Mechanistic understanding of the root microbiome interaction for sustainable agriculture in polluted soils

Abstract In agricultural soils, the root microbiome plays a significant role in promoting plant growth for enhanced yield and also regulates soil fertility. It is important to understand the root microbiome of the different crop plants for improving the sustainable agriculture in contaminated soils. Plants and bacteria can form specific associations in which the plant provides the bacteria with a specific carbon source that induces the microbiome to reduce the phytotoxicity of heavy metals/organic pollutants in the contaminated soils. Thus, toxicity of organic/inorganic pollutants to plants can be relieved by introduction of plant growth-promoting bacteria (PGP) with beneficial effects on plant development. These microbiomes have the ability to promote plant growth directly or indirectly through release of hormones or enzymatic or organic acid release or by reducing the ethylene stress or by nutrient assimilation and supply to plants. The present chapter highlights the composition and diversity of the root microbiome in polluted sites/soils and their potential applications on alleviating heavy metal stress in different agricultural crops. Examples of promising PGP bacteria involved in the reduction of metal accumulation in plant aerial parts have been summarized. Microbe-mediated remediation of organic and inorganic pollutants are discussed. Further, the chapter highlights different mechanisms of plant growth-promoting rhizobacteria (PGPRs) in alleviating heavy metal toxicity in agricultural crops.