The colonization of soil microorganism affected the growth and the accumulation of secondary metabolites of Bletilla striata (Thunb.) Rchb. F

Abstract

Abstract Bletilla striata (Thunb.) Rchb. F., a perennial herbaceous plant known for its medicinal properties. The growth and secondary metabolite production of B. striata can be influenced by soil microorganisms. To investigate the soil microbes that enhance B. striata growth and quality, we planted B. striata sterile seedlings in radiation-sterilized soil amended with microbiota from sandy clay or sandy loam soils. After two years of growth, we conducted 16S and ITS Illumina sequencing to identify bacteria and fungi colonizing B. striata rhizosphere soil, roots, tubers, and leaves. We determined the growth indices of the B. striata, simultaneously, we used UHPLC-MS/MS to determine metabolites in B. striata tubers, finally, we quantified the index component militarine in B. striata, we found significant differences in B. striata metabolites among different soil microbial treatments, with sandy loam microorganisms promoting the growth of B. striata, while sandy clay microorganisms increased the content of secondary metabolites. We identified specific microbes predominantly in loam soil that colonized roots and promoted growth (e.g., Entrophospora, Aspergillus, Fusarium). Similarly, certain microbes in loam soil colonized tubers and enhanced their growth (e.g., Sphingomonas, Hyphomicrobium). Additionally, microbes predominantly found in sandy soil colonized tubers and stimulated the synthesis of secondary metabolites (e.g., Myrmecridium, Apiotrichum montevideense). The Aspergillus versicolor (B-6) isolated from the B. striata rhizosphere soil after transplantation of sandy loam microorganisms, after inoculation with B-6 with B. striata sterile seedlings, it was found that B-6 could promote B. striata sterile seedlings growth. Our analysis uncovers that the soil microorganisms can colonize various regions of B. striata, thereby influencing its growth and secondary metabolite production. These findings hold implications for enhancing the yield and quality of B. striata in both medicinal and agricultural contexts.