转NDR1基因烟草对赤星病和晚疫病的抗性增强

 NDR1(nonrace-specific disease resistance)基因在植物系统获得性抗性的信号传导途径中起着重要的作用,过量表达该基因的拟南芥对不同病原菌的抗性都有提高。利用PCR技术首次克隆了拟南芥Wassilewskija生态型的NDR1基因,与Columbia生态型相比,该基因共有7处碱基不同,引起编码氨基酸变化4处。构建了植物高效表达载体,利用农杆菌介导法转化烟草,经PCR和Southern鉴定,外源基因已整合到植物基因组中。随机挑选10个转基因株系进行抗病性分析,其中3个株系对赤星病和晚疫病的抗性明显增强。     

改进单纯形法拟合多形地位指数曲线模型的研究

本文采用改进单纯形法拟合了福建省中心产区杉木人工林8参数Richards多形地位指数曲线模型．精度验证的结果表明，所拟合的模型符合精度要求．对不同地位指数优势高生长特性进行了分析，结果表明：地位指数越高，则林分优势高速生期来得越早，生长潜力也越大．     

An empirical approach to target DNA quantification in environmental samples using real-time polymerase chain reactions

Recent advances in molecular techniques have allowed for the routine examination of nucleic acids in environmental samples. Although current methodologies are very sensitive, accurate target DNA quantification from environmental samples remains challenging. To facilitate high-throughput DNA quantification from environmental samples, we developed a novel DNA quantification method based on a non-linear curve-fitting approach to extract additional information from quantitative PCR amplification curves and used the fitted parameters to develop multiple regression standard equations for target DNA quantification. A 3-parameter sigmoidal function performed superior to a 4-parameter Weibull function for generating the multiple regression standard equations. In a verification experiment, target DNA was quantified in a series of ‘unknown’ samples in three soils using this approach and the results were compared to target DNA values determined using corrected and uncorrected Ct-based (threshold cycle) methods. For each method, the deviations from the expected target DNA content were determined. Results clearly showed that over all DNA concentrations, target DNA content determined by the non-linear curve-fitting method was more accurate and more precise than values predicted by all other methods. Analysis of variance conducted on the predicted DNA contents also revealed fewer statistical artifacts with the non-linear curve fitting method compared to the conventional Ct-based methods. The novel approach described here is accurate, inexpensive, and very amenable for automation and high-throughput applications.     

Suppression of root-knot disease by Pseudomonas fluorescens CHA0 in tomato: importance of bacterial secondary metabolite, 2,4-diacetylpholoroglucinol

The antimicrobial metabolites 2,4-diacetylphloroglucinol (2,4-DAPG) and pyoluteorin contribute to the ability of Pseudomonas fluorescens strain CHA0 to control plant diseases caused by soil-borne pathogens. P. fluorescens strain CHA0 and its derivatives CHA89 (antibiotics-deficient) and CHA0/pME3424 (antibiotics overproducing) were investigated as potential biocontrol agents against Meloidogyne javanica the root-knot nematode. Exposure of root-knot nematode to culture filtrates of P. fluorescens under in vitro conditions significantly reduced egg hatch and caused substantial mortality of M. javanica juveniles. Nutrient broth yeast extract (NBY) medium amended with 2% (w/v) glucose or 1 mM EDTA markedly repressed hatch inhibition activity of the strain CHA0 but not that of CHA0/pME3424 or CHA89. On the other hand, NBY medium amended with glucose significantly enhanced nematicidal activity of the strain CHA0/pME3424. Neither glucose nor EDTA had an influence on the nematicidal activity of the strains CHA0 and CHA89. Under in vitro conditions, antibiotic overproducing strain CHA0/pME3424 and CHA0 expressed phl‘-’lacZ reporter gene but strain CHA89 did not. Expression of the reporter gene reflects actual production of DAPG. In general, CHA0/pME3424 expressed reporter gene to a greater extent compared to its wild type counterpart CHA0. Regardless of the bacterial strains, reporter gene expression was markedly enhanced when NBY medium was amended with glucose but EDTA had no such effect. A positive correlation between the degree of juvenile mortality and extent of phl‘-’lacZ reporter gene expression was also observed in vitro. Strain CHA0 produced zones of 4-6 mm on MM medium containing gelatin while strain CHA0/pME3424 and CHA89 did not. When MM medium containing gelatin was amended with 2% glucose of 1 mM EDTA size of haloes produced by the strain CHA0 reduced to 2 mm. Under glasshouse conditions aqueous cell suspension of the strains CHA0 or CHA0/pME3424 at various inoculum levels (10⁷, 10⁸ or 10⁹ cfu ml⁻¹) significantly reduced root-knot development. CHA89 caused significant reduction in galling when applied at 10⁹ cfu ml⁻¹. To better understand the mechanism of nematode suppression, split root bioassay was performed. Split-root experiments, that guarantee a spatial separation of inducing agent and a challenging pathogen, showed that soil treatment of one half of the root system with cell suspension of CHA0 or CHA0/pME3424 resulted in a significant systemic induced resistance leading to reduction of M. javanica infection of tomato roots in the non-baterized nematode treated half. The results clearly suggest that the antibiotic 2,4-DAPG from P. fluorescens CHA0 act as the inducing agents of systemic resistance in tomato roots. Populations of CHA0 and its derivatives declined progressively by 10-fold between first and fourth harvests (0-21 days after inoculation). However, bacterial populations increased at final harvest (28 days after application).     

玉米中转基因成分筛查策略

根据商业化转基因玉米外源基因元件信息,构建玉米转基因检测分子特征矩阵,并根据元件信息建立转基因玉米的筛查检测策略。结果表明:利用CaMV35S启动子、NOS终止子2个元件的组合,可完成对现有转基因玉米转化事件的筛查检测,检测灵敏度可达到1g/kg。该筛查方法可对玉米中的转基因成分进行快速、高灵敏度的筛查。     

西安市公众对转基因食品接受度的调查分析

为了了解西安市公众对转基因食品的认知度、接受度、态度以及期望和建议,分析当前转基因技术发展的形势以及现状,对当地不同区域的人群随机发放调查问卷进行了调研.调查结果表明:当地消费者对转基因食品的认知度普遍较低;对转基因食品相关标识的关注力度较低;对转基因态度以及评价主要受到网络等新媒体的相关报道的影响.在调查分析的基础上提出了加大转基因技术及其产品的科普宣传力度、提高公众对转基因食品的科学认知等对策建议.     

Agar/galactomannan blends for strawberry (Fragaria x ananassa Duchesne) cv. Pelican micropropagation

The efficacy of partial substitution of agar by galactomannans (GMs) obtained from different sources was tested in strawberry (Fragaria x ananassa Duchesne) cv. Pelican micropropagation. GMs extracted from seeds of Cassia fastuosa (cassia) and Cyamopsis tetragonolobus (guar gum – a commercial GM) were mixed with agar in the proportion of 0.3/0.3% (w/v) in MS medium, and the performance was compared with behaviour of medium containing agar only (0.6%, w/v) as gelling agent. The results obtained showed that agar could be partially replaced by GMs, since the rheological measurements confirmed a good interaction between the polysaccharides. Also, better performance and enhanced proliferation of strawberry shoots were observed; where in the modified medium the length of roots was higher. Thus, the behaviour of the agar/galactomannans gels and the commercial cost effectiveness, which is lower for the modified medium compared with the system solidified with agar only, showed the potential use of these galactomannans for application in plant tissue culture.     

蘑菇保鲜技术及其生理效应

试验比较了~(60)Co—r 射线辐照、气调、药剂等保鲜方法对双孢蘑菇保鲜的效果,得出以纸塑袋密封包装,加天然去异味剂,采用自发气调法保鲜,效果最佳。在5℃左右温度条件下可以保存10—15天,开伞率不超过3%,基本无褐变和异味,失重率在2%以内,质地基本不下降。同时,研究了自发气调保鲜的作用机制,证明自发气调保鲜法,氧与二氧化碳分压可分剐调整到2—3%和10—15%,在这种条件下,多酚氧化酶的活性明显下降。     

改性异氰酸酯树脂胶玉米秸秆皮板工艺

以异氰酸酯(PMDI)改性的脲醛胶作为胶黏剂,采用正交试验法分析了热压时间、成板密度、施胶量、胶混合比对玉米秸秆皮板主要物理性能的影响。结果表明:热压时间对玉米秸秆皮板的24 h吸水厚度膨胀率(24h TS)、弹性模量(MOE),成板密度和改性脲醛胶/异氰酸酯(UF/PMDI)的混合比例对24 h TSI、B、MOE以及施胶量对24 h TS均有高度显著性影响。在一定范围内,秸秆皮板材的物理力学性能指标随着热压时间、密度以及施胶量的增加而增大,异氰酸酯施加量的增加能持续提高板的性能。当工艺条件为:热压时间4～5 min,板密度0.9 g/cm3,施胶量12%,胶量比(UF/PMDI)7∶3时制得的板材性能最佳。     

改性脲醛树脂胶玉米秸秆皮碎料板的制备工艺

研究了玉米秸秆的结构及组成、玉米秸秆中皮、瓤、叶各部分所占的比例及皮与瓤的化学组成,分析探讨了合理的玉米秸秆的皮、瓤、叶分离工艺,对分离后玉米秸秆皮原料的加工处理工艺进行了探索。为确定改性脲醛树脂胶玉米秸秆皮板的制板工艺,通过正交试验对比分析了4个因素(热压时间、热压温度、密度和施胶量)对碎料板性能指标的影响,确定较佳的玉米秸秆皮板生产工艺为:热压温度155℃、热压时间4 min(板厚度10mm)、施胶量12%、密度为0.7 g/m3。