Microbial co-inoculation and extracellular vesicles: new frontiers for soybean productivity

Over the past decades, the intensive use of chemical fertilizers in agriculture has shown low efficiency while causing serious environmental issues and leading to soil nutrient imbalances. These challenges are compounded by climate change, increasing incidence of diseases and pests, and soil acidification, factors that jeopardize agricultural productivity and, consequently, threaten global food security. Soybean (Glycine max L.) is one of the world's most important crops, serving as a key source of protein and oil for both human consumption and animal feed. Its global relevance continues to grow with rising demand for food, biofuels, and industrial applications, with Brazil, the United States, and Argentina leading production. Beyond its economic value, soybean contributes to agricultural sustainability through symbiotic nitrogen fixation, reducing the need for synthetic fertilizers. However, maintaining high yields under changing environmental conditions requires innovative management strategies. In this context, one promising strategy to mitigate these problems is the use of plant growth-promoting bacteria (PGPB), which contribute to more sustainable crop yield. Although numerous studies are underway regarding the potential of PGPB, further research is still necessary due to the limited understanding of their mechanisms of action and the vast range of benefits they may offer. Currently, there is a wide variety of inoculants based on different bacterial species, which play a key role in stimulating plant growth and reducing reliance on agrochemicals. Among emerging technologies, noteworthy examples include molecular inoculants (still not widely adopted commercially), bacterial and fungal consortia formulated into a single product, and inoculants containing genetically edited microorganisms-all of which have shown great promise in enhancing the performance of beneficial microbial species. The selection and genetic editing of rhizosphere-associated PGPB-an essential component of the plant microbiome-are viable alternatives for promoting more sustainable agriculture. Thus, this review examines the main inoculant technologies aimed at obtaining efficient microorganisms capable of improving rhizosphere conditions and microbial community dynamics, representing a strategic opportunity for developing solutions that enhance soybean sustainability.