外源GA_3对白桦成花基因影响的定量PCR分析

植物开花是高等植物由营养生长向生殖生长转变的重要生理过程,是个体发育和后代繁衍的中心环节。赤霉素是调节植物生长发育的五大激素之一(Takahashi et al.,1991),赤霉素处理也是人工调控植物成花的最有效途径之一,因而成为近年来成花     

抗生素/抗性细菌/抗性基因在土壤-植物系统中迁移转化及阻控消减的研究进展

抗生素在土壤环境中的迁移转化过程及生态毒理效应已成为各国土壤学、植物学、环境科学和食品科学等领域学者及政府关注的热点。阐明抗生素及其复合抗性污染物在土壤-植物系统中的环境行为及生态毒理学机理,对管控生态环境风险及保障食品安全具有重要的意义。本文综述了近年来国内外关于土壤-植物系统中抗生素的迁移转化规律,抗生素/抗性细菌/抗性基因的生态风险以及复合抗性污染物阻控消减技术的研究进展。本综述可以为土壤-植物系统中抗生素抗性污染风险的管控和消减提供科学支撑。     

Phylogeny and nodulation signal molecule of rhizobial populations able to nodulate common beans—other than the predominant species Rhizobium etli—present in soils from the northwest of Argentina

We examined the bean rhizobia community other than the predominant species Rhizobium etli present in soils of a region that is part of the range occupied by the host in Northwest Argentina, which showed Rep and 16S rDNA RFLP polymorphism. Two populations represented by isolates T29N3L and T44N22P were found to be distinct chromosomal genotypes and closely related to species Rhizobium tropici and Agrobacterium rhizogenes. Their symbiotic genes were analyzed and found to cluster with those from R. tropici as well as with rhizobia isolated from leguminous trees. Three nodulation metabolites produced by T44N22P were detected which are tetra- and pentameric chitocompounds, N-methylated, O-carbamoylated, and N-substituted either by a C_18:0 or C_18:1 acyl chain at their non-reducing end, and all them sulphated at the reducing end. Isolates T29N3L and T44N22P exhibited broad host range but unlike T29N3L, only T44N22P was able to efficiently nodulate Medicago truncatula.     

水稻白叶枯病黄单胞菌中与甘蓝黑腐病黄单胞菌致病因子调控基因(rpf 基因)同源基因的分子克隆

DNA-DNA 杂交结果表明,水稻白叶枯病黄单胞菌总 DNA 中存在着与甘蓝黑腐病黄单胞菌致病因子调控基因(rpf 基因)具有同源性的 DNA 外段.应用广谱性寄主载体pLAFRI,在大肠杆菌中建立了水稻白叶枯病黄单胞菌野生型菌株 T3000的基因文库.从文库中筛选到与 rpf 基因具有同源性的克隆 pGXN3000,将重组质粒 pGXN3000通过三亲本接合转入甘蓝黑腐病黄单胞菌 rpf 基因突变体,发现 pGXN3000能互补甘蓝黑腐病黄单胞菌 rpf突变体,恢复其致病性胞外酶和胞外多糖的产生及致病性.转座子 Tn5诱变,缺失分析及DNA-DNA 杂交实验结果表明,重组质粒 pGXN3000中确实含有与甘蓝黑腐病黄单胞菌编码。双组份调控系统”蛋白的 rpfC 基因功能相同的基因,此基因被定位于 pGXN3000中的3kb BamHl 片段中。     

Iron and zinc accumulation in winter wheat regulated by NICOTIANAMINE SYNTHASE responded to increasing nitrogen levels

Nitrogen (N) is critical for micronutrient biofortification in wheat grain and is essential for a series of nitrogenous compounds biosynthesis. This study aims to assess the role of improved N supply in iron (Fe) and zinc (Zn) enrichment and expression of genes related to Zn and Fe chelation and transport in winter wheat. Potting and hydroponic culture experiments were conducted to study the effect of increasing N application on Zn and Fe uptake and translocation from roots to leaves and the temporal and spatial gene expression profiles of the NICOTIANAMINE SYNTHASE (NAS) genes in wheat. Plants were grown with low, medium and high N supply levels. The results showed that higher N application increased Fe and Zn content in leaves, and decreased Fe and Zn content in root compared with the lower N supply. High N application also increased the distribution of Fe and Zn from roots to leaves. Expression analysis showed that increased N application resulted in up-regulation of two wheat NAS genes, TaNAS1 and TaNAS2. Highly positive response between NAS genes and increasing N application indicated that abundance nicotianamine (NA) resulted from highly expressed NAS genes might involve in the chelation of Fe and Zn in the phloem and favor Fe and Zn uptake and accumulation in wheat leaves.     

Evapotranspiration and crop coefficient of Populus euphratica Oliv forest during the growing season in the extreme arid region northwest China

Based on successive observation, fifteen-day evapotranspiration (ET_c) of Populus euphratica Oliv forest, in the extreme arid region northwest China, was estimated by application of Bowen ratio-energy balance method (BREB) during the growing season in 2005. During the growing season in 2005, total ET_c was 446.96 mm. From the beginning of growing season, the ET_c increased gradually, and reached its maximum value of 6.724 mm d⁻¹ in the last fifteen days of June. Hereafter the ET_c dropped rapidly, and reached its minimum value of 1.215 mm d⁻¹ at the end of growing season. The variation pattern of crop coefficient (K_c) was similar to that of ET_c. From the beginning of growing season, the K_c value increased rapidly, and reached its maximum value of 0.623 in the last fifteen days of June. Afterward, with slowing growth of P. euphratica, the value dropped rapidly to the end of growing season. According to this study, the ET_c of P. euphratica forest is affected not only by meteorological factors, but by water content in soil.     

双抗虫基因三倍体毛白杨对舞毒蛾幼虫的抗性研究

用室内群体饲养舞毒蛾幼虫的方法,对15个双抗基因三倍体毛白杨株系进行饲虫试验。结果表明:校正死亡率划分了高抗、中抗、低抗虫植株,舞毒蛾校正死亡率在95以上为高抗株系;40～75为中抗株系,30以下为低抗株系。舞毒蛾的发育历期、蜕皮指数和毒效反映的规律相一致。     

Optimal utilisation of natural resources for agricultural sustainability in rainfed hill plateaus of Orissa

The climatic data for 17 years from 1988 to 2004 of the rainfed hill plateaus of Kandhamal district of Orissa (India) were analyzed to find out the monthly climatic index from the calculated values of effective rainfall and evapotranspiration. The 80% dependable monthly climatic index was correlated with crop coefficient and suitable cropping period and sequences for the study area were suggested based on it. The extent of investment, net return and soil loss from agriculture were estimated as per the present condition and for the suggested cropping patterns. A mathematical model was formulated for optimal allocation of area to different crop sequences with different objectives viz. minimization of soil loss, minimization of investment and maximization of net return from agriculture and was solved using linear goal programming technique. The model suggested to take up food crops in area of 1,30,777 ha and perennial grass cover in 3223 ha with a cropping intensity of 1.61 resulting in a net return of Rs 1064.775 millions sustaining soil loss to a tune of 9489.67 thousand tons per year. The model was found to be favourable in respect of higher net return of Rs 8862.34 and lesser soil loss of 23.41 tons/ha than the corresponding present values. But more investment of Rs 4489.01 per ha was required to fulfill the objectives.