Improved drought tolerance of transgenic Zea mays plants that express the glutamate dehydrogenase gene (gdhA) of E. coli

Genetic modification of nitrogen metabolism via bacterial NADPH- dependent glutamate dehydrogenase (GDH; E.C.4.1.2.1) favorably alters growth and metabolism of C3 plants. The aim of this study was to examine the effect of expression of GDH in the cytoplasmic compartment of Zea mays cells. The gdhA gene from Escherichia coli , that encoded a NADPH-GDH, was ligated to the ubiquitin promoter that incorporated the first intron enhancer and used to transform Z. mays cv. ‘H99’ embryo cultures by biolistics. R0–R3 generations included selfed inbreds, back-crossed inbreds, and hybrids with B73 derivatives. The lines with the highest GDH specific activity produced infertile R0 plants. The highest specific activity of GDH from the fertile Z. mays plants was sufficient to alter phenotypes. Plant damage caused by the phosphinothricin in gluphosinate-type herbicides, glutamine synthetase (GS; EC 6.1.3.2) inhibitors, was less pronounced in Z. mays plants with gdhA pat than in gusA pat plants. Germination and grain biomass production were increased in gdhA transgenic plants in the field during seasons with significant water deficits but not over all locations. Water deficit tolerance under controlled conditions was increased. Crops modified with gdhA may have value in semi-arid locations.     

Degradation of [14C]phosphinothricin (glufosinate) in soil under laboratory conditions: Effects of concentration and soil amendments on 14CO2 production

Summary Degradation of the herbicide phosphinothricin (L-homoalanine-4-yl-(methyl)-phosphinic acid) in a phaeozem was investigated by monitoring the ¹⁴CO₂ release from [1-¹⁴C] and [3,4-¹⁴C]phosphinothricin. The degradation was largely due to microbial activity, since the rate decreased by more than 95% when the soil was sterilized by -radiation. Data obtained with both labels suggested that decarboxylation of phosphinothricin preceded oxidation of its C-atoms 3 and 4, since a metabolite, probably 3-methylphosphinico-propanoic acid, was only labelled when [3,4-¹⁴C]phosphinothricin was used as the substrate. Maximum rates of ¹⁴CO₂ production from both the 1- and 3,4-label positions occurred without a lag phase during the breakdown of phosphinothricin as monitored for a total of 30 days at 5-day intervals. This result indicated that a phosphinothricin-degrading microbial community was already present in the soil. With low concentrations of [1-¹⁴C]phosphinothricin (10.7 mg kg^-1 soil), complete decarboxylation at 25°C was observed within 30 days of incubation, compared to 15.9% ¹⁴CO₂ release from [3,4-¹⁴C]phosphinothricin. Increasing the quantity of the herbicide in the soil (10.7–1372 mg kg^-1) resulted in increased degradation rates, irrespective of whether the herbicide was labelled in the positions 1 or 3 and 4. Addition of glucose and other carbohydrates stimulated ¹⁴CO₂ release while addition of a yeast extract had a negative effect. Glucose stimulation was reversed by ammonium nitrate, suggesting that the microorganisms were using the herbicide as a source of N.     

拟南芥转化体筛选中Basta喷洒时期和浓度试验

为了更加方便有效地利用Basta来筛选带草铵磷(PPT)抗性Bar基因的转基因拟南芥,对不同时期喷洒不同浓度Basta的效果进行了研究。结果表明:拟南芥转化体刚长出2片真叶时对Basta比较敏感,此时开始喷施效果比较好;PPT含量为13.5%的情况下,稀释2 000～4 000倍喷施效果好,此时既可有效筛选出阳性苗,又不会抑制阳性苗的生长;第一次喷施后6天左右移栽阳性苗较好,此时可以明显区分出阳性苗,且移栽后缓苗快、长势好。     

转基因抗草丁膦油菜籽中B arnase基因 的实时荧光定量PCR检测

利用荧光定量PCR技术,对进口抗草丁膦油菜籽中的B arnase基因进行了定量检测,分别建立了抗草丁 膦油菜籽参照样品外源B arnase基因和内标准HMG基因Ct值与模板量之间的标准曲线和线性回归方程,运用所 建立起来的方法对14批油菜籽样品进行了定量分析。 转基因油菜籽; 草丁膦; B arnase基因; HMG基因; 定量PCR