为材料,探讨了农杆菌介导的和PEG介导的外源DNA转移到豇豆细胞的条件,并获得外源基因稳定表达的转化愈伤组织。豇豆原生质体分离与培养:豇豆种子用0.1%HgCl_2灭菌20min,无菌水冲洗数次后,置1/2MS_0培养基上萌发3—4天(25℃),在超净工作台上切取子叶。参照我们以前所采用的方法分离和培养豇豆原生质体(MS培养基)。     

Molecular strategies for gene containment in transgenic crops

The potential of genetically modified (GM) crops to transfer foreign genes through pollen to related plant species has been cited as an environmental concern. Until more is known concerning the environmental impact of novel genes on indigenous crops and weeds, practical and regulatory considerations will likely require the adoption of gene-containment approaches for future generations of GM crops. Most molecular approaches with potential for controlling gene flow among crops and weeds have thus far focused on maternal inheritance, male sterility, and seed sterility. Several other containment strategies may also prove useful in restricting gene flow, including apomixis (vegetative propagation and asexual seed formation), cleistogamy (self-fertilization without opening of the flower), genome incompatibility, chemical induction/deletion of transgenes, fruit-specific excision of transgenes, and transgenic mitigation (transgenes that compromise fitness in the hybrid). As yet, however, no strategy has proved broadly applicable to all crop species, and a combination of approaches may prove most effective for engineering the next generation of GM crops.     

Transgenes sustain epigeal insect biodiversity in diversified vegetable farm systems

Many ecological studies have focused on the effects of transgenes in field crops, but few have considered multiple transgenes in diversified vegetable systems. We compared the epigeal, or soil surface-dwelling, communities of Coleoptera and Formicidae between transgenic and isoline vegetable systems consisting of sweet corn, potato, and acorn squash, with transgenic cultivars expressing Cry1(A)b, Cry3, or viral coat proteins. Vegetables were grown in replicated split plots over 2 yr with integrated pest management (IPM) standards defining insecticide use patterns. More than 77.6% of 11,925 insects from 1,512 pitfall traps were identified to species, and activity density was used to compare dominance distribution, species richness, and community composition. Measures of epigeal biodiversity were always equal in transgenic vegetables, which required fewer insecticide applications than their near isolines. There were no differences in species richness between transgenic and isoline treatments at the farm system and individual crop level. Dominance distributions were also similar between transgenic and isoline farming systems. Crop type, and not genotype, had a significant influence on Carabidae and Staphylinidae community composition in the first year, but there were no treatment effects in the second year, possibly because of homogenizing effects of crop rotations. Communities were more influenced by crop type, and possibly crop rotation, than by genotype. The heterogeneity of crops and rotations in diversified vegetable farms seems to aid in preserving epigeal biodiversity, which may be supplemented by reductions in insecticide use associated with transgenic cultivars.     

REVIEW ARTICLE: Transgenic plants and the environment

With a continued increase in the range of transgenes, and plantspecies for which genetic modification is possible, this reviewattempts to bring together some of the factors that will influencethe eventual fate of transgenes in the environment, and theeffects that such a dispersal may have. The review is developedfrom papers presented at the SEB Swansea meeting (April, 1994). Using experiments with GM (genetically modified) plants, andmarkers in non-GM plants, as well as observations on naturaland crop populations, it is possible to predict isolation distancesrequired for limiting the unintentional release from GM crops,and the probable fate of both GM pollen and seed if it is releasedbeyond the GM plot. Knowledge of wild relatives of crop plants,and ecological mechanisms can also give insights into the possibleeffects of different transgenes on native plants, and otheragricultural crops. A large number of limited scale releasesof GM plants have now taken place from which we can gain informationon the performance of GM crops in an agricultural environment,and the stability of the GM phenotype. All this information,can help to form a sound basis for regulations on the releaseof GM plants, an assessment of the need for, and scope of monitoring,and the best way in which to use GM crops. Key words: Transgenic releases, genetically-modified plants, molecular ecology, transgene stability     

The impact of hybrids between genetically modified crop plants and their related species: biological models and theoretical perspectives

Forces affecting the rate of spread and increase of hybrids between genetically modified crop plants and their related species remain qualitatively similar, irrespective of whether genetic modification was achieved using traditional methods, those of biotechnology or as a result of the natural evolutionary process. However, the precise magnitude of the forces and, consequently, the likely environmental impact of such hybrids, may depend strongly on the nature of the gene or genes introduced into the native species. While many classes of transgenes are similar to those manipulated by conventional breeding techniques or evolution, biotechnology offers the potential to introduce genes into crops which are novel both from the point of view of function and origin. The qualitative similarity between transgenes and the products of conventional or evolutionary modification suggests that a historical view of the environmental impact of hybrids between traditionally produced crops or exotic species and their relatives would be of use in estimating the probable fate of hybrids containing transgenes in the environment. However, with certain classes of transgenes for which there are no existing analogues, there will need to be greater care in assessing the possible risks associated with release into the environment.     

Aphid resistance in Brassica crops: challenges, biotechnological progress and emerging possibilities

Aphids, (Hemiptera: Aphidoidea) a nefarious insect pest of Brassicaceae members including major vegetable and oilseed crops have coevolved with their host plant and emerged as most economically important insect pest of crop Brassicas. Their atypical feeding mechanism and unusual reproductive biology made them intractable to control below economic threshold level of damage to the crops. To a large extent aphid infestation is controlled by spraying agrochemicals of systemic mode of action and rarely by biological control. Use of systemic insecticides is highly cost intensive as well poses bigger threat of their incorporation in dietary chain. Breeding for genetic resistance against aphids has not been possible owing to the non-availability of resistance source within the crossable germplasms and lack of knowledge of the genetics of the trait. Genetic engineering with insect resistant transgenes seems to be the only potential avenue to address this difficult-to-accomplish breeding objective. Some success had been achieved in terms of developing aphid resistant cultivars through genetic engineering however, commercial utilization of such crops are still awaited. Thus protection of crops against aphids necessarily requires more research to identify either more effective insecticidal transgenes or biological phenomenon that can usher to new mechanism of resistance. The present review is an attempt to highlight the current status and possible avenues to develop aphid resistance in Brassicaceae crops.     

Examining the behavior of crop-derived antibiotic resistance genes in anaerobic sludge batch reactors under thermophilic conditions

The consumption of transgenic crops and their by-products has become increasingly common in the United States. Yet, uncertainty remains regarding the fate and behavior of DNA within food matrices once it exits the digestive track and enters into wastewater treatment plants (WWTPs). Because many transgenic crops have historically contained antibiotic resistance genes as selection markers, understanding the behavior and uptake of these transgenes by environmental microbes is of critical importance. To investigate the behavior of free transgenic crop DNA, thermophilic anaerobic batch reactors were amended with varying concentrations of transgenic crop genes (i.e., LUG, nptII, and bla) and the persistence of those genes was monitored over 60 days using quantitative PCR. Significant levels of nptII and bla were detected in extracellular DNA (eDNA). Furthermore, LUG maize marker genes were also detected in the control reactors, suggesting that other crop-derived transgenes contained within digested transgenic foods may also enter WWTPs. Possible bacterial transformation events were detected within the highest dose treatments at Days 30 and 60 of incubation. These findings suggest that within the average conventional digester residence times in the United States (30 days), there is a potential for bacterial transformation events to occur with crop-derived transgenes found in eDNA.     

Excision of selectable marker genes from transgenic plants

Selectable marker genes are required to ensure the efficient genetic modification of crops. Economic incentives and safety concerns have prompted the development of several strategies (site-specific recombination, homologous recombination, transposition, and co-transformation) to eliminate these genes from the genome after they have fulfilled their purpose. Recently, chemically inducible site-specific recombinase systems have emerged as valuable tools for efficiently regulating the excision of transgenes when their expression is no longer required. The implementation of these strategies in crops and their further improvement will help to expedite widespread public acceptance of agricultural biotechnology     

Transgene-induced lesion mimic

Lesion mimic, i.e., the spontaneous formation of lesions resembling hypersensitive response (HR) lesions in the absence of a pathogen, is a dramatic phenotype occasionally found to accompany the expression of different, mostly unrelated, transgenes in plants. Recent studies indicated that transgene-induced lesion formation is not a simple case of necrosis, i.e., direct killing of cells by the transgene product, but results from the activation of a programmed cell death (PCD) pathway. Moreover, activation of HR-like cell death by transgene expression is viewed as an important evidence for the existence of a PCD pathway in plants. The study of lesion mimic transgenes is important to our understanding of PCD and the signals that control it in plants. PCD-inducing transgenes may provide clues regarding the different entry points into the cell death pathway, the relationships between the different branches of the pathway (e.g., developmental or environmental), or the different mechanisms involved in its induction or execution. Cell death-inducing transgenes may also be useful in biotechnology. Some lesion mimic transgenes were found to be induced in plants a state of systemic acquired resistance (SAR). These genes can be used in the development of pathogen-resistant crops. Other cell death-inducing transgenes may be used as specific cell ablation tools. Although mainly revealed unintentionally, and at times considered `an adverse phenotype', lesion mimic transgenes should not be ignored because they may prove valuable for studying PCD as well as developing useful traits in different plants and crops.