Abstract Arbuscular Mycorrhizal Fungi Research Articles

MAXIMIZING THE SHELF LIFE OF MONOXENICALLY PRODUCED CARRIER-BASED AM FUNGAL BIO-INOCULA FOR MAINTAINING ITS LONG-TERM VIABILITY

Arbuscular mycorrhizal (AM) fungi are often applied as bio-inoculants due to their plant growth promoting benefits. The objectives of the present work were to maximize the shelf life of monoxenically produced carrier-based AM fungal bio-inocula of Rhizoglomus intraradices and Funneliformis mosseae. Shelf life of in vitro produced inoculum was studied by assessing the infectivity potential of in vitro produced inocula in an optimum carrier formulation (vermiculite: cow dung powder: wood powder: wood ash in the ratio of 20:8:2:1) during storage at three different temperatures viz., 4 °C, 25 °C and room temperature (RT). The re-germination potential of in vitro produced spores from carrier-based inocula to in vitro conditions was also examined. The in vitro produced inocula stored at 25 °C remained viable up to 6 mo in the organic carrier formulation. 100 % germination was recorded when the spores of both AM species were cultured back to in vitro conditions indicating high viability, and efficiency of the carrier formulation in maintaining vigour of in vitro produced propagules.

Arbuscular mycorrhizal fungal communities associated with two dominant species differ in their responses to long‐term nitrogen addition in temperate grasslands

Abstract Arbuscular mycorrhizal (AM) fungi are important components of grassland ecosystems and are sensitive to enhanced atmospheric nitrogen (N) deposition. Enhanced N deposition has been widely reported to reduce species richness and alter species composition across different types of grasslands world‐wide. Despite extensive studies on effects of N deposition on AM fungal communities of grasslands, few studies have specifically focused on effects of N deposition on AM fungi associated with dominant species in grasslands. We investigated long‐term (12‐year) effects of N addition (80 kg ha−1 year−1) on AM fungal community richness in roots and rhizosphere biomass of two dominant plant species (forb Artemisia frigida and grass Stipa krylovii) in temperate steppes of northern China. We found that AM fungi associated with the two dominant plant species differed in their responses to N addition. Nitrogen addition led to a significant reduction in AM fungal richness colonized in roots, and biomass in the rhizosphere of A. frigida, while N addition had little impacts on AM fungi colonized in roots and rhizosphere of S. krylovii. Nitrogen addition significantly reduced AM fungal colonization in roots and AM fungal spore density in the rhizosphere soils of A. frigida. In contrast, N addition had no effect on AM fungal colonization in roots and spore density in the rhizosphere of S. krylovii. Nitrogen addition markedly suppressed photosynthetic rates in A. frigida due to excessive foliar accumulation of manganese. The N‐induced reduction in photosynthetic rates reduced allocation of C into roots in A. frigida, leading to a lower root/shoot ratio, and suppression of AM fungal community associated with A. frigida. The inhibition of AM fungi would render A. frigida less competitive in terms of acquisition of mineral nutrients in soils, thus contributing to its loss in the steppe community under conditions of elevated N deposition. These findings provide a mechanistic explanation for N‐evoked differential responses of AM fungal communities associated with A. frigida and S. krylovii by linking soil properties and host plants to AM fungal communities. A plain language summary is available for this article.

Growth and Photosynthetic Responses of Litchi Seedlings to Arbuscular Mycorrhizal Fungal Inoculation: Differences between Two Genotypes

Arbuscular mycorrhizal (AM) fungi are beneficial symbiotic soil microorganisms and AM technology can find its potential application in the nursery of horticultural industry. When AM fungi have been successfully applied to many wood fruit tree species, little information is available in litchi (Litchi chinensis Sonn.). In this study, the seedlings of two litchi genotypes (‘Baila’ and ‘Heiye’) were inoculated with two AM fungal species (Rhizophagus irregularis and Gigaspora margarita) in the nursery conditions, and the growth and photosynthetic responses of seedlings to AM fungal inoculation were investigated. Results indicated that AM fungi significantly promoted the plant growth of ‘Heiye’ seedlings in terms of biomass, plant height, stem diameter and leaf number, while they slightly decreased these parameters of ‘Baila’. The inoculation effect can be explained by the changes in photosynthetic characteristics induced by AM fungi, because AM fungi increased Amax, Aqe, LSP and decreased LCP of ‘Heiye’ but did not affected those of ‘Baila’. Pn was not affected by AM fungi, however, regression analysis indicated a weaker relationship between biomass and Pn than those between biomass and Amax, LSP or LCP. Our results strongly suggest that AM fungi can differentially affect the seedling growth of litchi genotypes mainly via their effects on photosynthetic characteristics, and that precautions should be taken to select appropriate genotypes as rootstock if AM technology is applied in litchi nursery.

Can Cd translocation in Oryza sativa L. be attenuated by arbuscular mycorrhizal fungi in the presence of EDTA?

Arbuscular mycorrhizal (AM) fungi play an important role in plant tolerance of heavy metal contamination. In this study, a pot experiment was conducted to illustrate the effects of the two AM fungi species Funneliformis mosseae (Fm) and Rhizophagus irregularis (Ri) on plant growth of Oryza sativa L. either with or without ethylenediamine tetraacetate (EDTA) addition and during exposure to five Cd concentrations (in the range of 0-5mgkg-1). The results showed that Fm inoculation achieved greater mycorrhizal colonization and mycorrhizal dependency indexes than Ri inoculation. In addition, the effects of AM fungi on Cd biosorption and translocation in rice were also investigated in the presence of EDTA. Despite cooperative adsorption, the Freundlich isotherm could describe the biosorption effects of Cd on rice roots regardless of AM fungi inoculation or EDTA addition. Cd concentrations in mycorrhizal roots increased but decreased in mycorrhizal shoots in contrast to the control treatment. Although EDTA addition negatively inhibited the uptake of Cd to mycorrhizal shoots, lower translocation factor (TF) and bioconcentration factor (BCF) were still observed in treatments with EDTA compared to control treatment. Our findings suggest that Ri and Fm inoculation enhanced Cd immobilization in the roots, thus preventing Cd entry into the food chain during exposure to low and high Cd stress, respectively.

Hyphosphere regulation of earthworms and arbuscular mycorrhizal fungus on soil N and P availability

ABSTRACTEarthworms and arbuscular mycorrhizal (AM) fungi are important ecosystem engineers that co-occur in soil and belong to different guilds. In this study, hyphosphere interactions between earthworms and AM fungi on soil nitrogen (N) and phosphorus (P) availability were investigated under field conditions with a modified chamber near the maize root. The experimental design consisted of root exclusion chambers that either allowed (30 μm pores) or precluded (0.45 μm pores) growth of AMF hyphae (AM factor), with or without earthworm addition (earthworm factor). Hyphal length density, soil and content, soil available P concentration, urease and alkaline phosphatase activities were tested at maize VT (tassel), R1 (silking), R2 (blister), R3 (milk) and R4 (dough) stage. Results showed that earthworms did not impact hyphal length density in the hyphosphere. AM and AM + E treatments caused a decrease in available phosphorus, while the E treatment increased and content during the whole experiment period. AM and AM + E treatments could significantly increase soil alkaline phosphatase activities compared to non-AMF treatments, while E and AM + E treatment could significantly increase soil urease activities compared to non-Earthworm treatments. Hyphosphere regulation of earthworms and arbuscular mycorrhizal fungus on soil N and P availability might lead to greater nutrient uptake by plant. These interactions are important for utilization of soil biological fertilization in sustainable agro-ecosystems.

Plant community, geographic distance and abiotic factors play different roles in predicting AMF biogeography at the regional scale in northern China

Arbuscular mycorrhizal fungi (AMF) are ubiquitous mutualists of terrestrial plants and play key roles in regulating various ecosystem processes, but little is known about AMF biogeography at regional scale. This study aims at exploring the key predictors of AMF communities across a 5000-km transect in northern China. We determined the soil AMF species richness and community composition at 47 sites representative of four vegetation types (meadow steppe, typical steppe, desert steppe and desert) and related them to plant community characteristics, abiotic factors and geographic distance. The results showed that soil pH was the strongest predictor of AMF richness and phylogenetic diversity. However, abiotic factors only have a low predictive effect on AMF community composition or phylogenetic patterns. By contrast, we found a significant relationship between community composition of AMF and plants, which was a surprising result given the extent of heterogeneity in the plant community across this transect. Moreover, the geographic distance predominantly explained the AMF phylogenetic structure, implying that history evolutionary may play a role in shaping AMF biogeographic patterns. This study highlighted the different roles of main factors in predicting AMF biogeography, and bridge landscape-scale studies to more recent global-scale efforts. This article is protected by copyright. All rights reserved.

In Winter Wheat, No-Till Increases Mycorrhizal Colonization thus Reducing the Need for Nitrogen Fertilization

Arbuscular mycorrhizal fungi (AMF) play a major role in the uptake of nutrients by agricultural plants. Nevertheless, some agricultural practices can interrupt fungal-plant signaling and thus impede the establishment of the mycorrhizal symbiosis. A field experiment performed over a 5-year period demonstrated that both the absence of tillage and of nitrogen (N) fertilization improved AMF colonization of wheat roots. Moreover, under no-till conditions, N uptake and aboveground biomass production did not vary significantly between N-fertilized and N-unfertilized plots. In contrast, both N uptake and above ground biomass were much lower when N fertilizer was not added during conventional tillage. This finding strongly suggests that for wheat, no-till farming is a sustainable agricultural system that allows a gradual reduction in N fertilizer use by promoting AMF functionality and at the same time increasing N uptake.

Phylogenetically Structured Differences in rRNA Gene Sequence Variation among Species of Arbuscular Mycorrhizal Fungi and Their Implications for Sequence Clustering.

Arbuscular mycorrhizal (AM) fungi form mutualisms with plant roots that increase plant growth and shape plant communities. Each AM fungal cell contains a large amount of genetic diversity, but it is unclear if this diversity varies across evolutionary lineages. We found that sequence variation in the nuclear large-subunit (LSU) rRNA gene from 29 isolates representing 21 AM fungal species generally assorted into genus- and species-level clades, with the exception of species of the genera Claroideoglomus and Entrophospora However, there were significant differences in the levels of sequence variation across the phylogeny and between genera, indicating that it is an evolutionarily constrained trait in AM fungi. These consistent patterns of sequence variation across both phylogenetic and taxonomic groups pose challenges to interpreting operational taxonomic units (OTUs) as approximations of species-level groups of AM fungi. We demonstrate that the OTUs produced by five sequence clustering methods using 97% or equivalent sequence similarity thresholds failed to match the expected species of AM fungi, although OTUs from AbundantOTU, CD-HIT-OTU, and CROP corresponded better to species than did OTUs from mothur or UPARSE. This lack of OTU-to-species correspondence resulted both from sequences of one species being split into multiple OTUs and from sequences of multiple species being lumped into the same OTU. The OTU richness therefore will not reliably correspond to the AM fungal species richness in environmental samples. Conservatively, this error can overestimate species richness by 4-fold or underestimate richness by one-half, and the direction of this error will depend on the genera represented in the sample. Arbuscular mycorrhizal (AM) fungi form important mutualisms with the roots of most plant species. Individual AM fungi are genetically diverse, but it is unclear whether the level of this diversity differs among evolutionary lineages. We found that the amount of sequence variation in an rRNA gene that is commonly used to identify AM fungal species varied significantly between evolutionary groups that correspond to different genera, with the exception of two genera that are genetically indistinguishable from each other. When we clustered groups of similar sequences into operational taxonomic units (OTUs) using five different clustering methods, these patterns of sequence variation caused the number of OTUs to either over- or underestimate the actual number of AM fungal species, depending on the genus. Our results indicate that OTU-based inferences about AM fungal species composition from environmental sequences can be improved if they take these taxonomically structured patterns of sequence variation into account.

Land-Cover Legacy Effects on Arbuscular Mycorrhizal Abundance in Human and Wildlife Dominated Systems in Tropical Savanna

Arbuscular mycorrhizal fungi (AMF) can be important mutualists to plant hosts in acquiring soil nutrients. Past work has not explored whether previous land-cover history influences current AMF abundance in croplands and whether different land-cover histories in grazed but not cultivated areas influence AMF. This study was conducted to assess the effects of land-cover history in and near Serengeti National Park on AMF abundance in areas with three different land uses. The results showed that land-cover history influenced a number of soil physicochemical properties following conversion of grassland to cropland or woodland to cropland during the past 27 years. Different original land cover generally did not significantly influence current AMF abundance in croplands or livestock-grazed soils. However, livestock-grazed current grasslands that were formerly woodlands had lower AMF abundance than sites that had been grasslands since 1984. These results suggest that lower AMF abundance in livestock-grazed and cropland areas as compared to protected wildlife-grazed areas may reflect reduced total carbon inputs and higher disturbance and are not strongly influenced by the legacy of previous land cover. Given that recent studies have detected legacy effects on AMF, such effects may reflect more the impact on the taxonomic composition of AMF rather than their total abundance.

DNA-Based Characterization and Identification of Arbuscular Mycorrhizal Fungi Species.

Arbuscular mycorrhizal fungi (AMF) are obligate symbionts of most land plants. They have great ecological and economic importance as they can improve plant nutrition, plant water supply, soil structure, and plant resistance to pathogens. We describe two approaches for the DNA-based characterization and identification of AMF, which both can be used for single fungal spores, soil, or roots samples and resolve closely related AMF species: (a) Sanger sequencing of a 1.5 kb extended rDNA-barcode from clone libraries, e.g., to characterize AMF isolates, and (b) high throughput 454 GS-FLX+ pyrosequencing of a 0.8 kb rDNA fragment, e.g., for in-field monitoring.

Formononetin associated with phosphorus influences soybean symbiosis with mycorrhizal fungi and Bradyrhizobium

Arbuscular mycorrhizal fungi play an important role on nutrient supply to plants, specially P. However, the availability of inoculants for large-scale usage in agriculture is still limited because these organisms are obligatory symbionts. The use of symbiosis stimulants such as flavonoids can be an alternative to improve the beneficial effects of mycorrhiza for plant nutrition. The aim of this study was to evaluate the effect of the isoflavonoid biostimulant formononetin (7-hydroxy, 4’-methoxy isoflavone) in combination with three levels of phosphorus fertilization on mycorrhizal colonization, nodulation, and productivity of soybean, under field conditions. A 3 x 4 factorial scheme (levels of P: 0, 60 and 120 kg ha -1 P 2 O 5 and doses of formononetin: 0, 25, 50 and 100 g ha -1 ) was used with five replicates. The following parameters were quantified at full bloom: plant height, shoot dry weight, nodule number, nodule dry weight, mycorrhizal colonization, and shoot N and P concentrations. Productivity was also evaluated at the end of the crop cycle. Formononetin stimulated mycorrhizal colonization at lower levels of P (0 and 60 kg ha -1 ), with colonization increasing from 56 to 64%. When applied with 60 kg ha -1 P 2 O 5 , formononetin increased soybean productivity to values similar to those observed when 120 kg ha -1 de P 2 O 5 , was applied. At doses above 50 g ha -1 , formononetin applied to the seeds can reduce the need of P fertilization by 50%.

A Study on the Reclamation and Ecological Restoration in Subsidence Land in Chinese Coal Mine Area

Arbuscular mycorrhizal fungi (AMF) technology of bioremediation becomes one of the most hotspots in the research on coal-mining subsidence land. This article based on amorpha fruiticosa planting in the mining subsidence of Shendong mining area as a study object, arbuscular mycorrhizal fungi was vaccinated on amorpha fruiticosa after different monitor time, respectively measures are used to analyze its effect on the growth of plant and on rhizosphere soil physical properties. The correlation between hyphae density and Olsen-P of rhizosphere is analyzed. By using regression analysis, we found that in different monitoring time, hyphae density and effective phosphorus in September had better linear fitting than that in June, which is closely associated with development time of mycorrhizal. With the time passing by, the correlation of vaccination between hyphae density and effective phosphorus content is gradually decreased; however, the positive correlation of un-vaccinated is gradually emerged. The results of mycorrhizal bioremediation on mining subsidence in Shendong mining area prove that vaccination not only could effectively promote growth and development of amorpha fruiticosa in macroscopic, but also could improve the growth matrix conditions in microscopic.

Impact of an invasive nitrogen-fixing tree on arbuscular mycorrhizal fungi and the development of native species.

Arbuscular mycorrhizal fungi (AMF) are obligate soil biotrophs that establish intimate relationships with 80 % of terrestrial plant families. Arbuscular mycorrhizal fungi obtain carbon from host plants and contribute to the acquisition of mineral nutrients, mainly phosphorus. The presence of invasive plants has been identified as a soil disturbance factor, often conditioning the structure and function of soil microorganisms. Despite the investigation of many aspects related to the invasion ofAcacia dealbata, the effect produced on the structure of AMF communities has never been assessed. We hypothesize thatA. dealbatamodifies the structure of AMF community, influencing the establishment and growth of plants that are dependent on these mutualisms. To validate our hypothesis, we carried out denaturing gradient gel electrophoresis (DGGE) analysis and also grew plants ofPlantago lanceolatain pots using roots of native shrublands or fromA. dealbata, as inoculum of AMF. Cluster analyses from DGGE indicated an alteration in the structure of AMF communities in invaded soils. After 15 weeks, we found that plants grown in pots containing native roots presented higher stem and root growth and also produced higher biomass in comparison with plants grown withA. dealbatainoculum. Furthermore, plants that presented the highest biomass and growth exhibited the maximum mycorrhizal colonization and phosphorus content. Moreover, fluorescence measurements indicated that plants grown withA. dealbatainoculum even presented higher photosynthetic damage. Our results indicate that the presence of the invaderA. dealbatamodify the composition of the arbuscular fungal community, conditioning the establishment of native plants.

Subcritical soil hydrophobicity in the presence of native and exotic arbuscular mycorrhizal species at different soil salinity levels

Soil salinity and arbuscular mycorrhizal fungi (AMF) influence the soil hydrophobicity. An experiment was performed to determine the effects of soil salinity and AMF species on soil water repellency (SWR) under wheat (Triticum aestivum L.) crop. Six AMF treatments, including four exotic species (Rhizophagus irregularis, Funneliformis mosseae and Claroideoglomus claroideum, a mix of three species), one mix native AMF species treatment and an AMF-free soil in combination with four salinity levels (1, 5, 10, and 15 dS m−1) were used. The soil repellency index (RI) increased with salinity increment ranging from 2.4 to 10.5. The mix of three exotic and native AMF treatments enhanced the RI significantly compared to AMF-free soil in all salinity levels with one exception for native treatment at 1 dS m−1. Among individual AMF species, the C. claroideum treatment at 10 dS m−1 increased the RI by 67% compared to AMF-free soil. The native AMF treatment was more efficient in root colonization, glomalin production and SWR development at 10 and 15 dS m−1, compared to exotic species. In addition to the net positive effect of salinity on SWR, the AMF influences on the RI were greatly dependent on salinity levels.

English

Arbuscular mycorrhizal fungi (AMF) are important microbial symbionts for plants especially when soil phosphorus (P) and nitrogen (N) are limited. Little is known about the distribution of AM hyphae in natural systems of tropical soils across landscapes and their association with different land uses. We studied mycorrhizal hyphal abundance in a wildlife grazed system, a livestock grazed system and under cultivated soils in and near Serengeti National Park, Tanzania. Samples of the upper 15 cm of soil beneath locally dominant plant species were collected. Hyphae were preserved on permanent slides and the length of hyphae per cubic centimeter of soil was calculated. Significant differences (p<0.001) in AM hyphal densities were observed across land use systems, as mean hyphal densities were 61.03±22.02, 52.89±16.41 and 47.9±22.65 m/cm3 for wildlife grazed system, livestock grazed system and croplands, respectively. There were significant correlations between soil P and N on AM hyphal densities that reflected a pattern of decreasing hyphal densities with increasing soil P and N across sites. These results are congruent with the functional equilibrium hypothesis, which predicts that plants allocate relatively more to belowground structures when they are more limited by belowground resources than by aboveground resources, because AMF densities were highest at the sites with the lowest soil resources. Key words: Land use, mycorrhizal, hyphal, abundance, soil, Serengeti, Tanzania.

Uptake Kinetics of Arsenic in Upland Rice Cultivar Zhonghan 221 Inoculated with Arbuscular Mycorrhizal Fungi

Arbuscular mycorrhizal fungi (AMF) appear to be highly associated with arsenic (As) uptake in host plants because arsenate (As(V)) and phosphorus (P) share the same transporter, whereby AMF can enhance P uptake. A short-term experiment was conducted for low- (0 to 0.05 mM As) and high-affinity (0 to 2.5 mM As) uptake systems, to investigate the AMF role on As uptake mechanism in plants, which may explain As uptake kinetics in upland rice cultivar: Zhonghan 221. When concentration of As ranged from 0 to 0.05 mM, Funneliformis geosporum (Fg) significantly decreased arsenite (As(III)) and monomethylarsonicacid (MMA) uptake when (p < 0.05) compared to non-mycorrhizal (NM) treatment, since the major route for (As(III)) in rice roots—rice silicon transporter Lsi1 would be influenced by Fg inoculation at high As concentrations. Fg can also reduce As(V) uptake significantly (p < 0.05) under both uptake systems relative to NM treatment, whereas, Funneliformis mosseae (Fm) increased As(V) and MMA uptake in rice roots, with MMA uptake rate generally lower than As(III) and As(V). Using suitable AMF species inoculation with rice, As uptake and accumulation in rice grains can be reduced and the risk to human health, once consumed, can be minimized.

English

Arbuscular mycorrhizal fungi (AMF) are obligatory biotrophics, which complicates the feasibility of producing inoculants. Thus, the discovery of substances capable of stimulating mycorrhizal colonization, as the isoflavone formononetin emerges as a promising alternative to explore the benefits of AMF native soil in extensive crops. The objective of this study was evaluate the application of the isoflavone formononetin (7-hydroxy-4'-methoxy isoflavone), fungicide application via seed in Cerrado soil in no-tillage system and fertilized with two doses of phosphorus in soybean under field and controlled conditions. In the field experiment treatments there were three levels of formononetin (0, 0.5 and 1.0 mg/seed Formononetin), in the absence and presence of fungicide (Carbendazim + Thiram commercial mix) applied to seeds and two doses of phosphorus (100 % and 33% of the recommended fertilization). The study was conducted until the maturation of soybeans. The greenhouse conditions experiment was implemented with the same treatments used in the field study and the flowering stage of the soybean plant was simulated water stress for 10 days, returning to normal irrigation to harvest the grain. Applying formononetin stimulated increased mycorrhizal colonization, number of nodules, vegetative growth and soybean production in the greenhouse and in the field and contributes to attenuate the negative effect of the fungicide Carbendazim + Thiram in soybean reflecting increased soybean production and adequate supply of soil phosphorus and high density of propagules of natives AMF contributed to reduce the benefits of stimulating mycorrhizal (formononetin) in the studied soil.

Distribution and Association of Arbuscular Mycorrhizal Fungi in Different Cultivars of Wheat from Lalganj Pratapgarh District of Utter Pradesh, India

Arbuscular mycorrhizal fungi are key components of soil micro-flora and obviously interact with other microorganisms in the rhizosphere which is the zone of influence of plant roots on microbial populations and other soil constituents. Keeping in view the importance of AM fungi, the present study was undertaken for assessing the AM fungal spore population dynamics in the rhizosphere soil and its colonization in rhizosphere soils in relation to soil physico-chemical factors. Present study represents an attempt to establish the qualitative and quantitative distribution of AM fungal species in rhizosphere soils of wheat. Thirteen different wheat cultivars collected from four different sites of Lalganj Pratapgarh (U.P.), India were examined for the AM infection. All the wheat cultivars were found to be infected with arbuscular mycorrhizae. However, their population in rhizosphere and root infection varied to a considerable extent from species to species. The maximum spore population and highest percentage of root colonization were found with the rhizosphere soil of cultivars Ankur Kedar.

Differential Growth Responses of Rice Cultivars to an Arbuscular Mycorrhizal Fungus, Funneliformis mosseae

Arbuscular mycorrhizal fungi support the absorption of mineral nutrients by their host plants in exchange for photosynthate. We evaluated the growth responses of 64 rice cultivars to root colonization by an arbuscular mycorrhizal fungus, Funneliformis mosseae, and identified the most positively responsive cultivar as indica rice, ARC5955. We compared the changes of mineral contents of ARC5955 under colonization by the fungus with those of a nonresponsive japonica cultivar, Nipponbare. Colonization increased the contents of beneficial elements such as P and decreased those of deleterious elements such as Cu and Al in both ARC5955 and Nipponbare. However, only ARC5955 showed strong growth stimulation. These results may provide new insights for breeding and yield increase of rice in sustainable agriculture.

Mycorrhizal function on soil aggregate stability in root zone and root-free hyphae zone of trifoliate orange

Arbuscular mycorrhizal fungi (AMF) influence soil aggregate stability through their hyphae, roots, and glomalin-related soil protein (GRSP); however, the individual effect of these factors is difficult to distinguish. Pots separated by a 37-μm mesh bag buried in the middle of each pot was used to establish root zone (root + hyphae) and hyphae zone (roots free), where the Poncirus trifoliata seedlings were colonized by Funneliformis mosseae or Paraglomus occultum in root zone. AMF inoculation significantly increased shoot, root, and plant’s total biomass, soil organic carbon, GRSP fractions, 2–4 and 1–2 mm size water-stable aggregates, and mean weight diameter (MWD) in root or hyphae zone. Within root zone, root colonization and biomass presented stronger relationship with MWD than GRSP fractions. While, within hyphae zone, total of GRSP fraction was significantly correlated with MWD. The study, suggested further that root biomass and colonization were the main mechanisms in root zone for improving aggregate stability, whereas total of GRSP fractions was of paramount importance in hyphae zone. Mycorrhizal effect on aggregate stability was observed to be contrastingly different between root zone and hyphae zone.