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Keywords: Plant growth promoting rhizobacteria (PGPR), Mechanisms of action of
PGPR, Biofertilizer, Phytostimulator, Biopesticides.

1. Introduction

The world's plants, animals, fungi, and microorganisms are the functioning parts of Earth's

life- emotionally supportive networks. Losing them imposes direct economic losses and
reduces the effectiveness of nature to serve needs of individuals. At least 40% of the world’s

economy and 80% of the requirements of the poor are derived from biological resources (Dow
et al., 2016). Soil is a biologically, physically and chemically different entity that forms the

essential substrate of terrestrial ecosystems, upholds numerous human activities and

provides a multitude of highly valuable ecosystem services (Dominati et al., 2010).
The Population of the present reality is around 8 billion and expanding step by step with this

worry to create more nourishment has been expanded. In developing countries, agriculture is

taken into account as a fundamental pillar of economy for the development (Zahid, 2015). As
we have constrained land for agriculture it is the need of great importance to develop new

innovations to expand crop production. To upgrade crop yield it is important to control plant

maladies and utilization of composts.
Soil is an essential living space for many microorganisms including a variety of algae, fungi,
protozoa, actinobacteria and bacteria are able to associate with organic matter of soil within

the rhizosphere which necessary for the plant growth and development (Nihorimbere et al.,

2011). Plant roots release various exudates like organic acid, sugars and amino acids which
will attract microbes (Amora-Lazcano et al., 2010). In exchange, they are able to protect plants

against various pathogens and also enhance the nutrient uptake. Carbon containing
compounds can attract pathogens (Yuan et al., 2018). Soil microorganisms drive the

biogeochemical processes that are the basis for life by interacting with plant roots and soil

constituents at the root-soil interface, where root exudates and decaying plant material
provide sources of carbon compounds for the heterotrophic biota. The number of bacteria in

the rhizosphere and rhizoplane is higher than in the soil devoid of plants (Russo et al., 2012).
Diverse group of soil microorganisms live in harmony amongst each other and with plants

resulting into enhanced plant growth. These plant microbe interactions influence the growth

of plant, change the nutrient elements and modify the plants susceptibility to various abiotic
stresses and diseases (B. K. Yadav et al., 2015). Various sorts of plant microbe interactions

include competition, mutualism, parasitism and commensalism (C. H.Wu et al., 2009).

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