Morphological Structures as Determinants of Secondary Metabolite Biosynthesis and Localization in Medicinal Plants: A Comprehensive Review
Ismail M. A. M. Shahhat1,2 *
Australian Herbal Insight 8(1) 1-8 https://doi.org/10.25163/ahi.8110232
Submitted: 06 January 2025 Revised: 13 March 2025 Published: 16 March 2025
Abstract
Secondary metabolites—such as alkaloids, terpenoids, flavonoids, and phenolic compounds—play critical ecological and pharmaceutical roles in medicinal plants. Their biosynthesis and accumulation are not random but are closely associated with specific morphological and anatomical structures, including glandular trichomes, laticifers, idioblasts, secretory ducts, and oil cells. These specialized tissues serve as both biosynthetic and storage sites, reflecting a profound integration between plant form and metabolic function. The primary aim of this review is to systematically explore how plant morphological structures regulate the localization, biosynthesis, and ecological function of secondary metabolites across different organs and environmental conditions. This review also examines how developmental stages, environmental cues (light, water stress, herbivory), and hormonal signaling modulate the formation of these structures and, in turn, affect metabolite output. To achieve this, we critically analyzed and synthesized findings from over 150 peer-reviewed articles published between 1990 and 2023, encompassing multiple disciplines including plant anatomy, phytochemistry, molecular biology, and biotechnology. Special attention is given to case studies in key medicinal species such as Artemisia annua, Mentha × piperita, Catharanthus roseus, Papaver somniferum, and Hypericum perforatum. Additionally, this review highlights biotechnological and breeding strategies aimed at enhancing secondary metabolite yields through manipulation of structural traits—ranging from classical selection to CRISPR/Cas-mediated genome editing and elicitor-induced tissue culture systems. By integrating structural biology with metabolomic insights, this review provides a comprehensive framework for understanding and engineering morphology-based phytochemical enhancement in medicinal plants.
Keywords: Medicinal plants, Environmental modulation, Metabolite localization, Morpho-metabolic integration, Glandular trichomes
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