Herbicide tolerance has been the dominant trait introduced during the global commercialization of genetically modified(GM)crops.Herbicide-tolerant crops,especially glyphosate-resistant crops,offer great advantages for...Herbicide tolerance has been the dominant trait introduced during the global commercialization of genetically modified(GM)crops.Herbicide-tolerant crops,especially glyphosate-resistant crops,offer great advantages for weed management;however,despite these benefits,glyphosate-resistant maize(Zea mays L.)has not yet been commercially deployed in China.To develop a new bio-breeding resource for glyphosate-resistant maize,we introduced a codon-optimized glyphosate N-acetyltransferase gene,gat,and the enolpyruvyl-shikimate-3-phosphate synthase gene,gr79-epsps,into the maize variety B104.We selected a genetically stable high glyphosate resistance(GR)transgenic event,designated GG2,from the transgenic maize population through screening with high doses of glyphosate.A molecular analysis demonstrated that single copy of gat and gr79-epsps were integrated into the maize genome,and these two genes were stably transcribed and translated.Field trials showed that the transgenic event GG2 could tolerate 9000 g acid equivalent(a.e.)glyphosate per ha with no effect on phenotype or yield.A gas chromatography-mass spectrometry(GC–MS)analysis revealed that,shortly after glyphosate application,the glyphosate(PMG)and aminomethylphosphonic acid(AMPA)residues in GG2 leaves decreased by more than 90%compared to their levels in HGK60 transgenic plants,which only harbored the epsps gene.Additionally,PMG and its metabolic residues(AMPA and N-acetyl-PMG)were not detected in the silage or seeds of GG2,even when far more than the recommended agricultural dose of glyphosate was applied.The co-expression of gat and gr79-epsps,therefore,confers GG2 with high GR and a low risk of herbicide residue accumulation,making this germplasm a valuable GR event in herbicide-tolerant maize breeding.展开更多
To label embryonic stem (ES) cells with enhanced green fluorescent protein (EGF P) on the hypoxanthineguanine phosphoribosyl transferase (HPRT) gene locus for t he first time to provide a convenient and efficient way ...To label embryonic stem (ES) cells with enhanced green fluorescent protein (EGF P) on the hypoxanthineguanine phosphoribosyl transferase (HPRT) gene locus for t he first time to provide a convenient and efficient way for cell tracking and ma nipulation in the studies of transplantation and stem cell therapy Methods Homologous fragments were obtained by polymerase chain reaction (PCR), from whic h the gene targeting vector pHPRT EGFP was constructed The linearized vector was introduced into ES cells by electroporation The G418 r6TG r cell clones were obtained after selection with G418 and 6TG media The integration patterns of these resistant cell clones were identified with Southern blotting Results EGFP expressing ES cells on the locus of HPRT were successfu lly generated They have normal properties, such as karyotype, viability and di fferentiation ability The green fluorescence of EGFP expressing cells was main tained in propagation of the ES cells for more than 30 passages and in different iated cells Cultured in suspension, the 'green' ES cells aggregated and forme d embryoid bodies, retaining the green fluorescence at varying developmental sta ges The 'green' embryoid bodies could expand and differentiate into various t ypes of cells, exhibiting ubiquitous green fluorescence Conclusions This generation of 'green' targeted ES cells is described in an efficient proto col for obtaining the homologous fragments by PCR Introducing the marker gene in the genome of ES cells, we should be able to manipulate them in vitro and use them as vehicles in cell replacement therapy as well as for other biomedical a nd research purposes展开更多
基金supported by the National Transgenic Major Program of China(2016ZX08003001),。
文摘Herbicide tolerance has been the dominant trait introduced during the global commercialization of genetically modified(GM)crops.Herbicide-tolerant crops,especially glyphosate-resistant crops,offer great advantages for weed management;however,despite these benefits,glyphosate-resistant maize(Zea mays L.)has not yet been commercially deployed in China.To develop a new bio-breeding resource for glyphosate-resistant maize,we introduced a codon-optimized glyphosate N-acetyltransferase gene,gat,and the enolpyruvyl-shikimate-3-phosphate synthase gene,gr79-epsps,into the maize variety B104.We selected a genetically stable high glyphosate resistance(GR)transgenic event,designated GG2,from the transgenic maize population through screening with high doses of glyphosate.A molecular analysis demonstrated that single copy of gat and gr79-epsps were integrated into the maize genome,and these two genes were stably transcribed and translated.Field trials showed that the transgenic event GG2 could tolerate 9000 g acid equivalent(a.e.)glyphosate per ha with no effect on phenotype or yield.A gas chromatography-mass spectrometry(GC–MS)analysis revealed that,shortly after glyphosate application,the glyphosate(PMG)and aminomethylphosphonic acid(AMPA)residues in GG2 leaves decreased by more than 90%compared to their levels in HGK60 transgenic plants,which only harbored the epsps gene.Additionally,PMG and its metabolic residues(AMPA and N-acetyl-PMG)were not detected in the silage or seeds of GG2,even when far more than the recommended agricultural dose of glyphosate was applied.The co-expression of gat and gr79-epsps,therefore,confers GG2 with high GR and a low risk of herbicide residue accumulation,making this germplasm a valuable GR event in herbicide-tolerant maize breeding.
文摘To label embryonic stem (ES) cells with enhanced green fluorescent protein (EGF P) on the hypoxanthineguanine phosphoribosyl transferase (HPRT) gene locus for t he first time to provide a convenient and efficient way for cell tracking and ma nipulation in the studies of transplantation and stem cell therapy Methods Homologous fragments were obtained by polymerase chain reaction (PCR), from whic h the gene targeting vector pHPRT EGFP was constructed The linearized vector was introduced into ES cells by electroporation The G418 r6TG r cell clones were obtained after selection with G418 and 6TG media The integration patterns of these resistant cell clones were identified with Southern blotting Results EGFP expressing ES cells on the locus of HPRT were successfu lly generated They have normal properties, such as karyotype, viability and di fferentiation ability The green fluorescence of EGFP expressing cells was main tained in propagation of the ES cells for more than 30 passages and in different iated cells Cultured in suspension, the 'green' ES cells aggregated and forme d embryoid bodies, retaining the green fluorescence at varying developmental sta ges The 'green' embryoid bodies could expand and differentiate into various t ypes of cells, exhibiting ubiquitous green fluorescence Conclusions This generation of 'green' targeted ES cells is described in an efficient proto col for obtaining the homologous fragments by PCR Introducing the marker gene in the genome of ES cells, we should be able to manipulate them in vitro and use them as vehicles in cell replacement therapy as well as for other biomedical a nd research purposes
