Application of plant-microbe interactions in contaminated agroecosystem management

Abstract

Agroecosystem is often confronted with a variety of pollutants. The application of plant-microbe interactions in remedying the ecosystem is called phytoremediation. Within the rhizosphere, plant roots interact with microorganisms and the soil, and plants usually secrete substances which affect microbial growth. Some plant-microbe relationships are beneficial to the plant while others are not. However, these interactions largely ensure a healthy plant growth while eliminating plant pathogens from the soil either by separate or combined activities of the plant exudates and beneficial microbes. The nature of microbes associated with each plant is apparently related to the exudates and signal molecules emanating from the plant and the interactive signals of the microbes. Sometimes, the soil is contaminated either deliberately or inadvertently by a variety of chemicals and heavy metals. To control or eliminate these contaminants, chemical and physical means have largely been applied. Unfortunately, some of these control measures introduce their own contaminants thereby causing secondary contamination. This necessitates the need and application of eco-friendly and sustainable solar-driven technology, viz., phytoremediation, to restitute the soils. Microbe-plant interactions sometimes improve the absorptive capacity of the plant for contaminants. Some microbes modify soil contaminants by using organic acids, redox reactions, producing siderophores, metal chelators, biosurfactants, causing bioleaching, biosorption, and bioexclusion. These microbes-contaminants interactions boost the reduction of toxicity and elimination of contaminants via various phytoremediation processes, viz., phytostimulation, phytodegradation, phytoextraction/phytoaccumulation, phytostabilization, phytovolatilization, and rhizofiltration. Nevertheless, phytoremediation faces certain major challenges as regards to its commercialscale application in the field. To overcome these limitations, it is essential to have a better understanding of the relationships among plant microbes, soil types, chemicals, and heavy metal contaminants within an agroecosystem. Besides, it is important to develop phyto-hyper-accumulators and super microbial solubilizers, for various soil types.