Arbuscular Mycorrhizal Symbiosis Research Articles

Distinct impact of arbuscular mycorrhizal isolates on tomato plant tolerance to drought combined with chronic and acute heat stress

Arbuscular mycorrhizal (AM) fungi could mitigate individual drought and heat stress in host plants. However, there are still major gaps in our understanding of AM symbiosis response to the combined stresses. Here, we compared seven AM fungi, Rhizophagus irregularis, Funneliformis mosseae, Funneliformis geosporum, Funneliformis verruculosum, Funneliformis coronatum, Septoglomus deserticola, Septoglomus constrictum, distributed to many world regions in terms of their impacts on tomato endurance to combined drought and chronic heat as well as combined drought and heat shock. A multidisciplinary approach including morphometric, ecophysiological, biochemical, targeted metabolic (by ultrahigh-performance LC-MS), and molecular analyses was applied. The variation among AM fungi isolates in the enhancement in leaf water potential, stomatal conductance, photosynthetic activity, and maximal PSII photochemical efficiency, proline accumulation, antioxidant enzymes (POD, SOD, CAT), and lowered ROS markers (H2O2, MDA) in host plants under combined stresses were observed. S. constrictum inoculation could better enhanced the host plant physiology and biochemical parameters, while F. geosporum colonization less positively influenced the host plants than other treatments under both combined stresses. F. mosseae- and S. constrictum-associated plants showed the common AM-induced modifications and AM species-specific alterations in phytohormones (ABA, SA, JA, IAA), aquaporin (SlSIP1-2; SlTIP2-3; SlNIP2-1; SlPIP2-1) and abiotic stress-responsive genes (SlAREB1, SlLEA, SlHSP70, SlHSP90) in host plants under combined stresses. Altogether, mycorrhizal mitigation of the negative impacts of drought + prolonged heat and drought + acute heat, with the variation among different AM fungi isolates, depending on the specific combined stress and stress duration.

A perspective on cross-kingdom RNA interference in mutualistic symbioses.

RNA interference (RNAi) is arguably one of the more versatile mechanisms in cell biology, facilitating the fine regulation of gene expression and protection against mobile genomic elements, whilst also constituting a key aspect of induced plant immunity. More recently, the use of this mechanism to regulate gene expression in heterospecific partners - cross-kingdom RNAi (ckRNAi) - has been shown to form a critical part of bidirectional interactions between hosts and endosymbionts, regulating the interplay between microbial infection mechanisms and host immunity. Here, we review the current understanding of ckRNAi as it relates to interactions between plants and their pathogenic and mutualistic endosymbionts, with particular emphasis on evidence in support of ckRNAi in the arbuscular mycorrhizal symbiosis.

Arbuscular mycorrhizal symbiosis and melatonin synergistically suppress heat-induced leaf senescence involves in abscisic acid, gibberellin, and cytokinin-mediated pathways in perennial ryegrass

Leaf senescence is a prominent symptom of heat injury observed in cool-season plants. The application of melatonin (MT) and inoculation with mycorrhizal fungi can mitigate heat-induced leaf senescence. The current research aims to examine the individual and combined effects of arbuscular mycorrhizal (AM) inoculation and MT application on heat-related leaf senescence in perennial ryegrass (Lolium perenne L.). In addition, whether the effects of these treatments were in any way associated with abscisic acid (ABA), gibberellin (GA), and cytokinin (CTK) for exerting the bioactivity. According to the results, the suppression of heat-mediated leaf senescence using MT treatment and AM inoculation manifested as increased photosynthesis, turf quality (TQ), and plant growth, and reduced membrane lipid peroxidation levels as well as the chlorophyll catabolic genes (CCGs) and senescence-associated genes (LpSAG12.1 and Lph36) transcript levels in the heat-stressed plants. MT application and AM inoculation elevated the internal MT, GA, and CTK levels, while reducing the ABA levels in the heat-stressed plants. In addition, the MT biosynthesis genes (LpTDC1, LpTDC2, LpCOMT1, LpASMT1, and LpASMT3), the ABA catabolic gene, the GA biosynthesis genes, CTK biosynthesis genes, along with the associated signal transduction response transcription factors (TFs) (type-B ARRs) exhibited increased levels, whereas the expressions of the GA and CTK catabolic genes and the biosynthesis and signal transduction genes related to ABA exhibited decreased levels after MT application and AM inoculation in the heat-stressed plants. Furthermore, the application of exogenous MT notably elevated the AM colonization rate at high temperature (HT) condition. After 28 days of heat stress, compared to the treatment with neither AMF nor MT application, AM combined with MT achieved a synergistic effect, resulting in a 25.32%, 87.21%, 58.69%, 57.17%, and 28.46% increase in TQ, leaf chlorophyll content, net photosynthesis (Pn), leaf photochemical efficiency (Fv/Fm), and relative water content (RWC), respectively, in perennial ryegrass. Additionally, this treatment significantly reduced the electrolyte leakage (EL), hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels by 30.76%, 38.19%, and 31.95%, respectively, and also significantly reduced the transcription levels of CCGs and senescence-associated genes. Consequently, it was inferred that a combination of AM and MT treatments promotes plant growth and development and suppresses heat-induced leaf senescence in plants.

Aromatic amino acid biosynthesis impacts root hair development and symbiotic associations in Lotus japonicus.

Legume roots can be symbiotically colonized by arbuscular mycorrhizal (AM) fungi and nitrogen-fixing bacteria. In Lotus japonicus, the latter occurs intracellularly by the cognate rhizobial partner Mesorhizobium loti or intercellularly with the Agrobacterium pusense strain IRBG74. Although these symbiotic programs show distinctive cellular and transcriptome signatures, some molecular components are shared. In this study, we demonstrate that 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase 1 (DAHPS1), the first enzyme in the biosynthetic pathway of aromatic amino acids (AAAs), plays a critical role in root hair development and for AM and rhizobial symbioses in Lotus. Two homozygous DAHPS1 mutants (dahps1-1 and dahps1-2) showed drastic alterations in root hair morphology, associated with alterations in cell wall dynamics and a progressive disruption of the actin cytoskeleton. The altered root hair structure was prevented by pharmacological and genetic complementation. dahps1-1 and dahps1-2 showed significant reductions in rhizobial infection (intracellular and intercellular) and nodule organogenesis and a delay in AM colonization. RNAseq analysis of dahps1-2 roots suggested that these phenotypes are associated with downregulation of several cell wall-related genes, and with an attenuated signaling response. Interestingly, the dahps1 mutants showed no detectable pleiotropic effects, suggesting a more selective recruitment of this gene in certain biological processes. This work provides robust evidence linking AAA metabolism to root hair development and successful symbiotic associations.

Screening of Streptomyces strains helping arbuscular mycorrhizal symbiosis against pepper (Capsicum annuum L.) Phytophthora blight

Mycorrhiza helper bacteria (MHB) can promote the formation and functioning of arbuscular mycorrhizal (AM) symbiosis, but their role and application potential in coping with soil-borne diseases are still unclear. The aim of this 14-week greenhouse pot experiment was to obtain several actinomycetes strains which could help AM symbiosis in suppressing the Phytophthora blight of pepper (Capsicum annuum L.), using a soil inoculated with Phytophthora capsici after sterilization. Five Streptomyces strains, including S. pseudogriseolus, S. albogriseolus, S. griseoaurantiacus, S. tricolor and S. tendae, as well as the AM fungus (Funneliformis caledonium) were tested. The Phytophthora blight severity reached 66% at full productive stage in the control, and only F. caledonium, S. griseoaurantiacus and S. tricolor alone remarkably decreased (P < 0.05) it to 47%, 40%, and 35%, respectively. Compared to F. caledonium alone, only additional inoculation of S. tricolor and S. tendae which were isolated from the rhizosphere of a healthy individual in an infected field substantially elevated (P < 0.05) root mycorrhizal colonization, root biomass, fruit yield, and total K acquisitions of pepper, and further dramatically decreased (P < 0.05) the severity. According to the feature of enhancing disease-suppression by AM symbiosis, both S. tricolor and S. tendae were confirmed as MHB strains here. Specifically, S. tendae had a stronger performance in directly accelerating mycorrhization, while S. tricolor was also an antagonist to the pathogenic P. capsici. Furthermore, S. griseoaurantiacus with the independent disease-suppression function was not a MHB strain here. The redundancy analyses demonstrated that when AM fungus present, root mycorrhizal colonization replaced soil pH becoming the main factor impacting pepper Phytophthora blight. Thus, S. tricolor and S. tendae seemed to have the value of preparation and application in the future to help AM symbiosis against pepper Phytophthora blight.

Arbuscular Mycorrhizal Symbiosis in Two Cannabis Varieties (Khardala and Critical) in Morocco

Arbuscular Mycorrhizal Symbiosis in Two Cannabis Varieties (Khardala and Critical) in Morocco

Plant lysin motif extracellular proteins are required for arbuscular mycorrhizal symbiosis

Arbuscular mycorrhizal fungi (AMF) can form a mutually beneficial symbiotic relationship with most land plants. They are known to secrete lysin motif (LysM) effectors into host root cells for successful colonization. Intriguingly, plants secrete similar types of LysM proteins; however, their role in plant-microbe interactions is unknown. Here, we show that Medicago truncatula deploys LysM extracellular (LysMe) proteins to facilitate symbiosis with AMF. Promoter analyses demonstrated that three M. truncatula LysMe genes MtLysMe1/2/3, are expressed in arbuscule-containing cells and those adjacent to intercellular hyphae. Localization studies showed that these proteins are targeted to the periarbuscular space between the periarbuscular membrane and the fungal cell wall of the branched arbuscule. M. truncatula mutants in which MtLysMe2 was knocked out via CRISPR/Cas9-targeted mutagenesis exhibited a significant reduction in AMF colonization and arbuscule formation, whereas genetically complemented transgenic plants restored wild-type level AMF colonization. In addition, knocking out the ortholog of MtLysMe2 in tomato resulted in a similar defect in AMF colonization. In vitro binding affinity precipitation assays suggested binding of MtLysMe1/2/3 with chitin and chitosan, while microscale thermophoresis (MST) assays revealed weak binding of these proteins with chitooligosaccharides. Moreover, application of purified MtLysMe proteins to root segments could suppress chitooctaose (CO8)-induced reactive oxygen species production and expression of reporter genes of the immune response without impairing chitotetraose (CO4)-triggered symbiotic responses. Taken together, our results reveal that plants, like their fungal partners, also secrete LysM proteins to facilitate symbiosis establishment.

Arbuscular mycorrhizal symbiosis alleviates ozone injury in ozone-tolerant poplar clone but not in ozone-sensitive poplar clone

Tropospheric ozone (O3) is a typical air pollutant with harmful effects on plants, whereas arbuscular mycorrhizal (AM) fungi are ubiquitous plant symbionts that enhance plant resistance to various abiotic stresses. However, whether AM symbiosis decreases plant O3 sensitivity and what the underlying mechanisms are remain unclear. In this study, O3-tolerant poplar clone 107 and O3-sensitive poplar clone 546 were used as test plants. An open-top chamber experiment was conducted to investigate the effects of AM inoculation on plant growth and physiological parameters under O3 enrichment. The results showed that O3 enrichment significantly decreased plant biomass and net photosynthetic rate and increased the leaf shedding rate and malondialdehyde concentration of clone 546. Generally, clone 107 was less responsive to O3 enrichment than clone 546 was. Differences in antioxidant enzyme activity, rather than in specific leaf weight or stomatal conductance, were responsible for the differences in O3 sensitivity between the two clones. AM inoculation significantly increased the biomass and decreased the leaf shedding rate and malondialdehyde concentration of clone 107 but had no significant effect on almost all the indexes of clone 546, suggesting a species-specific mycorrhizal effect on plant O3 sensitivity. Mechanistically, AM symbiosis did not significantly affect nutrient uptake, stomatal conductance, or specific leaf weight of poplar but did significantly increase antioxidant enzyme activity. Linear regression analysis of antioxidant enzyme activities and the effect of O3 on growth and physiological parameters showed that AM symbiosis mediated antioxidant enzyme activities to mitigate O3 injury to the two poplar clones. This study improved the understanding of the protective effects of AM fungi on plants against O3 pollution.

Variation of growth and transcriptome responses to arbuscular mycorrhizal symbiosis in different foxtail millet lines

BackgroundArbuscular mycorrhizal fungi (AMF) have been applied to promote the growth of different crop species, but knowledge about the impacts of symbiosis on foxtail millet at the physiological and molecular levels have remained limited. In this study, we compared the mycorrhization phenotypes of one cultivar and three different landraces and performed a comprehensive transcriptomic analysis to assess the effects of genetic variation on the responses to symbiosis.ResultsOur results showed that colonization by AMF did not enhance biomass accumulation but significantly increased grain production only in three lines. More than 2,000 genes were affected by AMF colonization in all lines. Most AM symbiosis-conserved genes were induced, but the induction levels varied between lines. Gene Ontology (GO) analysis showed that Biological Function terms related to nitrogen transport and assimilation were only enriched in TT8. Similarly, two of phosphate starvation-induced phosphate transporters were only simultaneously downregulated in TT8. In the other two lines, the enrichment of GO terms associated with cell wall reorganization and lignification was observed, though the effects were different.ConclusionThis study reveals the impacts of genetic variation of millet lines on the responses to AM symbiosis and provides information regarding AMF application for millet production.

Effects of Pesticides on the Arbuscular Mycorrhizal Symbiosis

Substantial amounts of pesticides, used in agricultural production to control pests, diseases, and weeds, and thereby attain high product quantities and quality, can severely affect the ecosystem and human health. The amounts of pesticides used depend on the specifics of the current production system but also exhibit large effects of past practices. Pesticides do not act only on the target organisms but also on organisms for which the chemicals were not specifically formulated, constituting hazardous molecules for humans and the environment. Pesticides, therefore, also influence soil microbial communities including organisms that engage in mutualistic plant symbioses that play a crucial role in its mineral nutrition, such as arbuscular mycorrhizal fungi. In this review, we summarize the current knowledge on the effects of synthetic and natural (‘green’) pesticides (fungicides, herbicides, and insecticides) on arbuscular mycorrhizal symbiosis. We deal with both the direct effects (spore germination and extraradical and intraradical growth of the mycelium) and indirect effects on the agroecosystem level. Such indirect effects include effects through the spread of herbicide-resistant crops and weeds to neighboring ecosystems, thereby modifying the mycorrhizal inoculum potential and altering the plant–plant interactions. We also briefly discuss the possibility that mycorrhizal plants can be used to enhance the phytoremediation of organic pesticides.

Diversity of Arbuscular Mycorrhizal Fungi Associated with Six Rice Cultivars in Italian Agricultural Ecosystem Managed with Alternate Wetting and Drying

Alternate wetting and drying (AWD) system, in which water has been reduced by approximately 35% with an increased occurrence of beneficial arbuscular mycorrhizal (AM) symbiosis and no negative impact on rice yield, was proposed to utilize water and nutrients more sustainable. In this study, we selected six rice cultivars (Centauro, Loto, Selenio, Vialone nano, JSendra and Puntal) grown under AWD conditions, and investigated their responsiveness to AM colonization and how they select diverse AM taxa. In order to investigate root-associated AM fungus communities, molecular cloning-Sanger sequencing on small subunit rDNA data were obtained from five out of the six rice cultivars and compared with Next Generation Sequencing (NGS) data, which were previously obtained in Vialone nano. The results showed that all the cultivars were responsive to AM colonization with the development of AM symbiotic structures, even if with differences in the colonization and arbuscule abundance in the root systems. We identified 16 virtual taxa (VT) in the soil compartment and 7 VT in the root apparatus. We emphasized that the NGS analysis gives additional value to the results thanks to a more in-depth reading of the less represented AM fungus taxa.

Symbiosis of Arbuscular Mycorrhizal Fungi and Lycium barbarum L. Prefers NO3− over NH4+

Nitrogen (N) is an essential nutrient that plants require and is, most of the time, limited in different terrestrial ecosystems. Forming symbioses with plants, arbuscular mycorrhizal (AM) fungi improve mineral element uptake and the net primary production of plants. Recent reports have suggested that AM fungi mediate N uptake in plants. However, there are fewer studies on the influence of AM fungi on the response of Lycium barbarum, a medicinal plant in northwest China, under different N-addition conditions. In this study, the effect of Rhizophagus irregularis, N forms (NO3− and NH4+), and N levels (1.5, 7.5, 15, 30 mM) on the performance of L. barbarum was evaluated through a pot experiment. The application of R. irregularis significantly improved L. barbarum biomass, net photosynthetic rate, and root tissue viability under adequate NO3− and NH4+ supplies, and mycorrhizal plants showed better performance under NO3− supply. AM colonization enhanced N acquisition under adequate NO3− supply and strongly induced the expression of LbAMT3-1 in L. barbarum roots. Based on these results, we propose that NO3−-dominated N supply favors mycorrhizal symbiosis to a greater extent than NH4+; this study provides a basis for maintaining beneficial AM symbiosis during nitrogen fertilizer use in arable land.

Grazing intensity mediates effects of plant arbuscular mycorrhizal symbiosis on nitrogen and phosphorus resorption in semiarid grasslands

Grazing intensity mediates effects of plant arbuscular mycorrhizal symbiosis on nitrogen and phosphorus resorption in semiarid grasslands

Role of melatonin in enhancing arbuscular mycorrhizal symbiosis and mitigating cold stress in perennial ryegrass (Lolium perenne L.).

Melatonin is a biomolecule that affects plant development and is involved in protecting plants from environmental stress. However, the mechanisms of melatonin's impact on arbuscular mycorrhizal (AM) symbiosis and cold tolerance in plants are still unclear. In this research, AM fungi inoculation and exogenous melatonin (MT) were applied to perennial ryegrass (Lolium perenne L.) seedlings alone or in combination to investigate their effect on cold tolerance. The study was conducted in two parts. The initial trial examined two variables, AM inoculation, and cold stress, to investigate the involvement of the AM fungus Rhizophagus irregularis in endogenous melatonin accumulation and the transcriptional levels of its synthesis genes in the root system of perennial ryegrass under cold stress. The subsequent trial was designed as a three-factor analysis, encompassing AM inoculation, cold stress, and melatonin application, to explore the effects of exogenous melatonin application on plant growth, AM symbiosis, antioxidant activity, and protective molecules in perennial ryegrass subjected to cold stress. The results of the study showed that compared to non-mycorrhizal (NM) plants, cold stress promoted an increase in the accumulation of melatonin in the AM-colonized counterparts. Acetylserotonin methyltransferase (ASMT) catalyzed the final enzymatic reaction in melatonin production. Melatonin accumulation was associated with the level of expression of the genes, LpASMT1 and LpASMT3. Treatment with melatonin can improve the colonization of AM fungi in plants. Simultaneous utilization of AM inoculation and melatonin treatment enhanced the growth, antioxidant activity, and phenylalanine ammonia-lyase (PAL) activity, while simultaneously reducing polyphenol oxidase (PPO) activity and altering osmotic regulation in the roots. These effects are expected to aid in the mitigation of cold stress in Lolium perenne. Overall, melatonin treatment would help Lolium perenne to improve growth by promoting AM symbiosis, improving the accumulation of protective molecules, and triggering in antioxidant activity under cold stress.

Iron in the Symbiosis of Plants and Microorganisms.

Iron is an essential element for most organisms. Both plants and microorganisms have developed different mechanisms for iron uptake, transport and storage. In the symbiosis systems, such as rhizobia-legume symbiosis and arbuscular mycorrhizal (AM) symbiosis, maintaining iron homeostasis to meet the requirements for the interaction between the host plants and the symbiotic microbes is a new challenge. This intriguing topic has drawn the attention of many botanists and microbiologists, and many discoveries have been achieved so far. In this review, we discuss the current progress on iron uptake and transport in the nodules and iron homeostasis in rhizobia-legume symbiosis. The discoveries with regard to iron uptake in AM fungi, iron uptake regulation in AM plants and interactions between iron and other nutrient elements during AM symbiosis are also summarized. At the end of this review, we propose prospects for future studies in this fascinating research area.

The mycorrhizal root-shoot axis elicits Coffea arabica growth under low phosphate conditions.

Coffee is one of the most traded commodities world-wide. As with 70% of land plants, coffee is associated with arbuscular mycorrhizal (AM) fungi, but the molecular bases of this interaction are unknown. We studied the mycorrhizal phenotype of two commercially important Coffea arabica cultivars ('Typica National' and 'Catimor Amarillo'), upon Funnelliformis mosseae colonisation grown under phosphorus limitation, using an integrated functional approach based on multi-omics, physiology and biochemistry. The two cultivars revealed a strong biomass increase upon mycorrhization, even at low level of fungal colonisation, improving photosynthetic efficiency and plant nutrition. The more important iconic markers of AM symbiosis were activated: We detected two gene copies of AM-inducible phosphate (Pt4), ammonium (AM2) and nitrate (NPF4.5) transporters, which were identified as belonging to the C. arabica parental species (C. canephora and C. eugenioides) with both copies being upregulated. Transcriptomics data were confirmed by ions and metabolomics analyses, which highlighted an increased amount of glucose, fructose and flavonoid glycosides. In conclusion, both coffee cultivars revealed a high responsiveness to the AM fungus along their root-shoot axis, showing a clear-cut re-organisation of the major metabolic pathways, which involve nutrient acquisition, carbon fixation, and primary and secondary metabolism.

Suppression of Sclerotium rolfsii and Fusarium oxysporum through Glomalin a Glycoprotein Produced by Arbuscular Mycorrhizal Fungi under in vitro Condition

For sustainable agriculture to succeed, especially in the production of organic food, the use of biofertilizers and biopesticides is essential. Arbuscular mycorrhizal symbiosis is important for improving plant development through increased nutrient intake, soil stabilization, and carbon sequestration through the creation of glomalin, a distinct and specialized protein. It was not determined whether glomalin affects soil-borne fungi infections. Therefore, using glomalin isolated from the soil used to raise maize plants inoculated with various arbuscular mycorrhizal fungi (AMF), the inhibition of soil-borne plant diseases Sclerotium rolfsii and Fusarium oxysporum was examined. The outcomes demonstrated that there was variation in the quantity of glomalin generated by various AMF species. Glomalin isolated from soil inoculated with Glomus coronatum suppressed Sclerotium rolfsii and Fusarium oxysporum more effectively in in-vitro tests than soil inoculated with Glomus intraradices and Glomus mosseae.

Host filtering, not competitive exclusion, may be the main driver of arbuscular mycorrhizal fungal community assembly under high phosphorus

Abstract A major goal in ecology is understanding the factors which determine the diversity and distribution of organisms. The outcome of the symbiotic relationship between plants and arbuscular mycorrhizal (AM) fungi is strongly influenced by soil phosphorus (P) availability. Despite this knowledge, there is still much to uncover about how soil P status can shape the taxonomic and phylogenetic assembly of root‐colonising AM fungi. Additionally, there is a paucity of understanding about the implications of these changes for the outcome of the AM symbiosis in terms of plant growth, nutrient status and defence traits. We conducted a factorial pot experiment where sorghum (Sorghum bicolor) was grown under three different P treatments (low, medium and high), in the presence or absence of a natural AM fungal community. By analysing the diversity and community structure of the fungal community colonising roots, we aimed to determine if and how soil P influences the relatedness of these communities and whether competitive exclusion or environmental filtering play a more significant role in their assembly. Additionally, we evaluated the concomitant outcomes for plant growth, nutrient acquisition and defensive chemistry (phenolics). Increasing P availability reduced AM fungal richness and increased community evenness. Root‐colonising AM fungal communities under the high P treatment had significantly reduced phylogenetic diversity and comparatively lower mean pairwise distances among all treatments. This indicated that AM fungal communities became more closely related (phylogenetically clustered) with increasing soil P. The mycorrhizal growth and mycorrhizal P responses of plants were positive under low and medium P, but this was lost under high P, however, plant phenolics were increased. Our results suggest that under high P conditions, environmental filtering plays an important role in AM fungal community assembly as host plants alter their selectivity of fungal functional groups prioritising those associated with enhancing plant stress resistance and defences, rather than nutrient acquisition. Here we demonstrated how soil P status can shape taxonomic and phylogenetic assembly of AM fungi and the associated functional outcomes for the host. Read the free Plain Language Summary for this article on the Journal blog.

Epigenetic control is involved in molecular dialogue in plant-microbe symbiosis.

This article is a Commentary on Vigneaud et al. (2023), 238: 2561–2577.

Arbuscular mycorrhizal fungi regulate plant mineral nutrient uptake and partitioning in iron ore tailings undergoing eco-engineered pedogenesis

Excess available K and Fe in Fe-ore tailings with organic matter and water-deficiencies may restrain plant colonization and growth, which hinders the formation of eco-engineered soil from these tailings for sustainable and cost-effective mine site rehabilitation. Arbuscular mycorrhizal (AM) fungi are widely demonstrated to assist plant growth under various unfavorable environments. However, it is still unclear whether AM symbiosis in tailings amended with different types of plant biomass, and under different water conditions could overcome the surplus K and Fe stress for plants in Fe ore tailings, and if so, by what mechanisms. Here, host plants (Sorghum spp. Hybrid cv. Silk) either colonized or non-colonized by the AM fungi (Glomus spp.), were cultivated in Lucerne hay- (C: N ratio of 18, LH) or Sugarcane mulch- (C: N ratio of 78, SM) amended Fe-ore tailings under well-watered (55% water holding capacity (WHC) of tailings) or water-deficient (30% WHC of tailings) conditions. Mycorrhizal colonization, plant growth, and mineral elemental uptake and partitioning were examined. The results indicated that AM fungal colonization improved plant growth in tailings amended with plant biomass under water deficient conditions. AM fungal colonization enhanced plant mineral element uptake, especially P, both in the LH- and SM-amended tailings regardless of water condition. Additionally, AM symbiosis development restrained the translocation of excess elements (i.e., K and Fe) from roots to shoots, thereby relieving their phytotoxicity. AM roles in phosphorus uptake, and excess elemental partitioning were greater in tailings with LH amendment than those with SM amendment. Water deficiency weakened AM fungal colonization and functions in terms of mineral element uptake and partitioning. These findings have highlighted the vital role AM fungi played in regulating plant growth and nutrition status in Fe-ore tailings technosols, providing the basis for involvement of AM fungi in the eco-engineered pedogenesis of iron ore tailings.