Pesticides as Antagonists of Rhizobia and the Legume-Rhizobium Symbiosis: a Paradigmatic and Mechanistic Outlook

Legume-Rhizobium symbiosis is very specific mutualism between rhizobia and the host legumes. This association is the result of interplay of many consecutive molecular interactions between specific legumes and their rhizobial counterparts. Different chemical pesticides, applied in farming practices to protect the legume plants from a range of phyto-pathogenic pests and in turn to expedite crop yields, are accumulated in soils. These agrichemicals not only affect the growth and plant-beneficial physiological activities of rhizobia but also inhibit the molecular signaling between rhizobia and the host legume plants essential to establish symbiosis. With the general description of pesticides, their environmental fates and the extensive listing of their noxious impacts on both the rhizobia and the symbiotic parameters of legumes, this review highlights the mechanistic basis of pesticide-mediated inhibition of rhizobia and legume-Rhizobium symbiosis in detail with current perspectives.