**1. Introduction**

The productivity of crops is considerably impacted by nitrogen and phosphorous deficiencies, which are important for regulating the growth and development of crop plants [1]. To address this problem, it is important to carry out effective nitrogen management for sustainable agriculture. One of the interesting methods is to involve the use of microorganisms biologically fixing nitrogen which is utilized by the plant directly and is least susceptible to leaching and volatilization. Legumes establish a symbiotic interaction with the soil bacteria, termed Rhizobia, to fix atmospheric nitrogen. This helps in improving soil fertility, improving plant growth and prevents the necessity to use chemical fertilizers [2]. Besides this, agricultural productivity is significantly affected by the changing physical and biological properties of the soil [3]. In the past few years, the word "plant microsymbionts" has gained significant interest as plant microsymbionts directly affect the plant's performance and productivity. The plant microbiome comprises the complex adaptive gene pool, which originates from prokaryotic and eukaryotic organisms and even viruses, associated with the host's ecosystem [4]. Also, it has been well established that apart from changes in morphology, Bacteroides exhibit tremendous transcriptomic shifts and changes in biochemical processes especially in contrast to free-living bacteria [5]. There are various genetic and molecular pathways that govern the symbiotic compatibility, involving a wide variety of host and bacterial genes/signals with distinct adjuvants [6]. Consequently, understanding of the biological and molecular basis of symbiotic compatibility is essential in the development of tools for genetic modification of the host and/or bacteria to increase the efficiency of nitrogen fixation and to use it as a biocontrol agent. Here, in this review, we will address our latest summary of the microbial interactions, rhizobial efficacy, mechanisms as biocontrol, role in plant growth promotion, stress resistance and triggered immunity (ISR) against other microbes (pathogens). In fact, an insight into the genomes and recognition of candidate genes responsible for antibiotics, ISR and other metabolites from microbes is now possible. But the full range of molecular moieties involved in microbial interaction at an ecological scale deserves further study. Eventually, a definite and real improvement in the long term lies with the use of advanced analytical tools and their unification with classical experimental techniques to comprehend and then exploit soil–plant-microbe associations. Overall, it can help to improve biodiversity, agriculture and environmental studies further.
