Integrating environmental adaptation, breeding, and rhizobia bioinoculants for soybean expansion in Europe

Europe's heavy dependence on imported protein is environmentally and strategically costly. Soybean (Glycine max) offers a great opportunity to close this gap. Soybean cultivation can reduce reliance on synthetic nitrogen (N) fertiliser through its symbiosis with N-fixing bacteria (rhizobia). Nevertheless, it remains a relatively new crop across much of Europe and establishing it in the continent's diverse environments raises challenges of climate adaptation, symbiotic N fixation, and crop management. We argue that these challenges must be addressed together rather than separately, because yield stability, N fixation, and environmental stress resilience emerge from the interactions between plant genotype, rhizobial strain, environment, and soil and crop management practices. Drawing on lessons from major soybean-producing regions, we review environmental adaptation through maturity-group selection and stress-resilience breeding, rhizobia inoculant design, and the management practices that shape symbiotic and crop performance. We further examine genetic, genomic, and computational resources that make these interactions predictable and optimisable and identify priorities for future research and practice.