Using plant growth-promoting rhizobacteria (PGPR) combined with hyperaccumulator is an ecologically viable way to remediate cadmium (Cd) pollution in agricultural soil. Despite recent advances in elucidating PGPR-enhanced phytoremediation, the response of plant-associated microbiota to PGPR remains unclear. Here, we found that the effective colonization of PGPR reshaped the rhizosphere nutrient microenvironment, especially driving the nitrogen cycle, primarily mediated by soil nitrate reductase (S-NR). Elevated S-NR activity mobilized amino acid metabolism and synthesis pathways in the rhizosphere, subsequently driving a shift in life history strategies of the rhizosphere microbiota, and enriching specific rare taxa. The reconstructed synthetic community (SynCom3) confirmed that the inclusion of two crucial collaborators (Lysobacter and Microbacterium) could efficiently foster the colonization of PGPR and aid PGPR in executing phytoremediation enhancement. Finally, the multi-omics analysis highlighted the critical roles of phenylpropanoid biosynthesis and tryptophan metabolism pathways in inducing SynCom3 reorganization and PGPR-enhanced phytoremediation. Our results underscore the significance of the rhizosphere microenvironment modification by PGPR for its colonization and efficacy, and highlight the collaborative role of rare microbiota in the context of PGPR-enhanced phytoremediation.

Salinity poses serious threats to landscapes across the globe, decreasing the capacity of all types of terrestrial ecosystems in providing services by threatening our biodiversity, lowering agricultural productivity, deteriorating the environment, contaminating groundwater below standard level, enhancing flood risks, food security issues and restricting the economic growth of a community. Reclamation measures are required to reverse the process of land degradation caused by salinization; otherwise, the trend towards salinization is expected to grow beyond control in developing countries. The scientific community and the policy-makers around the globe have been testing long-term technologies including physicochemical, conventional breeding and genetic engineering involving state of the art molecular tools for more than three decades. Nevertheless, they have failed due to reasons like non-technical feasibility reports, reliability and affordability issues coupled with sustainability constraints at field level. This review discusses the potential prospects of Pennisetum genus (Poaceae) for integrated, sustainable, robust and profitable saline agriculture based on phytoremediation agro-technique. Our approach is the first ever record, providing a novel insight into a cost-effective biotech agro-technique. Pennisetum species are environment-friendly future candidates with prospects for all stakeholders to materialize higher average productivity at the field level, posing lesser competition for resources with standard conventional crops.