Plant-Microbial Interaction: A Dialogue Between Two Dynamic Bioentities

Since the time of evolution, the earth’s plant floral community remained associated with ubiquitous population of microbes by a wide array of interactive relationships, ranging from symbiotic to parasitic. The ecology of plant-microbial association has influenced the plant’s diversity, metabolism, morphology, productivity, physiology, defence system and tolerance against adversities. Similarly, the microbial population has also been affected in terms of morphology, diversity, community composition, etc. In plant-microbial association, microbes obtain shelter, protection and nutrients from the plants either positively or negatively without affecting the plant’s health. In symbiotic plant-microbial interaction, plants provide habitat, nutrients and protection against the adverse environment, while in return, the microbes render several benefits such as protection against pathogens, plant growth promotions, resistance towards abiotic stress, improved nutrient uptake and fitness. The microbial endophytes and epiphytes are generally regarded as plant symbionts. The antagonistic association between these two living systems, in which the plant antagonist kills the microbial pathogens by producing toxic phytochemicals or the microbial parasite adversely affects the plant’s fitness by withdrawing essential plant nutrients for their own survival and altering the physiology of the host plant. How do the plants cross talk to the microbes to establish the associations? Various response-related signals drive such cross talks. The omics (genomics, proteomics and metabolomics) approach is being used to unveil the role of complex cryptic signalling process in the plant and microbe interaction. In this chapter, the existing understandings about the plant-microbial interactions and the roles of signalling mechanisms in such interactions have been discussed.