Quorum sensing in plant microbe interaction

Abstract

The coordinated behaviors, at the population level, occur in bacteria due to communication between the cells, which is defined as quorum sensing (QS). These communications help the bacteria to respond in terms of extracellular factors which are involved in scavenging for nutrients; biosynthesis of exopolysaccharides, extracellular hydrolytic enzymes, siderophores, antibiotics, pigments, hypersensitive reaction; aiding motility; and providing scaffolding for biofilms to grow as well as those involved in conjugation and epiphytic fitness. Even in parasitic species, these signals help in regulation of bacterial growth, virulence, and damage caused to hosts. QS signal molecules are regulated by autoinduction and positive feedback mechanism at high cell densities. A detailed mechanism involved in QS is discussed in this chapter with special reference to rhizosphere microflora. The rhizosphere is a digestive system of the plants wherein several microorganisms influenced by root exudates in turn favor its growth. In the future, understanding QS related to plant growth-promoting bacteria and its interspecific bacterial communication may offer good opportunities to manipulate bacterial community structure in the rhizosphere for the benefit of agriculture.