Engineering Plant-Associated Microorganisms for Bioremediation and Sustainable Agriculture.

As food demand increases, agricultural practices have evolved, prompting increased exploration of sustainable ecological techniques and utilization of plant-associated microorganisms. In this context, plant fitness has been enhanced by plant growth-promoting microorganisms (PGPM), which stimulate growth through direct mechanisms, such as improved nutrient availability and phytohormone production, as well as indirect mechanisms, including protection against phytopathogens and suppression of soil-borne diseases. However, these innate capabilities of PGPM can be further improved through genomic modification or editing. This article reviews advances in the genomic engineering of plant-beneficial microorganisms as tools to enhance their positive effects on crop performance and environmental remediation. The genetic modification strategies analyzed here include random mutagenesis, targeted genome editing (such as CRISPR-Cas), gene over-expression, genome shuffling, RNA interference, metabolic pathway engineering, and synthetic biology approaches. These tools have enabled the optimization of functions, such as nitrogen fixation, phosphate solubilization, secondary metabolite production, biocontrol, stress tolerance, and bioremediation. However, we propose expanding the discussion of their regulation and use in various countries. Additionally, these modifications must be efficient and safe for the beneficial microbiota associated with the target crop, as well as for humans, animals, and the environment, all of which depend on sustainable agricultural practices.