Rhizosphere endophytes as allies in plant defense against heavy metals and organic pollutants in soil: Advances and applications

Abstract

Soil degradation caused by heavy metals and organic pollutants poses a critical global threat to environmental health and agricultural sustainability. Rhizosphere endophytes have garnered significant attention in their roles in enhancing agricultural productivity, promoting ecological sustainability, and serving as effective tools to support host plants in resisting or remediating soil contaminants. This review synthesizes current knowledge of the diversity, sources, and colonization mechanisms of rhizosphere endophytes. It highlights their dual roles in directly mitigating pollutant stress and indirectly enhancing plant resilience, while exploring their potential applications in environmental remediation. Rhizosphere endophytes are valuable sources of bioactive compounds and functional enzymes, secreting extracellular polymers and degradative enzymes to degrade organic pollutants or reduce the bioavailability of heavy metals. These microorganisms engage in co-metabolic processes with their hosts, enhancing plant antioxidant systems and mitigating the accumulation of organic pollutants and heavy metals in plant tissues. Furthermore, rhizosphere endophytes support host plants through indirect mechanisms by promoting plant growth, enhancing defenses against pathogens and pests, and modulating rhizosphere niches to recruit beneficial microbial communities, thereby enhancing plant resilience to environmental stress. Further research is necessary to improve the remediation efficiency of rhizosphere endophyte–plant systems, refine the selection of effective endophytes, and expand their ecological applications. This review underscores their ecological and biotechnological potential and outlines key research priorities to advance their use in sustainable soil remediation.