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1.
The study examined the effect of ploidy elevation through unreduced gametes on transgene expression in potato. Tetraploid transgenic progenies were obtained from one tetraploid potato cultivar crossed with 2n pollen producing diploid clones harbouring an exogenous transgene (cry3Aa). Both single‐ and multiple‐insert diploid transgenic lines that were regenerated by Agrobacterium tumefaciens leaf disc inoculation were used in crosses. A DAS‐ELISA system and no‐choice feeding bioassay enabled characterization of the parental lines as either ‘high’ or low’ expressers of the Cry3Aa protein. High Cry3Aa expression was observed for both single‐insert transgenic diploids and their 4x‐2x progeny. On the contrary, 68% of 4x‐2x progeny derived from a multiple‐insert, diploid transgenic had significantly reduced Cry3Aa expression compared with the parent, with 32% demonstrating nearly complete silencing of the transgene. Multiple copies of a transgene, like homologous native genes, may be susceptible to transgene silencing following polyploidization. Therefore, incorporation of exogenous transgenes into a true potato seed (TPS) production system is feasible if a single‐insert diploid parent is used. Gene‐centromere mapping of the cry3Aa transgene demonstrated that a non‐transgenic refuge might be naturally created in a TPS hybrid system through genetic recombination. 相似文献
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The commercial and economic value of genetically modified crops is determined by a predictable, consistent and stable transmission
and expression of the transgenes in successive generations. No gene inactivation is expected after selfings or crosses with
non-transformed plants of homozygous transgenic oilseed rape plants if the expression of the transgene in homozygous or hemizygous
nature in such plants is stable. The segregation ratios of phosphinothricin (PPT) tolerance in successive generations of selfings
and mutual crosses of a few independent transgenic PPT-tolerant oilseed rape plants indicated a dominant, monogenic inheritance.
In within-variety and between-variety crosses no transgene inactivation was observed. However, after selfings and backcrosses
with non-transgenic oilseed rape infrequent loss of the expression of the PPT tolerance transgene was observed independent
from its homozygous or hemizygous nature. Molecular analysis of PPT-susceptible plants showed that the loss of expression
was due to gene inactivation and not to the absence of the transgene. Methylation and co-suppression are mechanisms that might
cause reduced or even loss of expression of the transgene in later generations. The implications of this observation for seed
multiplication of varieties and breeding activities with transgenic oilseed rape are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Acyl‐acyl carrier protein (ACP) thioesterase (TE) is involved in the biosynthetic fatty acid pathway of plants. Conventional canola lines transformed individually with the bay‐TE (Uc FatB1), elm‐TE (Ua FatB1), nutmeg‐TE (Mf FatB1) or Cuphea‐TE transgene (Ch FatB1), produce seed oil with modified fatty acid compositions. This study assessed the effects of genetic background, cytoplasm, maternal parent, and interaction of different TE transgenes, on the target fatty acids using F1 seeds and double haploid (DH) lines. The F1 seeds were produced by crossing four TE transgenic parental lines and three non‐transgenic cultivars with distinct fatty acid compositions. The DH lines were developed from microspores of F1 plants. DH lines from different crosses showed that genetic background does not have an effect on the relative levels of the target fatty acids of the same TE, indicating the stability of the substrate specificity of the TE within canola. However, significant effects of genetic background on the content of the major target fatty acids, lauric acid (C12:0) or palmitic acid (C16:0) depending on the TE, were observed. Expression of the TE in low erucic acid (C22:1) genotypes resulted in higher target fatty acid levels than expression in high C22:1 genotypes. Reciprocal crosses showed maternal effects, but not cytoplasmic effects. In addition, co‐expression of two different TE transgenes in the same seeds was observed. These results indicate the importance of selection for appropriate genetic backgrounds in order to maximize the expression of the target fatty acids of TE transgenes, and also indicate potential uses of TE co‐expression in modifying canola seed oil. 相似文献
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Summary The use of transgenic plants in breeding makes it possible to utilise a wide variety of novel genes from unrelated plants, microbes and animals. Because of the diversity of genes that have now become available for modifying crop plants, it is agreed internationally that there should be a risk assessment before transgenic plants are grown outside the laboratory or glasshouse. Various aspects are considered in a risk assessment including any non-target effects of the transgene, changes in plant persistence and invasiveness, and the possibility of movement of the transgenes to wild populations by cross pollination. It is generally argued that the need for risk assessment and regulation should be determined by an analysis of certain products of transformation, rather than a risk assessment being required for all plants modified by the process of transformation. A possible consequence of considering the product only, however, could be that some of the products of conventional breeding may need to be assessed by the risk assessment procedures developed for transgenic plants. There are discussions with interest groups on the use of transgenic plants in the environment and in food products. It is likely that some form of labelling will be required for certain foods containing ethically-sensitive genes. There is little doubt that transgenic plants will make a significant contribution to agriculture in the coming decades. Developments in the patenting of genes, release regulations, food labelling, consumer reaction etc., will influence the rate of progress and should be considered in the strategic planning of plant breeding programmes. 相似文献
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Summary The performance of transgenic varieties depends not only upon the stable and correctly-regulated expression of specific transgenes but also upon the agronomic potential of the background genotype. Ideally, transgenes should be introduced into agronomically-superior cultivars and transgenic varieties will become out-classed if their agronomic properties are not continually improved. It will often prove desirable to use conventional breeding techniques, as opposed to new cycles of transformation, to carry out this process of varietal improvement.Continuing advances in marker-assisted selection have made possible the selection and manipulation of an entire genetic background. This means that transgenes can be transferred to new and often untransformable varieties with relative ease. To carry out this process efficiently requires the correct choice of male and female parents, the use of appropriate marker-systems and the concentration of selection on the most appropriate generations.Efficient, phenotypically-neutral marker-systems have revolutionised the identification and manipulation of quantitative trait loci (QTLs). The loci which modify the expression of transgenes are a form of QTL. Desirable alleles at modifier QTLs can be transferred to new varieties along with the transgenes themselves, using marker-assisted breeding.The strategies for maker-assisted selection are becoming ever more sophisticated. A range of complementary marker systems allows the selection of desirable genotypes. In addition, the meiotic reassortment and recombination of chromosomes which produces new genotypes is becoming better understood. The most efficient plant breeding methods and the most powerful genetics will make optimal use of both markers and meiosis. 相似文献
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Consequences of classical and biotechnological resistance breeding for food toxicology and allergenicity 总被引:1,自引:0,他引:1
The first food products derived from transgenic plants that are resistant to diseases, insects or viruses are now reaching the market and there is growing public concern about problems of allergenicity and toxicological changes in such transgenic food plants. We review the modifications being carried out or envisaged in molecular resistance breeding and specifically consider the allergenic and toxicological potential of the gene products used. Several protein families that contribute to the defence mechanisms of food plants have members which are allergens or putative allergens and some of these proteins are used in molecular approaches to increase resistance. These include α-amylase and trypsin inhibitors, lectins and pathogenesis-related proteins. An assessment procedure to avoid the transfer of such allergens is described. The source of the transgene is of great importance for the application of immunological assays. In addition to putative changes in the allergenic potential, the toxicological implications of classical and molecular resistance breeding are discussed. Several ‘self defence’ substances made by plants are highly toxic for mammals, including humans. Examples of molecular approaches that could be of toxicological concern are given. The source of the transgene is of no relevance in assessing the toxicological aspects of foods from transgenic plants. Food safety can also be severely influenced by invading pathogens and their metabolic products. This may result in a trade-off situation between ‘nature's pesticides’ produced by transgenic plants or varieties from traditional breeding programmes, synthetic pesticides and mycotoxins or other poisonous products of pests. 相似文献
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获得转化梨几丁质酶基因Lchi1的烟草,检测组成型表达Lchi1基因烟草是否能提高对梨腐烂病菌(Valsa ceratosperma)的抗性,从而初步确定Lchi1基因的功能,为进一步开展梨抗腐烂病分子育种工作提供参考。构建梨几丁质酶基因Lchi1的植物表达载体,通过农杆菌介导的叶盘法转化烟草,进而对转化的烟草T2代进行PCR及RT-PCR检测。利用离体叶片接种法,更直观地验证转基因烟草对梨腐烂病菌的抗性。Lchi1基因已经整合到烟草基因组中,并在烟草T2代中有效表达,在接种腐烂病菌后转基因烟草较未转基因烟草的抗腐烂病菌能力明显增强。梨几丁质酶基因Lchi1与腐烂病抗性相关联,可作为今后梨的抗腐烂病分子育种研究重要的基因来源。 相似文献
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Agronomic and morphological characterization of Agrobacterium-transformed Bt rice plants 总被引:2,自引:0,他引:2
Qing-yao Shu Hai-rui Cui Gong-yin Ye Dian-xing Wu Ying-wu Xia Ming-wei Gao Illimar Altosaar 《Euphytica》2002,127(3):345-352
The agronomic and morphological characteristics of Agrobacterium-transformed rice plants carrying the synthetic cry1Ab or cry1Ac gene were investigated. Tremendous variations in plant height, seed fertility, grain size and other traits were seen in 80
T1 lines, derived from 80 T0 plants of 9 rice varieties. On average, about 33% T1 lines had either morphological or agronomic variant plants. Most of the variations in T1 plants had no significant correlation with transgene insertion and were proved heritable to their progenies. Genetic analysis
in T3 or T4 generations showed some simple mutations such as chlorophyll deficiency and stunted plants were independent of transgene
insertion and seemed to be controlled by a pair of single genes. However, in two independent transgenic progenies of Xiushui
11, all plants homozygous for transgenes showed dwarfism while all hemizygous and null segregants had normal plant heights.
Two advanced homozygous Bt lines, KMD1 and KMD2, were developed from these two progenies. Comparison of the agronomic traits
of KMD1 and KMD2 with their parent displayed marked differences among them in terms of seedling growth, tillering ability,
yield components and yield potential. The genetic variation observed was generally not linked to the transgene locus and was
ascribed to somaclonal variation, but other causes might also exist in particular cases. The results are discussed in the
context of choosing appropriate transformation methodology for rice breeding programs.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Brassica napus is one of the crops at the forefront of biotechnological development. The procedures used to produce transgenic varieties
are all prone to generating plants with multiple transgene copies. There has been considereable interest in the behaviour
of such multi-copy lines because gene dosage rarely appears to correlate simply with gene expression. Here we report the analysis
of a population of 107 progeny from a B. napus transformant containing multiple copies of a GUS marker gene construct. A total of 12 GUS sequence copies were identified
including one that was non-functional. The expression of GUS increased with increasing copy number but this increase only
made up a small proportion of the total variation between lines. There was no evidence of interaction between the various
GUS copies and they appeared to segregate independently. The variation between progeny lines indicated that the number of
gene copies was not a good guide to the expression of the gene product and hence that the expression of the gene in progeny
from a multiple-copy parent could not be predicted. The importance of these findings in relation to plant breeding and the
risk assessment process is discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Hervé Vaucheret Jean-Christophe Palauqui Philippe Mourrain Taline Elmayan 《Euphytica》1997,93(2):195-200
Nitrate assimilation is a fundamental function in any plant including those that can fix atmospheric nitrogen in symbiosis with soil bacteria. In recent years, attempts have been made to understand the biological significance of the complex regulation of this pathway using genetic engineering techniques. Transgenic plants that either over- or under-express genes of the nitrate assimilation pathway were created in order to determine whether such directed changes affect the regulation of the metabolism. Apart from interesting physiological results, unexpected gene silencing phenomena have been observed resulting from the introduction of five different transgenes derived from either the tobacco Nia or Nii genes encoding nitrate reductase and nitrite reductase, respectively. In this review, each of these five silencing phenomena is described, with the emphasis on the advantages provided by the use of both Nia and Nii genes to analyze the molecular and genetic basis of gene silencing in transgenic plants. 相似文献
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脱水素基因转化的矮牵牛对干旱胁迫的反应 总被引:11,自引:0,他引:11
将厚叶旋蒴苣苔脱水素(Dehydrin)基因BDN1置于CaMV35S启动子的调控之下,并插入于表达载体pCAMBIA3300中,通过根癌土壤杆菌(Agrobacterium tumefaciens)介导导入矮牵牛(Vetunia Hybrida),经PCR及Southem杂交表明BDN1已转入矮牵牛基因组中,Northem实验证明,BDN1基因在矮牵牛中在RNA水平有较强的表达。通过对转BDN1基因矮牵牛的保水力和低温离子渗漏的测定,初步验证转基因矮牵牛对水分胁迫的能力在一定程度上有所增加。 相似文献
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本研究旨在使用试纸条检测方法在玉米苗期从常规玉米育种材料中发现转基因植株,以预防非预期的转基因漂移。以转基因和非转基因玉米为材料,以笔者过去开展转基因玉米材料筛选的经验总结为基础,开发出试纸条快速检测方法。本研究介绍了检测所需用品和取样方法,并且详细讨论了样品数量、操作步骤及注意事项等。还具体演示分析了2个典型检测案例的过程和结果。本方法的操作步骤简便易学,适合专业和非专业育种者或检测人员对田间材料在自查或检验中使用。熟练掌握试纸条快速检测法,能有效筛查和预防由于花粉或种子非预期混杂造成的转基因漂移。 相似文献
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Jonathan Mkumbira Linley Chiwona-Karltun Ulf Lagercrantz Nzola Meso Mahungu John Saka Albert Mhone Mpoko Bokanga Leon Brimer Urban Gullberg Hans Rosling 《Euphytica》2003,132(1):7-22
Cassava roots, a major food in Africa, contain cyanogenic glucosides that may cause toxic effects. Malawian women farmers
considered fields of seemingly similar cassava plants to be mixes of both ‘cool’ and ‘bitter’ cultivars. They regard roots
from ‘cool’ cultivars as non-toxic. Roots of ‘bitter’ were considered to require extensive traditional processing done by
women to be safe for consumption. But curiously, these women farmers preferred ‘bitter’ cultivars since toxicity confers protection
against theft, which was a serious threat to the food security of their families. We studied how well these farmers comprehend
the effects of genetic variations in cassava when dealing with cyanogenesis in this complex system. Using molecular markers
we show that most plants farmers identified as belonging to a particular named cultivar had a genotype typical of that cultivar.
Farmers' ethno-classification into ‘cool’ and ‘bitter’ cultivars corresponded to a genetic sub-division of the typical genotypes
of the most common cultivars, with four-fold higher cyanogenic glucoside levels in the bitter cultivars. Examining morphology,
farmers distinguished genotypes better than did the investigators when using a standard botanical key. Undoubtedly, these
women farmers grasp sufficiently the genetic diversity of cassava with regard to cyanogenesis to simultaneously benefit from
it and avoid its dangers. Consequently, acyanogenic cassava – the breeding of which is an announced good of some cassava genetic
improvement programmes – is not a priority to these farmers. Advances in molecular genetics can help improve food supply in
Africa by rapid micropropagation, marker assisted breeding and introduction of transgenic varieties, but can also help to
elucidate tropical small-scale farmers' needs and skills.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Inheritance and expression of transgenes in T2 and T3 generations of Lotus corniculatus transformed using Agrobacterium tumefaciens 总被引:2,自引:0,他引:2
K. Judith Webb Mervyn O. Humphreys Leif Skøt Margaret Gibbs John Gatehouse 《Euphytica》1999,108(3):169-179
The inheritance and expression of the reporter gene uidA, encoding β-glucuronidase (GUS), was previously analysed in the T1 generation of 25 independent transformed lines of Lotus corniculatus cv. Leo. In the work reported here, GUS activity in various tissues of seven of these lines was tested in the T2 generation. Four representative lines were chosen for more detailed study in the T3 generation. Lines 25 and 38 had multiple, independently segregating transgene inserts; lines 24 and 39 appeared to transmit one segregating transgene insert to their T1 progeny, although transgene expression was low and was detected in fewer seedlings than expected in line 39. The uidA gene was inherited and expressed in seedlings of T1, T2 and T3 generations of all four lines. In all lines, transgene expression varied between tissues, with more embryos than seedlings
having detectable GUS activity. Studies in the T2 generation showed that use of transgenic plants as female or male parents altered the frequency of expression of the transgene
in progeny. By contrast, in the T3 generation the use of transgenic plants as female or male parents did not effect either frequency of transmission, or expression
of the transgene, in any of the four lines. Transgene inheritance was also similar among individual pods within flower heads
and between individual flower heads.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Biotechnology approaches to overcome biotic and abiotic stress constraints in legumes 总被引:1,自引:0,他引:1
Miguel A. Dita Nicolas Rispail Elena Prats Diego Rubiales Karam B. Singh 《Euphytica》2006,147(1-2):1-24
Summary Biotic and abiotic stresses cause significant yield losses in legumes and can significantly affect their productivity. Biotechnology
tools such as marker-assisted breeding, tissue culture, in vitro mutagenesis and genetic transformation can contribute to solve or reduce some of these constraints. However, only limited
success has been achieved so far. The emergence of “omic” technologies and the establishment of model legume plants such as
Medicago truncatula and Lotus japonicus are promising strategies for understanding the molecular genetic basis of stress resistance, which is an important bottleneck
for molecular breeding. Understanding the mechanisms that regulate the expression of stress-related genes is a fundamental
issue in plant biology and will be necessary for the genetic improvement of legumes. In this review, we describe the current
status of biotechnology approaches in relation to biotic and abiotic stresses in legumes and how these useful tools could
be used to improve resistance to important constraints affecting legume crops. 相似文献