Low phosphorus promotes caryophyllene biosynthesis by regulating AaTPS3 in Artemisia argyi

This study promotes AaTPS3-mediated caryophyllene synthesis by negatively regulating AaWRKY1/2 under low-phosphorus conditions, and enhances Artemisia argyi quality via appropriate phosphorus fertilizer application. Artemisia argyi (A. argyi), a plant species within the Asteraceae family, is extensively applied in pharmaceuticals, dietary therapy, and cultural practices. Caryophyllene, its primary bioactive compound, exhibits mosquito-repellent, analgesic, and anti-inflammatory activities. While there are preliminary understandings of the caryophyllene biosynthesis pathway in A. argyi, the functional characterization of critical synthases and the regulatory effects of environmental factors on caryophyllene accumulation remain incompletely understood. Phosphorus (Pi), an essential element for plant growth, plays an unclear role in regulating A. argyi development and caryophyllene metabolism at the molecular level. In this study, we treated A. argyi with varying phosphorus concentrations, measuring growth parameters, morphological changes, and yield of A. argyi. Under low-phosphorus (NKP_1/5) treatment, the contents of caryophyllene (in volatile oil and fresh leaves), soluble sugar, soluble protein, root activity, chlorophyll content, and total flavonoids of mugwort were notably higher than those under normal phosphorus (NKP₁) treatment, while the fluff rate and yield showed no significant differences between the two treatments. Low phosphorus promoted the content of caryophyllene and the expression of terpene synthase gene (AaTPS3). We also identified two low-phosphorus-responsive transcription factors AaWRKY1 and AaWRKY2, which negatively regulate the transcription of AaTPS3. The content of caryophyllene in A. argyi overexpressing AaWRKY1/2 decreased significantly. The above results uncover the molecular mechanism by which low phosphorus promotes caryophyllene synthesis through the "AaWRKY1/2-AaTPS3" pathway. It fills a research gap in the relationship between phosphorus and caryophyllene biosynthesis in A. argyi and provides a theoretical foundation for optimizing phosphorus management and enhancing A. argyi quality.