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Longbiao Guo ;Lilian Ma ;Hua Jiang ;Dali Zeng ;Jiang Hu ;Liwen Wu ;Zhenyu Gao ;Guangheng Zhang ;Qian Qian 《Acta Botanica Sinica》2009,(1):45-51
To identify genetic loci controlling grain weight, an elite indica rice variety, Baodali, with large grains was identified and used in this study. Its derived F2, F3 and BC2 F2 with another japonica rice variety Zhonghua 11 were used as mapping populations. Linkage analyses demonstrated that two genes controlling grain weight, designated as GW3 and GW6, were mapped to chromosome 3 and chromosome 6, respectively. Fine mapping delimited GW3 to a 122 kb physical distance between two sequence tagged site markers (WGWt6 and WGW19) containing 16 open reading frames annotated by The Institute for Genomic Research (http://www.tigr.org). GW6 was further mapped between two simple sequence repeat markers (RM7179 and RM3187). These results are useful for both marker assisted selection of grain weight, and for further cloning of GW genes, which will contribute to the dissection of the molecular mechanism underlying grain weight in rice. 相似文献
953.
L. Scaramelli A. Balestrazzi M. Bonadei E. Piano D. Carbonera M. Confalonieri 《Plant cell reports》2009,28(2):197-211
Expression of the uidA reporter gene was tested in transformation experiments of barrel medic (Medicago truncatula Gaertn.) with the ipt-type control vectors pIPT5, pIPT10 and pIPT20 and distinct in vitro culture conditions. The highest GUS expression levels
were obtained with the pIPT10 construct carrying the ipt gene under the control of the native ipt promoter and using kanamycin as selective agent. The ipt-shooty transformants, characterized by the absence of both rooting ability and apical dominance associated with vitrification,
were easily identified by visual selection. Using only the ipt gene as selectable marker, we obtained a stable transformation frequency of 9.8% with pIPT10 construct. The ipt-type MAT vector pEXM2 was then used to monitor the excision events mediated by the yeast Recombinase and the consequent production
of ipt marker-free transgenic plants. Transgenic ipt-shooty lines were recovered at a frequency of 7.9% in the absence of kanamycin-based selection. The ipt-shooty phenotype was maintained in all the transgenic lines and no reversion to the normal phenotype occurred. PCR analysis
revealed the presence of the ‘hit and run’ cassette in the genome of all the regenerated ipt-shooty lines while RT-PCR experiments confirmed the expression of the R gene, encoding the yeast Recombinase. A detailed molecular investigation, carried out to verify the integrity of the RS sites,
revealed that these regions were intact in most cases. Our results with barrel medic suggest that the MAT system must be carefully
evaluated and discussed on a case by case basis.
L. Scaramelli, A. Balestrazzi and M. Confalonieri have contributed equally to this work. 相似文献
954.
Evaluation of a morphological marker selection and excision system to generate marker-free transgenic cassava plants 总被引:1,自引:0,他引:1
Laddawan Saelim Salak Phansiri Malinee Suksangpanomrung Supatcharee Netrphan Jarunya Narangajavana 《Plant cell reports》2009,28(3):445-455
The efficacy of the ipt-type Multi-Auto-Transformation (MAT) vector system to transform the extensively grown cassava cultivar “KU50” was evaluated.
This system utilizes the isopentenyltransferase (ipt) gene as morphological marker for visual selection of transgenic lines. The extreme shooty phenotype (ESP) of transgenic
lines is lost due to the removal of ipt gene mediated by the yeast Rint/RS system. As a result, phenotypically normal shoots, considered marker-free transgenic plants,
could be obtained. When transforming KU50 cassava cultivar with two different ipt-type MAT vectors, transformation frequency at 19–21% was observed. Among the total number of ESP explants, 32–38% regained
normal extended shoot phenotype and 88–96% of which were confirmed to represent the marker-free transgenic plants. This is
the first demonstration of the efficacy of Rint/RS system in promoting excision of ipt marker gene in cassava specie, with the consequent rapid production of marker-free transgenic plants. The high efficiency
of this system should facilitate pyramiding a number of transgenes by repeated transformation without having to undergo through
laborious, expensive and time-consuming processes of sexual crossing and seed production. The generation of marker-free, thus
environmentally safe, genetically modified cassava clones should also ease the public concerns regarding the use of transgenic
cassava in both food and nonfood industries. 相似文献
955.
Molecular genetic studies on the model plant Arabidopsis thaliana often involve multiple rounds of Agrobacterium-mediated transformation. Such procedures require multiple marker genes that would allow for efficient selection of transgenic
plants in each cycle of transformation. Here, we report on a selection marker cassette based on a codon-modified glyphosate
N-acetyltransferase (GAT) gene whose expression is driven by a powerful EL2Ω promoter. After introduction of the GAT expression cassette into A. thaliana via Agrobacterium-mediated transformation, glyphosate-resistant primary transformants are efficiently selected by glyphosate, either added to
the culture medium or by spraying a glyphosate solution onto seedlings grown in soil. Robust glyphosate-resistant phenotypes
are always associated with the presence of the GAT cassette. In addition, RT-PCR analysis of T2 transformants has demonstrated that resistance to glyphosate is associated with higher levels of GAT expression. Resistance conferred by GAT is specific to glyphosate and not to other commonly used selection chemical compounds. These results demonstrate the versatility
of the GAT cassette suitable for both large-scale, soil-based selection system of transgenic plants as well as their characterization
in vitro. 相似文献
956.
Laurent Lehmann Marcus W. Feldman François Rousset 《Evolution; international journal of organic evolution》2009,63(11):2896-2913
Natural selection may favor two very different types of social behaviors that have costs in vital rates (fecundity and/or survival) to the actor: helping behaviors, which increase the vital rates of recipients, and harming behaviors, which reduce the vital rates of recipients. Although social evolutionary theory has mainly dealt with helping behaviors, competition for limited resources creates ecological conditions in which an actor may benefit from expressing behaviors that reduce the vital rates of neighbors. This may occur if the reduction in vital rates decreases the intensity of competition experienced by the actor or that experienced by its offspring. Here, we explore the joint evolution of neutral recognition markers and marker-based costly conditional harming whereby actors express harming, conditional on actor and recipient bearing different conspicuous markers. We do so for two complementary demographic scenarios: finite panmictic and infinite structured populations. We find that marker-based conditional harming can evolve under a large range of recombination rates and group sizes under both finite panmictic and infinite structured populations. A direct comparison with results for the evolution of marker-based conditional helping reveals that, if everything else is equal, marker-based conditional harming is often more likely to evolve than marker-based conditional helping. 相似文献
957.
Summary Evaluation of HIV vaccine candidates in nonhuman primates (NHPs) is a critical step toward developing a successful vaccine to control the HIV pandemic. Historically, HIV vaccine regimens have been tested in NHPs by administering a single high dose of the challenge virus. More recently, evaluation of candidate HIV vaccines has entailed repeated low‐dose challenges, which more closely mimic typical exposure in natural transmission settings. In this article, we consider evaluation of the type and magnitude of vaccine efficacy from such experiments. Based on the principal stratification framework, we also address evaluation of potential immunological surrogate endpoints for infection. 相似文献
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