Medicinal-plant immunity and specialized metabolism in plant-pathogen interactions: mechanisms and applications

Medicinal-plant immunity and specialized metabolism are mechanistically linked, but rigorous receptor validation, causal multi-omics, and field trials are needed for reliable translational applications. Medicinal plants combine classical immune signaling with lineage-specific specialized metabolism. This review focuses on the immune systems of medicinal plants and on how pathogen perception reshapes the biosynthesis of pharmacologically valuable secondary metabolites. We synthesize evidence for pattern-triggered immunity (PTI) and effector-triggered immunity (ETI), emphasizing pattern-recognition receptors (PRRs), nucleotide-binding leucine-rich repeat (NLR) proteins, MAP kinase (MAPK) signaling, calcium influx, reactive oxygen species (ROS), salicylic acid (SA), jasmonic acid (JA), ethylene (ET), and abscisic acid (ABA) crosstalk. Examples from Atractylodes macrocephala, Panax ginseng, Cannabis sativa, Catharanthus roseus, Artemisia annua, Hypericum perforatum, Salvia miltiorrhiza, and Withania somnifera illustrate both progress and major knowledge gaps. We distinguish well-validated medicinal-plant mechanisms from inferences based on Arabidopsis, rice, tomato, and Nicotiana reference systems. The review further evaluates elicitor treatments, microbial inoculants, genetic engineering, genome editing, integrated pest management (IPM), multi-omics, and microbiome engineering as strategies to improve both disease resistance and metabolite quality. We propose that future studies should test mechanistic links between receptor activation, transcription-factor networks, metabolite flux, and field-level medicinal quality through paired transcriptomics, proteomics, metabolomics, microbiome profiling, and targeted perturbation experiments. This synthesis provides a focused framework for translating plant-pathogen biology into resilient and chemically consistent medicinal-plant production.