磷高效转基因大豆对根际微生物群落的影响

旨在了解转拟南芥紫色酸性磷酸酶基因的磷高效转基因大豆AP15-1的种植对土壤微生物生态的影响。于春秋两季在网室种植转基因大豆AP15-1及其受体YC03-3,在大豆幼苗期、盛花期和成熟期,分别采集根际土和非根际土。平板菌落计数的实验结果显示:AP15-1和YC03-3根际土与非根际土中可培养细菌、真菌和放线菌的数量在不同的季节和不同的生长期是会发生一定的变化,但没有明显的规律;两者根际土间及根际与非根际土间,细菌、真菌和放线菌数量没有明显的差异。BIOLOG生态板实验对碳源代谢特征分析结果显示:同季AP15-1和YC03-3根际土中微生物总体代谢活性要强于非根际土,但AP15-1和YC03-3根际土间及根际与非根际土间,微生物碳代谢活性差异均不显著;并且AP15-1与YC03-3根际土微生物对四大类碳源的代谢也没有明显的偏好。对春秋季成熟期的BIOLOG数据进行生态学丰富度与多样性指数计算分析,也未发现AP15-1和YC03-3根际土及非根际土间存在显著性差异。主成份和聚类分析结果显示:相同季节和相同生长期,AP15-1和YC03-3根际间的差异小于根际与非根际间的差异;季节和大豆生长时期对根际微生物群落造成的影响要大于AP15-1与YC03-3个体差异所产生的影响。研究结果表明转酸性磷酸酶基因的磷高效转基因大豆种植对根际土壤可培养微生物的数量和群落结构没有产生显著的影响。     

抗真菌转基因水稻秸秆降解对土壤细菌数量及多样性的影响

【背景】随着转基因作物的大面积种植,其潜在的环境安全性问题备受关注。转基因作物收获后,大部分残留物会重返土壤,可能对土壤微生物造成影响。【方法】通过室内模拟田间秸秆降解试验,采用平板计数法、表面荧光显微镜直接计数法（FDC）以及变性梯度凝胶电泳（DGGE）技术,分析了抗真菌转基因水稻秸秆降解对土壤细菌数量及多样性的影响。【结果】平板计数表明,在整个降解过程中,转基因与非转基因处理土壤可培养细菌数量的变化趋势有所差别,但差异不显著。FDC结果表明,转基因与非转基因处理土壤细菌总数差异不显著。DGGE指纹图谱显示,转基因与非转基因处理土壤样品之间的多样性指数、均匀度和丰富度均无显著差异。【结论与意义】抗真菌转基因水稻秸秆降解并未对土壤细菌数量和多样性产生显著影响。本研究为抗真菌转基因水稻的环境安全性评估提供了依据。     

转Bt+CpTI基因棉花对根际土壤细菌及氨氧化细菌数量的影响

转基因棉花对根际土壤微生物的影响在转基因作物风险评估中具有重要意义。【目的】通过研究转基因棉花根际微生物群落变化来评估转基因棉花的生态风险。【方法】以转Bt+CpTI基因抗虫棉(SGK321)及非转基因亲本棉花石远321(SY321)根际土壤总细菌和氨氧化细菌为研究对象,分别在种植前和棉花的不同生长时期(蕾期、花期、铃期和絮期)取样。采用微滴数码PCR方法对土壤中总细菌16S rRNA和氨氧化细菌的功能基因amoA基因进行定量分析。【结果】结果发现两种棉花根际土壤中的总细菌数量随棉花生长的不同时期没有显著差异。但是对氨氧化细菌的定量结果表明随棉花不同生长时期,两种棉花根际土壤中的氨氧化细菌数量均发生显著变化,但变化趋势不同:在蕾期,SY321和SGK321根际土壤中的氨氧化细菌数量分别增加了4倍和2倍;在花期,SY321根际氨氧化细菌与蕾期相比显著降低至5.96×105copies/g dry soil,而SGK321根际氨氧化细菌则显著增加至1.25×106copies/g dry soil;在铃期,SY321根际氨氧化细菌显著增加至1.49×106copies/g dry soil,而SGK321根际土壤中氨氧化细菌数量没有发生显著变化;絮期两者均表现为降低,但差异显著。与非转基因棉花相比,转基因棉花根际土壤中的氨氧化细菌变化相对较为平缓。【结论】这表明氨氧化细菌数量既受棉花生长时期的影响,同时也受转基因棉花的影响,转基因棉花通过影响氨氧化细菌的数量减缓氨的转化速度,这在一定程度上有利于植物生长。     

转Bt + CpTI基因棉花对根际土壤细菌及氨氧化细菌数量的影响

摘要:转基因棉花对根际土壤微生物的影响在转基因作物风险评估中具有重要意义。【目的】通过研究转基因棉花根际微生物群落变化来评估转基因棉花的生态风险。【方法】以转Bt + CpTI基因抗虫棉(SGK321)及非转基因亲本棉花石远321(SY321)根际土壤总细菌和氨氧化细菌为研究对象,分别在种植前和棉花的不同生长时期(蕾期、花期、铃期和絮期)取样。采用微滴数码PCR方法对土壤中总细菌16S rRNA和氨氧化细菌的功能基因amoA基因进行定量分析。【结果】结果发现两种棉花根际土壤中的总细菌数量随棉花生长的不同时期没有显著差异。但是对氨氧化细菌的定量结果表明随棉花不同生长时期,两种棉花根际土壤中的氨氧化细菌数量均发生显著变化,但变化趋势不同:在蕾期,SY321和SGK321根际土壤中的氨氧化细菌数量分别增加了4倍和2倍;在花期,SY321根际氨氧化细菌与蕾期相比显著降低至5.96×105 copies/g dry soil,而SGK321根际氨氧化细菌则显著增加至1.25×106 copies/g dry soil;在铃期,SY321根际氨氧化细菌显著增加至1.49×106 copies/g dry soil,而SGK321根际土壤中氨氧化细菌数量没有发生显著变化;絮期两者均表现为降低,但差异显著。与非转基因棉花相比,转基因棉花根际土壤中的氨氧化细菌变化相对较为平缓。【结论】这表明氨氧化细菌数量既受棉花生长时期的影响,同时也受转基因棉花的影响,转基因棉花通过影响氨氧化细菌的数量减缓氨的转化速度,这在一定程度上有利于植物生长。     

EG03菌剂对辣椒青枯病的防治效果及对根围土壤微生物群落的影响

EG03菌剂由多种抗青枯劳尔氏菌(Ralstonia solanacearum)的拮抗细菌复配而成,田间施用能有效防治辣椒青枯病,平均防效达85.8%.采用稀释平板法、最大或然数(MPN)法以及Biolog微孔板培养系统研究了EG03菌剂对田间辣椒根围土壤微生物群落特征的影响.结果表明:EG03菌剂对根围土壤微生物群落的影响随时间变化而不同,施用后不同程度提高了真菌和芽孢杆菌的数量,并显著增加了自生固氮细菌的数量.根围土壤微生物群落平板每孔颜色平均变化率(AWCD)的变化随培养时间呈现典型的"S"型曲线,辣椒生长后期根围土壤AWCD值高于前期.6类碳源利用分析表明,EG03菌剂的施用在短期内会降低根围土壤微生物的碳源利用率,辣椒生长后期根围土壤中以糖类物质作为碳源的微生物占主导地位.微生物多样性指数分析发现,EG03菌剂施用前期会不同程度降低根围土壤微生物各项多样性指数,但施用后期会提高各项多样性指数,尤其在Simpson指数和McIntosh均匀度两项指标上差异显著.     

抗草甘膦转基因大豆（RRS）对根际土壤细菌数量和多样性的影响

为深入研究种植抗草甘膦转基因大豆的黑土生态区根际土壤中细菌数量及多样性的变化,试验采用DGGE-cloning测序技术与传统培养相结合的方法,研究了抗草甘膦转基因大豆(RRS)对根际土壤细菌数量以及细菌群落多样性的影响.传统培养试验结果为RRS显著降低了土壤细菌的数量;DGGE图谱分析表明,RRS根际土壤细菌16SrDNA条带数、多样性指数及均匀度指数均要低于其他处理,聚类分析显示RRS带谱与RRS-S和Y-S差异较大,相似性分别为64%和64.4%;DGGE-cloning测序结果表明,在RRS处理中缺失条带1和条带12分别属于Uncultured bacterium和Nitrospira门Nitrospira属,其中条带1与其他切取条带最小遗传距离达0.4,与其他处理相比表现出弱势差异的条带2、4、5和条带11均属于Uncultured bacterium.研究表明,RRS不同程度上降低了根际土壤细菌的数量和细菌群落的多样性,并对根际土壤中Nitrospira属细菌有一定的抑制作用.     

转Bt基因抗虫棉根际微生物区系和细菌生理群多样性的变化

在大田栽培条件下 ,以转 Bt基因抗虫棉 GK-12和常规棉花泗棉 3号作为材料 ,在棉花不同发育时期 ,于 2 0 0 1和 2 0 0 2连续两年测定棉花根际土壤细菌、放线菌和真菌数量的变化 ,并在 2 0 0 2年棉花的花铃期和吐絮期对根际细菌生理群的数量和多样性进行了分析 ,结果表明 :虽然不同年份和生育期棉花根际微生物数量存在差异 ,但是 ,年度间和相同的发育时期棉花根际微生物的数量变化趋势一致。在棉花的苗期和吐絮期 ,转 Bt基因抗虫棉根际微生物的数量与对照差异不显著 ;在棉花的花铃期 ,转 Bt基因抗虫棉根际细菌的数量比对照增加 ,放线菌的数量差异不显著 ,而真菌的数量变化没有规律。在棉花发育的花铃期和吐絮期 ,Bt棉根际细菌生理群的总数量比常规棉增加 ,但是根际细菌生理群的 Simpson指数、Shannon-Wiener指数和细菌生理群分布的均匀度下降     

转基因棉花种植对根际土壤微生物群落功能多样性的影响

应用Biolog方法对两种转基因棉花及其亲本非转基因棉花根际土壤微生物的单一碳源利用水平进行了比较分析,探讨转基因棉花种植对其根际土壤微生物群落功能多样性的影响.结果表明：与非转基因亲本相比,在苗期、蕾期、吐絮期、衰老期转基因棉花种植对根际土壤微生物群落碳源利用能力、Shannon功能多样性指数和均匀度指数的影响均不显著,而在花铃期根际土壤微生物群落碳源利用能力和Shannon功能多样性指数显著降低.主成分分析表明,花铃期转基因棉花与非转基因棉花根际土壤微生物碳源利用在两主成分轴上的分异较大,碳源利用模式差异显著.     

黄河流域棉区转Bt基因棉种植对根际土壤微生物数量及细菌多样性的影响

采用传统培养与PCR-DGGE相结合的方法研究了黄河流域棉区4个省份种植的转Bt基因棉在4个生长时期（播种后第30天、第60天、第90天和第120天）的根际土壤微生物数量及细菌多样性.结果表明：同一省份同一生长时期转Bt基因棉根际土壤微生物数量与常规棉相比均无显著差异,其数量主要受不同生长时期影响,而不同省份间主要受地域条件的影响.4个省份转Bt基因棉根际土壤细菌多样性较丰富,同一省份同一生长时期内转Bt基因棉与常规棉根际土壤细菌多样性指数、均匀度和丰富度均无显著差异.不同省份间细菌多样性主要因地域条件而有所不同,但差异较小.     

转Bt基因玉米根际微生物和细菌生理群多样性

大田栽培条件下,以转Bt玉米Mon810及其亲本非转基因玉米为研究对象,在玉米的不同生育期测定根际土壤微生物的数量变化,并对细菌群落结构及多样性进行了分析。结果表明,各生育期内Bt玉米与对照相比根际土壤真菌无显著差异,但细菌在抽丝期,放线菌在苗期二者有显著差异。同种细菌功能群的数量变化在Bt玉米和对照各生育期内趋势一致,不同的菌群表现不同。亚硝化细菌、好气固氮菌、氨化细菌和钾细菌的数量变化波动较大,其中Bt玉米和对照相比好气固氮菌的数量在生育期内有5个生育期有显著差异,而氨化细菌、钾细菌和亚硝酸菌仅分别在乳熟期、喇叭口期及拔节期和抽雄期差异显著。好气纤维分解菌和硝化细菌在苗期、拔节期和喇叭口期差异显著,无机磷分解菌在乳熟期和完熟期数量差异显著。整个生育期内3种群落特征参数均保持基本稳定,除乳熟期和完熟期外Bt玉米根际微生物群落特征参数均高于对照。     

重金属污染下曼陀罗种群分化的RAPD分析

将不同空间地段上获得的同一种质但污染年代各不相同的4个曼陀罗材料种子易地种植在同一模拟重金属污染生境中,对这4个曼陀罗种群进行RAPD分析,结果表明,在105个检测位点中发现有78个位点呈多态性。在这些多态位点中未发现与重金属抗性有关的特异性多态DNA片段。S hannon-Weiner指数计算结果表明,在短期污染时间内曼陀罗种群遗传多样性水平降低。随着污染时间的推移,曼陀罗种群逐渐在污染迹地上稳定下来,曼陀罗种群遗传多样性水平有所回升和提高,4个曼陀罗种群遗传多样性由高到低排列顺序为L＞CK＞M＞S。遗传多样性指数表明曼陀罗种群间变异程度远小于种群内的遗传变异。4个种群两两间遗传距离较小,遗传距离最大的种群为L和S,最小的为L和CK种群。因此,在重金属胁迫环境选择下,曼陀罗种群发生了一定程度的分化与微进化,轻高水平的遗传多样性可能是植物适应重金属污染胁迫环境的基础。     

农用化学品污染对土壤微生物群落DNA序列多样性影响研究

采用ＲＡＰＤ分子遗传标记技术研究了农用化学品不同使用环境下的４种土壤微生物群落ＤＮＡ序列多样性的变化。结果表明,４种土壤微生物群落ＤＮＡ序列在其丰富度、多样性指数、均匀度等方面均存在差异;农用化学品的使用会对土壤微生物群落在ＤＮＡ分子水平上的多样性产生影响;而冰同的农用化学品对土壤微生物群落ＤＮＡ序列多样性影响各不相同：化肥污染会引起某些土壤微生物的富集和一些微生物物种的丧失;农药杂会引起土壤微生     

烟草连作障碍与土壤理化性质及微生物多样性特征的关联

【背景】烟草是我国最重要的经济作物之一,其忌连作的特点严重影响了我国烟草产业的发展。【目的】通过研究烟草连作障碍、土壤理化性质和微生物多样性特征的关系,为解决烟草连作障碍问题、制定有效的烟草生产技术提供理论基础。【方法】选择连作障碍严重烟田和克服连作障碍烟田作为研究对象,基于高通量测序技术,探究烟田连作障碍情况、烟田理化性质与土壤微生物多样性的联系。【结果】克服连作障碍的烟田土壤pH、总氮和有机质含量显著高于连作障碍严重的烟田土壤,克服连作障碍烟田和连作障碍严重烟田土壤微生物多样性之间不存在显著差异,但土壤微生物优势群落发生了显著改变,烟田土壤的pH、有机质、有效磷、总氮都与微生物群落显著相关。【结论】烟田克服连作障碍的差异,可能与烟田土壤的理化性质以及微生物组成的差异有关,此研究为解决湘西烟区连作障碍问题提供理论基础和技术支持。     

转基因甘蔗对根际土壤微生物多样性的影响

应用Biolog法研究了转几丁质酶和β-1,3-葡聚糖酶基因甘蔗对根际土壤微生物多样性的影响。结果表明:转基因甘蔗根际土壤微生物利用单一碳源能力(AWCD)要高于非转基因甘蔗的根际土壤微生物;转基因甘蔗和非转基因甘蔗根际上壤样品的Simpson指数(1/D)、Shannon-Wiener指数(H)、Mclntosh指数(U)均存在差异,其中转基因甘蔗根际土壤微生物的Simpson指数显著高于非转基因甘蔗土壤微生物,两种土壤微生物群落优势度的差别很大,其次是Mclntosh指数(U)指数,丰富度的差别不是很大。说明转基因甘蔗根系在生长期的分泌物刺激根际土壤微生物群落的生长,可能诱导了具有某些特定生理特征的微生物群落的发展,因此转基因甘蔗对根际土壤微生态有一定的影响。     

Effects of continuous cucumber cropping and alternative rotations under protected cultivation on soil microbial community diversity

The diversity of soil microbial communities as affected by continuous cucumber cropping and alternative rotations under protected cultivation were evaluated using community level physiological profiles (CLPP) and random amplified polymorphic DNA (RAPD) analysis. The soils were selected from six cucumber cropping systems, which cover two cropping practices (rotation and continuous cropping) and a wide spectrum for cucumber cropping history under protected cultivation. Shannon–Weaver index and multivariate analysis were performed to characterize variations in soil microbial communities. Both CLPP and RAPD techniques demonstrated that cropping systems and plastic-greenhouse cultivation could considerably affect soil microbial functional diversity and DNA sequence diversity. The open-field soil had the highest Shannon–Weaver index (3.27 for CLPP and 1.50 for RAPD), whereas the lowest value occurred in the 7-year continuous protected cultivation soil (3.27 for CLPP and 1.50 for RAPD). The results demonstrated that continuous plastic-greenhouse cultivation and management can cause the reduction in the species diversity of the biota. Higher Shannon–Weaver index and coefficients of DNA sequence similarity were found in soils under rotation than those under continuous cropping. Cluster analysis also indicated that microbial community profiles of continuous cultivation soils were different from profiles of rotation soils. The reduction in diversity of microbial communities found in continuous cultivation soils as compared with rotation soils might be due to the differences in the quantity, quality and distribution of soil organic matter. Section Editor: D. E. Crowley     

The expression of cecropin peptide in transgenic tobacco does not confer resistance to Pseudomonas syringae pv tabaci

Summary We used in vitro growth inhibition assays to demonstrate that synthetic cecropin protein has potent activity against a range of plant pathogenic bacteria. We then prepared transgenic tobacco plants which express cecropin mRNA and protein. We have used Pseudomonas syringae pv tabaci infection of these transgenic tobacco as a model system to evaluate whether the plants which express cecropin protein also have increased tolerance to infection. We found no dramatic difference in disease response between plants which are expressing cecropin protein and control plants which were derived from the transformation with a binary vector which did not carry the gene encoding cecropin protein.     

Forest gene diversity is correlated with the composition and function of soil microbial communities

The growing field of community and ecosystem genetics indicates that plant genotype and genotypic variation are important for structuring communities and ecosystem processes. Little is known, however, regarding the effects of stand gene diversity on soil communities and processes under field conditions. Utilizing natural genetic variation occurring in Populus spp. hybrid zones, we tested the hypothesis that stand gene diversity structures soil microbial communities and influences soil nutrient pools. We found significant unimodal patterns relating gene diversity to soil microbial community composition, microbial exoenzyme activity of a carbon-acquiring enzyme, and availability of soil nitrogen. Multivariate analyses indicate that this pattern is due to the correlation between gene diversity, plant secondary chemistry, and the composition of the microbial community that impacts the availability of soil nitrogen. Together, these data from a natural system indicate that stand gene diversity may affect soil microbial communities and soil processes in ways similar to species diversity (i.e., unimodal patterns). Our results further demonstrate that the effects of plant genetic diversity on other organisms may be mediated by plant functional trait variation.     

Effect of ferritin overexpression in tobacco on the structure of bacterial and pseudomonad communities associated with the roots

The genetic structures of total bacterial and pseudomonad communities were characterized in rhizosphere soil and rhizoplane+root tissues of tobacco wild type and a ferritin overexpressor transgenic line (P6) by a cultivation-independent method using directly extracted DNA at the end of three consecutive plant cultures. The structure of total bacterial communities was characterized by automated ribosomal intergenic spacer analysis (A-RISA), and that of pseudomonad communities was characterized by PCR-restriction fragment length polymorphism (PCR-RFLP) from DNA amplified with specific primers. The structure of total bacterial communities was significantly modified in the rhizosphere soil by the overaccumulation of iron in the tobacco transgenic P6 line at the first culture, to a lesser extent at the second culture, and not at all at the third culture. No significant difference was recorded between the total communities associated with the roots (rhizoplane+root tissues) of the two plant genotypes in any of the cultures. In contrast, the difference in pseudomonad structure between the two plant genotypes increased with successive culture at the root level, but was not detected at a significant level in the rhizosphere soil. The impact of iron overaccumulation by the tobacco transgenic P6 line on pseudomonads supports previous findings on the importance of iron competition among fluorescent pseudomonads.     

种植阔叶树种和毛竹对土壤有机碳矿化与微生物群落结构的影响

为探明种植阔叶树种和毛竹对土壤有机碳矿化与微生物群落特征的影响,本研究通过盆栽试验和室内培养法比较分析种植香樟、木荷、青冈等阔叶树种与毛竹的土壤有机碳矿化速率和累计矿化量,并结合末端限制性片段长度多态性(T-RFLP)以及荧光定量PCR技术,分析土壤细菌、真菌群落组分与数量特征。结果表明: 与种植阔叶树种的土壤相比,种植毛竹的土壤活性碳组分和碳矿化总量显著提高,且其地下生物量高于阔叶树种。种植毛竹的土壤真菌/细菌丰度比也高于种植阔叶树种的土壤,土壤细菌群落组分对树种的响应比真菌群落更加敏感。种植毛竹的土壤真菌群落多样性显著低于阔叶树种;与细菌群落相比,真菌群落多样性与pH、有机碳含量、碳矿化速率更为相关。与阔叶树种相比,种植毛竹能显著增加土壤碳矿化总量,而毛竹土壤真菌群落结构是导致碳矿化量较高的原因之一。     

Transgenic Bt cotton has no apparent effect on enzymatic activities or functional diversity of microbial communities in rhizosphere soil

A transgenic Bt cotton (Sukang-103) and its non-Bt cotton counterpart (Sumian-12) were investigated to evaluate the potential risk of transgenes on the soil ecosystem. The activities of urease, phosphatase, dehydrogenase, phenol oxidase, and protease in cotton rhizosphere were assayed during the vegetative, reproductive, and senescing stages of cotton growth and after harvest. A Biolog system was used to evaluate the functional diversity of microbial communities in soils after a complete cotton growth cycle. Enzymatic activities in soils amended with cotton biomass were also assayed. Results showed that there were few significant differences in enzyme activities between Bt and non-Bt cottons at any of the growth stages and after harvest; amendment with cotton biomass to soil enhanced soil enzyme activities, but there were no significant difference between Bt and non-Bt cotton; the richness of the microbial communities in rhizosphere soil did not differ between Bt and the non-Bt cotton, and close to that of control soil; the functional diversity of microbial communities were not different in rhizosphere soils between Bt and non-Bt cotton. All results suggested that there was no evidence to indicate any adverse effects of Bt cotton on the soil ecosystem in this study.