Experimental determination of climate‐change effects on above‐ground and below‐ground organic matter in alpine grasslands by translocation of soil cores

We used the soil‐core translocation method to investigate the effect of increased temperature on above‐ and below‐ground phytomass and organic matter in cool alpine areas. The translocation of undisturbed soil cores from a high alpine site (2525 m a.s.l.) to an alpine site near the timberline (1895 m a.s.l.) achieved an effective artificial warming of 3.3 K. From a methodological point of view, the translocation of soil cores was performed successfully. Soil cores moved to a new site at the same altitude showed no change in above‐ and below‐ground vegetation, bulk density, and soil skeleton. At both sites, soils were Haplic Podzols with a similar chemistry and clay mineralogy. At the lower elevation site, however, podzolization processes seemed to be more pronounced. As a consequence, the translocation of the soil cores probably led to a disturbance of the actual steady state that had been established after about 10,000–13,000 years of soil formation. This might have affected the adaptability of the vegetation system. Therefore, it cannot be fully excluded that the experimental design influenced the results. Translocation of soil cores from a very cool to a warmer site led to a distinct decrease in above‐ground phytomass (about –45%) over the experimental period of two years. Below‐ground phytomass significantly decreased (up to –50%) in the topsoil (0–5 cm) after artificial warming. Possible mechanisms are that roots reduced photosynthesis and hence C flow below‐ground, a reduction of soil moisture that would have led to root death (not a very probable cause, however) or an abrupt change in the radiation duration and flux which affected root growth (also not very probable). Fast climate change exceeded the ability of the above‐ground and below‐ground phytomass to adapt quickly. Whether the decrease in phytomass was a short‐term or a long‐term response to climate warming remains uncertain. Based on a gradient study (climosequence at the same locality), we hypothesize that the decreased plant productivity might be a short‐term effect.     

不同耕作方式对冬播亚麻成苗及原茎产量的影响

通过成苗数、苗期根系生长、有效收获株数、收获时主要经济性状及原茎产量的考查结果分析，认为免耕、免镇压等耕作方式对亚麻成苗数和苗期根系生长有一定的影响。但由于亚麻自．身群体结构调控能力较强，各处理在收获时其有效收获株数、收获时主要经济性状及原茎产量差异不大。建议南方冬播亚麻生产区在土壤、气候条件适宜的情况下，可采用免耕、免镇压措施，降低种植亚麻的劳动强度和生产成本，促进农民种植亚麻的积极性．提高种植亚麻的经济效益．     

转基因毛白杨根部土壤微生物数量的季节变化

为了对转基因植物的生态安全性研究提供依据,采用土壤梯度稀释法对转基因毛白杨和非转基因毛白杨根部微生物数量的季节变化趋势进行研究。结果表明：转基因毛白杨根际、根表和根皮3个层面的根部细菌数量变化均是春季较少,夏季有不同程度的增多,秋季减少,根内的细菌数量极少;非转基因毛白杨根际细菌数量的变化表现为春季较少,夏季增多,秋季减少;根表和根皮则表现为春季到秋季细菌数量呈下降趋势。转基因毛白杨根部真菌数量变化趋势均为春季较少,夏季有不同程度的增多,秋季减少;非转基因毛白杨根部真菌的数量为从春季到秋季呈逐渐减少的趋势。     

大麦芽根发酵培养苏云金杆菌的初步研究

大麦芽根是啤酒工业的副产品，它含有较丰富的粗蛋白质和可溶性无氮物。采用麦芽根培养基，进行了苏云金杆菌HD－1发酵试验。结果表明，在适当的配比条件下，该菌生长良好，产晶体蛋白能力也正常。发酵液活孢子数可以达到3．7×109／mL，而原料成本只相当于对照鱼粉、玉米培养基的1／4。     

Variation in Crown and Root Organic Reserves Among Lucerne Genotypes of Different Morphology and Flower Colour

Previous evidence indicates that differences in the concentration of underground organic reserves can drive the survival and growing ability of lucerne under cold and defoliation stresses. In order to provide the selection process with further information on compounds that may influence plant performance under grazing, we assessed variations in cold‐season concentrations of nitrogen and carbon reserves on genotypes that had been identified for morphological features that possibly enhance grazing tolerance. The selected genotypes encompassed distinct morphological patterns (defined as ‘models’) and different taxa within the Medicago sativa complex, as shown by different flower colours. Crown concentrations of reserves were determined on 90 genotypes, whereas root concentrations were measured on a subsample of 15 genotypes. Wide intergenotypic variation was observed for all reserve substances. Comparisons among models and among flower colour classes highlighted the high concentrations of crown carbohydrates and root and crown‐soluble proteins of the model coded as ‘D1’, characterized by prostrate, rhizomatous habit and long dormancy, which largely corresponded to plants with yellow or variegated flowers, typical of ssp. falcata and × varia, respectively. There was a strong ‘flower colour × storage organ’ interaction for sugar concentration, and the results suggested a preferential compartment of sugars in the roots of purple‐flowered genotypes that belonged to the ssp. sativa. A rank correlation analysis indicated a positive relationship between persistence after two years under grazing of half‐sib progenies deriving from 19 genotypes out of the 90 and crown concentrations of carbohydrates of the 19 mother plants.     

不同因素对水稻离体根吸收四价硒影响

研究结果显示,pH对水稻离体根吸收4价硒(Se)有显著影响,这与不同pH下4价Se的存在形式有关。进一步研究表明,低温抑制4价Se吸收和一定浓度的NaCl促进4价Se吸收,可能在于低温和NaCl影响到根内代谢而间接影响4价Se吸收,而P抑制4价Se吸收可能与二者拥有共同吸附位点有关。     

酸枣根中鞣质含量测定及提取工艺研究

[目的]优化酸枣根鞣质的提取工艺,建立稳定的酸枣根中鞣质的含量测定方法。[方法]用干酪素法测定总鞣质的含量,并以提取物中鞣质含量为评价指标,以丙酮浓度、提取时间、料液比及提取次数为考察因素,采用正交设计法筛选酸枣根的提取工艺条件。[结果]提取次数为主要影响因素;最佳提取条件为:超声提取的丙酮浓度为70%,料液比为1∶20(W/V,g/ml,下同),提取时间为30 min,提取3次;在此条件下,酸枣根中鞣质的含量为6.82%。[结论]所优选的鞣质提取工艺合理,操作简便可行。     

苦参毛状根诱导及其培养条件的研究

[目的]为药用成分苦参碱及氧化苦参碱的来源提供新途径。[方法]考察了R1601菌株对苦参不同外植体在不同浓度乙酰丁香酮和侵染时间影响下苦参毛状根的诱导率;研究了培养基中的组分和浓度对苦参毛状根继代生长的影响。[结果]以苦参幼芽为外植体,在R1601菌液中添加100μmol/L乙酰丁香酮,侵染20 min,(25±1)℃,MS共培养基上暗培养2 d,苦参毛状根的诱导效果较好,诱导率28.6%,存活率46.7%;苦参毛状根在改良的继代培养基上生长良好。[结论]苦参毛状根的最佳诱导条件:以生长1周的苦参幼芽为外植体,R1601为菌株,添加100μmol/L的乙酰丁香酮,侵染20 min,(25±1)℃暗处诱导。     

双链RNA干扰技术在毛状根体系中对何首乌芪合酶基因Fm STS功能研究中的应用

[目的]将双链RNA介导的基因沉默与发根农杆菌瞬间表达渗入相结合,为植物功能基因的研究提供一套有效的方法。[方法]构建含gfp基因、CaMV 35S启动子及基于何首乌中芪合酶Fm STS基因序列设计的双链RNA的干扰重组质粒pBIN-35S-正向-反向-GFP(干扰),并将其与空白表达质粒pBIN-35S-GFP(空白)分别导入野生型发根农杆菌MSU440中,转化何首乌无菌苗的叶片,诱导生成毛状根。[结果]双链RNA介导的芪合酶Fm STS基因表达沉默,空白对照组二苯乙烯苷含量为2.18 mg/g,是双链RNA干扰组(0.65 mg/g)的3倍多。[结论]应用dsRNA介导的RNAi能有效沉默何首乌Fm STS基因,芪合酶Fm STS基因是何首乌中二苯乙烯苷合成代谢的关键酶基因。     

发根农杆菌介导不同基因型大豆转化效率的筛选

基因型是影响发根农杆菌转化大豆的主要因素之一,为筛选转化效率高的大豆基因型,利用不同基因型大豆的下胚轴接种发根农杆菌K599(含GUS基因),待长出毛状根后,根据不同基因型大豆发根诱导率和发根数的差异,选择适宜大豆基因型进行GUS基因的组织化学染色和RT-PCR分析。结果表明,34个大豆基因型发根诱导率和发根数有很大差异,选择发根诱导率大于60%以及发根数大于1.6条的20个大豆基因型毛状根进行GUS基因组织化学染色,其中Y091、Z184、P108、L010等4个大豆基因型的GUS基因转化效率较高,分别为96.2%、91.7%、87.5%、86.4%;进一步对以上4个大豆基因型毛状根进行RT-PCR分析,结果表明,GUS基因均得到了正确转录。表明大豆基因型Y091、Z184、P108、L010是发根农杆菌转化大豆较为理想的受体材料。