Linkages between plant rhizosphere and animal gut environments: Interaction effects of pesticides with their microbiomes

ABSTRACT: Pesticides are becoming a significant transnational pollutant in agricultural production environments. This review presents the interconnectedness and interaction effects of pesticides with the microbiomes in the environments of plant rhizosphere and animal (limited to insect and human) guts. The metabolic growth and functions of rhizosphere microbiomes are altered by complex mechanisms involving redox reactions and preferential substrate utilization. The rhizospheres of crop plants with the assemblies of microbiota and other biotic components are sensitive to the deliberate introduction of pesticides. Pesticides become one of the major drivers for the metabolic processes, which rely on the evolutionary mechanisms, including the genetic exchange events within the rhizosphere microbiomes. Pesticides, even at the below detection levels, in the rhizosphere enable the plant uptake which can be up to 1% of the dose applied and trophic transfers involving the animal gut environments. To overcome the metabolic constraints due to the nutrient-poor plant diets contaminated with pesticides, insects gain the resistance traits, mainly due to the pesticide-degrading members of the gut microbiomes. Such evolved microbiome members and their genes can increase their spread of resistance in the environment. Like the insect gut microbiomes, the human gut microbiomes get modulated by the pesticide-laden plant foods, leading to dysbiosis. The confounding effects of pesticides on the gut microbiomes which include mutational and genetic exchange events can upsurge many health disorders. The evolutionary and microbiome perspectives on the rhizosphere and animal guts as the hotspots of metabolic and horizontal gene transfer (HGT) events need careful considerations to mitigate the risks and health hazards due to extensive and intensive application of synthetic chemical pesticides in the modern agriculture.