Medicago root nodule microbiomes: insights into a complex ecosystem with potential candidates for plant growth promotion

Studying the legume nodule microbiome is important for understanding development and nutrition of plants inhabited by various microbes within upon them. We analyzed microbiomes these underground organs from both an crop plant (Medicago sativa) a related (M. polymorpha) using metagenomic culture-based techniques to identify main cultivatable contributors growth enhancement. Using high-throughput sequencing, culturing, in planta techniques, we identified broad population bacterial taxa Medicago nodules surrounding soil. Fifty-one distinct strains were isolated characterized species their growth-promoting activities studied. Sequencing 16S rRNA gene amplicons showed that addition Ensifer, dominant genus, large number Gram-positive bacteria belonging Firmicutes Actinobacteria also present. After performing ecological trait analyses, selecting most promising strains, then assays, found Bacillus Micromonospora among others could play roles supporting growth, health, productivity host plant. To our knowledge, comparison biodiversity microbiota undomesticated vs. cultivated roots novel shows range potential Plant Growth-Promoting Bacteria be used agricultural interest. These other nodule-isolated serve as inoculants with rhizobia goal replacing synthetic fertilizers pesticides sustainable agriculture.