Root exudate-mediated interspecific interactions reshape the rhizosphere microbiome and promote the accumulation of bioactive compounds in Pinellia ternata.

Plant recognition and responses to neighbors are key mechanisms that regulate interspecific interactions. Although aboveground signaling via volatile organic compounds has received increasing attention, the role of soil-derived signals in belowground interactions remains poorly understood. In this study, a peanut (Arachis hypogaea L.)-Pinellia ternata (Thunb.) Makino intercropping system was used to investigate how root exudates regulate the recruitment of rhizosphere microbes to neighboring plants, with the aim of providing a theoretical basis for understanding how intercropping promotes plant growth. Intercropping with peanut significantly altered the rhizosphere microbial community structure of P. ternata and markedly enhanced the colonization of Sphingomonas spp. Inoculation experiments revealed that Sphingomonas sp. Y6 significantly increased both plant biomass and bioactive compounds of P. ternata. A belowground segregation experiment supported the role of root exudates as important mediators of interspecific interactions between peanut and P. ternata. Peanut-derived L-proline promoted the recruitment of Sphingomonas sp. Y6, increasing its rhizosphere colonization by 1.96-fold in the split-root experiment. Metabolomic profiling further indicated that exposure to peanut-derived signals was associated with increased accumulation of nucleoside compounds in P. ternata root exudates, which enhanced chemotaxis and biofilm formation by Sphingomonas sp. Y6. Overall, these findings identify a potentially important mechanism linking interspecific plant interactions, metabolite-mediated changes in root exudates, and rhizosphere microbial recruitment, ultimately contributing to increased bioactive compound accumulation in P. ternata, and provide new insights into optimizing plant-microbe interactions to enhance the accumulation of bioactive compounds in medicinal plants.