Recovery and evaluation of soybean plants transgenic for aBacillus thuringiensis var.Kurstaki insecticidal gene

Summary Lepidopteran insects are major defoliating pests of soybean in the southeastern United States. Soybean plants transgenic for a nativecryIA(b) gene fromBacillus thuringiensis var.kurstaki HD-1 were obtained. Embryogenic cultures were induced by plating cotyledons on a Murashige and Skoog-based medium supplemented with 40 mg/liter of 2,4-dichlorophenoxyacetic acid (2,4-D). The embryogenic cultures were maintained in liquid medium containing 5 mg/liter 2,4-D. These cultures were subjected to microprojectile bombardment, followed by selection on 50 mg/liter hygromycin. Resistant embryogenic cell lines were transferred to growth regulator-free medium to permit recovery of mature somatic embryos. After a desiccation period, the somatic embryos were returned to growth regulator-free medium for conversion into plants. Southern hybridization analysis verified transformation. Feeding assays of T₁ plants from one cell line deterred feeding, development, and survival of velvetbean caterpillar at a level comparable to that of GatIR81-296, a soybean breeding line with a high level of insect resistance. Reduced feeding on T₁ plants correlated with the presence of the transgene.     

Diverse flowering responses subjecting to ambient high temperature in soybean under short-day conditions

Flowering time is one of important agronomic traits determining the crop yield and affected by high temperature. When facing high ambient temperature, plants often initiate early flowering as an adaptive strategy to escape the stress and ensure successful reproduction. However, here we find opposing ways in the short-day crop soybean to respond to different levels of high temperatures, in which flowering accelerates when temperature changes from 25 to 30 °C, but delays when temperature reaches 35 °C under short day. phyA-E1, possibly photoperiodic pathway, is crucial for 35 °C-mediated late flowering, however, does not contribute to promoting flowering at 30 °C. 30 °C-induced up-regulation of FT2a and FT5a leads to early flowering, independent of E1. Therefore, distinct responsive mechanisms are adopted by soybean when facing different levels of high temperatures for successful flowering and reproduction.     

中国转基因大豆的产业化策略

大豆是事关人民生活和经济社会发展的重要农产品之一,提高大豆生产水平和增加自给能力,是中国农业生产必须解决的重大问题。由于中国耕地资源不足的限制,科技创新是提升大豆生产能力的唯一出路。转基因育种是推动大豆生产发展的颠覆性技术,对美国、巴西和阿根廷等世界主产国大豆产业的发展发挥了重要作用。经过20多年的科技创新,中国转基因耐除草剂和抗虫育种技术已经成熟,这些产品的产业化种植可显著降低大豆生产成本和提升单产水平。基于中国转基因大豆技术发展进度和大豆生产的国情特点,我们提出了采用如下策略科学有序推进产业化工作。一是,在产品应用时间上,按照单一耐草甘膦除草剂、多个基因耐草甘膦和草铵膦等多种除草剂,以及耐除草剂与抗虫等复合性状等产品,依次推进相关种子的产业化;二是,在产品区域布局上,按照靶标杂草和害虫的地理分布特点顶层设计各种耐除草剂和抗虫大豆产品的种植区域;三是,在生物安全管理上,研发应用抗性杂草和害虫种群监测与治理技术,延长转基因产品的使用寿命。同时,还要加强野生大豆资源的保护工作,降低转基因大豆基因漂移对野生大豆生物多样性的影响。     

固相萃取与气相色谱⁃质谱法联用测定食用植物油和含脂肪食品中氯丙醇酯的方法验证研究

氯丙醇酯是国际上广泛关注的食品加工过程污染物,其水解产物氯丙醇对人体（特别是婴幼儿）危害风险较大。采用固相萃取与气相色谱-质谱（gas chromatography-mass spectrometry,GC-MS）联用技术,对食用植物油和含脂食品中的氯丙醇酯[3-氯-1,2-丙二醇脂肪酸酯（简称3-MCPD酯）和2-氯-1,3-丙二醇脂肪酸酯（简称2-MCPD酯）]进行检测。该方法准确度高（3-MCPD酯和2-MCPD酯的平均回收率分别为98.9%和96.5%)、灵敏度高(3-MCPD酯和2-MCPD酯的检出限分别为0.042 mg·kg^-1和0.058 mg·kg^-1)、重现性好(相对标准偏差均低于5%)。76批次监测样品中,3-MCPD酯和2-MCPD酯的含量分别为0.042~4.865 mg·kg^-1(平均值为0.773 mg·kg^-1)和0.058~2.592 mg·kg^-1(平均值为0.469 mg·kg^-1)。经机构间的协同验证和英国FAPAS样的能力验证,2种氯丙醇酯在0.200~3.000 mg·kg^-1范围内线性良好,为进一步研究奠定了基础,同时也为食品加工企业严格控制生产过程建立了一种可行的检测方法。     

Light, temperature and nutrients as factors in photosynthetic adjustment to an elevated concentration of carbon dioxide

The short-term stimulation of the net rate of carbon dioxide exchange of leaves by elevated concentrations of CO₂ usually observed in C₃ plants sometimes does not persist. Experiments were conducted to test whether the patterns of response to the environment during growth were consistent with the hypotheses that photosynthetic adjustment to elevated CO₂ concentration is due to (1) feedback inhibition or (2) nutrient stress. Soybean [Glycine max (L.) Merr. cv. Williams] and sugar beet (Best vulgaris L. cv. Mono Hye-4) were grown from seed at 350 and 700 μl^? CO₂, at 20 and 25°C, at a photon flux density of 0.5 and 1.0 mmol m^?2 S^?1 and with three nutrient regimes until the third trifoliolate leaf of soybean or the sixth leaf of sugar beet had finished expanding. Net rates of CO₂ exchange of the most recently expanded leaves were then measured at both 350 and 700 μl 1^?1 CO₂. Plants grown at the elevated CO₂ concentration had net rates of leaf CO₂ exchange which were reduced by 33% in sugar beet and 23% in soybean when measured at 350 μl 1^?1 CO₂ and when averaged over all treatments. Negative photosynthetic adjustment to elevated CO₂ concentration was not greater at 20 than at 25°C, was not greater at a photon flux density of 1.0 than at 0.5 mmol m^?2 S^?1 and was not greater with limiting nutrients. Furthermore, in soybean, negative photosynthetic adjustment could be induced by a single night at elevated CO₂ concentration, with net rates of CO₂ exchange the next day equal to those of leaves of plants grown from seed at the elevated concentration of CO₂. These patterns do not support either the feedback-inhibition or the nutrient-stress hypothesis of photosynthetic adjustment to elevated concentrations of CO₂.     

Protoplasts as tools in cell biology

Studies of plant protoplasts using both fluorescent dyes and electron dense probes have demonstrated endocytosis in plants. Ultrastructural work with soybean protoplasts using cationized ferritin (CF) revealed an endocytotic pathway from coated pits at the plasma membrane to coated vesicles, the partially coated reticulum, Golgi bodies, multivesicular bodies and finally the vacuole. Endocytosis may be responsible for membrane retrieval from the cell surface or degradation of elicitors or toxins during host-pathogen interactions. Immunofluorescence studies of dividing plant protoplasts have provided new information about the preprophase band (PPB) of microtubules and the shape of spindles. Studies of PPBs in soybean protoplast cultures permitted detailed examination of PPB development and an assessment of the usefulness of the PPB index for identifying morphogenic cultures. In multinucleate protoplasts the size and number of PPBs were apparently not controlled by nuclear number. Research with conifer protoplasts resulted in the discovery of new features of gymnosperm spindles.     

抗旱性不同的两个大豆品种对外源H_2O_2的响应

两个品种的大豆叶圆片经１０－４ｍｏｌ／Ｌ和１０－３ｍｏｌ／Ｌ的Ｈ２Ｏ２处理１２ｈ后,超氧物歧化酶（ＳＯＤ）、过氧化氢酶（ＣＡＴ）与谷胱甘肽还原酶（ＧＲ）活性明显增加,但１０－２ｍｏｌ／Ｌ的Ｈ２Ｏ２处理却使这些酶活性降低。抗旱性较强的大豆品种小粒豆１号较抗旱性较弱的鲁豆４号能维持较高的叶绿素含量和较高的ＳＯＤ、ＣＡＴ及ＧＲ活性,对Ｈ２Ｏ２的抗性较强。５０μｍｏｌ／Ｌ的亚胺环已酮（ＣＨＭ）能消除Ｈ２Ｏ２对ＳＯＤ、ＣＡＴ与ＧＲ活性的刺激作用,而同样浓度的放线菌素Ｄ（ＡＭＤ）则不能。     

不同蔬菜防癌抗促活性的比较研究

本研究采用EBV-EA诱导抑制实验的方法,对40种蔬菜,60个品种,共150个样品的防癌抗促作用效果进行了筛选与比较,其中具有中等以上抑制活性的样品117个,占样品总数的78％,尤其以非洲野苋菜、辣椒、羽衣甘蓝、山药芋头、苦瓜及紫苏、罗勒等一些芳香莱的效果较好。不同品种、不同植株部位、不同提取方法以及不同产地,对蔬菜的抗促活性也有影响,值得进一步研究。     

Nitrate fluxes in soybean seedling roots and their response to amino acids: an approach using 15N

This study was undertaken to determine which of the two NO₃^? fluxes (influx or efflux) across plasma membranes of root cells is the target of those amino acids which have been shown to inhibit net NO₃^? uptake (Muller & Touraine 1992, Journal of Experimental Botany 43 , 617–623). Parallel experiments were performed to mea-sure either the time course of ¹⁵NO₃^? release from roots of soybean seedlings previously labelled with this isotope into non-labelled solution, or the time course of ¹⁵N accumulation from labelled ¹⁵NO₃^? solution in non-labelled seedlings. Focusing on the fate of ¹⁵NO₃^? in the cytoplasmic compartment, a model is developed to describe the time courses of the accumulation and release of tracer across the plasma membranes of root cells. Both time courses can be described by the sum of an exponential plus a linear term. In our material, the linear part of the accumulation time course is obscured by the NO₃^? fluxes exiting the cytoplasm, and the curve thus appears to be quasilinear over several minutes. However, we show that the use of the net tracer accumulation rate during this time period as an estimate of NO₃^? influx does not provide accurate estimates of influx and efflux. By contrast, ¹⁵NO₃^? efflux analysis permits calculation of the unidirectional fluxes across plasma membranes of root cells and the kinetic parameters of the cytoplasmic NO₃^? pool. Under our experimental conditions, efflux accounted for 30 to 50% of influx, and the cytoplasmic NO₃^? content was found to be in the 70–400nmol g^?1 fw range. Using this methodology, the effect of amino acid accumulation on unidirectional fluxes of nitrate was then examined. Pretreatments of the seedlings with an amino acid which has been shown to inhibit net NO₃^? uptake led to concomitant decreases in net accumulation rates of ¹⁵NO₃^? and of reduced ¹⁵N in roots and total ¹⁵N in cotyledons. NO₃^? influx was markedly inhibited by these treatments, while NO₃^? efflux remained essentially unaffected, or even decreased. It is concluded that the target of the regulation of NO₃^? uptake by phloemtranslocated amino acids is the influx system.     

Site-specific isotope fractionation of hydrogen in the biosynthesis of plant fatty acids

The overall deuterium content of plant lipids has been investigated by isotope ratio mass spectrometry (IRMS), and the site-specific natural isotope fractionation of hydrogen has been studied by ²H-NMR at natural abundance (SNIF-NMR). An analytical strategy has been developed in order to exploit the isotopomeric composition determined in clusters associated with different chemical sites of one or several fatty acid components. The method, which combines spectrometric and chromatographic data, enables isotopic criteria to be directly derived from raw vegetable oils containing in general two saturated and two unsaturated fatty acids. These results provide new information on isotopic fractionation caused by biochemical, physiological and natural environmental effects. Some alternation in the molecular deuterium distribution has been detected which may be related to the mechanism of fatty acid elongation. The successive methylene groups introduced through malonyl CoA are the subjects of different kinetic isotope effects since one of them is exclusively derived from NADH whereas the other has a contribution from pyruvate. A discriminant analysis of the cluster isotopic parameters enables several kinds of botanical precursors to be distinguished. The authenticating performances can be improved by taking into account the influence of climatic effects related to the region in which the plant grew.