Synergy for plant health - plant growth-promoting rhizobacteria and nanomaterials

The combined activity of plant growth promoting rhizobacteria (PGPR) and nanomaterials offers a ray of hope in the pursuit of sustainable production of crops, beyond the capacity of either of the two used alone. Plant stress resistance, effective nutrient use and reduction in the rate of environmental degradation are promoted by the all-inclusive use of both techniques together. In this review, we provide a comprehensive overview of the role played by nanoparticles in promoting the development of crops. It is well known that PGPRs function to promote biological nitrogen fixation and hormone production in plants. On the other hand, nanoparticles promote the slow release of nutrients and the balancing of plant hormones. However, when combined, their individual functions can create a compounded effect; nanoparticles symbiotically associated with PGPR creates a nutrient-rich environment for them to proliferate in the rhizosphere leading to increased production of key plant metabolites, while PGPR, in return, improves the bioavailability of nutrients being warehoused by the nanoparticles, thus maximizing nutrient assimilation by plants. This review infuses a novel perspective on the molecular and eco-friendly basis for this symbiosis. Existing studies have demonstrated significant improvement in plant biomass, physiological, biochemical and molecular parameters because of the co-application of PGPR and nanoparticles. The challenges and regulatory considerations associated with the use of nanomaterials, current safety assessments, and public perception are major constraints hampering its development. The current work further reinforces the need for continued research into the application of nanobiofertilizers, gaining knowledge of their lasting consequences on ecosystem sustainability, with the hope of optimizing their benefits while ensuring effective and safe integration into farming practices.