ITS rhizosphere soil
The development of high-yield, superior-quality forages is fundamental to sustainable animal husbandry. While Medicago sativa and Melilotus officinalis are key leguminous forages, the mechanisms behind their divergent growth traits are not fully understood. This study investigated the contrasting performance through an integrated analysis of plant phenotype, rhizosphere microbiome, and root metabolome. Medicago sativa exhibited superior growth vigor, biomass production and relative feed value over Melilotus albus. Rhizosphere bacterial and fungal communities were distinctly assembled by each plant species, with M. Sativa sustaining a more complex and stable network. Key discriminatory genera enriched in M. Sativa included the beneficial bacteria Enteractinococcus and fungi Rhizomucor and Mucor, whereas the potentially pathogenic bacteria Brachybacterium was enriched in M. albus. Root metabolomics further revealed a species-specific landscape: M. Sativa was characterized by an upregulation of phenylpropanoid metabolism, leading to the accumulation of growth-promoting metabolites like 1-O-sinapoyl-beta-D-glucose. In contrast, M. albus showed an activation of purine/pyrimidine metabolism and decrease of coniferyl alcohol, indicative of stress resistance. Strong correlations were identified between these differential microbes and metabolites, suggesting a cross-kingdom interaction network. Our findings reveal that the superior performance of M. Sativa is underpinned by a synergistic interplay between a beneficial rhizosphere microbiome and a growth-favorable root metabolome, providing crucial insights for future forage improvement strategies through the manipulation of plant-microbe-metabolite interactions.