Study on the diversity, structure, and function of endophytic bacteria in seeds of genuine medicinal plants in gansu province.

BACKGROUND: Seeds harbor diverse endophytic bacterial communities that are critical for seed health and plant fitness, however, their functional potential in medicinal plants remains underexplored. This study employed integrated high-throughput sequencing and culturomics to characterize the endophytic bacterial communities in seeds of 10 endemic medicinal plants from Gansu, China, and evaluate their roles in germination enhancement. RESULTS: We identified 26,167 bacterial OTUs, with 19 core OTUs consistently present across all samples. The dominant phyla were Proteobacteria, Firmicutes, Bacteroidota, and Actinomycetota, collectively comprising over 80% of relative abundance. Plant species identity was the primary factor shaping bacterial community structure. Among 89 isolated endophytic bacterial strains, 72% exhibited multiple plant growth-promoting (PGP) traits in vitro, including indole-3-acetic acid (IAA) synthesis, siderophore production, phosphate solubilization, and nitrogen fixation. Preliminary validation experiments using wheat (Triticum aestivum ‘Jimai 22’) under controlled conditions indicated that seed-derived Bacillus and Pseudomonas strains significantly promote radicle elongation and improve vigor indices under saline-alkaline stress compared to axenic controls. CONCLUSIONS: These findings highlight medicinal plant seeds as reservoirs of culturable bacteria with multifunctional PGP capabilities. The host-specific community patterns and the in vitro PGP traits suggest these isolates warrant further investigation as potential candidates for bioinoculant development, pending validation on the host medicinal plants themselves.