Dynamic Succession of Soil Bacterial Community during Continuous Cropping of Peanut (Arachis hypogaea L.)

Plant health and soil fertility are affected by plant–microbial interactions in soils. Peanut is an important oil crop worldwide and shows considerable adaptability, but growth and yield are negatively affected by continuous cropping. In this study, 16S rRNA gene clone library analyses were used to study the succession of soil bacterial communities under continuous peanut cultivation. Six libraries were constructed for peanut over three continuous cropping cycles and during its seedling and pod-maturing growth stages. Cluster analyses indicated that soil bacterial assemblages obtained from the same peanut cropping cycle were similar, regardless of growth period. The diversity of bacterial sequences identified in each growth stage library of the three peanut cropping cycles was high and these sequences were affiliated with 21 bacterial groups. Eight phyla: Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Gemmatimonadetes, Planctomycetes, Proteobacteria and Verrucomicrobia were dominant. The related bacterial phylotypes dynamic changed during continuous cropping progress of peanut. This study demonstrated that the bacterial populations especially the beneficial populations were positively selected. The simplification of the beneficial microbial communities such as the phylotypes of Alteromonadales, Burkholderiales, Flavobacteriales, Pseudomonadales, Rhizobiales and Rhodospirillales could be important factors contributing to the decline in peanut yield under continuous cropping. The microbial phylotypes that did not successively changed with continuous cropping, such as populations related to Rhizobiales and Rhodospirillales, could potentially resist stress due to continuous cropping and deserve attention. In addition, some phylotypes, such as Acidobacteriales, Chromatiales and Gemmatimonadales, showed a contrary tendency, their abundance or diversity increased with continuous peanut cropping progress. Some bacterial phylotypes including Acidobacteriales, Burkholderiales, Bdellovibrionales, and so on, also were affected by plant age.     

添加毛叶苕子对红壤旱地土壤真菌群落的影响

【目的】长期高强度的连作及大量化肥施用导致红壤旱地退化和土传植物病原菌累积。真菌是农业生态系统中与土壤健康密切相关的微生物。本文通过研究土壤真菌群落的变化,探究施用毛叶苕子对红壤旱地农业生态系统的影响。【方法】采用定量聚合酶链式反应和高通量测序技术,研究红壤旱地真菌群落对单施矿质肥(mineral nitrogen,phosphorus and potassium fertilization,NPK)与矿质肥配施毛叶苕子(mineral nitrogen,phosphorus and potassium fertilization with hairy vetch,NPKG) 2种施肥措施的响应。【结果】与对照NPK相比,NPKG显著提高土壤肥力、花生产量和土壤真菌丰度,降低土壤p H和土壤真菌多样性。不同处理显著改变土壤真菌群落组成。与对照NPK相比,NPKG处理土壤腐生营养型真菌相对丰度显著提高37.42%,花生尾孢菌(Cercospora arachidicola)和可可毛色二孢菌(Lasiodiplodia theobromae) 2种花生病原菌相对丰度分别降低89.11%和8...     

生物炭对温室黄瓜不同连作年限土壤养分和微生物群落多样性的影响

以温室黄瓜连作6年和10年土壤添加质量比为5%生物炭为处理,以不添加生物炭为对照,采用桶栽的方法,研究了生物炭对不同年限连作土壤养分和微生物群落多样性的影响.结果表明: 与连作土壤相比,生物炭处理的连作6年土壤的黄瓜单株产量提高11.4%,连作10年土壤产量提高62.8%.施入生物炭显著降低了2种连作土壤容重,显著提高了有机质、速效磷含量、阳离子交换量(CEC)和pH;显著提高了土壤细菌数量和细菌/真菌,降低了真菌和尖孢镰刀菌数量,使土壤类型由真菌型向细菌型转变,尤其对连作10年土壤作用最为明显,土壤细菌和细菌/真菌分别是未处理的2.00和3.64倍,真菌和尖孢镰刀菌数量分别是未处理的54.8%和55.9%.土壤微生物群落碳源利用分析表明,10年连作土壤施入生物炭可显著提高土壤微生物活性、Shannon指数和均匀度指数,分别是未处理的1.50、2.14和1.31倍,同时显著提高了土壤微生物对糖类、氨基酸类、酚酸类和胺类碳源的利用强度,分别是未处理的1.62、1.81、1.74和1.93倍.相关性分析表明,土壤容重、速效磷含量、CEC和pH 4个指标对微生物群落变化的影响较显著.综上,生物炭通过对连作土壤理化性质及土壤微生物生态系统的改善,优化了黄瓜根区环境,促进了黄瓜产量的提高,缓解了温室黄瓜连作障碍.     

Soil Fungal Diversity and Community Composition in Response to Continuous Sweet Potato Cropping Practices

Soil fungi are extremely important for maintaining soil health and plant production in agricultural systems. Currently, the effect of continuous cropping of sweet potato on soil fungal communities and physiochemical parameters has not been well documented. In the present study, four sweet potato fields consecutively monocultured for 1, 2, 3, and 4 years were selected to investigate the effect of monoculture on soil fungal communities through Illumina MiSeq sequencing. Continuous cropping of sweet potatoes dramatically altered the fungal community composition, whereas fungal diversity was almost unchanged. Ascomycota and Basidiomycota were the most abundant phyla in all soil samples, accounting for 32.59% and 21.14% of the average relative abundance, respectively. The abundance of some potential pathogens, such as Ascobolus spp, specifically Ascobolus stercorarius, and some unknown fungi increased significantly as the sweet potato monoculture period increased, and their presence were highly positively correlated with disease incidence. In contrast, Basidiomycota, Bullera, Fusarium and Trichocladium most likely play roles as antagonists of sweet potato disease development, as their relative abundance decreased significantly over time and were negatively correlated with disease incidence. Redundancy and correlation analyses revealed that soil pH and organic carbon content were the most important factors driving these changes. Our findings provided a dynamic overview of the fungal community and presented a clear scope for screening beneficial fungi and pathogens of sweet potato.     

添加高粱根茬根际土对连作黄瓜生长和根际微生物的影响

为了分析添加高粱根茬根际土对连作黄瓜生长和根际微生物群落特征的影响,本研究通过盆栽试验,采用荧光定量PCR和高通量测序技术分析土壤细菌和真菌群落组成的差异。试验共设4个处理: CK(不施肥),T₁(单施化肥),T₂(优化施肥),T₃(优化施肥+高粱根茬根际土)。结果表明: 与其他处理相比,T₃处理促进了黄瓜生长发育,提高了土壤中16S rRNA和ITS rRNA基因数量。与T₁处理相比,T₂和T₃处理明显提高了细菌群落的丰富度和多样性,不同处理间真菌群落的丰富度和多样性差异不明显。添加高粱根茬根际土在一定程度上改变了基于门、属水平上的细菌和真菌群落结构。其中,细菌中提高了酸杆菌门和拟杆菌门的丰度,降低了变形菌门、厚壁菌门、硝化螺旋菌门和芽孢杆菌属的丰度;真菌中提高了担子菌门、木霉菌属和假散囊菌属的丰度,降低了镰刀菌属和绿僵菌属的丰度。冗余分析表明,土壤硝态氮和有机质含量分别是影响细菌和真菌群落结构差异的关键因子。添加高粱根茬根际土不仅提高了连作黄瓜土壤微生物数量和细菌多样性,而且增加了有益菌木霉菌属的丰度,降低了致病镰刀菌的丰度和数量,保障了黄瓜存活率,为缓解黄瓜连作障碍提供了一条切实可行的解决途径。     

水旱轮作对滩涂绿花椰菜根际土壤真菌群落结构的影响

本研究比较轮作和连作下滨海滩涂地绿花椰菜根际土壤真菌群落结构和多样性的变化特征,以探索不同轮作方式减缓绿花椰菜连作田连作障碍的效果。采用Illumina Miseq高通量测序技术,分析单季稻-绿花椰菜水旱轮作、南瓜-绿花椰菜旱旱轮作和绿花椰菜连作3种耕作方式对绿花椰菜根际土壤真菌群落结构和多样性的影响。结果表明,在浙江省台州湾滨海滩涂地绿花椰菜种植区,水旱轮作、旱旱轮作和连作绿花椰菜根际土壤共获得11门、27纲、52目、94科、155属真菌。在门水平上相对丰度较高的为子囊菌门Ascomycota、油壶菌门Olpidiomycota、担子菌门Basidiomycota、接合菌门Zygomycota、壶菌门Chytridiomycota。与连作相比,轮作显著提高了绿花椰菜根际土壤中子囊菌门、壶菌门菌群的相对丰度,而以水旱轮作对其相对丰度的提高幅度更大。轮作显著降低了绿花椰菜根际土壤中油壶菌门、接合菌门菌群的相对丰度,而以水旱轮作对这2门菌群相对丰度的降低幅度更大。在属水平上轮作显著降低了绿花椰菜根际土壤中油壶菌属Olpidium、镰刀菌属Fusarium等的相对丰度,显著提高了绿花椰菜根际土壤中格孢腔菌属Pleospora的相对丰度,而水旱轮作更提高了格孢腔菌属的相对丰度,降低了油壶菌属、镰刀菌属的相对丰度。因此,轮作能改善台州湾滨海滩涂地上绿花椰菜根际土壤真菌群落结构,但水旱轮作更能增加绿花椰菜根际土壤真菌有益菌丰度,减少绿花椰菜根际土壤真菌有害菌群丰度,提高根际土壤真菌多样性指数,改良绿花椰菜根际土壤生态环境。     

连作对芝麻根际土壤微生物群落的影响

采用稀释平板计数法研究了不同连作年限处理芝麻根际土壤细菌、真菌、放线菌、芽孢杆菌、尖孢镰刀菌(FO)和青枯劳尔氏菌(RS)数量的变化情况。结果表明,随着连作年限的增加,芝麻根际土壤中细菌和放线菌的数量下降,而真菌的数量则呈上升趋势。新种芝麻地根际土壤芽孢杆菌数量显著高于连作2a处理和连作5a处理,而连作2a处理又显著高于连作5a处理;连作5a芝麻根际土壤尖孢镰刀菌数量显著高于新种地、轮作1a和连作2a等3个处理;轮作1a、连作2a及连作5a等3个处理青枯劳尔氏菌数量显著高于新种地处理。说明连作导致土壤微生物环境恶化,引起根际微生物区系结构发生定向改变。连作2a与轮作1a相比,各菌群(类群)数量差异均不显著。     

轮作和连作对胡萝卜根际和非根际细菌多样性的影响

细菌是土壤最重要的组成部分,土壤细菌的群落结构对土壤的健康至关重要,可以直接影响植物的生长。胡萝卜的长年连作导致其产量低、质量差等一系列问题的发生,连作问题已成为不可忽视的问题。本研究通过HiSeq PE250高通量测序和生物信息学方法获得了玉米胡萝卜轮作种植和胡萝卜连作种植中胡萝卜根际和非根际土壤细菌的组成结构。研究结果表明,相较于胡萝卜连作,玉米胡萝卜轮作种植改变了胡萝卜根际土壤细菌的组成和群落多样性。RM.M (玉米胡萝卜轮作根际土壤样品)样品中的优势菌门为放线菌门和厚壁菌门,RM.R (胡萝卜连作根际土壤样品)的优势菌门是变形菌门;有益菌如芽孢杆菌属和根瘤菌属在玉米胡萝卜轮作种植中的胡萝卜根际富集。RM.M与RM.R的细菌类群差异显著,群落多样性较低;NRM.M(玉米胡萝卜轮作非根际土壤样品)和NRM.R (胡萝卜连作非根际土壤样)的细菌类群差异不明显,群落多样性较高。与连作根际土壤相比,轮作根际土壤中有益菌的相对丰度较大,细菌相对丰度明显增加。本研究结果对通过调节根际土壤细菌组成来保证胡萝卜产量和质量的稳定,解决连作问题具有重要的意义。     

Effects of tobacco–peanut relay intercropping on soil bacteria community structure

A reasonable cultivation pattern is beneficial to maintain soil microbial activity and optimize the structure of the soil microbial community. To determine the effect of tobacco−peanut (Nicotiana tabacum−Arachis hypogaea) relay intercropping on the microbial community structure in soil, we compared the effects of relay intercropping and continuous cropping on the soil bacteria community structure. We collected soil samples from three different cropping patterns and analyzed microbial community structure and diversity using high-throughput sequencing technology. The number of operational taxonomic units (OTU) for bacterial species in the soil was maximal under continuous peanut cropping. At the phylum level, the main bacteria identified in soil were Proteobacteria, Actinobacteria, and Acidobacteria, which accounted for approximately 70% of the total. The proportions of Actinobacteria and Firmicutes increased, whereas the proportion of Proteobacteria decreased in soil with tobacco–peanut relay intercropping. Moreover, the proportions of Firmicutes and Proteobacteria among the soil bacteria further shifted over time with tobacco–peanut relay intercropping. At the genus level, the proportions of Bacillus and Lactococcus increased in soil with tobacco–peanut relay intercropping. The community structure of soil bacteria differed considerably with tobacco–peanut relay intercropping from that detected under peanut continuous cropping, and the proportions of beneficial bacteria (the phyla Actinobacteria and Firmicutes, and the genera Bacillus and Lactococcus) increased while the proportion of potentially pathogenic bacteria (the genera Variibacter and Burkholderia) decreased. These results provide a basis for adopting tobacco–peanut relay intercropping to improve soil ecology and microorganisms, while making better use of limited cultivable land.     

甘肃省中部沿黄灌区轮作和连作马铃薯根际土壤真菌群落的结构性差异评估

甘肃省中部沿黄灌区是西北地区乃至全国重要的加工型马铃薯生产基地,然而因集约化种植带来的连作障碍问题已经严重影响到当地马铃薯种植业的可持续发展。采用大田试验与PCR-DGGE(Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis)技术相结合的方法,并通过真菌的18S r DNA序列分析,评估轮作(未连作)和连作条件下马铃薯根际土壤真菌群落在组成结构上的差异,以期为甘肃省中部沿黄灌区马铃薯连作的土壤障碍机理研究提供新证据。结果表明,同轮作相比,连作显著降低了马铃薯块茎产量和植株生物量,并且随着连作年限的延长,连作障碍也愈加严重。长期连作(6a)也导致马铃薯根冠比显著增加和植株收获指数的显著下降。在根际土壤真菌的种群数量和多样性上,连作和轮作间无显著差异,但在群落组成结构上差异明显。真菌18S r DNA测序分析进一步表明,马铃薯连作较轮作相比增加了Fusarium sp.和Fusarium solani以及Verticillium dahliae的种群或个体数量,而这些真菌是导致马铃薯土传病害的主要致病菌类型。根际土壤真菌群落组成结构的改变特别是与土传病害有关的致病菌滋生可能是导致当地马铃薯连作障碍的重要原因。     

Analysis of bacterial communities in rhizosphere soil of continuously cropped healthy and diseased konjac

The bacterial community and diversity in healthy and diseased konjac rhizosphere soils with different ages of continuous cropping were investigated using next-generation sequencing. The results demonstrated that the number of years of continuous cropping significantly altered soil bacterial community and diversity. Soil bacterial Shannon diversity index and Chao 1 index decreased with the increasing cropping years of konjac. After 1 year of cropping, the soil exhibited the highest bacterial relative abundance and diversity. Of the 44 bacterial genera (relative abundance ratio of genera greater than 0.3%), 14 were significantly affected by the duration of continuous cropping and plant status. With increasing continuous cropping, Alicyclobacillus decreased, while Achromobacter, Lactobacillus, Kaistobacter, Rhodoplanes increased after 3 years continuous cropping. Continuous cropping altered the structure and composition of the soil bacterial community, which led to the reduction in the beneficial bacteria and multiplication of harmful bacteria. These results will improve our understanding of soil microbial community regulation and soil health maintenance in konjac farm systems.     

不同蔬菜与番茄轮作对设施土壤微生物多样性、酶活性及土壤理化性质的影响

[目的]番茄是一种受连作障碍影响明显的蔬菜作物,本试验旨在研究不同蔬菜作物与番茄轮作后对设施土壤微生物多样性、酶活性及土壤理化性质的影响,以期筛选出适宜与番茄轮作的蔬菜作物,为从设施栽培模式选择角度缓解或避免番茄连作障碍提供理论依据.[方法]试验以连续两茬种植番茄后分别种植大白菜(A)、黄瓜(B)、辣椒(C)、茄子(E...     

内生真菌与苍术粉对连作花生根际微生物区系和微量元素的影响

通过盆栽试验,研究了内生真菌拟茎点霉B3(Phomopsis liquidambari)及苍术(Atractylodes lancea)粉联合施用对连作花生根际土壤微生物区系、酶活性及有效态微量元素(Mo、B、DTPA-Fe、Zn、Cu、Mn)含量的影响。结果表明:内生真菌B3和苍术粉复合处理比内生真菌B3处理的荚果和秸秆产量分别增加10.28%和14.11%,内生真菌B3处理与正常施肥相比显著提高了根瘤数量、荚果和秸秆产重,各处理组与正常施肥对照相比分枝数和根长无显著差异。B3处理与对照相比显著提高了种子期、结荚期和成熟期根际土壤可培养细菌和放线菌数量,B3和苍术粉复合处理与对照相比显著提高种子期、花期和成熟期可培养真菌和放线菌数量;细菌DGGE指纹图谱聚类分析表明,B3和苍术粉复合处理相对于正常施肥处理,显著改变种子期、苗期、花期和成熟期花生根际土壤细菌群落结构,同时苗期、花期和结荚期的细菌条带数和香农指数也有所提高,真菌DGGE指纹图谱聚类分析表明,B3和苍术粉复合处理对真菌群落影响较大,除种子期以外的生育期真菌条带数和香农指数都有明显提高,花期真菌群落结构变化最大,相似度仅为49.6%。花生关键生育期(花期和结荚期)根际土壤脲酶和蔗糖酶活性B3处理和复合处理都显著高于正常施肥对照,促进了连作花生生态系统的物质循环和能量流动。B3和苍术粉复合处理促进了花生生长发育必需微量元素Mo、B、Fe、Zn、Mn的活化,花生叶片和籽粒中微量元素Mo、B、Fe的积累显著增加。研究结果表明,内生真菌和苍术粉联合施用能有效改善连作花生根际微生物区系,提高土壤酶活性,促进微量元素的活化和吸收,对缓解花生连作障碍具有重要意义。     

甘草根际土壤微生物群落对长期连作的响应

光果甘草连年种植所引起的甘草产量下降、植株发育不良、根腐病频发严重影响甘草产业的持续发展,造成了重大的经济损失。然而,其机制却并不清楚。应用下一代测序技术,对未种植过光果甘草的土壤（Control）,生长1a （Gg1）和生长5a （Gg5）光果甘草的根际土壤行16S rDNA和18S rDNA ITS测序,并对比分析了甘草根际土壤和对照组之间,以及不同种植年限甘草根际土壤之间的微生物群落结构差异,以期探究光果甘草连作障碍的原因。结果表明,光果甘草连作增加了根际土壤细菌群落的丰富度,降低了真菌群落的丰富度（P>0.05）。主坐标分析显示,光果甘草的根际土壤微生物组成与对照组之间存在显著差异,并且光果甘草的种植年限显著地影响了根际土壤微生物的群落组成。在门水平上,光果甘草连作显著地增加了真菌Blastocladiomycota和Mortierellomycota的相对多度（P<0.05）。在属水平上,光果甘草连作显著地降低了有益细菌Arthrobacter和Pseudomona及有益真菌Naganishia的相对多度,而增加了病原真菌Fusarium和Thanatephorus的相对多度。由此推测,光果甘草根际土壤微生物群落结构的改变,以及有益微生物相对多度的降低和病原微生物相对多度的增加可能是导致光果甘草发生连作障碍的重要原因之一。     

灵芝连作土壤真菌群落分析

本研究通过Illumina MiSeq平台对邻近野生土壤（GL0）、种植1年（GL1）、2年（GL2）和4年（GL4）的灵芝覆土进行ITS1扩增子测序,分析灵芝连作覆土中真菌群落的变化,为揭示灵芝连作障碍的机理提供理论依据。研究结果表明,12个灵芝土壤样本一共获得349 642条有效序列,经聚类得到2 426个OTU,分别隶属于8门、28纲、64目、127科、233属和449种。在门水平上,随着连作年限的增加,灵芝覆土中真菌的多样性水平逐渐减低,在GL4组中只含有担子菌门（Basidiomycota,占85.03%）、子囊菌门（Ascomycota,占14.77%）和少量被孢霉门（Mortierellomycota,占0.20%）。其中,担子菌门的相对丰度随着连作年限的增加显著增加,子囊菌门的相对丰度显著减少,而被孢霉门的相对丰度无显著性差异。在属水平上,担子菌门灵芝属Ganoderma的相对丰度随着连作年限的增加而极显著增加,子囊菌门仅青霉属Penicillium菌群的相对丰度呈现先减少后增加的趋势,在GL4组中相对于GL0组其相对丰度增加了57.92%,表明青霉属可能是引发该地区灵芝连作障碍的重要菌群,该研究为探索灵芝连作障碍的分子机制和生态防控提供了理论依据。     

云南文山健康三七种植年限对根际微生物群落的影响

【背景】三七的连作障碍与微生物区系失衡有一定关联,了解种植年限对三七微生物区系的影响,判断根际微生物区系是否失衡,对三七连作障碍的防治具有重要意义。【目的】探究文山不同种植年限健康三七根际土壤细菌和真菌群落结构、多样性差异,以及与种植年限之间的关联,为后续缓解三七连作障碍提供理论依据。【方法】采集一年生、二年生和三年生健康三七根际土壤,采用16S rRNA基因和ITS序列进行高通量测序。对测序结果进行分析,比较一年生、二年生和三年生健康三七根际土壤细菌和真菌的多样性和群落分布规律及与种植年限的关联。【结果】一年生健康三七根际细菌和真菌群落的α指数均显著高于二年生和三年生。通过β多样性分析发现,一年生健康三七根际土壤中真菌群落结构与其他年限的真菌群落结构有较大差异。相关性分析结果表明,真菌的均匀度和香农指数与种植年限呈现显著的负相关性,其余指数不显著相关。三七根际丰富度前三的门和属,除Acidobacteria和Aquicella丰富度随着三七种植年限的增加而显著增加外,其余群落丰度都与种植年限呈负相关。细菌中Bacteroidetes、Proteobacteria和真菌中Ascomycota、Basidiomycota、Chytridiomycota的丰富度随着种植年限增加而降低。在属水平上,细菌中Opitutus和真菌中Mortierella、Clitopilus、Pholiota的丰富度随着三七种植年限的增加而降低。在二年生三七根际土壤中病原真菌Alternaria、Cylindrocarpon、Fusarium和Pestalotiopsis的丰富度低于一年生和三年生,而有益真菌Mucor和Bacillus的丰富度却呈相反趋势。同时,有益细菌Flavobacterium和有益真菌Myxocephala、Aspergillus的丰富度随着种植年限的增加呈下降趋势。【结论】三七种植年限的增加,会引起三七根际微生物区系失衡,增加根际病原真菌属的丰度,同时降低一些有益真菌属的丰度。     

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。     

Diversity of Rhizosphere Soil Arbuscular Mycorrhizal Fungi in Various Soybean Cultivars under Different Continuous Cropping Regimes

Recent studies have shown that continuous cropping in soybean causes substantial changes to the microbial community in rhizosphere soil. In this study, we investigated the effects of continuous cropping for various time periods on the diversity of rhizosphere soil arbuscular mycorrhizal (AM) fungi in various soybean cultivars at the branching stage. The soybean cultivars Heinong 37 (an intermediate cultivar), Heinong 44 (a high-fat cultivar) and Heinong 48 (a high-protein cultivar) were seeded in a field and continuously cropped for two or three years. We analyzed the diversity of rhizosphere soil AM fungi of these soybean plants at the branching stage using morphological and denaturing gradient gel electrophoresis (DGGE) techniques. The clustering analysis of unweighted pair-group method with arithmetic averages (UPGMA) was then used to investigate the AM fungal community shifts. The results showed that increasing the number of years of continuous cropping can improve the colonization rate of AM fungi in different soybean cultivars at the branching stage. The dominant AM fungi in the experimental fields were Funneliformismosseae and Glomus spp. The number of years of continuous cropping and the soybean cultivar both had obvious effects on the diversity of AM fungi, which was consistent with the results of colonization rate analysis. This study establishes a basis for screening dominant AM fungi of soybean. In addition, the results of this study may be useful for the development of AM fungal inoculants.     

Effects of the endophyte Epichloë coenophiala on the root microbial community and growth performance of tall fescue in different saline-alkali soils

Soil salinization is detrimental to plant growth and yield in agroecosystems worldwide. Epichloë endophytes, a class of clavicipitaceous fungi, enhance the resistance of host plants to saline-alkali stress. This study explored the effects of the systemic fungal endophyte Epichloë coenophiala on the root microbial community and growth performance of tall fescue (Lolium arundinaceum) growing under different saline-alkali stress conditions. Structural equation modeling (SEM) was conducted to analyze the direct and indirect effects (mediated by root microbial community diversity and soil properties) of the endophyte on the growth of tall fescue under saline-alkali stress. The endophyte-infected plants produced higher shoot and root biomass compared to endophyte-free plants under saline-alkali stress (200 and 400 mM). Endophyte infection increased the fungal community diversity and altered its composition in the roots, decreasing the relative abundance of Ascomycota and increasing that of Glomeromycota. Furthermore, endophyte infection decreased the bacterial community diversity and the relative abundance of dominant Proteobacteria. SEM showed that endophyte infection increased the shoot and root biomass under saline-alkali stress (200 and 400 mM) by increasing the arbuscular mycorrhizal fungal diversity in the roots, and soil total nitrogen and phosphorus concentrations. Therefore, it is important to examine aboveground microbes as factors influencing plant growth in saline-alkali stress by affecting belowground microbes and soil chemical properties.