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G. Garg et al.
an important role in the host plant’s growth either by the production of secondary
metabolite or nutrient assimilation. This helps the plant to adapt themselves to various
environmental stresses (i.e., salt and water), an important aspect of crop yields.
In the current scenario, enormous knowledge of endophytes, their roles for
increasing crop yields, disease-resistant plants, and facilitating the survival under
environmental stress is a requirement for the agricultural prosperity. Bacteria, actinobacteria, and some fungi comprise the endophytic microbial system. Endophytic
microbiota forms a network surrounding their host plants (Wang et al. 2011; Pahari
and Mishra 2017). Generally, they inhabit the intercellular spaces of the host plant.
The most common mode of entry for endophytic bacteria into plant tissues is through
primary and lateral root cracks, and diverse tissue wounds arising as a result of
plant growth (Sprent and de Faria 1998; Agarwhal and Shende 1987; Sørensen and
Sessitsch 2015). Endophytic bacteria not only escalate nitrogen fixation/phosphate
solubilization but under stress conditions (abiotic and biotic), they mount the production of phytohormones and regulate the biosynthetic pathway of ethylene. Endophytes in plant system synthesize many biologically active novel compounds without
any observable damage to the host tissue like alkaloids, terpenoids, steroids, peptides,
poly-ketones, quinols, flavonoids, phenols, and insecticide azadirachtin (Kusari
et al. 2012; Molina et al. 2012; Zinniel et al. 2002) antifungal compounds include
cryptocandin, pestaloside, cryptocin, ecomycins, pestalopyrone, and pseudomycins.
Endophytic microorganism increases plant resistance against the pathogen by
inducing defense mechanisms, the so-called induced systematic resistance (ISR)
(Zamioudis and Pieterse 2012). Another most significant and important mechanism
for endophyte inhabitation in plants is the production of the extracellular enzyme
exhibiting enormous industrial significance in different fields such as fermentation process and biotechnological applications. Some of the extracellular hydrolase enzymes augmented the plant responses to pathogenic infection (Leo et al.
2016). Endophytic strains of endophytic microflora are harnessed for commercialscale production as biofertilizers and biopreparations. Biofertilizers are defined as
substances that contain living organisms tending to inhabit with the rhizosphere or
the plant interior which are coalesced to seeds, plant surfaces, or soil. They increase
the availability and supply of the nutrient which boost plant growth.
The common bacteria’s, such as Azospirillum, Herbaspirrilum, Acetobacter,
Azotobacter, and Azoarocus, have been successfully used as biofertilizers. Nowadays, there is a quest for microbial strains which can contribute to the development
of bioinoculants, biofertilizers, and biopreparations, consequentially enhances the
growth and yield of crop plants. Biopreparations are the products that originate from
either living organisms or their metabolites, used in organic farming for environmental stress regulation. In the plant–soil interaction, there is a narrow region called
as rhizosphere, which directly influenced by root microbiome and root secretion. This
symbiotic association influenced the ability of the plant to absorb nutrients specifically phosphorus, nitrogen, iron, and potassium. In the soil symbiotic zone bacteria’s
grow, which directly and indirectly enhanced the growth of plants and hence considered as plant growth-promoting rhizobacteria (PGPB)/bioinoculants/microbial inoculants. In the agricultural field, PGPB is considered a green alternative to boost
G. Garg et al.
an important role in the host plant’s growth either by the production of secondary
metabolite or nutrient assimilation. This helps the plant to adapt themselves to various
environmental stresses (i.e., salt and water), an important aspect of crop yields.
In the current scenario, enormous knowledge of endophytes, their roles for
increasing crop yields, disease-resistant plants, and facilitating the survival under
environmental stress is a requirement for the agricultural prosperity. Bacteria, actinobacteria, and some fungi comprise the endophytic microbial system. Endophytic
microbiota forms a network surrounding their host plants (Wang et al. 2011; Pahari
and Mishra 2017). Generally, they inhabit the intercellular spaces of the host plant.
The most common mode of entry for endophytic bacteria into plant tissues is through
primary and lateral root cracks, and diverse tissue wounds arising as a result of
plant growth (Sprent and de Faria 1998; Agarwhal and Shende 1987; Sørensen and
Sessitsch 2015). Endophytic bacteria not only escalate nitrogen fixation/phosphate
solubilization but under stress conditions (abiotic and biotic), they mount the production of phytohormones and regulate the biosynthetic pathway of ethylene. Endophytes in plant system synthesize many biologically active novel compounds without
any observable damage to the host tissue like alkaloids, terpenoids, steroids, peptides,
poly-ketones, quinols, flavonoids, phenols, and insecticide azadirachtin (Kusari
et al. 2012; Molina et al. 2012; Zinniel et al. 2002) antifungal compounds include
cryptocandin, pestaloside, cryptocin, ecomycins, pestalopyrone, and pseudomycins.
Endophytic microorganism increases plant resistance against the pathogen by
inducing defense mechanisms, the so-called induced systematic resistance (ISR)
(Zamioudis and Pieterse 2012). Another most significant and important mechanism
for endophyte inhabitation in plants is the production of the extracellular enzyme
exhibiting enormous industrial significance in different fields such as fermentation process and biotechnological applications. Some of the extracellular hydrolase enzymes augmented the plant responses to pathogenic infection (Leo et al.
2016). Endophytic strains of endophytic microflora are harnessed for commercialscale production as biofertilizers and biopreparations. Biofertilizers are defined as
substances that contain living organisms tending to inhabit with the rhizosphere or
the plant interior which are coalesced to seeds, plant surfaces, or soil. They increase
the availability and supply of the nutrient which boost plant growth.
The common bacteria’s, such as Azospirillum, Herbaspirrilum, Acetobacter,
Azotobacter, and Azoarocus, have been successfully used as biofertilizers. Nowadays, there is a quest for microbial strains which can contribute to the development
of bioinoculants, biofertilizers, and biopreparations, consequentially enhances the
growth and yield of crop plants. Biopreparations are the products that originate from
either living organisms or their metabolites, used in organic farming for environmental stress regulation. In the plant–soil interaction, there is a narrow region called
as rhizosphere, which directly influenced by root microbiome and root secretion. This
symbiotic association influenced the ability of the plant to absorb nutrients specifically phosphorus, nitrogen, iron, and potassium. In the soil symbiotic zone bacteria’s
grow, which directly and indirectly enhanced the growth of plants and hence considered as plant growth-promoting rhizobacteria (PGPB)/bioinoculants/microbial inoculants. In the agricultural field, PGPB is considered a green alternative to boost