陆地农业生态系统丛枝菌根真菌物种多样性研究进展

丛枝菌根真菌(AMF)是一种古老的、在自然界中普遍存在的土壤微生物,能与大部分陆生植物形成互惠互利的菌根共生体.在这种共生关系中,AMF从植物获取自身生长所需碳源的同时,帮助宿主吸收氮、磷等营养物质.AMF在农业生态系统中具有重要作用,能够促进植物生长、改善作物品质、提高植物抗逆性、稳定土壤结构、维护生态平衡和维持农业可持续发展.本文总结了近几年来陆地农业生态系统AMF的研究进展,着重从我国陆地农业生态系统AMF物种多样性、AMF生物多样性时空分布特征及影响AMF多样性的因素等几个方面,综述了陆地农业生态系统AMF的物种多样性,并对以后的研究进行了展望.     

丛枝菌根真菌影响作物非生物胁迫耐受性的研究进展

土壤中存在着大量不同种类的微生物资源,土壤微生物能够与自然界中的大多数植物密切合作,其中丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)起着十分重要的作用。近年来,对于AMF的研究越来越多。AMF是存在于土壤中的重要真菌之一,是土壤中的菌根真菌菌丝与高等植物营养根系形成的一种联合体。AMF可以与陆地上90%左右的植物根系形成共生体,通过在植物根系形成重要的“丛枝菌根”结构而为植物提供更多的养分。为了了解接种AMF对作物生长过程中耐受一些非生物胁迫(如干旱、极端温度、重金属污染、盐分、不利的土壤pH变化等)性能方面的影响,基于之前接种AMF对养分胁迫下玉米生长影响的研究,在扩大作物品种的基础上,通过查阅大量文献,结合试验研究及对前人和近年来关于AMF的一些最新研究进展,获得了具有实践性意义的新发现：AMF与植物共生有助于植物生长,可以改善植物的营养状况,并且可以保护植物免受各种非生物环境胁迫的影响。由此可以得出结论：AMF通过各种机制改善植物生长状况,提高作物抗逆性,为作物增产、农民增收创造了福利,并且避免了由于肥料过量施用导致的一些污染环境问题。本文主要综述了接种AMF在各种非生物环境胁迫(干旱、极端温度、重金属污染、盐分、不利的土壤pH变化等)条件下对植株生长和发育的有利影响,并对目前存在的不足和今后研究的重点提出几点建议。     

丛枝菌根真菌(AMF)对植物群落调节的研究进展

1 引言 菌根(mycorrhiza)是土壤中的菌根真菌与高等植物营养根系形成的一种共生体,菌根的个主要的类型(即外生菌根Ectomycorrhiza、内生菌根Endomycorrhiza、内外生菌根Ectendomycorrhiza)中,内生性的丛枝状菌根(Vesicular-Arbuscular mycorrhiza,AM)是分布最广泛、最普遍的一类菌根。土壤中的丛枝菌根真菌(Abuscular mycorrhizal fungi, AMF)与高等植物营养根系形成丛枝菌根(abuscular mycorrhiza, AM),能促进宿主对土壤中矿质元素P、NK、Cu、Zn等的吸收,提高宿主根系对根部侵染病菌的抵抗能力和增强植物对干旱、高温、高盐和…     

丛枝菌根利用氮素研究进展

氮素是植物需求量最大的元素,丛枝菌根真菌与植物形成共生体后能从土壤中获取无机氮、简单的氨基酸,还能利用一些复杂的有机态氮.考虑到NH+4在土壤中的移动性低及丛枝菌根真菌的专性共生菌的特点,丛枝菌根真菌吸收NH+4对植物的贡献较大.近年来的研究发现丛枝菌根真菌内存在与氮素代谢有关的鸟氨酸循环,而精氨酸则是菌丝内氮素转移的主要形式.综述最近的AMF对氮素的吸收、转运、同化、交换等方面的文献,旨在揭示丛枝菌根真菌氮素利用特点,阐明丛枝菌根真菌在氮循环系统中的重要作用.     

丛枝菌根对有机污染土壤的修复作用及机理

丛枝菌根(AM)是丛枝菌根真菌(AMF)与植物根系相互作用的互惠共生体,能改良土壤结构,增强植物抗性.自然界中已知的AMF有170多种,分布广泛,且可与大多数植物共生.利用AM修复有机污染土壤正成为一个崭新的研究方向.本文综述了AM对多环芳烃、酞酸脂、石油和农药等一些典型有机污染物污染土壤的修复作用.AM修复有机污染土壤的机理主要包括:AMF代谢有机污染物;AM分泌酶,降解污染物;AM影响根系分泌作用,并促进根际微生物对有机污染物的降解;AMF宿主植物吸收积累污染物.AM修复研究中,高效AMF的筛选、复合菌种效应、土壤老化、AM作用下植物对有机污染物的吸收积累等几方面仍有待于深入研究.     

丛枝菌根真菌对小麦生长的影响

为了促进经济作物小麦的生长,提高土壤氮磷循环与转化效率,选择两种优良丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF)——摩西球囊霉(GM,Glomus mosseae)、根内球囊霉(GI,Glomus intraradices),研究AMF在小麦整个营养生长阶段中对其生长以及对土壤中植物生长需求的大量元素——氮、磷的作用及影响。结果表明:人工施加菌剂可显著提高AMF对小麦的侵染率,施加GM菌剂时,小麦侵染率提高24.54%,同时,株高提高14.08%,小麦地上生物量提高24.05%。GM效果优于GI。施加菌剂后,小麦侵染率与土壤中水解性氮呈显著正相关;植物地上生物量与土壤中总氮,水解性氮呈显著负相关。表明AMF可活化土壤中的氮元素,同时促进作物生长,强化对土壤中氮元素的利用。     

丛枝菌根对植物根际逆境的生态学意义

近年来,我国在菌根分子生物学、菌根营养学、菌根分类学和菌根生态学等方面取得了令人瞩目的研究成果,其中对丛枝菌根真菌(AMF)的研究居多。AMF能与大部分陆地植物根系形成共生关系,促进植物生长发育,提高植物抗逆性,在保持生态平衡、保护生态环境等方面发挥重要作用。本文主要从非生物胁迫(干旱胁迫、重金属污染、盐碱胁迫)和生物胁迫(致病菌和线虫侵染)方面介绍了AMF在植物根际逆境中发挥的生态功能及作用机制,提出了该研究领域尚存的不足之处和研究前景,为AMF后续研究提供参考。     

丛枝菌根真菌参与下植物-土壤系统的养分交流及调控

近几年随着有机农业的发展,丛枝菌根的作用受到特别关注。丛枝菌根是由植物根系与丛枝菌根真菌(AMF)形成的一种共生体。在植物-AMF-土壤系统中,AMF为植物提供N、P等营养的同时从根系得到所需的C。概述了植物-AMF-土壤系统中C、N、P等营养物质的交流以及AMF与土壤微生物的互作关系。丛枝菌根的形成可显著提高植物对P的吸收,且在高P条件下多余的P可储存于AMF中。AMF对土壤N循环的影响相当复杂,可能参与调控N循环的多个过程,如硝化作用、反硝化作用和氨氧化作用等。在有机质丰富的土壤中AMF菌丝可快速扩增并吸收其中的N,主要供菌丝自身所需,只有一小部分传递给植物。AMF对土壤C库的影响尚存争议,可能存在时间尺度的差异。短期内可活化土壤C,而在长期尺度上可能有利于土壤C的储存。AMF能够通过改变土壤微生物群落结构而影响植物-土壤体系的物质交流。AMF与解磷菌、根瘤菌和放线菌的协同增效作用可促进土壤有机质的降解或增强其固氮能力;AMF对氨氧化菌的抑制作用可降低氨的氧化减少N2O的释放。AMF与外生共生真菌EMF共存时,表现出协同增效作用,但EMF的优先定殖会限制AMF的侵染。AMF不同类群之间则主要表现为竞争和拮抗关系。AMF与土壤微生物之间的互作关系受土壤无机环境的影响,在养分亏缺条件下微生物之间往往表现为竞争关系。因植物、AMF与土壤微生物之间存在复杂的互作关系,为此AMF并不总是表现出其对植物营养的促进作用。目前关于AMF的作用机理仍以假说为主,需要进一步的实验验证。在植物-AMF-土壤系统中N与C的交流和P与C的交流并未表现出一致性,对N、P循环相互关系的进一步探讨有助于深入理解植物-土壤体系中的养分循环。植物、AMF和土壤微生物的养分来源及其对养分的相对需求强度和吸收效率尚未可知,因此无法深入理解AMF在植物-土壤体系中养分交流和转化的作用。在方法上,传统的土壤学方法在养分动态研究中存在局限性,现代分子生物学手段和化学计量学的结合值得尝试。     

丛枝菌根途径的土壤有机碳固存机制研究进展

菌根真菌已被认为是土壤碳库的重要部分,陆地植物中至少78%与丛枝菌根真菌(AMF)形成共生关系,故研究AMF途径的土壤有机碳(SOC)固存机投对提高生态系统碳汇具有重要意义,但目前缺乏系统探讨AMF途径的SOC固碳机制。AMF具有显著的生态特性,包括较根系更高的周转速度、广泛的菌丝扩展范围以及将代谢产物转化为土壤中的稳定碳源等,这些特征共同构成了AMF在固碳机制中的作用路径。AMF从植物根系获得碳源,经过菌丝生长、代谢产物(尤其球囊霉素相关蛋白)和残体形成,将其转化为AMF源碳。AMF的根外菌丝还能与其他微生物共存并协同作用,通过分解凋落物、促进微生物的合成代谢及其物质周转,不仅增加植物源碳输入和微生物源碳积累,还促进团聚体形成,有效保护土壤中的碳不被分解,从而实现AMF途径的土壤碳固存。AMF途径的土壤固碳能力在森林、草地和农田依次减弱,这与气候变化、土壤的生物与非生物因素、地下的共生菌根网络及人类活动紧密相关。还探讨了这些因素对AMF途径SOC固存的影响,并针对现有研究的不足提出了未来的研究展望。本综述以期更深入地理解AMF途径的SOC固存机制,为菌根途径提升生态系统碳汇能力的研究提供理论支持。     

金沙江支流普渡河、小江干热河谷的丛枝菌根

调查具有不同植物群落的金沙江支流普渡河、小江干热河谷中91种常见植物的丛枝菌根真菌的侵染率及孢子密度。普渡河样地调查了56种植物,其中54种(96%)植物能形成典型的丛枝菌根,其平均孢子密度为1423±175/100g土;小江样地35种植物中有34种(97%)植物能形成典型的丛枝菌根,其平均孢子密度为601±103/100g土。单因素方差分析表明两个样地植物的AMF总感染率差异不显著,但其根际土壤中AMF孢子密度却存在显著差异,小江样地的AMF孢子密度明显低于普渡河样地。相关性分析表明,干热河谷植物的AMF感染率与其根际土壤中的AMF孢子密度之间不存在相关性。此外,调查还发现91种植物中,有61种植物(67%)在形成AM的同时,也被黑色有隔内生菌感染。     

Isolate Identity Determines Plant Tolerance to Pathogen Attack in Assembled Mycorrhizal Communities

Arbuscular mycorrhizal fungi (AMF) are widespread soil microorganisms that associate mutualistically with plant hosts. AMF receive photosynthates from the host in return for various benefits. One of such benefits is in the form of enhanced pathogen tolerance. However, this aspect of the symbiosis has been understudied compared to effects on plant growth and its ability to acquire nutrients. While it is known that increased AMF species richness positively correlates with plant productivity, the relationship between AMF diversity and host responses to pathogen attack remains obscure. The objective of this study was to test whether AMF isolates can differentially attenuate the deleterious effects of a root pathogen on plant growth, whether the richest assemblage of AMF isolates provides the most tolerance against the pathogen, and whether AMF-induced changes to root architecture serve as a mechanism for improved plant disease tolerance. In a growth chamber study, we exposed the plant oxeye daisy (Leucanthemum vulgare) to all combinations of three AMF isolates and to the plant root pathogen Rhizoctonia solani. We found that the pathogen caused an 81% reduction in shoot and a 70% reduction in root biomass. AMF significantly reduced the highly deleterious effect of the pathogen. Mycorrhizal plants infected with the pathogen produced 91% more dry shoot biomass and 72% more dry root biomass relative to plants solely infected with R. solani. AMF isolate identity was a better predictor of AMF-mediated host tolerance to the pathogen than AMF richness. However, the enhanced tolerance response did not result from AMF-mediated changes to root architecture. Our data indicate that AMF communities can play a major role in alleviating host pathogen attack but this depends primarily on the capacity of individual AMF isolates to provide this benefit.     

Relatedness among arbuscular mycorrhizal fungi drives plant growth and intraspecific fungal coexistence

Arbuscular mycorrhizal fungi (AMF) form symbioses with most plant species. They are ecologically important determinants of plant growth and diversity. Considerable genetic variation occurs in AMF populations. Thus, plants are exposed to AMF of varying relatedness to each other. Very little is known about either the effects of coexisting AMF on plant growth or which factors influence intraspecific AMF coexistence within roots. No studies have addressed whether the genetics of coexisting AMF, and more specifically their relatedness, influences plant growth and AMF coexistence. Relatedness is expected to influence coexistence between individuals, and it has been suggested that decreasing ability of symbionts to coexist can have negative effects on the growth of the host. We tested the effect of a gradient of AMF genetic relatedness on the growth of two plant species. Increasing relatedness between AMFs lead to markedly greater plant growth (27% biomass increase with closely related compared to distantly related AMF). In one plant species, closely related AMF coexisted in fairly equal proportions but decreasing relatedness lead to a very strong disequilibrium between AMF in roots, indicating much stronger competition. Given the strength of the effects with such a shallow relatedness gradient and the fact that in the field plants are exposed to a steeper gradient, we consider that AMF relatedness can have a strong role in plant growth and the ability of AMF to coexist. We conclude that AMF relatedness is a driver of plant growth and that relatedness is also a strong driver of intraspecific coexistence of these ecologically important symbionts.     

Arbuscular mycorrhizal fungi in two mangroves in South China

The symbiosis between arbuscular mycorrhizal fungi (AMF) and mangrove plant species was investigated in two mangrove swamps in south China. AMF were mostly found in the form of hyphae and were commonly associated with all the mangrove species we investigated. Six AMF species belonging to the genera Glomus or Acaulospora were identified. Multiple step-wise linear regression analyses showed that hydrological conditions and phosphorus levels in the rhizosphere were the main abiotic factors affecting the colonization of mangrove species by AMF. A greenhouse experiment was conducted to evaluate the effects of AMF inoculation on the growth and nutrient uptake of a true mangrove plant species, Sonneratia apetala B. Ham. The inoculated AMF significantly improved growth, resulting in greater plant height, diameter at ground level and plant biomass, as well as increased absorption of N, P and K. These findings suggest that AMF play important roles in mangrove ecosystems.     

Variable responses of old-field perennials to arbuscular mycorrhizal fungi and phosphorus source

If arbuscular mycorrhizal fungi (AMF) promote phosphorus partitioning of plant hosts, they could provide one mechanism for the maintenance of plant community diversity. We investigated whether AMF improved the ability of old field perennials to grow on a range of phosphorus sources and whether AMF facilitated differential performance of plant species on different phosphorus sources (phosphorus niche partitioning). We manipulated form of phosphorus (control versus different inorganic and organic sources) and AM fungal species (control versus four individual AMF species or an AMF community) for five old field perennials grown in a greenhouse in individual culture. Based on biomass after four months of growth, we found no evidence for phosphorus niche partitioning. Rather, we found that effects of AMF varied from parasitic to mutualistic depending on plant species, AMF species, and phosphorus source (significant Plant × Fungus × Phosphorus interaction). Our results suggest that the degree of AMF benefit to a plant host depends not only on AMF species, plant species, and soil phosphorus availability (as has also been found in other work), but can also depend on the form of soil phosphorus. Thus, the position of any AMF species along the mutualism to parasitism continuum may be a complex function of local conditions, and this has implications for understanding plant competitive balance in the field.     

Current developments in arbuscular mycorrhizal fungi research and its role in salinity stress alleviation: a biotechnological perspective

Arbuscular mycorrhizal fungi (AMF) form widespread symbiotic associations with 80% of known land plants. They play a major role in plant nutrition, growth, water absorption, nutrient cycling and protection from pathogens, and as a result, contribute to ecosystem processes. Salinity stress conditions undoubtedly limit plant productivity and, therefore, the role of AMF as a biological tool for improving plant salt stress tolerance, is gaining economic importance worldwide. However, this approach requires a better understanding of how plants and AMF intimately interact with each other in saline environments and how this interaction leads to physiological changes in plants. This knowledge is important to develop sustainable strategies for successful utilization of AMF to improve plant health under a variety of stress conditions. Recent advances in the field of molecular biology, “omics” technology and advanced microscopy can provide new insight about these mechanisms of interaction between AMF and plants, as well as other microbes. This review mainly discusses the effect of salinity on AMF and plants, and role of AMF in alleviation of salinity stress including insight on methods for AMF identification. The focus remains on latest advancements in mycorrhizal research that can potentially offer an integrative understanding of the role of AMF in salinity tolerance and sustainable crop production.     

Transmembrane H + and Ca 2+ fluxes through extraradical hyphae of arbuscular mycorrhizal fungi in response to drought stress

丛枝菌根真菌(AMF)能够和大多数陆地植物形成共生体系, 对于植物生长发育和适应各种逆境胁迫具有重要作用。很多研究表明干旱胁迫下AMF能够促进宿主植物对水分的吸收从而增强植物抗旱能力, 但目前针对AMF根外菌丝响应水分胁迫的生理变化以及AMF与宿主植物逆境信号交流的研究并不多。该研究利用AMF Rhizophagus irregularis和胡萝卜(Daucus carota var. sativa)毛状根双重无菌培养体系获得纯净根外菌丝, 向培养基添加聚乙二醇(PEG)模拟干旱胁迫, 运用场发射扫描电子显微镜(FE-SEM-EDS)观察干旱胁迫对AMF根外菌丝形态的影响, 同时采用非损伤微测技术(NMT)观测根外菌丝跨膜H ⁺和Ca ²⁺离子流变化。结果发现, PEG处理1 h后菌丝尖端和侧面发生H ⁺外流和强烈的Ca ²⁺内流, 荧光探针分析也显示菌丝胞内pH值显著上升、Ca ²⁺浓度增加; PEG处理24 h后菌丝形态发生明显变化, 培养基pH值降低, P、Ca、Fe等元素在菌丝际积累。这些试验结果表明, 干旱胁迫下AMF根外菌丝跨膜H ⁺和Ca ²⁺流发生变化, 促进了菌丝与环境之间的物质交换。菌丝酸化生长环境有利于养分吸收, 并促进AMF与宿主植物之间的信号交流以增强植物的耐旱性。     

Plant mortality varies with arbuscular mycorrhizal fungal species identities in a self-thinning population

Because arbuscular mycorrhizal fungal (AMF) species differ in stimulating the growth of particular host plant species, AMF species may vary in their effects on plant intra-specific competition and the self-thinning process. We tested this hypothesis using a microcosm experiment with Medicago sativa L. as a model plant population and four AMF species. Our results showed that the AMF species Glomus diaphanum stimulated host plant growth more than the other three AMF species did when the plants were grown individually. Glomus diaphanum also induced the highest rate of mortality in the self-thinning plant populations. We also found a positive correlation between mortality and growth response to colonization. Our results demonstrate that AMF species can affect plant mortality and the self-thinning process by affecting plant growth differently.     

丛枝菌根真菌与深色有隔内生真菌生态修复功能与作用

生态修复是目前全球关注的热点问题,如何增加植被的覆盖度及生态修复效率是目前研究的重点。丛枝菌根真菌(arbuscular mycorrhiza fungi,AMF)和深色有隔内生真菌(dark septate endophyte,DSE)均是自然界植物根际分布广泛的一类内生真菌,均能与植物形成菌根共生体,具有一定的促进植物生长、抵抗逆境及修复污染土壤等功能与作用,在生态修复中具有广泛的应用潜力。本文综述了AMF及DSE两种微生物的功能、作用及其在生态修复应用中的研究进展,并进一步对AMF和DSE在生态修复中存在的问题和前景进行展望。     

Arbuscular mycorrhizal fungi alter plant community composition along a grazing gradient in Inner Mongolia Steppe

Arbuscular mycorrhizal fungi (AMF) have a significant influence on plant productivity and diversity in non-grazing grassland. However, the interactive effects between grazing intensity and AMF on plant community composition in natural grassland communities are not well known. We conducted a field experiment that manipulated AMF colonization and grazing intensity to study the impact of AMF suppression on plant community composition and nutrient status over 2 years (2015–2016) with contrasting rainfall levels. We found that AMF root colonization was significantly reduced by the application of the fungicide benomyl as a soil drench. Grazing intensity regulated plant community composition and aboveground biomass mainly by reducing the growth of Leymus chinensis over 2 years. AMF suppression increased the growth of Chenopodium glaucum, but it did not alter other plant species across all grazing intensities. The effects of AMF suppression on plant community composition changed along a grazing gradient considerably between years: AMF suppression increased the biomass of C. glaucum across all grazing intensities in 2015, but slightly increased it in 2016. Interactions between AMF suppression and grazing intensity altered the phosphorus concentration of Stipa grandis and Cleistogenes squarrosa in 2015 but not in 2016. AMF suppression decreased the shoot phosphorus content of L. chinensis but increased that of C. glaucum across all grazing intensities. Our results indicate that grazing intensity substantially alters aboveground community biomass and affects growth of dominant species; AMF by itself have limited effects on plant communities along a grazing gradient in typical steppe.