Regulatory mechanisms of secondary metabolite biosynthesis in medicinal plants under drought: advances and perspectives

Abstract

Background: Medicinal plants are widely used for applications in agriculture, food, medicine, and cosmetics due to their abundant bioactive secondary metabolites (SMs) such as terpenoids, phenylpropanoids, and alkaloids. The biosynthesis and accumulation of SMs are highly associated with multiple environmental factors. Among these abiotic stresses, drought plays a pivotal role in regulating the quality of medicinal plants. Understanding the regulatory mechanisms of medicinal plants in response to drought is beneficial for (i) cultivating high-quality traditional Chinese medicinal plants via targeted water management strategies; (ii) screening candidate marker genes to breed high-quality novel cultivars with enhanced bioactive compound accumulation under drought conditions, thereby addressing the adverse impacts of drought induced by global climate change; (iii) mining dual-functional genes that confer drought tolerance while maintaining high bioactive compound content, thus ensuring both the yield and quality of medicinal plants.

Purpose: To summarize the latest advances in the transcriptional regulation of SM biosynthesis with a focus on terpenoids, phenylpropanoids, and alkaloids in medicinal plants under drought conditions.

Methods: A comprehensive literature search was conducted in three electronic databases including PubMed, Scopus, and Web of Science using the search terms "regulatory mechanism", "secondary metabolites", "medicinal plants", "drought stress", "transcription factor", "bioactive compound", "synthetic biology", "smart irrigation", "terpenoid biosynthesis", "phenylpropanoid biosynthesis", "phenolic biosynthesis" and "alkaloid biosynthesis". All the retrieved data were then critically reviewed and summarized.

Results: Drought affects secondary metabolite biosynthesis via a complex molecular regulatory network, including shifts in microbial community composition, epigenetic remodeling, changes in global gene expression profiles, altered catalytic activity of core biosynthetic enzymes, as well as modifications of transcription factors.

Conclusion: This review offers novel insights into unraveling the underlying transcriptional regulatory networks, and practical implications for researchers in the fields of medicinal plant biology, natural product chemistry, and crop stress physiology.

Keywords: Bioactive compound; Drought stress; Medicinal plants; Regulatory mechanism; Secondary metabolites; Transcription factor.