间作作物种间相互作用对马铃薯根际土壤丛枝菌根真菌的影响

为揭示间作作物种间相互作用对土壤丛枝菌根(AM)真菌的影响,以马铃薯单作(T0)为对照,基于高通量测序平台的方法,研究了连续3年马铃薯‖玉米(T1)、马铃薯‖蚕豆(T2)下马铃薯根际土壤AM真菌群落组成、多样性与土壤环境因子间的相互关系。结果表明:共获得2893个AM真菌操作分类单元(OTUs),分属1门、3纲、4目、8科、11属、104种;幼套近明囊霉(Claroideoglomus)、球囊霉属(Glomus)、类球囊霉属(Paraglomus)为AM真菌优势属。玉米、蚕豆与马铃薯间作均改变了马铃薯根际土壤AM真菌属水平上的相对丰度;与T0相比,T1处理下幼套近明囊霉相对丰度降低,球囊霉属和类球囊霉属相对丰度增加;T2处理下幼套近明囊霉相对丰度增加,但球囊霉属和类球囊霉属相对丰度却降低。Metastats检验表明:T1和T2处理下,马铃薯根际土壤类球囊霉属AM真菌相对丰度存在显著差异(P=0. 024),耳孢囊霉属(Otospora)在T0和T2处理间存在极显著差异(P=0.005);土壤AM真菌香农指数在T1与T2间有显著差异(P<0.05)。主成分分析表明:T0和T1处理下,马铃薯根际土壤AM真菌群落组成较为接近;土壤碱解氮与AM真菌香农多样性指数呈显著负相关(P=0.043),基于属水平上的AM真菌幼套近明囊霉相对丰度与碱解氮呈极显著正相关(P=0.006),原囊霉属(Archaeospora)的相对丰度与速效磷呈显著正相关(P=0.046)。马铃薯间作玉米、蚕豆为主的种植模式具有间作优势,种间相互作用能改变马铃薯根际土壤AM真菌群落组成,这对于合理间作作物选择,稳定农业生态系统具有重要意义。     

黄顶菊与3种本地植物竞争对丛枝菌根真菌种类和多样性的影响

【目的】外来植物黄顶菊对生态环境和农业经济造成了严重危害,了解黄顶菊与3种不同本地植物种植生长对丛生菌根(AM)真菌群落结构和多样性造成的影响,可以从土壤微生物角度进一步解释黄顶菊的入侵机制。【方法】通过同质园小区试验模拟黄顶菊入侵的生态进程,以黄顶菊和3种本地植物狗尾草、藜、黄香草木樨为研究对象,采用AM真菌的形态学鉴定方法,研究黄顶菊与3种本地植物不同种植方式对AM真菌群落结构和多样性的影响。【结果】(1)黄顶菊根际土壤聚集的AM真菌种类与其伴生本地植物种类有关:黄顶菊与狗尾草混种处理中优势种为网状球囊霉和根内球囊霉,而黄顶菊分别与藜、草木樨混种处理中优势种均为网状球囊霉、根内球囊霉和缩球囊霉;(2)黄顶菊分别与狗尾草和黄香草木樨混种处理中AM真菌种类既高于本地单种处理,也高于黄顶菊单种处理,说明随着黄顶菊的入侵和地上植物多样性的改变,AM真菌种类也发生改变;(3)与3种本地植物单种相比,黄顶菊各混种处理和黄顶菊单种处理中黄顶菊根际土壤根内球囊霉的重要值均增加,表明黄顶菊入侵有利于根内球囊霉的生长和发育。【结论】黄顶菊入侵改变了根际土壤AM真菌的群落结构和多样性,AM真菌的改变既与本地植物种类有关,也与入侵程度有关。     

西藏高原针茅草地土壤因子对丛枝菌根真菌物种多样性的影响

在对西藏高原北部针茅草地根围土壤中的丛枝菌根(AM)真菌种类分离鉴定基础上,研究了藏北针茅草地的土壤质地、pH、有机质和有效磷含量对AM真菌孢子密度、分离频度、相对多度、重要值、物种多样性指数和均匀度的影响.结果表明: 针茅草地根围土壤中共分离鉴定出AM真菌3属15种,其中,球囊霉属9种、无梗囊霉属6种、盾巨孢囊霉属1种.球囊霉属和无梗囊霉属为藏北针茅草地AM真菌的优势属;近明球囊霉和光壁无梗囊霉为藏北高寒草原针茅属植物根围AM真菌的优势种.不同质地土壤中AM真菌孢子密度、分离频度、相对多度和重要值均表现出球囊霉属＞无梗囊霉属＞盾巨孢囊霉属的趋势;土壤pH值对AM真菌种群组成无明显影响,球囊霉属和无梗囊霉属真菌分离频度、相对多度和重要值随土壤pH升高而增加,盾巨孢囊霉属则呈现相反趋势;不同土壤有机质含量范围内,AM真菌孢子密度等各项指标均呈球囊霉属＞无梗囊霉属＞盾巨孢囊霉属,而AM真菌属的分布没有明显规律;土壤有效磷含量对AM真菌种丰度和孢子密度影响较小.研究区域内AM真菌物种多样性指数和均匀度随着土壤有效磷含量升高而增加.     

土壤因子对甘肃、宁夏和内蒙古盐碱土中AM真菌的影响

为探明甘肃、宁夏和内蒙古盐碱土中AM真菌多样性及其与土壤因子间的关系,2005年5月从甘肃、宁夏和内蒙古7个县(市)的盐碱土中采集主要植物的根围土壤样品,研究了AM真菌物种多样性.在分离的4属28种AM真菌中,球囊霉属(Glomus)20种,多孢囊霉属(Diversispora)2种,原囊霉属(Archaeospora)2种,无梗囊霉属(Acaulospora)4种.其中根内球囊霉(G.intraradices)和薄壁原囊霉(Ar.leptotihum)的分离频度最高.相关分析和通径分析(path analysis)结果表明,AM真菌种的丰度与土壤有机质和速效N含量呈显著负相关;Cl-、CO2-3、HCO-3、Na+、Ca2+、有机质、速效P和速效K直接影响AM真菌种的丰度,而SO2-4、K+、水溶性全盐、Mg2+、pH和速效N则间接影响AM真菌种的丰度;土壤有机质对AM真菌Shannon-Wiener多样性指数有显著直接负效应;Cl-、CO2-3、K+、Mg2+、有机质、速效P和速效K直接影响Shannon-Wiener多样性指数,而HCO-3、Na+、Ca2+、SO2-4、水溶性全盐、pH和速效N则间接影响Shannon-Wiener多样性指数.冗余度分析结果表明,AM真菌种的相对多度与土壤因子间有显著相关性.可见,甘肃、宁夏和内蒙古盐碱土中AM真菌种类丰富,其多样性与土壤养分状况、盐度以及离子含量有关.     

林火对植物根围丛枝菌根真菌多样性的影响

林火是森林生态系统的一种主要干扰因子,以青岛市三标山林火迹地为研究对象,采集荆条(Vitex negundo)、胡枝子(Lespedeza bicolor)、花木蓝(Indigofera kirilowii)、青花椒(Zanthoxylum schinifolium)和野青茅(Deyeuxia arundinacea)5种优势植物根围土壤,研究不同林火强度对丛枝菌根(AM)真菌多样性的影响。结果表明,AM真菌侵染率和孢子密度随火灾强度的加强而降低;非过火区植物根围土壤中,分离鉴定出AM真菌3属11种,轻度过火区分离鉴定出AM真菌3属10种,中度过火区分离鉴定出AM真菌3属9种,重度过火区分离鉴定出AM真菌3属8种。过火区AM真菌种丰度低于非过火区。过火区和非过火区AM真菌的重要值和优势种不同,非过火区植物根围的优势种是地球囊霉(Glomus geosporum)、台湾球囊霉(G.taiwanensis)、分支巨孢囊霉(Gigaspora ramisporophora)、极大巨孢囊霉(Gi.gigantean)、福摩萨球囊霉(G.formosanum)、悬钩子球囊霉(G.rubiforme)、柯氏无梗囊霉(Acaulospora koskei)和松蜜无梗囊霉(A.thomii);轻度过火区植物根围的优势种是地球囊霉和台湾球囊霉;中度过火区的是台湾球囊霉和地球囊霉(野青茅除外);重度过火区植物根围的优势种是地球囊霉。不同强度的过火区对AM真菌群落组成有不同程度的影响。认为林火降低植物根围土壤中AM真菌多样性。     

玉米秸秆还田对土壤丛枝菌根真菌群落的影响

为揭示农业管理活动对土壤丛枝菌根(AM)真菌的影响机制,基于Illumina Miseq高通量测序平台以及脂肪酸指纹图谱方法,研究了连续4年玉米秸秆还田后,AM真菌群落组成、AM真菌生物量及其与土壤环境因子间的相互关系.结果表明:所获得的2430个AM真菌OTUs从门到种依次分类,共分为1门、3纲、4目、8科、10属、143种,但不同处理间AM真菌群落丰富度(Chao1指数和ACE指数)、多样性(Shannon、Simpson多样性指数)没有显著差异.AM真菌中类球囊霉属、球囊霉属为优势属.随秸秆还田量的增加,球囊霉属丰度降低;3000、9000 kg·hm^-2秸秆还田量下,类球囊霉属、无梗囊霉属的丰度与对照(0 kg·hm^-2)间差异达极显著水平;原囊霉属、类球囊霉属、球囊霉属在3000 kg·hm^-2秸秆还田量下与对照间差异显著,非度量多维尺度(NMDS)分析表明,9000、12000 kg·hm^-2的秸秆还田量下土壤AM真菌β多样性与对照间聚集度较其他处理相差较远,秸秆还田量对AM真菌β多样性的影响显著.多元分析结果能在累积变量82.8%上揭示土壤主要理化性状与AM真菌丰富度、多样性的空间变化关系.土壤全氮、碱解氮是影响以磷脂脂肪酸表征的土壤主要微生物类群生物量以及以中性脂肪酸表征的AM真菌生物量的主要因子.持续玉米秸秆还田改变了AM真菌属水平上的分类学组成;随秸秆还田量的增加,AM真菌特有的微生物种类减少,AM真菌群落组成间的相似度下降;秸秆还田增加了土壤AM真菌生物量及其占土壤微生物总生物量的比例.     

高磷土壤中丛枝菌根真菌的分离鉴定

【背景】丛枝菌根(arbuscular mycorrhiza,AM)真菌具有广泛的寄主范围、环境适应性和优良的植物促生能力。然而,土壤的高磷水平严重抑制了AM真菌生长及AM形成。【目的】分离鉴定出耐较高有效磷含量的华南土著AM真菌菌株,为菌根学研究工作提供新颖材料。【方法】采用经典形态学和分子系统学方法鉴定高磷土壤中AM真菌。【结果】从有效磷含量为53-131 (平均值±标准差为88.2±17.6) mg/kg的根区土壤中鉴定出7属25种AM真菌,包括无梗囊霉属(Acaulospora) 12种、球囊霉属(Glomus) 7种、隔球囊霉属(Septoglomus) 2种、近明球囊霉属(Claroideoglomus) 1种、根孢囊霉属(Rhizophagus) 1种、硬囊霉属(Sclerocystis) 1种和类球囊霉属(Paraglomus) 1种,其中幼套近明球囊霉(Claroideoglomus etunicatum)和蜜色无梗囊霉(Acaulospora mellea)是优势种。在(87.7±8.0) mg/kg的高磷水平下,AM真菌仍能形成丛枝和泡囊。但当有效磷含量达到(99.7±1.2) mg/kg时,菌根侵染率和丛枝丰度显著下降,但仍能够形成泡囊。【结论】从广州市南沙区有效磷含量为(88.2±17.6) mg/kg的耕地植物根区土壤中,鉴定出具有耐高磷潜力的7属25种AM真菌,幼套近明球囊霉和蜜色无梗囊霉等分离株可作为后续高磷抑制机制解析及耐高磷AM真菌菌剂研发工作的试验菌株。     

内蒙古荒漠沙柳AM真菌物种多样性

分别于2009年5月、8月和10月在内蒙古黑城子、正蓝旗和元上都3个样地采集沙柳(Salix psammophila)根围0-50 cm土层土样,研究了AM真菌群落组成及其生态分布特点.在分离的4属37种AM真菌中,球囊霉属(Glomus)23种,无梗囊霉属(Acaulospora)10种,这两属是3样地共同优势属;盾巨孢囊霉属(Scutellospora)3种,仅分布在黑城子和正蓝旗样地;巨孢囊霉属(Gigaspora)1种,仪分布在正蓝旗样地;网状球囊霉(G.reticulatum)是3样地共同优势种.AM真菌种丰度、均匀度指数、Shannon多样性指数、Simpson多样性指数大小依次是正蓝旗>黑城子>元上都;元上都样地的AM真菌组成与其他样地差异显著;8月和10月的AM真菌种丰度、Shannon多样性指数显著高于5月.随土壤碱解N含量提高,AM真菌种丰度、均匀度指数、物种多样性指数先升后降.结果提示,在评估荒漠环境沙柳和AM真菌共生关系时,AM真菌生态分布和丰富度是十分有用的指标.     

我国东、南沿海地区AM真菌群落生态分布研究

在我国东、南沿海地区AM真菌资源调查的基础上研究了AM真菌的群落生态分布和特征。证明球囊霉属在该地区的出现频度和相对多度都最高,其次是硬囊霉属。该区内南四省AM真菌丰度、密度和物种多样性指数均比北三省高。聚类分析结果和上述相似,说明我国东、南沿海各省AM真菌的丰度、频度、密度、多度和多样性特征由北向南呈规律性变化。     

不同轮作模式下设施土壤丛枝菌根真菌群落结构的季相变化

以番茄-甜瓜、番茄-豆角两种轮作模式为研究对象,采集番茄生长季(休耕期、花期、果期)的土壤样品,利用Illumina MiSeq高通量测序技术分析两种轮作模式下土壤AM真菌群落结构的差异特征,并探讨驱动AM真菌多样性和群落组成差异的关键因子。结果表明: 引入豆科作物的轮作模式显著改变了AM真菌的α多样性,与番茄-甜瓜相比,番茄-豆角土壤中AM真菌Shannon多样性和Pielou均匀度分别显著降低了24.9%和24.0%。AM真菌丰富度、Shannon多样性和系统发育多样性在番茄生育期(花期、果期)相比于休耕期分别显著下降了55.6%～67.5%、49.6%～51.5%及21.4%～23.7%。引入豆科作物的轮作模式在3个时期均提高了球囊霉属的相对丰度,降低了花期和果期类球囊霉属及原囊霉属的相对丰度。近明球囊霉属的相对丰度在休耕期表现为番茄-甜瓜>番茄-豆角,花期则相反。两性囊霉属、多孢囊霉属和盾巨孢囊霉属仅在花期番茄-豆角土壤中存在。置换多元方差分析(PERMANOVA)和非度量多维度分析(NMDS)结果表明,轮作模式和生长季均显著影响AM真菌群落结构,土壤湿度、pH、速效磷等是调控AM真菌群落结构和多样性的主要环境因子。结构方程模型(SEM)结果进一步表明,轮作模式和生长季主要通过影响土壤pH间接驱动AM真菌群落组成及多样性变化。     

丛枝菌根真菌的生态分布及其影响因子研究进展

丛枝菌根(arbuscular mycorrhiza,AM)共生体系对于植物适应各种逆境胁迫具有重要积极作用。AM真菌还能够通过根外菌丝网络调节植物群落结构和演替,深刻影响生态系统结构和功能的稳定性。AM真菌生态生理功能的发挥主要取决于其生态适应性,明确AM真菌在不同环境中的多样性、生态适应性以及对各种生态因子的响应机制,是AM真菌资源管理、功能发掘与利用的前提。迄今为止,有关各种生态因子对AM真菌多样性的影响已有不少研究,但是AM真菌生态分布及其形成机制仍缺乏系统的研究和理论分析。综述了生物因子和非生物因子对AM真菌生态分布的影响,结合大型生物空间分布理论探讨了AM真菌生态分布规律和建成机制,分析了当前本研究领域所存在的问题和动向,以期推动相关研究进展。     

Interactions between invasive plants and heavy metal stresses: a review

入侵植物与重金属胁迫的相互作用研究进展 全球变化改变了植物群落的分布格局,包括入侵植物,而人为污染可能降低本地植物对入侵植物的抗性。因此,本文总结了近几十年本地植物、入侵植物和植物-土壤生态系统中重金属生物地球化学行为的研究,以加深我们对入侵植物与环境胁迫因子相互作用的认识。我们的研究结合已有文献报道表明：(i)入侵物种对环境胁迫的影响具有异质性, (ii)影响的大小是多变的, (iii)即使在同一影响类型内,影响类型也具有多向性。然而,入侵植物暴露在重金属环境中表现出更强的自我保护机制,对重金属的生物可利用性和毒性有正向或负向的影响。另一方面,由于入侵植物普遍具有较高的耐受性,加之本地植物暴露于有毒重金属污染时具有“逃逸行为”,重金属胁迫环境更有利于植物的成功入侵。但是,对于入侵植物的重金属等元素组成是否与污染地区的本地植物不同,目前尚无共识。因此,在全球范围内对外来入侵植物与本土植物的植物体内、凋落物和土壤污染物含量进行定量比较是今后研究的一个重要方向。     

Contribution of the arbuscular mycorrhizal symbiosis to heavy metal phytoremediation

High concentrations of heavy metals (HM) in the soil have detrimental effects on ecosystems and are a risk to human health as they can enter the food chain via agricultural products or contaminated drinking water. Phytoremediation, a sustainable and inexpensive technology based on the removal of pollutants from the environment by plants, is becoming an increasingly important objective in plant research. However, as phytoremediation is a slow process, improvement of efficiency and thus increased stabilization or removal of HMs from soils is an important goal. Arbuscular mycorrhizal (AM) fungi provide an attractive system to advance plant-based environmental clean-up. During symbiotic interaction the hyphal network functionally extends the root system of their hosts. Thus, plants in symbiosis with AM fungi have the potential to take up HM from an enlarged soil volume. In this review, we summarize current knowledge about the contribution of the AM symbiosis to phytoremediation of heavy metals.     

农业生态系统中的AM真菌多样性

农业生态系统复杂庞大,是由如麦田生态系统、水稻田生态系统、果园生态系统、草地生态系统、保护地生态系统等组成的一个复合生态系统。重点介绍农业生态系统中丛枝菌根(AM)和AM真菌多样性,探讨农业生态系统中调控AM真菌多样性的途径以及今后研究的动向。     

丛枝菌根真菌对大气CO2浓度升高和增温响应研究进展

全球变化深刻影响着陆地生态系统生物多样性及生态功能。丛枝菌根(AM)真菌可与绝大多数陆生植物根系形成互惠共生体,在协助宿主养分吸收、促进植物生长、维持植物多样性等方面发挥着重要作用。本文主要分析了大气CO₂浓度升高(eCO₂)和增温对森林和草地生态系统AM真菌群落组成及其功能的影响。eCO₂主要通过影响宿主植物、土壤碳(C)输入等方式间接影响AM真菌,可增加AM真菌的多度和活性,影响AM真菌的多样性与群落组成。增温可直接或间接地(通过宿主植物和土壤途径)影响AM真菌,显著改变森林土壤AM真菌的群落组成,但对草地土壤AM真菌群落组成的影响尚无定论。我们提出了当前研究中存在的主要问题及未来应重点关注的内容。本文旨在明晰AM真菌对eCO₂和增温的响应和适应,增进对AM真菌介导的土壤生态功能的认识,为利用AM真菌缓解全球变化、增强土壤功能的韧性和全球变化的生态系统适应性提供依据。     

Heavy metal contamination of soil and tree-ring in urban forest around highway in Shanghai,China

The heavy metal (HM) pollution of forest soil has been known as one of the most challenging pollution issues due to their characteristics. In order to know the HM pollution condition in urban forest, identify the possible source of HM, 102 sub-samples of soil in 34 sites and 39 tree rings sub-samples in 7 sites were collected in the outer-ring greenbelt (ORG) in Shanghai, China. Concentrations of Cu, Zn, Pb, and Cd in soil and tree rings were analyzed, and the soil properties pH, total nitrogen, total phosphorous, and organic matter were analyzed too. Geo-accumulation index and potential ecological risk index were used for assessing the contamination level of HMs. Nonparametric tests, one-way analysis of variance, correlation analysis, and principal component analysis were applied. The results showed that: (1) concentrations of Cu, Zn, and Cd in soil were significantly higher than their corresponding background values of Shanghai (BVs); concentrations of Cu, Zn, and Pb in tree rings increased gradually in the past 10 years; (2) Zn and Cd were in unpolluted to moderately polluted level, Cd has moderate degree potential ecological risk; (3) vehicle exhausts and abrasion of vehicle parts of tires and historical agricultural activities were the main sources of HM contamination; (4) Cinnamomum camphora (L.) Presl. has the potential to reconstruct the change of Cu, Zn, and Pb as a bioindicator. In conclusion, Cd should be considered as a priority control component. The relationship between plant and soil should take further focus and more studies of the behavior of HMs in soil and plants are required.     

青藏高原高寒草地AM真菌分布及其对近自然恢复的生态作用

超载过牧以及全球气候变化等导致大部分青藏高原高寒草地呈现持续退化态势。青藏高原高寒草地退化致使地上植物群落逐渐发生更替,地下土壤微生物群落多样性和丰富度发生改变。本文旨在探析青藏高原高寒草地丛枝菌根（arbuscular mycorrhizal,AM）真菌的分布特征、对近自然恢复的生理生态效应及其作用机制。青藏高原高寒草地中已报道4目14属61种AM真菌,约占已知AM真菌物种的20%。高寒草地禾本科植物根围AM真菌物种丰度最高,而莎草科植物根围AM真菌孢子密度最高。3种高寒草地植被类型中,高寒草原AM真菌丰度最高（33种）,山地灌丛草原次之（32种）,高寒草甸最低（22种）。高寒草原以光壁无梗囊霉Acaulospora laevis和闪亮和平囊霉Pacispora scintillans为优势种,山地灌丛草原以摩西斗管囊霉Funneliformis mosseae为优势种,高寒草甸以光壁无梗囊霉A. laevis、近明球囊霉Claroideoglomus claroideum和闪亮和平囊霉P. scintillans为优势种。高寒草地土著AM真菌与植物构建的菌根网络可以通过调节营养元素吸收、分配,促进植物建植和生长;但是毒杂草入侵可以改变土著AM真菌物种多样性和菌根网络,限制本地植被的实际生态位扩张。退化高寒草地中,AM真菌群落具有高的环境适应性和恢复力,其不仅调控地上植物群落建植和多样性,同时AM真菌建植也增加了代谢产物-球囊霉素相关土壤蛋白产生,进而协同改善地下土壤微生态系统,为退化高寒草地早期植被恢复塑造土壤生境。因此,AM真菌在退化高寒草地近自然恢复中具有较大的应用潜力。     

Host plant species effects on arbuscular mycorrhizal fungal communities in tallgrass prairie

Symbiotic associations between plants and arbuscular mycorrhizal (AM) fungi are ubiquitous in many herbaceous plant communities and can have large effects on these communities and ecosystem processes. The extent of species-specificity between these plant and fungal symbionts in nature is poorly known, yet reciprocal effects of the composition of plant and soil microbe communities is an important assumption of recent theoretical models of plant community structure. In grassland ecosystems, host plant species may have an important role in determining development and sporulation of AM fungi and patterns of fungal species composition and diversity. In this study, the effects of five different host plant species [Poa pratensis L., Sporobolus heterolepis (A. Gray) A. Gray, Panicum virgatum L., Baptisia bracteata Muhl. ex Ell., Solidago missouriensis Nutt.] on spore communities of AM fungi in tallgrass prairie were examined. Spore abundances and species composition of fungal communities of soil samples collected from patches within tallgrass prairie were significantly influenced by the host plant species that dominated the patch. The AM fungal spore community associated with B. bracteata showed the highest species diversity and the fungi associated with Pa. virgatum showed the lowest diversity. Results from sorghum trap cultures using soil collected from under different host plant species showed differential sporulations of AM fungal species. In addition, a greenhouse study was conducted in which different host plant species were grown in similar tallgrass prairie soil. After 4 months of growth, AM fungal species composition was significantly different beneath each host species. These results strongly suggest that AM fungi show some degree of host-specificity and are not randomly distributed in tallgrass prairie. The demonstration that host plant species composition influences AM fungal species composition provides support for current feedback models predicting strong regulatory effects of soil communities on plant community structure. Differential responses of AM fungi to host plant species may also play an important role in the regulation of species composition and diversity in AM fungal communities. Received: 29 January 1999 / Accepted: 20 October 1999     

Variation in aluminum resistance among arbuscular mycorrhizal fungi

Arbuscular mycorrhizal (AM) fungi mediate interactions between plants and soils, and are important where nutrient or metal concentrations limit plant growth. Variation in fungal response to edaphic conditions may influence the effectiveness of the plant-mycorrhizal association in some soil environments. Andropogon virginicus (broomsedge) colonizes disturbed sites in the eastern United States, including acidic mine soils where aluminum (Al) is phytotoxic, and Al resistance in broomsedge has been associated with colonization by the AM fungus Glomus clarum. In the present study, inter- and intra-specific variation to confer Al resistance to broomsedge was assessed among selected species of AM fungi. Broomsedge seeds were grown in sand culture inoculated with one of five isolates of three species of fungi (G. clarum, Acaulospora morrowiae, and Scutellospora heterogama). Plants were exposed to 0 or 400 µM Al in nutrient solution and harvested after 4 or 9 weeks of growth. Mean infection percentage, plant biomass, and plant tissue Al and phosphorus (P) concentrations were measured. G. clarum conferred the greatest Al resistance to broomsedge, with the lowest variability among isolates for colonization and growth inhibition by Al [tolerance indices (TI) between 22.4 and 92.7%]. Broomsedge plants colonized by A. morrowiae were consistently the most sensitive to Al, with little variation among isolates (TI between 1.6 and 12.1%). Al resistance by S. heterogama isolates was intermediate and wide-ranging (TI between 3.9 and 40.0%). Across all AM fungal isolates, resistance was associated with high rates of colonization and low tissue Al concentrations of broomsedge plants. The functional diversity in Al resistance displayed by these AM fungi reflect variation in acclimation mechanisms operating in the mycorrhizal symbiosis under environmental stress.     

重金属对土壤微生物的生态效应

通过分析重金属对土壤微生物生化过程与数量、种群及群落的影响、影响重金属对土壤微生物毒性的因素、重金属对土壤微生物毒性的评价指标、微生物对重金属的耐性与适应性以及重金属毒性的差异 ,综合评述了重金属对土壤微生物的生态效应 .