蚯蚓与丛枝菌根真菌的相互作用及其对植物的影响

蚯蚓和丛枝菌根(Arbuscular mycorrhiza,AM)真菌都是有益的土壤生物,对提高土壤养分有效性和植物吸收利用营养元素具有重要影响。本文综述了蚯蚓对AM真菌取食、传播和侵染的影响、蚯蚓与AM真菌相互作用的效应和机制方面的最新研究进展,以及AM真菌与蚯蚓互作改善植物营养和生长以及协同修复土壤重金属方面的作用,以期为今后研究发展提供依据。     

植物泡囊丛枝菌根及其应用展望

阐述了植物泡囊丛枝菌根（ＶＡ菌根）的形态特征、对植物的营养作用及其与根瘤菌等微生物的关系,分析了环境条件、栽培管理和耕作制度等对ＶＡ菌的影响,提出应加强ＶＡ菌根的基础研究,试验接种外来菌源以及利用土壤的原有菌源,以充分利用ＶＡ菌根这一潜在的生物资源使农作物持续稳定增产。     

植物泡囊丛枝菌根及其应用展望

阐述了植物泡囊丛枝菌根(VA菌根)的形态特征、对植物的营养作用及其与根瘤菌等微生物的关系,分析了环境条件、栽培管理和耕作制度等对VA菌根的影响.提出应加强VA菌根的基础研究,试验接种外来菌源以及利用土壤的原有菌源,以充分利用VA菌根这一潜在的生物资源使农作物持续稳定增产.     

丛枝菌根对芘污染土壤修复及植物吸收的影响

采用温室盆栽试验方法,研究了两种丛枝菌根真菌Glomus mosseae和 Glomus etunicatum对三叶草(Trifolium subterraneum L.)和辣椒（Capsicum annuum L.）修复芘污染土壤的影响。供试土样中芘初始浓度为0 ~ 75.18 mg/kg。结果表明,接种AMF可促进供试植物对土壤中芘的吸收,并且显著提高三叶草根的芘含量、根系富集系数、根和茎叶的芘积累量,但对辣椒根和茎叶芘含量、根系富集系数的影响不显著,这主要与植物的菌根侵染率和“菌根依赖度”不同有关。接种AMF土壤中芘的削减率高于普通植物修复,但植物吸收积累对修复的贡献率小于0.2%;因此推测,AM作用下良好的根际环境对土壤微生物数量和活性的提高、进而对土壤中芘降解的促进可能是菌根修复的主要机理。     

丛枝菌根真菌在植物修复砷污染土壤中的作用

丛枝菌根真菌能增强植物对矿质元素的吸收、提高植物的抗逆性、增强抗病性、改善植物根际微环境,减轻重金属对植物的毒害,影响植物对重金属的吸收和转运,在重金属污染土壤的植物修复中显示出极大的应用潜力。近年来,As污染已成为全球非常突出且急需解决的环境问题之一,对As污染土壤的生物修复也因而成为研究热点。本文主要从丛枝菌根真菌改变土壤pH和酶活性、增强植物对As的耐性和影响植物对As的吸收方面综述了丛枝菌根在As污染土壤修复中应用的研究进展,揭示出菌根应用在As污染土壤中的作用潜力和研究方向。     

丛枝菌根与土壤修复

菌根是真菌与植物根系所建立的互惠共生体, 其中以丛枝菌根在自然界中分布最广。近年来,随着菌根研究的发展,丛枝菌根在土壤修复中的应用日益受到人们的关注。本文综述了丛枝菌根在土壤重金属污染、有机污染、放射污染以及土壤退化修复中的作用,并对当前研究中存在的问题和未来发展前景作了探讨。     

丛枝菌根真菌对西藏高原草地植物和土壤环境的影响

采用三室隔网装置，就Glomus etunicatum、Glomus intraradices、Glomus mossecte对2种高山草地植物和土壤环境的影响进行了研究。结果表明：（1）接种AM真菌对草地植物的侵染和生长均具显著效应，植株地上部、根系干物重以及含磷量、吸磷量均显著高于不接种处理，菌根菌丝对植株吸磷的贡献率达47.8％-69．5％。其中，Glomus intraradices、Glomus mosseae分别对穗序剪股颖、紫羊毛吸收土壤磷索更具促进作用。（2）各接种处理中室土壤中各类微生物数量均显著高于边室土壤，但边室土壤中放线菌，特别是细菌、真菌的平均增幅均远高于中室土壤，表明菌根际、菌丝际土壤中各类微生物的数量差异趋于明显缩小，微生物区系构成得以平衡与改善；解磷细菌（芽孢杆菌）亦呈同一趋势。（3）2—1 mm粒径团聚体在土壤水稳性团聚体构成中占有绝对比重，菌根菌丝对距根表不同距离处2—1 mm团聚体形成的贡献率均在70％以上，但距根表2—4cm处菌根菌丝贡献率明显低于0-2、4-6cm处，并未表现出随菌丝密度增加而提高的趋势；5—2mm水稳性团聚体仅距根表较远处有少量形成（菌丝贡献率达100％），0-2、2—4cm处则未见分布。（4）同一、不同AM真菌对不同或同一草地植物的侵染及所产生的菌根效应具有不同程度的差异，穗序剪股颖各接种处理普遍优于紫羊毛，紫羊毛＋Glomus mosseae、穗序剪股颖＋Glomus intraradices优于同组其他接种处理的趋势较为明显。     

丛枝菌根提高植物耐盐性的研究进展

近年来,土地盐渍化越来越多的引起人们的关注,已成为最常见的农业问题之一,其对人类造成的危害主要是使农作物减产甚至绝收,并间接造成生态环境恶化。研究表明丛枝菌根真菌(Arbuscular Mycorrhiza Fungi,AMF)在盐胁迫下能与很多种植物共生,能够提高植物的耐盐性,促进植物在盐胁迫中生长。因此,探索AMF缓解盐胁迫对植物的危害是近年来生态学和农业生产中的热点问题。综述了AMF在植物干物质的积累、营养吸收、渗透调节、抗氧化酶系统、叶绿素浓度、水分状况、植物激素信号以及一些耐盐相关基因方面国内外最新的研究成果,并对利用AMF提高植物耐盐性相关研究提出了展望,以期为盐碱地的改良及农业生产提供参考依据。     

煤矿区先锋植物猪屎豆接种丛枝菌根的效应研究

以煤矿尾矿区土著先锋植物猪屎豆(Crotalaria pallida Ait.)为研究对象,开展了3种基质配比、4种丛枝菌根接种后的效应研究.结果表明:(1)从宿主生物量、菌根侵染率及侵染强度、50 g干土中的孢子数、根系活力看,A4菌根是最适合梅州明山矿区先锋植物猪屎豆的优势菌种,菌剂与基质优势组合是A4B1;(2)不同菌种、植株及地上部/地下部对镉、锌、铜、镍、锰5种重金属元素的吸收-排斥效应是不同的.从镉元素看,与对照A5相比,A1、A3、A4菌根促进或抑制对镉吸收-排斥效应均达极显著差异水平,这3种菌根结合猪屎豆可作为明山废矿区镉污染丛枝菌根-植物联合修复的优势菌种;4种菌根对促进或阻止铜、锰吸收-排斥效应均不显著;(3)覆土少的(覆2 cm厚黄土于9 cm厚煤矸石上)相应高于不接种且覆土厚(覆7 cm厚黄土于4 cm厚煤矸石上)的,说明接种菌根具有抵消由于覆土少而导致的植株生物量降低的潜力,极大地节约了复垦费用,综合经济效益十分可观.     

砷污染土壤中接种丛枝菌根真菌和蚯蚓对土壤线虫群落和植物砷吸收的影响

The influences of arbuscular mycorrhizal fungi (MF, Acaulospora spp. and Glomus spp.), rice straw and earthworms (RE, Eisenia foetida) on nematode communities and arsenic (As) uptake by maize (Zea mays L.) in As-contaminated soils were examined in a field experiment conducted in Wujiang, Jiangsu Province, China. The experiment was designed as a 2 × 2 factorial with the factors of MF (inoculated or uninoculated) and RE (added or not added). The results demonstrated that MF inoculation led to significantly higher root colonization of MF and root dry weight. Plants inoculated with both MF and RE had the highest As concentrations in root. The number of total nematodes increased with MF inoculation when RE was absent, and decreased with RE addition when MF was inoculated. The improved abundance of nematodes with the MF treatment implied that the tested MF acted as food sources for fungivores. The abundances of omnivores-predators and plant parasites were reduced by earthworm activity. Twenty-seven genera of nematodes were identified, with Filenchus dominant in all treatments. Trophic diversity (TD), Shannon-Weaver diversity (H′), Simpson dominance index (λ), and species richness (SR) indicated higher species diversity, more proportionate species composition, evenly distributed species, and more food sources in the MF, RE, and their interaction treatments. Maturity index (MI) showed a moderately disturbed environment due to As pollution. Besides enhancing plant uptake of contaminants, MF and RE amendments could also improve soil health by restoring the structure of soil communities, as reflected by more stable nematode community structure.     

Dual plant host effects on two arbuscular mycorrhizal fungi

Mycorrhizal fungi may simultaneously associate with multiple plant hosts, and the implications of this for the fungi involved are not well understood. To address this question, two arbuscular mycorrhizal fungi (AMF), Glomus clairoideum (a treatment referred to as “Glo”) and Scutellospora fulgida (a treatment referred to as “Scut”), were grown separately in pots that each consisted of two plant compartments separated by a root-free-compartment (RFC). Fungi within each two-plant-compartment pot were exposed to either two individuals of indiangrass (Sorghastrum nutans), two individuals of big bluestem (Andropogon gerardii), or one of each. A non-inoculated treatment (“Non”) was included to help gauge the potential influence of greenhouse contaminant fungi, cross-contamination, or any misidentification of non-AMF hyphae. The two host species had additive effects on the growth of AM hyphae in plant compartments of Scut, Glo, and Non pots, and in the RFCs of Scut pots. In Glo RFCs, however, they were antagonistic in their effects. Synergism between hosts in Non RFCs suggested that any potential contaminants or misidentification could not explain this result. Underyielding was not seen in shoot weight, root weight, or root length in dual host pots, and also therefore could not explain the result. Hyphal growth in the Scut treatment was evenly distributed between the RFC and plant compartments (or marginally skewed toward the RFC), while hyphal growth in the Glo treatment was skewed toward plant compartments (nearer roots). However, hyphal lengths were more highly correlated across plant compartments within a common pot in the Glo treatment, suggesting that this AMF bridged the RFC to experience the entire two-host pot as a single environment to a greater extent than Scut did. These AMF differed in how they responded to both the species composition of the two-host environment and its spatial structure; potential implications for mycorrhizal community dynamics are discussed.     

AM 菌根真菌诱导对提高玉米纹枯病抗性的初步研究

试验研究玉米接种摩西球囊霉后对纹枯病抗性反应的结果表明,接种摩西球囊霉能明显减轻玉米纹枯病的发病率和病情指数,减轻病害。接种摩西球囊霉还能促进玉米营养生长,但立枯丝核菌侵袭会降低菌根的侵染率,表明摩西球囊霉与立枯丝核菌间存在相互作用。     

丛枝菌根真菌对棉花耐盐性的影响研究

盆栽灭菌试验研究丛枝(AM)真菌对棉花耐盐性的影响结果表明,自然盐渍化土壤和人工模拟盐渍条件下接种AM真菌处理的生物产量显著高于不接种处理,相同土壤下菌根真菌对棉花植株生长的促进作用随盐水平的提高而增大,表明AM真菌与植株建立的共生关系有利于棉花在盐渍土壤中生长。盐胁迫下棉花植株对P的需要量增加,接种AM真菌可提高植株含P量,促进植株生长,提高棉花的耐盐性。     

Global diversity and distribution of arbuscular mycorrhizal fungi

Arbuscular mycorrhizal (AM) fungi form associations with most land plants and can control carbon, nitrogen, and phosphorus cycling between above- and belowground components of ecosystems. Current estimates of AM fungal distributions are mainly inferred from the individual distributions of plant biomes, and climatic factors. However, dispersal limitation, local environmental conditions,and interactions among AM fungal taxa may also determine local diversity and global distributions. We assessed the relative importance of these potential controls by collecting 14,961 DNA sequences from 111 published studies and testing for relationships between AM fungal community composition and geography, environment, and plant biomes. Our results indicated that the global species richness of AM fungi was up to six times higher than previously estimated, largely owing to high beta diversity among sampling sites. Geographic distance, soil temperature and moisture, and plant community type were each significantly related to AM fungal community structure, but explained only a small amount of the observed variance. AM fungal species also tended to be phylogenetically clustered within sites, further suggesting that habitat filtering or dispersal limitation is a driver of AM fungal community assembly. Therefore, predicted shifts in climate and plant species distributions under global change may alter AM fungal communities.     

N,P Contribution and soil adaptability of four arbuscular mycorrhizal fungi

Abstract

A glasshouse study was conducted to investigate the symbiotic efficiency and soil adaptability of four AMF using glass-bead cultivation systems. The results showed that efficiency and adaptability of four fungi varied among three soils. Particularly, efficiency of BEG167 shifted from positive in Beijing soil to negative in Guangdong soil. Furthermore, BEG167 had high adaptability in all three soils. Intraspecific differences of BRG168 and BEG221 were found in efficiency and adaptability in three soils. Taking efficiency and adaptabilty into consideration, it was concluded that BEG167, BEG168 and BEG221 in Beijing soil, BEG151 in Hubei soil, and BEG151 and BEG168 in Guangdong soil were effective AMF for maize.     

Soil tillage and herbicide applications in pea: arbuscular mycorrhizal fungi,plant growth and nutrient concentration respond differently

ABSTRACT

We conducted a field- and pot experiment with peas to investigate the impact of soil tillage and herbicide applications on arbuscular mycorrhizal fungi (AMF), plant growth, phosphorus concentrations, C:N ratio in plants and yield. The field study was carried out in a long-term soil tillage experiment where four tillage treatments have been compared. Field soil from the experimental plots were used for the pot experiment. AMF were not affected by herbicide (MCPB) application, neither in the field nor in the pot experiments. However, AMF root colonization was enhanced by reduced tillage, minimum tillage and no-tillage practices, compared to conventional tillage. In the pot experiment, plant growth and nodulation of pea roots was negatively affected by the high herbicide dosage. In the field experiment neither tillage nor herbicide treatment exert specific effects on root growth parameters, phosphorus concentrations, C:N ratio and plant dry matter. This work demonstrates that an appropriate herbicide usage coupled with conservation soil tillage techniques can favour AMF root colonization and benefit plant growth.

Abbreviations: AMF: arbuscular mycorrhizal fungi; CT: conventional tillage; RT: reduced tillage; MT: minimum tillage; NT: no tillage; P: Phosphorus; C:N ratio: carbon:nitrogen ratio     

Molecular diversity of arbuscular mycorrhizal fungi associated with an Mn hyperaccumulator—Phytolacca americana,in Mn mining area

Arbuscular mycorrhizal fungi (AMF) have great potential for assisting metal-hyperaccumulating plants in the remediation of contaminated soils. However, little information is available about the symbiosis and community composition of AMF associated with manganese (Mn) hyperaccumulator, such as Phytolacca americana, growing on Mn-contaminated soils under natural conditions. Therefore, the objective of this study was to analyze AMF diversity and community composition in P. americana roots growing at an Mn mining site. Molecular techniques were used to analyze AMF community composition and phylogenetic relationship in P. americana roots sampled from three Mn mine spoils and one adjacent reference areas. Results obtained showed that mycorrhizal symbionts successfully established even in the most heavily Mn-polluted sites. Root colonization and AMF diversity were significantly negatively correlated with total and extractable Mn concentrations. Principal component analysis (PCA) revealed that Mn contamination impacted AMF diversity, and shaped AMF community structure. Phylogenetic analyses demonstrated that all species were affiliated with Glomus, suggesting that Glomus was the dominant genus in this AMF community. Some unique sequences that occurred exclusively in heavily polluted sites associated with P. americana may belong to symbiotic fungi with great potential for improving the phytoremediation efficiency of Mn-contaminated soils.     

AM菌对三叶草吸收、累积重金属的影响

采用4室根箱培养系统,探讨了Cu、Zn、Pb、Cd 4种重金属复合污染土壤中,丛枝菌根菌对三叶草生长及吸收、累积重金属的作用,结果表明:重金属Cu 100mg/kg、Zn 600mg/kg、Pb 300mg/kg、Cd 10mg/kg的复合污染对三叶草生物量影响较小,但土壤重金属处理使丛枝菌根菌Glomus intraradices和Glomus caledonium对三叶草的侵染率分别降低53%和56%,菌种G.intraradice的菌丝密度降低73%;接种菌根真菌能明显减少重金属复合污染土壤中三叶草对Cu、Cd和Pb的吸收,并强化根系在限制重金属Pb和Cd向地上部运输中的作用,地上部Pb和Cd含量分别下降24.2%~55.3%和65%~97.9%,使三叶草地上部Cd和Pb含量均低于我国牧草重金属安全含量,提高了三叶草可食部分的质量;不同菌根真菌对三叶草吸收、累积及分配重金属的影响有明显差异,Glomus intraradices对减少三叶草对重金属的吸收及其在地上部可食部分的累积的作用大于Glomus caledonium。丛枝菌根菌对于强化三叶草根系对重金属的固持作用,调节生态系统中重金属的生物循环,减轻重金属对食物链的污染风险方面起着重要作用。     

多样化培肥模式调控丛枝菌根真菌促进玉米磷素吸收

利用丛枝菌根真菌（Arbuscular mycorrhizal fungi，AMF）从农田生态系统获取养分，是红壤作物吸收土壤磷（P）素的有效途径。针对我国南方红壤生物功能退化、P素生物有效性低、作物产量低等问题，如何调控作物根际AMF群落，优化其与宿主的互惠共生关系，是打破红壤区作物P摄取瓶颈的关键。本研究结合红壤旱地生态间作与有机（秸秆、猪粪、生物肥）无机肥料配施的4种多样化培肥措施，基于作物产量和红壤磷素活化水平，筛选最优培肥模式。进一步利用扩增子高通量测序和显微观察等技术，解析红壤旱地最优培肥措施调控AMF群落组成，揭示优化的AMF群落激发宿主玉米P素摄取机理。结果表明，花生/玉米间作结合秸秆/生物肥的有机无机配施（In+NPKSB）相较于其他培肥方式使红壤旱地全磷（TP）提高29.07%、有效磷（AP）提升1.35倍，且增强了玉米根内AMF群落科水平间的联系。该措施AMF定殖率是传统培肥措施的2.24倍，提高玉米根际酸/碱性磷酸酶（ACP/ALP）活性32.18%和41.66%，玉米生物量提高34.98%，产量提高67.27%。本研究证实红壤旱地花生/玉米生态间作结合秸秆/生物肥有机无机配施的培肥措施可通过优化玉米根内AMF群落组成，促进土壤P素活化，为在红壤旱地因地制宜推广可持续农业发展的集成应用提供理论依据。     

AM真菌接种对甘薯产量和品质的影响

通过田间试验方法研究了接种AM真菌对甘薯产量和品质的影响。结果表明,种植6周时接种能够提高甘薯的菌根侵染率、生长和吸P量,收获时可提高甘薯的产量和品质。从接种效果看,本地分离的菌株接种效果好于异地分离菌株,混合菌株好于单一菌株。