**1. Introduction**

In past decades, there are escalating events of abiotic stress like drought, low or high-salinity, soils contaminated with heavy metals, extremely high or low temperatures and other extreme calamities of climate such as hurricanes, tornadoes have always been detrimental to agriculture and industries. Added to the list, increasing effects of the unseasonal climatic changes such as earthquakes, tsunamis have immensely damaged our lands. On top of everything else, agricultural malpractices like poorly managed animal feeding operations, overgrazing, plowing, tilling, excessive fertilizer usage, genetically modified crops, deforestation, excessive irrigation, pesticides, phosphorous mining, poor agricultural waste management, increasing soil pathogens have severely crippled the agricultural yields [1]. The world populace is projected to be 9.7 billion in 2050 and approximately 11 billion around 2100 according to UN population division and thus the global need for increased food sources by agricultural production must be definitely promoted to keep up with the population. Many improvements must come up for better agricultural quality and productivity shortcomings with insightful management.

#### **Figure 1.**

*Mycorrhizal fungal association in roots of legumes (photo courtesy: Corsi and Muminjanov [2]).*

The Food and Agriculture Organization (FAO) United Nations reveals major challenges to sustainable intensification of land and agricultural practices such as land degradation due to tillage erosion, soil compaction, overgrazing, nutrient mining, overuse of mineral fertilizers and herbicides, inefficient irrigation practices, ignorant crop management practices and other malpractices [2] that needs immediate attention. The FAO Agricultural Development Economics Division voice out for crucial remedial measures on agricultural practices as the population growth and global food demand towards 2030/50 seems worrisome [3].

Studies show that AMF associated agricultural practices can offer major relief by sustainable and beneficial consequences for both agricultural and natural ecosystems through its association with the plants and soil. This chapter presents the symbiotic interconnections of AMF for the advantageousness in agriculture and industry are highlighted (**Figure 1**).

#### **2. AMF background and evolvement**

The fungus is a eukaryotic organism that belonged to the plant kingdom at the beginning; nonetheless, as the studies unfolded its unique features, scientists realized that fungi were much alike animals than plants by exhibiting features like cell membrane-bound organelles, distinct nuclei, and lack of chlorophyll in their cells. Fungi have an exclusive life cycle of having principal modes of vegetative growth, nutrient intake unlike animals that enabled it to have a distinguished identity. The kingdom of fungi has about 1.5 million known species covering the yeasts, rusts, smuts, mildews, molds, and mushrooms. Some organisms like slime molds and oomycetes (water molds) show many fungi-like features and are included in the kingdom of Chromista. Fungi are widely distributed on earth and are mostly free-living, some form parasitic or symbiotic relationships with plants or animals. Many fungi are of great environmental and medical importance and its study is termed as Mycology [4].

A typical fungus has minute filamentous cytoplasmic morphologies bounded by a plasma membrane and cell wall known as hyphae. Their cell walls are made up of flexible polysaccharides called chitin, resembling the exoskeleton of insects. The hyphae have many auxiliary cell walls, known as cross-walls or septa, typically perforated with pores that are large enough for ribosomes, mitochondria, and nuclei to flow. The hyphae branch extensively as they mature, forming complex multicellular structures known as mycelium. A mycelium gives heterotrophic nourishment as they feed on organic food sources, digest them externally before absorption by secreting valuable enzymes into its surroundings. These mycelia can spread to vast areas that

**33**

**Figure 2.**

**Figure 3.**

*@ GPNMAG.COM 2018).*

arbuscular mycorrhizal fungi (AMF).

*Advantages of Arbuscular Mycorrhizal Fungi (AMF) Production for the Profitability…*

*Transmission Electron micrographic view of a colonized host cell with an arbuscular branch (fungus),* 

*surrounded by the peri arbuscular membrane (photo courtesy: Chen et al. [8]).*

serve as a phenomenal symbiotic benefit to the plant root system, giving it a unique chance to obtain phosphate and other minerals far off the nutriment depleted zones, while the fungal takes sugars from the plant. Symbiotic association between a fungus and the roots of a vascular plant is often termed as Mycorrhiza or root fungi [5]. The mycorrhization of a plant root that develops as a cover surrounding the roots is termed mantle, from which the hyphae grow, and this is Ectomycorrhiza. On the other hand, Endomycorrhiza is when the mycelium is implanted within the root tissue and these are also termed as the arbuscular mycorrhizae (AM) or

*Scanning electron micrograph of mycorrhizal hyphae and spores (photo curtesy: Mycorrhizal applications* 

More than 80% of the terrestrial plants show symbiosis with AMF and they belong to Phylum Glomeromycota. AMFs are obligate biotrophs, absorb photosynthetic byproducts and lipids in the plant symbiotic connections [6]. AM are expected to have originated approximately 480 million years ago, the fossilized fungal hyphae and spores from the Ordovician of Wisconsin (USA) bear a strong resemblance with the current AMF (Glomales, Zygomycetes). These fossils suggested that Glomales-like fungi existed in the bryophytic vegetation. Later many

*DOI: http://dx.doi.org/10.5772/intechopen.95458*

*Advantages of Arbuscular Mycorrhizal Fungi (AMF) Production for the Profitability… DOI: http://dx.doi.org/10.5772/intechopen.95458*

#### **Figure 2.**

*Mycorrhizal Fungi - Utilization in Agriculture and Forestry*

The Food and Agriculture Organization (FAO) United Nations reveals major challenges to sustainable intensification of land and agricultural practices such as land degradation due to tillage erosion, soil compaction, overgrazing, nutrient mining, overuse of mineral fertilizers and herbicides, inefficient irrigation practices, ignorant crop management practices and other malpractices [2] that needs immediate attention. The FAO Agricultural Development Economics Division voice out for crucial remedial measures on agricultural practices as the population

Studies show that AMF associated agricultural practices can offer major relief

The fungus is a eukaryotic organism that belonged to the plant kingdom at the beginning; nonetheless, as the studies unfolded its unique features, scientists realized that fungi were much alike animals than plants by exhibiting features like cell membrane-bound organelles, distinct nuclei, and lack of chlorophyll in their cells. Fungi have an exclusive life cycle of having principal modes of vegetative growth, nutrient intake unlike animals that enabled it to have a distinguished identity. The kingdom of fungi has about 1.5 million known species covering the yeasts, rusts, smuts, mildews, molds, and mushrooms. Some organisms like slime molds and oomycetes (water molds) show many fungi-like features and are included in the kingdom of Chromista. Fungi are widely distributed on earth and are mostly free-living, some form parasitic or symbiotic relationships with plants or animals. Many fungi are of great environ-

growth and global food demand towards 2030/50 seems worrisome [3].

*Mycorrhizal fungal association in roots of legumes (photo courtesy: Corsi and Muminjanov [2]).*

mental and medical importance and its study is termed as Mycology [4].

A typical fungus has minute filamentous cytoplasmic morphologies bounded by a plasma membrane and cell wall known as hyphae. Their cell walls are made up of flexible polysaccharides called chitin, resembling the exoskeleton of insects. The hyphae have many auxiliary cell walls, known as cross-walls or septa, typically perforated with pores that are large enough for ribosomes, mitochondria, and nuclei to flow. The hyphae branch extensively as they mature, forming complex multicellular structures known as mycelium. A mycelium gives heterotrophic nourishment as they feed on organic food sources, digest them externally before absorption by secreting valuable enzymes into its surroundings. These mycelia can spread to vast areas that

industry are highlighted (**Figure 1**).

**Figure 1.**

**2. AMF background and evolvement**

by sustainable and beneficial consequences for both agricultural and natural ecosystems through its association with the plants and soil. This chapter presents the symbiotic interconnections of AMF for the advantageousness in agriculture and

**32**

*Transmission Electron micrographic view of a colonized host cell with an arbuscular branch (fungus), surrounded by the peri arbuscular membrane (photo courtesy: Chen et al. [8]).*

#### **Figure 3.**

*Scanning electron micrograph of mycorrhizal hyphae and spores (photo curtesy: Mycorrhizal applications @ GPNMAG.COM 2018).*

serve as a phenomenal symbiotic benefit to the plant root system, giving it a unique chance to obtain phosphate and other minerals far off the nutriment depleted zones, while the fungal takes sugars from the plant. Symbiotic association between a fungus and the roots of a vascular plant is often termed as Mycorrhiza or root fungi [5].

The mycorrhization of a plant root that develops as a cover surrounding the roots is termed mantle, from which the hyphae grow, and this is Ectomycorrhiza. On the other hand, Endomycorrhiza is when the mycelium is implanted within the root tissue and these are also termed as the arbuscular mycorrhizae (AM) or arbuscular mycorrhizal fungi (AMF).

More than 80% of the terrestrial plants show symbiosis with AMF and they belong to Phylum Glomeromycota. AMFs are obligate biotrophs, absorb photosynthetic byproducts and lipids in the plant symbiotic connections [6]. AM are expected to have originated approximately 480 million years ago, the fossilized fungal hyphae and spores from the Ordovician of Wisconsin (USA) bear a strong resemblance with the current AMF (Glomales, Zygomycetes). These fossils suggested that Glomales-like fungi existed in the bryophytic vegetation. Later many

reports supported that AMF was essential constituents in predominant land plants in most taxa in all the ecological niches for ages. The Glomeromycota are a distinctive obligate biotrophic fungi that majorly comprises AMF related in symbiosis with many Embryophytes [7]. Nevertheless, certain mycoheterotroph plant species on AMF symbiosis turned in to obligate parasites having completely lost plastid genetic apparatus, photosynthesis genes with secondary functions, NADH dehydrogenaselike genes and photosynthesis genes. As another diversity was seen in plant taxa such as Brassicacea (or Cruciferae) and Chenopodiaceae, where they have shown asymbiotic interaction with AMF and these plants developed other strategies for their nutritional requirements (**Figures 2** and **3**) [9].

### **3. AMF as biofertilizers**

Many active or dormant strains of bacteria or fungi or in combinations are used diametrically or collaterally to activate the rhizo-microbiome and trigger the nutrient supply from soil to plants that would ultimately result in enhancement of crop yields. These microbial strains are broadly termed as biofertilizers, bioinoculants, agricultural inoculants, soil inoculants, or microbial inoculants. These bio-inoculants with unique merits are highly encouraged globally and are earning prominence in modern agricultural customs, practices and maneuvers contrasting to other conventional or synthetic pesticides and fertilizers. These biofertilizers are safe to handle, are required only in small quantities as they capable of fast replication, their action can be leveraged or optimized based on their incumbencies, decompose quickly with negligible ill effects to the environment and show lower resistance to host plant and infective organisms [10].

Plant growth promoting and disease suppressing microbial inoculants such as *Azospirillum, Bacillus, Pseudomonas, Rhizobium, Serratia, Stenotrophomonas,* and *Streptomyces, Ampelomyces, Coniothyrium, Glomus,* and *Trichoderma are* extensively examined and analyzed for their mechanism of action and regulatory gear. Even though multiple categories of biofertilizers are at hand, the AMF is reported of manifold advantages and graded high for soil health and crop productivity [11]. Studies have shown comparative progress where plants get better nourishment with greater AMF colonization than that of the non-mycorrhizal plants even with conditions like mineral deficiency and abiotic stress. AMF establishes symbiotic interconnection with many different types of Plants or the other way round, that leads to the formation of common mycorrhizal networks (CMNs) and such mycorrhizal interactions are exceptionally valuable for healthier plant growth and yield in most of the scenarios [12].

Certain AMF show specific combinatorial benefits with specific types of plant species from all types of geographical locations that can result in positive mycorrhizal growth response (MGR) and this is a progressive mutual adaptation that did not correlate with phylogenetic lineage patterns relevant to variant species [13]. Contrarily, some studies though agree with the functional specialization of AMF, proved that such incidence is a flexible phenomenon where plant species are required to show compatibility with at least a few AMF. This scenario with minimal host specificity and broad functional specialization encourages vast biodiversity and productivity in plant communities [14].

Rampant use of inorganic fertilizers, herbicides, and fungicides are causing multiple injurious health risks to every living organism by hazardous impacts on the quality of food, soil, air, and water systems [15]. Over the years, many investigations have proven the efficacy of AMF for best agricultural production compared to other synthetic or chemical fertilizers under the prevalent stressful conditions, as addressed below.

**35**

*Advantages of Arbuscular Mycorrhizal Fungi (AMF) Production for the Profitability…*

Drought is the scarcity of water in soil for prolonged durations affects plant growth. It has severe implications on the entire plant biorhythm and growth at every notch. Deficit water supply to roots causes oxidative stress due to anomalies in transpiration [16], affects enzyme activity, ion uptake, and nutrient assimilation [17]. Many investigations have evidenced that AMF can allay drought stress in varied crop like wheat, barley, maize, soybean, strawberry, and onion [18]. This remarkable tolerance is reasoned essentially due to the extra-radical hyphae of AMF that has the capability of vast area spread [19]. Further, the osmotic adjustment, stomatal regulation, enhanced proline, and glutathione level are exhibited to have augmented root efficiency, leaf area index, and biomass under the instant drought conditions and against severe environmental conditions. Reports have demonstrated that the enhancement in growth and photosynthesis in C3 (*Leymus chinensis*) and C4 (*Hemarthria altissima*) plant species through up-regulation of

Soil salinization is an aggravating issue threatening global food safety as it suppresses the plant development leading to reduced crop harvest (due to enormous formation of reactive oxygen species (ROS)) [21]. Many research reports showed the efficiency of AMF to enhance growth and crop yield under salinity stress. AMF association triggered the synthesis of plant hormones such as jasmonic acid and

*2017 California spring trials. Coreopsis plants (image 1) inoculated with AMF (left) showed better tolerance than plants without AMF under same drought stress. Coreopsis plants (image 2) treated with AMF showed improved top growth and root system development (left) than that without AMF inoculation (right) (photo* 

conditions [22]. Some mycorrhizal associated plants showed increased amount of biomass, proline, N2, and remarkable alteration in ionic uptake. AMF inoculation showed better levels of key growth regulators such as cytokinin, polyamine and strigolactone concentrations, suppressing lipid membrane peroxidation and regula-

Extreme temperatures such as Heat stress and Cold stress are prevalent challenges faced by plants globally. Heat stresses reduce seed germination, growth rate

) under salt stress

salicylic acid, and inorganic nutrients (P, Ca2+, N, Mg2+, and K+

*DOI: http://dx.doi.org/10.5772/intechopen.95458*

antioxidant system by AMF symbiosis (**Figure 4**) [20].

**5. Salinity stress alleviation**

*courtesy: Mycorrhizal applications @ GPNMAG.COM 2018).*

**Figure 4.**

tion of the osmoregulation [23].

**6. Resilience to extreme temperatures**

**4. Drought tolerance**

*Advantages of Arbuscular Mycorrhizal Fungi (AMF) Production for the Profitability… DOI: http://dx.doi.org/10.5772/intechopen.95458*
