Prospects for Allelochemicals Utilization for Managing the Plant-Soil-Microbiome System in Phytostimulation Technologies

Abstract

Phytostimulation is an environment friendly, cost-effective phytoremediation technique based on mutualistic interactions between plants and rhizosphere microbiome capable of degrading hazardous pollutants. Allelochemicals found in plant root exudations, to a significant extent, shape the structure and functional state of the rhizosphere microbiome through direct and indirect effects. In this review, the various classes of allelochemicals (viz. organic acids, amino acids, phenolic acids, flavonoids, coumarins, tannins, triterpenoids, and benzoxazinoids) have been analyzed as to the character and physiological mechanisms of their effect on the populations of soil rhizobacteria and fungi taxonomical groups, promising as bioremediants. All considered classes of allelochemicals demonstrated selective activity in relation to different species of soil microorganisms. This allows using such compounds as markers of the "suitability" of plant species or cultivars as host plants in phytostimulation technologies. The possibility of controlling the bioremediation potential of the rhizosphere microbiome by including allelopathic plants into phytoremediation practices is considered. The implementation of an allelopathic approach in phytostimulation technology will allow to create stable associations of plants with bioremediating microorganisms, overcome the negative influence of biotic and abiotic factors on the soil microbiome and plants, improve the effectiveness of bioremediation technologies, and promote sustainable agricultural development.