Isolation of rhizobia from Ontario soils that are effective at fixing nitrogen with common bean (Phaseolus vulgaris).

Diverse Rhizobium species, including two novel ones, from Ontario soils exhibit high symbiotic effectiveness with common bean, with one species showing the highest average effectiveness.

• Why it matters: Suboptimal nitrogen fixation limits common bean productivity and increases reliance on synthetic fertilizers, impacting sustainability in temperate agroecosystems.
• What they did: Isolated 216 common bean-nodulating rhizobia from southern Ontario soils using nodule trapping, performed whole genome sequencing, and conducted greenhouse assays to assess symbiotic effectiveness.
• The result: The collection reveals substantial species and genomic diversity, with multiple high-quality strains capable of effective nitrogen fixation, supporting development of targeted inoculants for Ontario growers.