Intricate microbe-plant-metabolic remodeling mediated by intercropping enhances the quality of Panax quinquefolius L.

Improving the cultivation mode and technology for traditional Chinese medicine has become important for its sustainable development. Monoculture enhances plant diseases, which decreases yield and quality. Intercropping is an effective measure to counterbalance that negative effect. In this study, we focused on Panax quinquefolium L. (ginseng) and four treatments were set up: the control without intercropping, P. quinquefolius + ryegrass (Lolium perenne L.), P. quinquefolius + red clover (Trifolium pratense L.), and P. quinquefolius + ryegrass + red clover. An LC-MS/MS system was used to detect the changes in the P. quinquefolius secondary metabolites, and high-throughput sequencing technology was used to determine the changes in the P. quinquefolius' rhizosphere soil microorganisms. Ginsenoside content, soil enzyme activities, and arbuscular mycorrhizal infection rate of P. quinquefolius were also measured using HPLC, ELISA kits, and microscopy, respectively. Co-intertia and Pearson's analysis were performed to explore the relationship between the metabolites and the P. quinquefolius microorganisms. Intercropping significantly increased the content of ginsenoside metabolites and recruited a large number of beneficial bacteria to the P. quinquefolius rhizosphere. The P. quinquefolius secondary metabolites were associated with the rhizosphere microbial community. For example, the dominant microorganisms, such as Acidobacteriota and Chloroflexi, played a key role in promoting the synthesis of ginsenoside Rd and (20R) ginsenoside Rg3 by P. quinquefolius. Intercropping led to changes in the P. quinquefolius secondary metabolites by driving and reshaping the rhizosphere microorganisms. These findings revealed the potential application of intercropping for improving the quality of P. quinquefolius.