A study on the metabolic characteristics of three rhizosphere bacteria promoting the growth of C.dahurica Maxim (Cimicifuga dahurica (Turcz.))

Cimicifuga dahurica (C. dahurica) is an important medicinal plant in the northern region of China. The rhizobacteria could serve as a crucial resource foundation for high-quality fertilizers, thereby promoting plant growth. This study aimed to investigate the effects of three rhizobacteria strains on the growth, antioxidant activity, and metabolite profile of Cimicifuga dahurica (C. dahurica). One-year-old C. dahurica seedlings were used as experimental material, from which different rhizobacteria were isolated and irrigated the roots respectively. The used rhizobacteria strains were identified respectively as SM1 (Pantoea agglomerans), SM2 (Citrobacter freundii), and SM3 (Bacillus toyonensis) according to the results of 16S rRNA gene sequence analysis. The results showed that compared with CK, the plant growth characteristics and oxidative stress response traits were differently promoted under different rhizobacteria treatments. It was most effective for promoting overall plant growth and enhancing antioxidant capacity under SM3 treatment, while oxidative stress was significantly reduced under SM1 treatment. KEGG analysis showed that the pathways of galactose metabolism, glyoxylate and dicarboxylate metabolism, and starch and sucrose metabolism were significantly regulated under different SMs treatments. Correlation analysis further verified that there was a significantly positive relationship between biomass and D-Glucose under SM3 treatments, and D-mannitol played a key role in root development under SM2 treatment. This research proved that three rhizobacteria strains significantly enhanced the growth of C.dahurica, with SM3 exhibiting the most promoted effect on growth. These findings provide a novel perspective on exploring the metabolic mechanisms by which rhizobacteria influence plant growth, and offer high-quality bacterial manure germplasm resources for the efficient cultivation of medicinal materials.