The rhizosphere is the most active zone of soil and plays a significant role
in soil health management. The rhizosphere concept is more than a century old and has
played a pivotal role in understanding the mutual association of microbes and plants
over that period. This has opened many interesting facts about wonderful plant-microbe
associations. During these years, the concept has evolved from the rhizosphere to the
phyllosphere and more recently, to the holosphere/holobiont level. The earlier
understanding of how bacteria inhabit plants and, in particular, how bacteria feed
plants, has greatly expanded. Recently, it has been observed that plants take bacteria
inside their cells and use them as a source of nutrients (rhizophagy). This
understanding has completely changed the dimensions of the rhizosphere concept, and
we need to think more rationally to understand the bacteria-plant association during the
coming years. This chapter covers the wonderful overview of soil-inhabitant bacteria
with special emphasis on rhizobacteria in general and plant growth promotion for an
enhanced yield of crop plants in particular.
Keywords: Engineering, Rhizosphere Structure, Rhizophagy, Trichoderma.
