Plant rhizosphere microbial communities

Abstract

Plants have evolved in a microbial world. Thus, plant-microbe interactions may be inherent to plants' adaptation to their environment. On the other hand, plants are the major source of organic nutrients in the soil, the driving force for microbial activity. The soil microflora interacts with plant roots and can even modulate the plant's response to both biotic and abiotic stresses. Here, we describe the rhizosphere as an organized unit, composed of the root and its associated microbiome. This interaction occurs in the limited soil region directly influenced by the living plant root. The presence and activities of the root affect the surrounding soil chemically, physically, and biologically. Thus, numerous processes occur in parallel in the rhizosphere, creating a unique and active niche. The chemical processes involve passive and active deposition of a multitude of compounds, mostly labile organic matter from the plant root and sloughed-off plant cells and tissues. The deposits discharged from the roots into the surrounding soil include different amino acids and proteins, organic acids, carbohydrates and sugars, vitamins, and the mucilage, accounting for a large proportion of the plant's fixed carbon. These, of course, are the driving force for alterations in the activity, function, abundance, composition and structure of the soil microbial community. The rhizosphere community will, in turn, affect root health and development.