What Do Arbuscular Mycorrhizal Fungi Do? A Comprehensive Guide to Nature's Underground Partnership

Photo credit: University of Montreal

Introduction

Arbuscular mycorrhizal fungi (AMF) represent one of nature's most remarkable agricultural innovations—yet most farmers and gardeners remain unaware of the extraordinary benefits these microscopic organisms deliver beneath the soil surface. These fungi form symbiotic relationships with approximately 80% of terrestrial plant species, creating an invisible underground network that fundamentally transforms how plants access nutrients, water, and essential minerals from the soil.journaljabb+1

The term "arbuscular mycorrhizal fungi" might sound esoteric, but the functions these organisms perform are nothing short of revolutionary for sustainable agriculture. They act as nature's nutrient delivery system, expanding a plant's effective root reach by 100 to 1,000 times, mobilizing locked nutrients that would otherwise remain inaccessible, and significantly enhancing plant resilience to environmental stresses. In an era where agriculture faces mounting pressure from climate change, soil degradation, and the need for sustainable practices, understanding what arbuscular mycorrhizal fungi do—and how they accomplish these functions—becomes essential knowledge for anyone serious about productive, environmentally responsible farming and gardening.

This comprehensive guide explores the multifaceted roles of AMF in plant growth, nutrient acquisition, soil health, and stress resilience, revealing why these fungi have become central to modern sustainable agricultural practices.

What Are Arbuscular Mycorrhizal Fungi?

Before exploring what arbuscular mycorrhizal fungi do, it's important to understand their fundamental nature and structure. AMF belong to the phylum Glomeromycota and represent obligate symbionts—they cannot survive or complete their life cycle without a living plant host.mdpi+1

Structural Characteristics and Symbiotic Interface

Arbuscular mycorrhizal fungi colonize plant roots both intracellularly and intercellularly, forming distinctive structures that define their symbiotic relationship with host plants:[pmc.ncbi.nlm.nih]​

Arbuscules: These tree-like structures develop within the cortical cells of plant roots, creating the primary nutrient exchange interface between fungi and plant. The branching architecture of arbuscules maximizes surface area for nutrient transfer while maintaining the integrity of plant cell membranes.journaljabb+1

Vesicles: Storage structures that develop between cortical cells, containing lipids and carbohydrate reserves that sustain fungal metabolism during periods when photosynthetic carbon supply from the plant diminishes.

Hyphal Networks: The extensive underground mycelium extending far beyond the root system—potentially reaching 20-24 inches beyond root surfaces. These filamentous networks access soil volumes and micropores that plant roots cannot physically penetrate.frontiersin+1

The Mutualistic Exchange

The AMF-plant partnership operates through a fundamental biological exchange:pmc.ncbi.nlm.nih+1

Plants provide fungi with:

• Photosynthetically-derived sugars (up to 20% of total carbon fixed through photosynthesis)

• Carbohydrates necessary for fungal growth and hyphal network development

• Amino acids and other metabolic compounds supporting fungal metabolism

Fungi provide plants with:

• Phosphorus—mobilized from chemically unavailable soil forms

• Nitrogen—in ammonium and nitrate forms transported through hyphal networks

• Micronutrients—zinc, copper, iron, manganese, and other essential elements

• Water—delivered to roots during periods of soil moisture limitation

• Protective compounds and signaling molecules enhancing plant immunity

This elegant exchange has persisted for approximately 400 million years, becoming so fundamental to terrestrial plant ecology that the vast majority of agricultural and horticultural crops depend on AMF associations for optimal growth.pmc.ncbi.nlm.nih+1

The Primary Functions of Arbuscular Mycorrhizal Fungi

1. Enhanced Nutrient Uptake and Mobilization

The most celebrated function of arbuscular mycorrhizal fungi involves dramatically improving plant access to essential nutrients, particularly phosphorus—an element critical for plant energy metabolism, root development, flowering, and fruit production yet chronically unavailable in most soils.

Phosphorus Mobilization: The Revolutionary Impact

Phosphorus presents a unique agricultural challenge. In typical soil conditions, 80-90% of total phosphorus exists in chemically unavailable forms, bound to calcium, iron, and aluminum compounds. Plant roots cannot absorb this "locked" phosphorus. Arbuscular mycorrhizal fungi overcome this limitation through enzymatic and chemical mechanisms:ijsra+1

Organic Acid Production: AMF hyphal networks secrete extraordinary concentrations of organic acids—citric acid, oxalic acid, and gluconic acid—that dissolve phosphate minerals bound to soil particles, converting them into plant-available orthophosphate forms.[ijsra]​

Phosphatase Enzyme Activity: The fungal hyphae produce specialized enzymes that degrade organic phosphorus compounds, releasing inorganic phosphorus that plants can absorb.[frontiersin]​

Extended Exploration: The hyphal networks probe soil micropores and soil aggregates where roots cannot reach, accessing phosphorus reserves in volumes up to 100 times larger than the root system alone.[nature]​

Quantifiable Results: Research demonstrates that up to 80% of plant phosphorus uptake can occur through mycorrhizal pathways rather than direct root absorption—a finding that revolutionizes how growers think about phosphorus nutrition.pmc.ncbi.nlm.nih+1

This phosphorus-mobilization capability delivers profound practical benefits: growers can reduce chemical phosphorus fertilizer applications by 25-50% while maintaining or exceeding yields, simultaneously reducing fertilizer costs and environmental impact through reduced nutrient runoff.pmc.ncbi.nlm.nih+2

Comprehensive Nutrient Enhancement

While phosphorus receives justified emphasis, arbuscular mycorrhizal fungi enhance plant acquisition of an entire spectrum of essential nutrients:

Nitrogen Uptake Enhancement: AMF improve plant acquisition of both ammonium (NH₄⁺) and nitrate (NO₃⁻) nitrogen forms, with particular effectiveness in low-nitrogen soils. The fungal networks transport nitrogen through hyphal pathways as arginine—an amino acid that moves more efficiently through fungal tissues than inorganic nitrogen forms.pmc.ncbi.nlm.nih+1

Research documents that AMF colonization increases nitrogen uptake efficiency by 15-30%, particularly valuable in organic systems relying on mineralized organic nitrogen sources.[mdpi]​

Micronutrient Mobilization: AMF dramatically improve plant access to micronutrients—zinc, copper, iron, manganese—whose availability is limited by low solubility and restricted mobility in soil. The organic acids produced by AMF hyphae dissolve micronutrient minerals, making them bioavailable to both fungal and plant tissues.pmc.ncbi.nlm.nih+1

Potassium and Calcium Enhancement: While not as dramatically impacted as phosphorus, AMF colonization improves potassium and calcium uptake through expanded root surface area and enhanced ion transport efficiency.[pmc.ncbi.nlm.nih]​

Complete Nutrient Status: Studies quantifying all plant-available elements document that mycorrhizal plants contain increased concentrations of 20+ quantified nutrient elements compared to non-mycorrhizal counterparts, creating a comprehensive nutritional enhancement that supports optimal plant metabolism and physiology.[pmc.ncbi.nlm.nih]​

2. Expanded Root Architecture and Water Uptake

Beyond nutrient mobilization, arbuscular mycorrhizal fungi transform plant root systems themselves, promoting root growth and improving water acquisition capability.

Hyphal Network Extension and Root Zone Expansion

The extensive hyphal networks produced by AMF colonization create a virtual expansion of the plant's root system. This expansion delivers multiple benefits:pmc.ncbi.nlm.nih+1

Physical Reach Expansion: Fungal hyphae extend 20-24 inches beyond root surfaces, accessing soil moisture and nutrients in volumes far exceeding what roots alone could explore.[frontiersin]​

Water Availability Improvement: In drought-prone environments, the expanded hyphal network improves plant access to soil moisture stored in micropores inaccessible to roots. This expanded water acquisition translates to improved photosynthetic efficiency and biomass accumulation during water-limited periods.[pmc.ncbi.nlm.nih]​

Root Architecture Modification: AMF colonization stimulates lateral root branching and increased root hair production, further enhancing the root system's nutrient and water acquisition capability.[frontiersin]​

Quantifiable Water Stress Mitigation

Research on drought tolerance demonstrates that AMF colonization provides measurable protection against water stress:frontiersin+1

• Mycorrhizal plants maintain 15-25% higher relative water content during drought compared to non-mycorrhizal controls

• Photosynthetic efficiency remains 20-40% higher in mycorrhizal plants during moderate drought stress

• Overall biomass production under water limitation increases 20-60% with AMF colonization

• Root dry weight increases by 30-50%, reflecting enhanced root development capacity

These improvements become increasingly critical as climate variability intensifies, making AMF inoculation a proactive strategy for building drought-resilient agricultural systems.

3. Soil Health and Structure Improvement Through Glomalin Production

One of the most underappreciated functions of arbuscular mycorrhizal fungi involves their contribution to long-term soil structure and health through production of a remarkable compound called glomalin.

The Glomalin Revolution: Building Soil Structure

Glomalin is a glycoprotein—a carbohydrate-protein compound—produced by AMF hyphal networks and accumulated in soil. This compound functions as nature's soil cement, binding soil particles into stable aggregates that fundamentally improve soil physical properties.cdnsciencepub+2

Soil Aggregate Stability: Glomalin production creates water-stable soil aggregates that resist degradation from raindrop impact and mechanical disturbance. Soil large macroaggregates (>2mm) increase proportionally with glomalin concentration, with some soils showing 40-60% increases in large aggregate formation following AMF inoculation.pmc.ncbi.nlm.nih+2

Water Retention and Infiltration: The improved soil structure enhances pore space distribution, improving both water-holding capacity and water infiltration rates. This dual improvement means soils require less irrigation while maintaining better water availability during dry periods.[cdnsciencepub]​

Erosion Reduction: The stable soil aggregates resist water erosion, reducing surface runoff and soil loss on sloped terrain—a particularly valuable benefit in erosion-prone regions.[pmc.ncbi.nlm.nih]​

Carbon Sequestration: Glomalin represents a stable carbon pool with slow turnover rates, potentially persisting in soil for 10-15+ years. This carbon stability contributes to long-term soil organic matter accumulation and atmospheric carbon sequestration—a crucial benefit in addressing climate change.pmc.ncbi.nlm.nih+1

Quantifiable Glomalin Impacts

Research quantifying glomalin's soil improvement effects demonstrates:pmc.ncbi.nlm.nih+2

• Mean Weight Diameter (MWD) of soil aggregates increases 35-50% with AMF inoculation

• Water infiltration rates improve by 40-70% in AMF-colonized soils

• Soil water-holding capacity increases 20-35%

• Erosion rates decrease 50-80% on slopes receiving AMF inoculation

• Soil carbon stability increases by 25-40%

These improvements persist long-term, creating lasting benefits that justify multi-year AMF management investments.

4. Enhanced Disease Resistance and Biocontrol

Arbuscular mycorrhizal fungi function as biological defenders, protecting plants against pathogenic attacks through multiple overlapping mechanisms that collectively reduce disease incidence by 15-35%.frontiersin+1

Induced Systemic Resistance (ISR)

One of AMF's most sophisticated protective mechanisms involves triggering the plant's natural immune system through a process called Induced Systemic Resistance:tandfonline+2

Elicitor Release: AMF release signaling molecules (elicitors) derived from fungal cell walls that activate plant defense pathways throughout the plant, not just at infection sites.[pmc.ncbi.nlm.nih]​

Phytohormone Modulation: AMF colonization enhances the expression of defense-related phytohormones—salicylic acid, jasmonic acid, abscisic acid, and nitric oxide—creating a primed immune state where plants mount faster, more robust responses to pathogenic attack.[pmc.ncbi.nlm.nih]​

Defense Gene Activation: The fungal signals upregulate expression of pathogenesis-related genes that encode antimicrobial compounds, hydrolytic enzymes, and other proteins central to pathogenic suppression.frontiersin+1

Antioxidant System Enhancement: Colonization increases the activity of antioxidant enzyme systems (superoxide dismutase, catalase, peroxidase) that neutralize destructive reactive oxygen species produced during pathogenic attack.frontiersin+1

Physical and Chemical Protective Barriers

Beyond immune priming, AMF establish multiple physical and chemical barriers to pathogenic invasion:pmc.ncbi.nlm.nih+1

Cell Wall Reinforcement: AMF stimulate callose deposition and lignin synthesis in plant cell walls, creating stronger physical barriers that resist pathogenic penetration.[pmc.ncbi.nlm.nih]​

Root Biofilm Formation: The fungal networks form protective biofilms around root tissues, physically excluding pathogenic organisms from root colonization sites.[pmc.ncbi.nlm.nih]​

Rhizosphere Restructuring: AMF alter root exudation patterns, indirectly suppressing pathogenic organisms by restructuring the rhizosphere microbial community to favor beneficial antagonists over pathogens.frontiersin+1

Nematode Suppression: For root-knot nematodes and other parasitic organisms, AMF colonization reduces nematode reproduction and motility through multiple mechanisms including altered root exudates and enhanced plant vigor that allows plants to tolerate nematode populations.[pmc.ncbi.nlm.nih]​

Quantifiable Disease Suppression

Field studies document disease suppression benefits:frontiersin+1

• Damping-off disease reduction: 30-50% lower incidence in mycorrhizal seedlings

• Root rot disease suppression: 25-40% lower severity scores in mycorrhizal plants

• Foliar disease suppression: 20-35% reduction with AMF colonization

• Nematode population suppression: 40-60% reduction in root-knot nematode numbers

These benefits prove particularly valuable in intensive production systems where disease pressure creates significant economic losses.

5. Abiotic Stress Tolerance: Drought, Salinity, and Temperature Resilience

Beyond biotic stress (pathogens and pests), arbuscular mycorrhizal fungi dramatically enhance plant tolerance to abiotic stresses—environmental challenges that increasingly threaten global agriculture in an era of climate variability.

Drought Stress Mitigation

AMF's enhanced water acquisition capability translates to remarkable drought resilience:pmc.ncbi.nlm.nih+2

Osmotic Adjustment: AMF colonization stimulates increased synthesis of compatible solutes—proline, glycine betaine, and sugars—that lower cellular osmotic potential and improve water uptake efficiency during drought.[pmc.ncbi.nlm.nih]​

Antioxidant Defense: The enhanced antioxidant enzyme activity protects cellular structures from oxidative stress generated by drought-induced water deficit.[pmc.ncbi.nlm.nih]​

Photosynthetic Efficiency: Mycorrhizal plants maintain superior photosynthetic rates during drought, supporting continued biomass accumulation even under water limitation.[pmc.ncbi.nlm.nih]​

Practical Impact: Under moderate to severe drought, mycorrhizal crops maintain 20-60% higher yields than non-mycorrhizal counterparts, depending on crop type and drought severity.pmc.ncbi.nlm.nih+1

Salinity Stress Tolerance

In saline and salt-alkaline soils, AMF provides critical salinity tolerance mechanisms:nature+1

Sodium Exclusion: AMF help plants exclude sodium from sensitive tissues while maintaining potassium uptake—crucial for maintaining cellular function and osmotic balance in saline conditions.[nature]​

Ion Compartmentalization: The fungal-plant partnership facilitates selective ion uptake, accumulating essential nutrients (potassium, calcium, phosphorus) while excluding toxic ions (sodium, chloride).[nature]​

Enhanced Nutrient Status: Under salt stress, phosphorus availability particularly benefits from AMF mobilization, as mineral phosphorus fixation increases in alkaline saline soils.[nature]​

Quantifiable Salinity Tolerance: Soybean plants under saline-alkaline stress with AMF inoculation showed:[nature]​

• 36.8% increased root colonization at optimal phosphorus levels

• 13.95% increased plant height at moderate phosphorus supply

• 36.65% increased root length with optimal nutrient balance

• Enhanced nutrient accumulation (nitrogen, phosphorus, potassium) throughout tissues

Temperature Extremes and Other Abiotic Stresses

AMF also improve tolerance to temperature extremes, heavy metal toxicity, and other abiotic challenges:pmc.ncbi.nlm.nih+2

• Heavy metal stress: AMF help exclude or compartmentalize cadmium, lead, and other toxic metals

• Extreme temperatures: Enhanced cellular osmolyte production and membrane fluidity maintenance

• Soil compaction: Improved root penetration capability through enhanced root vigor

• Nutrient imbalance: AMF preferentially mobilize deficient nutrients, buffering against fertility imbalances

6. Carbon Cycling and Climate Change Mitigation

An emerging and increasingly important function of AMF involves their role in carbon cycling and long-term carbon sequestration—a function gaining prominence as agriculture seeks to address climate change.

Carbon Allocation to Soil

Arbuscular mycorrhizal fungi receive approximately 20% of plant photosynthetically-fixed carbon, which is allocated to hyphal growth, arbuscule maintenance, and glomalin production. This carbon ultimately enters soil carbon pools through:[journaljabb]​

Direct Hyphal Deposition: Fungal hyphae turn over continuously, with dead hyphae contributing to stable soil organic matter.

Glomalin Accumulation: The glomalin-related soil protein (GRSP) produced by AMF hyphae represents a stable carbon pool with slow decomposition rates, potentially sequestering carbon for decades.[journaljabb]​

Rhizosphere Priming: AMF exudates stimulate microbial decomposition of existing soil organic matter, creating feedback loops that influence overall soil carbon dynamics.[journaljabb]​

Climate Change Mitigation Potential

Research estimates that optimized AMF management could contribute meaningfully to soil carbon sequestration strategies:[journaljabb]​

• Average carbon sequestration: 0.5-2 tons of CO₂ equivalent per hectare annually

• Cumulative effect: Over 20 years, this represents 10-40 tons of sequestered carbon per hectare

• Scaling potential: If applied to marginal agricultural lands, could sequester billions of tons of atmospheric carbon

While not a complete climate solution, AMF optimization represents one component of comprehensive soil carbon management strategies supporting climate mitigation.

Plant Growth Enhancement: Quantifiable Yield and Productivity Improvements

The cumulative effects of AMF nutrient acquisition, stress tolerance, and disease suppression translate to remarkable improvements in plant growth, biomass production, and crop yields.

Biomass and Growth Metrics

Field trials across diverse crop systems document consistent biomass improvements:frontiersin+2

Aboveground Biomass: 15-40% increases compared to non-mycorrhizal controls, depending on initial soil fertility and environmental conditions.

Root Biomass: 25-60% increases reflecting enhanced root system development and hyphal colonization.

Plant Height and Architecture: Improved plant stature and branching development, particularly pronounced in nitrogen or phosphorus-limited soils.

Chlorophyll Content: 10-25% higher leaf chlorophyll content supporting improved photosynthetic capacity.

Crop Yield and Productivity Improvements

The ultimate measure of agricultural success involves crop yield and economic return. AMF colonization delivers consistent yield improvements:pmc.ncbi.nlm.nih+2

Cereal Crops: 15-35% grain yield increases depending on soil phosphorus status and rainfall patterns. Rainfed systems show the most dramatic improvements.

Vegetable Crops: 20-40% yield increases in fruiting vegetables (tomatoes, peppers, eggplants) and 15-30% improvements in leafy vegetables.

Legume Crops: 20-45% yield improvements reflecting enhanced phosphorus nutrition supporting nitrogen fixation.

Fiber and Oil Crops: 15-35% dry matter increases translating to improved fiber yields and oil production.

Economic Returns

Beyond biological improvements, AMF inoculation delivers economic benefits through reduced input costs:

Fertilizer Savings: 25-50% reduction in chemical phosphorus applications without yield penalty translates to direct cost savings of $15-45 per hectare annually.

Fungicide Reduction: 15-40% lower fungicide applications in disease-prone environments reduce pesticide costs and environmental contamination.

Improved Product Quality: Enhanced nutrient density improves produce quality (higher vitamin content, better flavor in vegetables), supporting premium pricing in specialty markets.

Labor Efficiency: Reduced disease pressure and transplant failures decrease labor requirements for disease management and replanting.

Frequently Asked Questions

How Long Does Colonization Take?

Initial root colonization typically occurs within 2-4 weeks of AMF application, with observable plant benefits becoming apparent after 6-8 weeks. Maximum benefits develop over the entire growing season as the fungal network matures.[pmc.ncbi.nlm.nih]​

Can AMF Be Used with All Plant Species?

Approximately 80% of plant species form mycorrhizal associations. Notable exceptions include members of the Brassicaceae family (cabbage, broccoli, radishes) and some aquatic plants. For optimal results, verify AMF compatibility with specific crops before inoculation.[pmc.ncbi.nlm.nih]​

How Do Soil Conditions Affect AMF Effectiveness?

Soil pH: AMF function optimally in slightly acidic to neutral soils (pH 6.0-7.5). Extreme pH conditions limit fungal diversity and effectiveness.

Phosphorus Status: Excessively high phosphorus (>50 ppm bioavailable) suppresses AMF development by reducing plant carbon allocation to fungi. This actually demonstrates the efficiency of the symbiotic exchange—when nutrients become abundant, plants reduce fungal dependence.[pmc.ncbi.nlm.nih]​ Soil Type: AMF thrive in most soil types but prove most valuable in nutrient-poor soils where nutrient mobilization capabilities become critical.

Should Chemical Fertilizers Be Eliminated When Using AMF?

Rather than complete elimination, reduce readily available phosphorus fertilization to 50-70% of standard recommendations. Maintain adequate nitrogen and potassium supplies, allowing AMF to mobilize phosphorus from soil reserves. This balanced approach optimizes both fungal colonization

and plant nutrition.[pmc.ncbi.nlm.nih]​

Can Fungicides Be Used with AMF Inoculants?

Avoid fungicide applications within 2-4 weeks of AMF inoculation, as many fungicides suppress fungal spore germination and colonization. After colonization establishment, selective fungicides targeting specific pathogens can be used, though broad-spectrum fungicides may suppress beneficial fungal activity.

Harnessing the Full Potential of Arbuscular Mycorrhizal Fungi

Arbuscular mycorrhizal fungi perform a remarkable suite of functions that fundamentally transform agricultural productivity and sustainability. From mobilizing locked nutrients and expanding plant water acquisition to suppressing diseases and building long-term soil health, AMF address virtually every major challenge facing modern agriculture.

The scientific evidence is overwhelming and unambiguous: arbuscular mycorrhizal fungi significantly enhance plant growth, reduce input requirements, improve environmental resilience, and contribute to long-term soil health. As agriculture confronts mounting pressures from climate change, soil degradation, and the need for sustainability, optimizing AMF associations represents one of the most cost-effective, biologically-sound strategies available to growers.

Whether operating a vegetable garden, managing field crops, or stewarding landscape plantings, understanding what arbuscular mycorrhizal fungi do—and deliberately cultivating these beneficial associations—represents an investment in both immediate productivity and long-term agricultural sustainability.

To explore premium AMF products and comprehensive technical resources, visit the Arbuscular Mycorrhizal Fungi page.

References

• Role of Arbuscular Mycorrhizal Fungi in Regulating Growth, Enhancing Productivity (2023)[pmc.ncbi.nlm.nih]​ 

• Arbuscular mycorrhizal fungi enhance soybean phosphorus uptake (2025)[nature]​ 

• Arbuscular Mycorrhizal Fungi-Mediated Carbon Sequestration (2025)[journaljabb]​ 

• Effects of combined inoculation of arbuscular mycorrhizal fungi (2025)[frontiersin]​ 

• Signals and Machinery for Mycorrhizae and Cereal Interactions (2024)[mdpi]​ 

• Symbiotic synergy: How Arbuscular Mycorrhizal Fungi enhance nutrient uptake (2025)[pmc.ncbi.nlm.nih]​ 

• Arbuscular mycorrhizal fungal contribution towards plant resilience to drought (2024)[pmc.ncbi.nlm.nih]​ 

• Arbuscular Mycorrhizal Fungi: Boosting Crop Resilience (2024)[pmc.ncbi.nlm.nih]​ 

• Arbuscular mycorrhizae increase crop yields (2022)[pmc.ncbi.nlm.nih]​ 

• Enhancing plant resilience: arbuscular mycorrhizal fungi's role in alleviating drought (2024)[frontiersin]​ 

• Effects of Arbuscular Mycorrhizal Fungi on the Growth (2025)[pmc.ncbi.nlm.nih]​ 

• The effects of arbuscular mycorrhizal fungi on glomalin (2017)[cdnsciencepub]​ 

• Roles of arbuscular mycorrhizal fungi in plant growth (2025)[pmc.ncbi.nlm.nih]​ 

• Understanding the mechanisms of nutrient transfer[ijsra]​ 

• Glomalin-related soil protein distribution and aggregate stability (2017)[pmc.ncbi.nlm.nih]​

• Arbuscular mycorrhizal fungi – a natural tool (2025)[tandfonline]​ 

• Arbuscular Mycorrhizal Fungi and Glomalin in soil aggregate stability (2022)[pmc.ncbi.nlm.nih]​Effects of arbuscular mycorrhizal fungi on plant growth (2023)[frontiersin]​ 

• Roles of arbuscular mycorrhizal fungi in plant growth and disease (2025)[frontiersin]​