**1. Introduction**

Fungi are the most valued and understudied group of microorganisms and are widely distributed in different ecological habitats that inhabit and the consequential requirement to contend against an assorted group of other microorganisms, that is, bacteria, fungi, and viruses also have a strong defense mechanism for survival as many scientists have studied their role industrially, ecologically, and biotechnologically; now, fungal association with trees, which termed as mycorrhiza, is becoming the center of focus for its role in forestry and ecosystem as a biofertilizer. Fungi as biofertilizers are considered the basic core of the ecosystem, and their impact will be felt more in the future; hence, the importance of fungi as biofertilizers cannot be denied. The term mycorrhiza originated from two Greek words "mykes and rhiza," which mean fungus and roots, respectively, was first coined in 1885 by Albert Bernhard

Frank who was a forest pathologist [1]. Frank also explained that mycorrhiza is an association of ectomycorrhiza (ECM) and roots of higher plant, and this relationship is symbiotic in nature; he further subdivided it into two subcategories, that is, ectomycorrhizal fungi (do not penetrate cortical cells) and endomycorrhizal fungi (penetrate cortical cells). A lot of research has been conducted on symbiotic relationships of fungi and plants by many scientists who showed that approximately 86% of territorial plants get their nutrients through mycorrhizal roots [2]. The number of fungal species that take part in ectomycorrhiza formation is about more than 7000, and, predominantly, species from basidiomycetes class contribute toward ectomycorrhiza formation. In ectomycorrhiza formation, a special network named as Hartig's is a bridge for the metabolic altercation of fungi and the roots through which it plays its role in the mobilization, translocation, and transportation of soil nutrients to the roots of plants through mycorrhizal mantle connection extended into the soil [3].

Many pieces of research also supported an assumption that ectomycorrhiza fungi developed polyphyletic assistance from multiple saprophytic species, as their diversity was initially based on the studies of the reproductive part of fungi, and now they are categorized based on their morph anatomical characteristics. With many significant and viable trees, such as poplar, pine, birch, and oak, ectomycorrhizal associations are being observed [4]. Mycorrhizal fungi (MF) can be helpful for the identification of the structure of the plant community. So, the determination of fungal companion, symbiotic relationship and to understand its structure, function and fundamental importance in ecology terms [5].

### **2. Role of microbes as biofertilizers**

In the recent era, the agricultural sector has mostly relied on synthetic and chemical fertilizers for their betterment, but the excessive use of chemicals has caused various environmental issues, such as increase in temperature, destruction of habitat, unavailability of nutrients due to change in soil structure or profile, and environmental pollution causing health hazards. Hence, researchers are working on different agricultural tools that are considered to be effective or environment friendly with less consumption of energy. Thus, natural ecofriendly microbes (algae, fungi, and bacteria) have been recommended as practicable solutions for extensive agricultural applications economically and also support soil structure as well as various forms of agricultural land, support plant growth by enhancing its nutrient absorbing capacity, and reduce chances of soil-borne diseases [6]. Bacteria as biofertilizer ensure the fixation of atmospheric nitrogen and its availability to plants by synthesizing plant-growth-promoting substances and increasing the solubility of phosphorous. Ectomycorrhizal fungi are an important tool for the absorption of different mineral nutrients such as phosphorus. Therefore, all microbes play an important role in the agricultural sector by providing different services, such as disease resistance, drought tolerance, and increasing and maintaining the nutrient quality of soil [7].

The forest biomes offer vital ecosystem amenities, which include providing habitats for organisms and acting as a sink for different nutrients such as carbon, sodium, and potassium, controlling different harsh factors, such as erosion of soil, extenuating climate change, and manufacturing vital assets, for example, wood timber, fuel, and bioproducts. Owing to different human actions, the efficiency of forests has declined significantly over the passage of time. To overcome the shortage of nutrients and phytopathogens, different chemically synthesized products
