The contribution of arbuscular mycorrhizal fungi in sustainable maintenance of plant health and soil fertility

Beneficial plant-microbe interactions in the rhizosphere are primary determinants of plant health and soil fertility. Arbuscular mycorrhizas are the most important microbial symbioses for the majority of plants and, under conditions of P-limitation, influence plant community development, nutrient uptake, water relations and above-ground productivity. They also act as bioprotectants against pathogens and toxic stresses. This review discusses the mechanism by which these benefits are conferred through abiotic and biotic interactions in the rhizosphere. Attention is paid to the conservation of biodiversity in arbuscular mycorrhizal fungi (AMF). Examples are provided in which the ecology of AMF has been taken into account and has had an impact in landscape regeneration, horticulture, alleviation of desertification and in the bioremediation of contaminated soils. It is vital that soil scientists and agriculturalists pay due attention to the management of AMF in any schemes to increase, restore or maintain soil fertility.     

Patterns of effects of arbuscular mycorrhizal fungi on plants grown in contaminated soil

Arbuscular mycorrhizal fungi (AMF) are integral functioning parts of plant root systems and are widely recognized for enhancing plant growth on severely disturbed sites, including those contaminated with heavy metals. However, the generality of detailed patterns observed for their influence on various metals and oxidative‐stress parameters in multiple plant species is not clarified. The goal of this study was to investigate the patterns of metal‐stress alleviation by AMF in four plant species. For this purpose, clover, sunflower, mustard, and phacelia were inoculated with Glomus intraradices and compared to noninoculated plants grown under heavy metal–stressed conditions. The study focused on the effect of AMF inoculation on plant biomass, assimilating pigments, total protein, superoxide dismutase and peroxidase activity, lipid peroxidation and As, Cd, Co, Cu, Fe, Mn, P, Pb, U, and Zn contents. As a result of inoculation very different patterns of variation were obtained for concentrations of elements and for biochemical parameters in plants. The particular effect of AMF inoculation on plants was species‐ and metal‐specific, although there was a general enhancement of plant growth.     

Cumulative effects of tree-based intercropping on arbuscular mycorrhizal fungi

In tree-based intercropping system (agroforestry), the role of perennial trees in maintaining active populations and mycelial networks of arbuscular mycorrhizal fungi (AMF) is well documented. Agroforestry positively influences the AMF community, but complete studies regarding mycorrhization in such systems are scarce. The present study was conducted to assess the effect of tree introduction in agriculture fields on mycorrhization. In particular, we investigated the effect of trees on AMF colonization of intercrops and vice versa, the effect of canopy management of trees on their root colonization, and the cross-infectivity of AMF isolated from tree rhizosphere in intercrops and vice versa. The results of the field study suggest that in agroforestry systems, trees acted as AMF inoculum reservoir for intercrops, especially during the rainy season. Intercropping (Phaseolus mungo and Triticum aestivum in the rainy and winter seasons, respectively) increased mycorrhization, i.e., root colonization and spore population in the rhizosphere of Albizia procera and Eucalyptus tereticornis. Canopy management, i.e., shoot pruning, reduces root colonization in A. procera, Anogeissus pendula, Dalbergia sissoo, Hardwickia binata, and Tectona grandis, especially in April 2005 (late spring), but during subsequent periods, differences among the treatments were at par. Results from greenhouse suggest that AMF are nonspecific in their selection of host since species isolated from tree rhizosphere could colonize the roots of crops and vice versa.     

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.     

Potential of arbuscular mycorrhizal fungi for soil health: A review

Soil health is an important component of “One Health”. Soils provide habitat to diverse and abundant organisms. Understanding microbial diversity and functions is essential for building healthy soils towards sustainable agriculture. Arbuscular mycorrhizal fungi (AMF) form potentially symbiotic associations with approximately 80% of land plant species that are well recognized for carbon flux and nutrient cycling. In addition to disentangling the signaling pathways and regulatory mechanisms between the two partners, recent advances in hyphosphere research highlight some emerging roles of AMF and associated microbes in the delivery of soil functions. This paper reviews the contribution of AMF to soil health in agroecosystems, with a major focus on recent progress in the contribution of hyphosphere microbiome to nutrient cycling, carbon sequestration, and soil aggregation. The hyphosphere microbiome and fungal stimulants open avenues for developing new fertilizer formulas to promote AMF benefits. In practice, developing AMF-friendly management strategies will have long-term positive effects on sustainable agriculture aiming at simultaneously providing food security, increasing resource use efficiency, and maintaining environment integrity.     

Disentangling the contributions of arbuscular mycorrhizal fungi to soil multifunctionality

Soil multifunctionality represents a range of soil processes driven by the interactions between soil abiotic and biotic components. As a group of ubiquitous fungi that form mutualistic symbiotic associations with a vast array of terrestrial plants, arbuscular mycorrhizal (AM) fungi may play a critical role in maintaining soil multifunctionality, but the characteristics of their contributions remain to be unraveled. This mini review aims to disentangle the contributions of AM fungi to soil multifunctionality. We provide a framework of concepts about AM fungi making crucial contributions to maintaining multiple soil functions, including primary productivity, nutrient cycling, water regulation and purification, carbon and climate regulation, habitat for biodiversity, disease and pest control, and pollutant degradation and detoxification, via a variety of pathways, particularly contributing to soil and plant health. This review contends that AM fungi, as a keystone component of soil microbiome, can govern soil multifunctionality, ultimately promoting ecosystem services.     

菌根与根瘤菌联合应用对复垦矿区根际土壤环境的改良后效

为了进一步确定微生物复垦对土壤的持续修复能力,在神东矿区活鸡兔开采沉陷试验基地,接种丛枝菌根真菌和大豆根瘤菌改良农用地土壤,已取得了较好的微生物复垦效果,经过2 a的退耕撂荒以后,对微生物复垦后效进行系统地研究。研究结果表明,撂荒后,接菌小区根外菌丝密度、根系侵染率和pH值均显著高于对照小区,分别比对照提高了90%、52%和1.3%;接菌小区细菌数量、微生物总量、有效磷含量、电导率和酸性磷酸酶活性也明显高于对照小区,但差异不显著。撂荒后与撂荒前相比,土壤呈退化趋势,但接菌小区菌丝密度几乎增加了1倍,差异显著,同时侵染率、细菌数量和酸性磷酸酶活性均明显升高,差异不显著;而在对照小区中,菌丝密度稍有增加,侵染率、细菌数量和酸性磷酸酶活性均明显降低,且差异不显著。利用丛枝菌根真菌与大豆根瘤菌联合作为绿色环保肥料,能够有效改善根际土壤环境,减轻土壤的退化程度,在弃耕状态下也能发挥良好的效用,对土地贫瘠的开采沉陷地进行生态修复具有重大意义。     

丛枝菌根真菌对玉米生长生态效应的影响

1996～1998年试验研究了大田不施肥条件下3种泡囊丛枝菌根真菌Arbuscular mycorrhizal fungi (AMF),即 Glomus mosseae(G.m)、Glomus versifome(G.v)、Sclerocystis sinousa(S.s)对玉米生长的生态效应.结果表明,AMF处理的玉米根系活力为对照的2.32～3.05倍,玉米N素吸收比对照增加24.14%～56.65%,玉米P素吸收比对照增加41.14%～78.29%,促进玉米生长发育显著;在灭菌条件下G.m、G.v、S.s处理分别比对照增产17.63%、22.91%和10.80%;而不灭菌条件下3个处理分别比对照增产10.35%、20.56%和4.53%,同时显著提高玉米的水分供应状况.     

丛枝菌根真菌领域专利情报分析

丛枝菌根真菌 (AMF) 与植物共生在提高植物的抗逆性、抗病性和维护植物健康方面发挥着关键作用,其在农业、林业和生态环境等方面的应用受到广泛关注。本研究基于incoPat科技创新情报平台,检索了2019年前国内外丛枝菌根真菌的专利产出,对专利申请数量、主要申请人、技术构成等方面进行了分析,以揭示国内外丛枝菌根真菌领域的研发状况、技术发展趋势和产学研合作情况。近年来,中国丛枝菌根真菌领域专利数量急剧增加,AMF产品化不断加强,AMF应用领域从农业领域向污染修复领域拓展,结合现代生物、信息技术等新兴技术的AMF检测技术和研究方法正在快速发展,新的研发充分考虑了AMF产品化和应用的结合;我国在丛枝菌根真菌领域的专利申请人多隶属高校和科研院所,企业参与度较低。AMF菌种扩繁和污染修复领域的应用已成为焦点,生物和信息新技术成果正引入AMF检测技术的开发;中国在丛枝菌根真菌领域的产学研合作研发亟需加强。     

转Bt基因作物对丛枝菌根真菌的影响研究进展

在过去的十年里，世界范围内转基因作物尤其是抗虫性转Bt基因作物的品种和种植面积迅速增加。同时，转Bt基因作物的环境安全性评价问题成为人们关注和研究的热点。丛枝菌根真菌（AMF）是生态系统中普遍存在的土壤微生物，能与绝大多数植物种类形成共生关系，在农业生态系统中起重要作用。转Bt基因作物环境释放后，其与AMF问的共生关系是否受所转入Bt基因的影响，以及影响机制需要及时研究。为此，综述了转Bt基因作物与AMF共生特征方面的研究进展，并根据Bt毒素发生的空间和时间规律提出了危害机制以及转Bt基因植物的规模化种植将降低农田系统中的AMF的生物多样性的观点。     

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.     

AM 真菌对蔬菜品质的影响

大田生产条件下试验研究丛枝菌根（Arbuscular mycorrhiza，AM）真菌4个高效菌种Glomus mosseae、Glo-mus versiforme、Gigaspora rosea 和Sclerocystis sinousa对西瓜、黄瓜、芋头和菜豆品质的影响结果表明，AM真菌能显著提高这些蔬菜维生素C、氨基酸、粗蛋白等营养成分含量，接种Glomus mosseae处理可分别增加菜豆维生素C含量25％、磷63％，芋头粗蛋白19％、氨基酸总量24％，黄瓜可溶性糖20％、磷26％、粗蛋白40％，西瓜可溶性固形物25％、维生素C32％。     

Suppression of other soil microorganisms by mycelium of arbuscular mycorrhizal fungi in root-free soil

The influence of mycelium of two arbuscular mycorrhizal (AM) fungi, Glomus intraradices and Glomus mosseae, on other soil microorganisms, was examined in root-free soil with and without organic substrate amendment in terms of cellulose. The AM fungi were grown in symbiosis with cucumber in a compartmented growth system, which allowed AM fungal external mycelium to grow into root-free compartments. The fungicide Benomyl was applied to the root-free compartments to create an alternative non-mycorrhizal control treatment. Whole cell biomarker fatty acids were employed to quantify different groups of soil microorganisms including the two AM fungi. Abundance of most microbial groups were reduced by external mycelium of both AM fungi, though differential effects on the microbial community composition were observed between the two AM fungi as revealed from principal component analysis. Inhibition of other soil microorganisms was more pronounced in root-free soil with mycelium of G. mosseae than with mycelium of G. intraradices. In general, cellulose increased the amount of biomarker fatty acids of most groups of soil microorganisms, but cellulose did not affect the influence of AM fungi on other soil microorganisms. Benomyl suppressed growth of the external mycelium of the two AM fungi and had limited non-target effects on other microbial groups. In conclusion, our results show differential effects of external mycelium of AM fungi on other soil microbial communities, though both AM fungi included in the study overall inhibited most microbial groups as examined using whole cell biomarker fatty acids.     

丛枝菌根真菌介导的土壤有机碳稳定机制研究进展

土壤有机碳(SOC)的稳定是陆地生态系统碳循环的关键过程之一,对维持土壤肥力和减少温室气体排放具有重要意义。以往认为植物残体中难降解性物质的物理保护和腐殖质影响土壤中有机碳库的稳定性。最近的研究结果表明,微生物介导的碳循环过程在土壤有机碳稳定中发挥着重要作用。丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)作为土壤中一类重要的共生微生物,参与植物光合碳向土壤的转运和分配,是陆地生态系统碳循环的重要一环,但其在土壤有机碳稳定中的作用潜力还未得到充分挖掘。基于此,本文估算了植物光合碳在AMF根外菌丝的分配量;总结了AMF介导的土壤有机碳稳定机制,主要包括AMF活体菌丝对碳的截留,分泌物及残体的分子结构抗性和土壤矿物吸附,提高植物源碳的质量和数量,菌丝分泌物及残体的激发效应和稳定土壤团聚体;探讨了影响AMF介导的稳定性有机碳形成的非生物(气候因子、土壤养分和土壤矿物)和生物因子(植物和AMF种类);提出了AMF与土壤有机碳周转互作机理进一步的研究方向,包括探究菌根植物光合碳转化为稳定性SOC的机制,解析不同生态系统中AMF对稳定性SOC的贡献及影响因素,并厘清...     

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。     

Linking sorghum nutrition and production with arbuscular mycorrhizal fungi and alternative soil amendments

Mounting fertilizer costs are disproportionally affecting farmers in developing countries. Alternative soil fertility amendments [worm compost, pyrolyzed carbon (biochar)] and arbuscular mycorrhizal fungi have the potential to reduce these costs while promoting soil health. Our greenhouse study investigated the role of mycorrhizal associations and alternative fertility amendments on the productivity and plant nutrition of grain sorghum. We assessed sorghum (Sorghum bicolor cv. Macia) grown with ten different treatments (combinations of biochar, worm compost, and commercial N and P fertilizers) plus a non‐amended control. An amendment blend containing worm compost, biochar, and 50% of the typically recommended commercial fertilizer rate produced similar plant biomass and protein, similar total tissue mineral contents (Ca, Fe, K, Mg, P, and Zn), and supported ≈ 60% more mycorrhizal fungi in the host plant's roots, compared to sorghum grown with the recommended rate of commercial fertilizer (N and P). Our results indicate the potential of biochar and worm compost to enhance the benefits of mycorrhizal fungi for grain sorghum production and plant nutrition while reducing commercial fertilizer applications.     

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.     

丛枝菌根对矿区环境修复的生态效应

针对煤矿区生态环境修复过程中存在的主要问题,通过定位监测菌根的生态来探索菌根生物技术在矿区环境治理的效应与推广模式.菌根对植物生长具有明显的促进作用,接种菌根6个月后杨树和白蜡的胸周和株高分别较对照明显增加,菌根侵染率达到80%以上,菌根与植物共生作用好.接种菌根菌6个月后,菌根际菌丝长度远远高于对照,产生的孢子数量也明显增加,接种菌根菌对于降低煤矿区环境修复成本以及增加未来生态收益具有很大的潜力,维持了矿区生态系统的稳定.     

Phylogenetic structure of arbuscular mycorrhizal community shifts in response to increasing soil fertility

Understanding the underlying mechanisms driving responses of belowground communities to increasing soil fertility will facilitate predictions of ecosystem responses to anthropogenic eutrophication of terrestrial systems. We studied the impact of fertilization of an alpine meadow on arbuscular mycorrhizal (AM) fungi, a group of root-associated microorganisms that are important in maintaining sustainable ecosystems. Species and phylogenetic composition of AM fungal communities in soils were compared across a soil fertility gradient generated by 8 years of combined nitrogen and phosphorus fertilization. Phylogenetic patterns were used to infer the ecological processes structuring the fungal communities. We identified 37 AM fungal virtual taxa, mostly in the genus Glomus. High fertilizer treatments caused a dramatic loss of Glomus species, but a significant increase in genus richness and a shift towards dominance of the lineage of Diversispora. AM fungal communities were phylogenetically clustered in unfertilized soil, random in the low fertilizer treatment and over-dispersed in the high fertilizer treatments, suggesting that the primary ecological process structuring communities shifted from environmental filtering (selection by host plants and fungal niches) to a stochastic process and finally to competitive exclusion across the fertilization gradient. Our findings elucidate the community shifts associated with increased soil fertility, and suggest that high fertilizer inputs may change the dominant ecological processes responsible for the assembly of AM fungal communities towards increased competition as photosynthate from host plants becomes an increasingly limited resource.     

Dependency of Cassia siamea on vesicular arbuscular mycorrhizal fungi

Thirty‐day‐old seedlings of Cassia siamea were transplanted into pots containing a subsurface Oxisol uninoculated or inoculated with Glomus agaregatum at two target soil solution phosphorus (P) concentrations. While no evidence of Vesicular‐arbuscular mycorrhizal fungal (VAMF) colonization was noted in the uninoculated soil, C. siamea roots were colonized to the extent of 63 and 61% at soil P concentrations of 0.02 and 0.2 mg/L, respectively. VAMF colonization led to significant increases in tissue P concentrations measured at harvest at both soil P concentrations. However, shoot dry matter yield was significantly increased only at the first soil P concentration. Shoot dry matter yield of mycorrhizal C. siamea at soil P concentration of 0.02 mg/L was comparable to mycorrhizal growth of C. siamea at soil P concentration of 0.2 mg/L but inferior to the nonmycorrhizal growth of the legume. Based on these response patterns, C. siamea was classified as a highly mycorrhizal dependent species.